Tracking down the asteroid that sealed the fate of the dinosaurs

Geoscientists from the University of Cologne have led an international study to determine the origin of the huge piece of rock that hit the Earth around 66 million years ago and permanently changed the climate. The scientists analysed samples of the rock layer that marks the boundary between the Cretaceous and Paleogene periods. This period also saw the last major mass extinction event on Earth, in which around 70 percent of all animal species became extinct. The results of the study published in Science indicate that the asteroid formed outside Jupiter's orbit during the early development of our solar system.

According to a widely accepted theory, the mass extinction at the Cretaceous-Paleogene boundary was triggered by the impact of an asteroid at least 10 kilometres in diameter near Chicxulub on the Yucatán Peninsula in Mexico.

On impact, the asteroid and large quantities of earth rock vaporized.

Fine dust particles spread into the stratosphere and obscured the sun.

This led to dramatic changes in the living conditions on the planet and brought photosynthetic activity to a halt for several years.

The dust particles released by the impact formed a layer of sediment around the entire globe.

This is why the Cretaceous-Paleogene boundary can be identified and sampled in many places on Earth.

It contains high concentrations of platinum-group metals, which come from the asteroid and are otherwise extremely rare in the rock that forms the Earth's crust.

By analysing the isotopic composition of the platinum metal ruthenium in the cleanroom laboratory of the University of Cologne's Institute of Geology and Mineralogy, the scientists discovered that the asteroid originally came from the outer solar system.

"The asteroid's composition is consistent with that of carbonaceous asteroids that formed outside of Jupiter's orbit during the formation of the solar system," said Dr Mario Fischer-Gödde, first author of the study.

The ruthenium isotope compositions were also determined for other craters and impact structures of different ages on Earth for comparison. This data shows that within the last 500 million years, almost exclusively fragments of S-type asteroids have hit the Earth. In contrast to the impact at the Cretaceous-Paleogene boundary, these asteroids originate from the inner solar system. Well over 80 percent of all asteroid fragments that hit the Earth in the form of meteorites come from the inner solar system. Professor Dr Carsten Münker, co-author of the study, added: "We found that the impact of an asteroid like the one at Chicxulub is a very rare and unique event in geological time. The fate of the dinosaurs and many other species was sealed by this projectile from the outer reaches of the solar system."

Read more at Science Daily

Agriculture: Less productive yet more stable pastures

Climate change will have a considerable influence on the biodiversity and productivity of meadows and pastures. However, according to the results of the large-scale climate and land use experiment, GCEF, which has been conducted at the Helmholtz Centre for Environmental Research (UFZ) for 10 years, the extent of these changes depends on the land use. Grassland optimised for high yield responds much more sensitively to periods of drought than less intensively used meadows and pastures. According to an article recently published in Global Change Biology, this can certainly have economic consequences for the farmers affected.

Grassland is one of the most important and most widespread ecosystems on earth. Such open landscapes with grasses and herbs not only cover more than one quarter of the entire land surface but also store at least one third of the terrestrial carbon, are crucial for food production, and can be extremely species-rich in a relatively small area. But what is the future of these habitats? The study provides new insights into this question.

It has long been clear that two environmental changes are threatening the world's grasslands. Particularly in Europe, grasslands are now fertilised much more heavily, mowed more frequently, and grazed more intensively. In addition, farmers often sow only a handful of grass varieties that promise a particularly high yield. This intensification of land use is fundamentally changing the species composition and functionality of meadows and pastures. The same applies to climate change. For Germany, climate change will result in a shift in the seasonal distribution of precipitation as well as an increase in hydrological extremes (e.g. heavy rainfall and droughts), among other things. It is considered the second largest threat for these ecosystems.

When both changes come together, they can reinforce each other. However, nobody yet knows exactly what will happen. Most experiments on this topic have so far focussed on either the climate or land use. "What makes our study unique is that we investigated the interaction of both factors," explains Dr Lotte Korell, biologist at the UFZ and first author of the publication.

This was made possible by the large-scale and long-term experiment of the UFZ in Bad Lauchstädt near Halle, the Global Change Experimental Facility (GCEF). It consists of 50 plots, each measuring 16 × 24 m; these are used with varying degrees of land use intensity. Temperatures and precipitation levels can also be manipulated with the help of mobile roof systems. For example, some plots receive 10% more precipitation in spring and autumn and 20% less in summer than the untreated control plots. This roughly corresponds to the conditions that climate models project for central Germany.

An eight-year data series from this experiment has now been compiled for the new study. The researchers analysed the biodiversity and productivity of the plants on the differently used plots between 2015 and 2022. "This period includes three of the driest years this region has experienced since beginning of records," recalls Korell. These droughts apparently had a much stronger effect on the plants than the experimentally simulated climate change.

However, in both cases, the trend pointed in the same direction: species-rich grassland that is only rarely mown or sparsely grazed withstood the heat and drought much better than the intensively used high-performance meadows. "Among other factors, this is probably related to the diversity of species," says Korell. This varied greatly depending on the land use of the grasslands.

A diverse mixture of more than 50 native grasses and herbs grew on the less intensively used meadows and pastures of the GCEF. However, on the intensively used grassland, the UFZ team had sown only the five grass varieties recommended to farmers by the Saxony-Anhalt State Institute for Agriculture and Horticulture for drier sites at the start of the experiment. These included varieties of meadow grass (Dactylis glomerata) and perennial ryegrass (Lolium perenne).

Because such grasses are bred for maximum yield and were also heavily fertilised -- as is common in agricultural practice -- the intensive meadows were initially much more productive than the more diverse grasslands. However, they were able to make use of this advantage only in favourable climatic conditions and were not able to withstand the drought as well as the plants in the low-intensity meadows and pastures. In times of drought, the grasses in the intensively used meadows increasingly died back and were replaced by other species such as chickweed (Stellaria media), shepherd's purse (Capsella bursa-pastoris), dandelion (Taraxacum officinale), and small-flowered cranesbill (Geranium pusillum). "These are mostly short-lived species that survive as seeds," explains Dr Harald Auge, also a biologist at the UFZ and senior author of the study. When the more competitive plants succumb to drought, these species take the opportunity to invade their habitats: they either migrate from the low-intensity grassland or germinate from the seed stock in the soil.

This shift in species composition is not particularly welcomed by farmers, especially because most of the new arrivals have a lower fodder quality than the grasses originally sown. The common ragwort (Senecio vulgaris), which was frequently represented among the immigrating species in the experiment, is in fact poisonous. All of this reduces the productivity of the land.

Farmers have long been aware of this kind of degradation of high-performance grassland by immigrating species. They therefore expect to have to plough up and reseed their land every few years. "However, climate change may accelerate this need and lead to additional costs," says Korell. Perhaps everything will go well for a few years and it will rain enough. However, it is also possible that several dry summers will follow one another. Climate change is making conditions even more unpredictable.

Read more at Science Daily

Ice age climate analysis reduces worst-case warming expected from rising CO2

As carbon dioxide accumulates in the atmosphere, the Earth will get hotter. But exactly how much warming will result from a certain increase in CO2 is under study. The relationship between CO2 and warming, known as climate sensitivity, determines what future we should expect as CO2 levels continue to climb.

New research led by the University of Washington analyzes the most recent ice age, when a large swath of North America was covered in ice, to better understand the relationship between CO2 and global temperature. It finds that while most future warming estimates remain unchanged, the absolute worst-case scenario is unlikely.

The open-access study was published April 17 in Science Advances.

"The main contribution from our study is narrowing the estimate of climate sensitivity, improving our ability to make future warming projections," said lead author Vince Cooper, a UW doctoral student in atmospheric sciences. "By looking at how much colder Earth was in the ancient past with lower levels of greenhouse gases, we can estimate how much warmer the current climate will get with higher levels of greenhouse gases."

The new paper doesn't change the best-case warming scenario from doubling CO2 -- about 2 degrees Celsius average temperature increase worldwide -- or the most likely estimate, which is about 3 degrees Celsius. But it reduces the worst-case scenario for doubling of CO2 by a full degree, from 5 degrees Celsius to 4 degrees Celsius. (For reference, CO2 is currently at 425 ppm, or about 1.5 times preindustrial levels, and unless emissions drop is headed toward double preindustrial levels before the end of this century.)

As our planet heads toward a doubling of CO2, the authors caution that the recent decades are not a good predictor of the future under global warming. Shorter-term climate cycles and atmospheric pollution's effects are just some reasons that recent trends can't reliably predict the rest of this century.

"The spatial pattern of global warming in the most recent 40 years doesn't look like the long-term pattern we expect in the future -- the recent past is a bad analog for future global warming," said senior author Kyle Armour, a UW associate professor of atmospheric sciences and of oceanography.

Instead, the new study focused on a period 21,000 years ago, known as the Last Glacial Maximum, when Earth was on average 6 degrees Celsius cooler than today. Ice core records show that atmospheric CO2 then was less than half of today's levels, at about 190 parts per million.

"The paleoclimate record includes long periods that were on average much warmer or colder than the current climate, and we know that there were big climate forcings from ice sheets and greenhouse gases during those periods," Cooper said. "If we know roughly what the past temperature changes were and what caused them, then we know what to expect in the future."

Researchers including co-author Gregory Hakim, a UW professor of atmospheric sciences, have created new statistical modeling techniques that allow paleoclimate records to be assimilated into computer models of Earth's climate, similar to today's weather forecasting models. The result is more realistic temperature maps from previous millennia.

For the new study the authors combined prehistoric climate records -- including ocean sediments, ice cores, and preserved pollen -- with computer models of Earth's climate to simulate the weather of the Last Glacial Maximum. When much of North America was covered with ice, the ice sheet didn't just cool the planet by reflecting summer sunlight off the continents, as previous studies had considered.

By altering wind patterns and ocean currents, the ice sheet also caused the northern Pacific and Atlantic oceans to become especially cold and cloudy. Analysis in the new study shows that these cloud changes over the oceans compounded the glacier's global cooling effects by reflecting even more sunlight.

In short, the study shows that CO2 played a smaller role in setting ice age temperatures than previously estimated. The flipside is that the most dire predictions for warming from rising CO2 are less likely over coming decades.

"This paper allows us to produce more confident predictions because it really brings down the upper end of future warming, and says that the most extreme scenario is less likely," Armour said. "It doesn't really change the lower end, or the average estimate, which remain consistent with all the other lines of evidence."

Read more at Science Daily

Alaska dinosaur tracks reveal a lush, wet environment

A large find of dinosaur tracks and fossilized plants and tree stumps in far northwestern Alaska provides new information about the climate and movement of animals near the time when they began traveling between the Asian and North American continents roughly 100 million years ago.

The findings by an international team of scientists led by paleontologist Anthony Fiorillo were published Jan. 30 in the journal Geosciences. Fiorillo researched in Alaska while at Southern Methodist University. He is now executive director of the New Mexico Museum of Natural History and Science.

University of Alaska Fairbanks geology professor Paul McCarthy, with the UAF Geophysical Institute and UAF College of Natural Science and Mathematics, was a leading contributor to the research. He and UAF graduate student Eric Orphys are among the eight co-authors.

Fiorillo and McCarthy are longtime collaborators.

"We've had projects for the last 20 years in Alaska trying to integrate sedimentology, dinosaur paleontology and the paleoclimate indicators," McCarthy said. "We've done work in three other formations -- in Denali, on the North Slope and in Southwest Alaska -- and they're about 70 million years old."

"This new one is in a formation that's about 90 to 100 million years old," he said.

Fiorillo said the additional age is notable.

"What interested us about looking at rocks of this age is this is roughly the time that people think of as the beginning of the Bering Land Bridge -- the connection between Asia and North America," he said. "We want to know who was using it, how they were using it and what the conditions were like."

Research into the paleoclimate can help scientists understand the warming world of today, the authors write.

"The mid-Cretaceous was the hottest point in the Cretaceous," said McCarthy, a sedimentologist and fossil soils specialist. "The Nanushuk Formation gives us a snapshot of what a high-latitude ecosystem looks like on a warmer Earth."

A rich find of evidence

The Nanushuk Formation is an outcropped layer of sedimentary rock 800 to 5,000 feet thick across the central and western North Slope. It dates to roughly 94 million to 113 million years ago in the mid-Cretaceous Period and about when the Bering Land Bridge began.

The fieldwork occurred in 2015-2017 and centered on Coke Basin, a circular geologic feature of the Nanushuk Formation. The basin is in the DeLong Mountains foothills along the Kukpowruk River, about 60 miles south of Point Lay and 20 miles inland from the Chukchi Sea.

In the area, Fiorillo and McCarthy found approximately 75 fossil tracks and other indicators attributed to dinosaurs living in a riverine or delta setting.

"This place was just crazy rich with dinosaur footprints," Fiorillo said.

One site stands out, Fiorillo said.

"We were at a spot where we eventually realized that for at least 400 yards we were walking on an ancient landscape," he said. "On that landscape we found large upright trees with little trees in between and leaves on the ground. We had tracks on the ground and fossilized feces."

They found numerous fossilized tree stumps, some 2 feet in diameter.

"It was just like we were walking through the woods of millions of years ago," he said.

The Nanushuk Formation encompasses rock of marine and non-marine characteristics and composition, but the authors' research focuses primarily on the non-marine sediments exposed along the upper Kukpowruk River.

"One of the things we did in our paper was look at the relative frequencies of the different kinds of dinosaurs," Fiorillo said. "What was interesting to us was that the bipedal plant eaters were clearly the most abundant."

Two-legged plant eaters accounted for 59% of the total tracks discovered. Four-legged plant eaters accounted for 17%, with birds accounting for 15% and non-avian, mostly carnivorous, bipedal dinosaurs at 9%.

"One of the things that was interesting is the relative frequency of bird tracks," Fiorillo said.

The authors point out that nearly half of North America's shorebirds breed in the warm months of today's Arctic. They suggest that the high number of fossil bird tracks along the Kukpowruk River indicates the warm paleoclimate was a similar driver for Cretaceous Period birds.

A wet and warm place

Carbon isotope analysis of wood samples led to a determination that the region received about 70 inches of precipitation annually. This record of increased precipitation during the mid-Cretaceous provides new data that supports global precipitation patterns associated with the Cretaceous Thermal Maximum, the authors write.

The Cretaceous Thermal Maximum was a long-term trend approximately 90 million years ago in which average global temperatures were significantly higher than those of today.

"The temperature was much warmer than it is today, and what's possibly more interesting is that it rained a lot," Fiorillo said. "The samples we analyzed indicate it was roughly equivalent to modern-day Miami. That's pretty substantial."

Of note is that the Alaska site investigated by Fiorillo and McCarthy was about 10 to 15 degrees latitude farther north in the mid-Cretaceous than it is today.

McCarthy's role as a fossil soils expert was to analyze old rocks and sediments to interpret the type of environment that existed at the time.

"We can say here's a river channel, here's a flood deposit, here's a levee, here's the floodplain, here's a swamp," he said. "And so if we're able to find tracks in that section, then you can sometimes say that a group of dinosaurs seems to have really liked being here as opposed to there."

Fiorillo said the site indicates there's much more work to be done.

Read more at Science Daily

In a warming world, climate scientists consider category 6 hurricanes

For more than 50 years, the National Hurricane Center has used the Saffir-Simpson Windscale to communicate the risk of property damage; it labels a hurricane on a scale from Category 1 (wind speeds between 74 -- 95 mph) to Category 5 (wind speeds of 158 mph or greater).

But as increasing ocean temperatures contribute to ever more intense and destructive hurricanes, climate scientists Michael Wehner of Lawrence Berkeley National Laboratory (Berkeley Lab) and James Kossin of the First Street Foundation wondered whether the open-ended Category 5 is sufficient to communicate the risk of hurricane damage in a warming climate.

So they investigated and detailed their extensive research in a new article published in the Proceedings of the National Academy of Sciences (PNAS), where they also introduce a hypothetical Category 6 to the Saffir-Simpson Wind Scale, which would encompass storms with wind speeds greater than 192 mph.

"Our motivation is to reconsider how the open-endedness of the Saffir-Simpson Scale can lead to underestimation of risk, and, in particular, how this underestimation becomes increasingly problematic in a warming world," said Wehner, who has spent his career studying the behavior of extreme weather events in a changing climate and to what extent human influence has contributed to individual events.

According to Wehner, anthropogenic global warming has significantly increased surface ocean and tropospheric air temperatures in regions where hurricanes, tropical cyclones, and typhoons form and propagate, providing additional heat energy for storm intensification.

When the team performed a historical data analysis of hurricanes from 1980 to 2021, they found five storms that would have been classified as Category 6, and all of them occurred in the last nine years of record.

They determined a hypothetical upper bound for Category 5 hurricanes by looking at the expanding range of wind speeds between the lower-category storms.

Hurricanes, tropical storms, and typhoons are essentially the same weather phenomenon; their name difference is purely geographical: storms in the North Atlantic and Northeast Pacific Oceans are called hurricanes, events in the Northwest Pacific Ocean are called typhoons, and occurrences in the South Pacific and Indian Oceans are called tropical cyclones.

In addition to studying the past, the researchers analyzed simulations to explore how warming climates would impact hurricane intensification.

Their models showed that with two degrees Celsius of global warming above pre-industrial levels, the risk of Category 6 storms increases by up to 50% near the Philippines and doubles in the Gulf of Mexico and that the highest risk of these storms is in Southeast Asia, the Philippines, and the Gulf of Mexico.

"Even under the relatively low global warming targets of the Paris Agreement, which seeks to limit global warming to just 1.5°C above preindustrial temperatures by the end of this century, the increased chances of Category 6 storms are substantial in these simulations," said Wehner.

Read more at Science Daily

Unprecedented ocean heating shows risks of a world 3°C warmer

Record-high ocean temperatures observed in 2023 could become the norm if the world moved into a climate that is 3.0°C warmer than pre-industrial levels, according to a new study.

From March 2023, the North Atlantic began to show extremely warm temperatures far exceeding anything seen in the past 40 years.

As of August 2023, the North Atlantic was about 1.4°C warmer than the 1982-2011 average.

Analysis of climate model projections showed that last year's extreme ocean conditions were similar to what scientists expect to be the average if global warming reaches 3°C of warming.

Currently, global temperatures have risen by about 1.2°C above pre-industrial levels.

New research, published this month in the Bulletin of the American Meteorological Society, examines the causes of the record-breaking ocean temperatures witnessed in 2023.

Dr Till Kuhlbrodt, of the University of Reading, led the study.

He said: "The extraordinary heat in the North Atlantic and missing sea ice in the Southern Ocean in 2023 tell us the oceans are sounding an alarm. We urgently need to understand exactly why parts of the ocean are warming rapidly so we can prepare for more frequent weather disruption across the planet. How often we get hit by more of these extremes hangs on figuring out what's driving the Atlantic and Southern Oceans into uncharted territory."

Climate connection?

The study highlights that Earth's energy imbalance is likely a key driver of extreme ocean temperatures, as the planet is currently absorbing more than 1.9 watts per square meter more solar energy than it radiates back to space as heat.

Across Earth, over a time span of one year, this is equivalent to roughly 300 times the global annual consumption of electric energy.

This imbalance has grown fast over recent decades mainly due to heat-trapping gases from human activity.

This increasing energy surplus is propelling ocean warming, with more than 90% of the excess energy accumulated by Earth being funnelled into the oceans.

Since 2016 the Atlantic Ocean has warmed faster than other ocean basins in the top 100 meters of ocean.

This enhanced Atlantic warming may be linked to record low levels of sea ice in the Southern Ocean, the researchers suggest.

The rapid Atlantic warming has coincided with a sharp decline in sea ice cover surrounding Antarctica.

In 2023, Antarctic winter sea ice extent reached by far the lowest levels since satellite monitoring began in the late 1970s.

The researchers emphasise the need to quantify how much the rapid Atlantic warming is impacting sea ice cover.

Reliably attributing the oceanic and sea ice extremes will ensure climate models can accurately predict future extremes, which will inform mitigation policies and resilience measures across the globe.

Read more at Science Daily

New research explores future limits of survival and livability in extreme heat conditions

Commonly associated with longer days and slower paces, this summer's record-smashing heat in Arizona demonstrated a concerning future for the planet's warmest season. From power outages endangering entire neighborhoods and heat-related deaths rising among some of the state's most vulnerable populations, the city of Phoenix found itself in national headlines. As national attention grew, one question became clear: How does anyone live there?

The consequences of extreme heat do not affect Arizona residents alone.

Extreme heat made worldwide news this year, including in November when a 23-year-old woman died of cardiorespiratory arrest at a Taylor Swift concert in Brazil where heat indexes that day exceeded 120 degrees.

Jennifer Vanos, associate professor in the School of Sustainability at Arizona State University, studies extreme heat and its health impacts.

She is the lead author of a new paper published Nov. 29 in Nature Communications. Titled "A physiological approach for assessing human survivability and liveability to heat in a changing climate," the paper explores temperatures at which humans can survive.

The research demonstrates that the current estimated upper temperature and humidity limits used for human survivability may not paint an accurate picture of the impacts of a warming planet on human health.

"For the past decade or so we have been using what we call a 'wet bulb temperature' of 35 degrees Celsius, or 95 degrees Fahrenheit, as the limit for human survivability," said Vanos, also a Senior Global Futures Scientist in the Julie Ann Wrigley Global Futures Laboratory.

The wet-bulb temperature limit for human survival indicates the maximum combinations of temperature and humidity that humans can tolerate without suffering inevitable heat stroke over a fixed duration of exposure.

"The idea is that you could survive for up to six hours at that level of heat exposure," Vanos said.

"That number really oversimplifies what happens physiologically in the body when your body is exposed to that temperature, and it doesn't account for important variables like age or other vulnerability factors."

Vanos said the commonly-used wet-bulb temperature for human survivability assumes the person is indoors or shaded, unclothed, completely sedentary, fully heat acclimatized and of an "average size." These assumptions do not align, in most cases, with how humanity navigates the summer season.

The paper models scenarios that adjust for factors such as humidity, age, activity level and sun exposure, and provides a range of safe temperatures based on a series of characteristics.

"We didn't only want to better understand the conditions that people could survive in," Vanos said.

"We wanted to understand the conditions that allowed people to live their lives. If the only safe way to live in an area is to be completely sedentary, people won't want to live there. Being able to spend time outdoors and live your life without seeing a sustained rise in core temperature is a really important metric to understand today and as we move into the future."

Vanos said Gisel Guzman Echavarria, an ASU student, was instrumental in creating the figures used throughout the paper to demonstrate the research findings.

The research, funded by the National Science Foundation, was conducted by a combination of climate scientists and physiologists, a collaboration that Vanos said was crucial in understanding the intertwined nature of heat and human health.

Ollie Jay, professor and director of the Heat and Health Research Incubator at the University of Sydney, said the combined perspectives allow for a cohesive understanding of exactly how climate outcomes can impact people on the physiological and biophysical level.

"The existing wet-bulb temperature estimate of 35 degrees Celsius is used very commonly, with one example being the Intergovernmental Panel on Climate Change report," said Jay, senior author of the paper.

"These kinds of reports can shape policy efforts, but they are using a model for heat that is a very conservative estimate of what the impacts are going to be on humans. If we start using a more realistic, human-based model, the impacts are going to be more severe. They're going to be more widespread and they're going to happen sooner than we are projecting."

Vanos and Jay agree that the survivability ranges provided in the paper can give an important glimpse into the future: one that includes an increased need for cooling infrastructure, a personalized approach to heat protection and possible heat-driven migration.

Read more at Science Daily

Climate: Why disinformation is so persistent

Melting of glaciers, rising sea levels, extreme heat waves: the consequences of climate change are more visible than ever, and the scientific community has confirmed that humans are responsible. Yet studies show that a third of the population still doubts or disputes these facts. The cause is disinformation spread by certain vested interests. To try and prevent this phenomenon, a team from the University of Geneva (UNIGE) has developed and tested six psychological interventions on nearly 7,000 participants from twelve countries. The research, published in the journal Nature Human Behavior, highlights the extremely persuasive nature of disinformation and the need to strengthen our efforts to combat it.

Fighting disinformation about climate change is a major challenge for society.

Although scientific consensus on human responsibility -- reaffirmed by the sixth report of the Intergovernmental Panel on Climate Change (IPCC) -- has been in place for decades, a third of the population still doubts or disputes it. This phenomenon can be explained by the disinformation spread by certain companies and lobbies over the last 50 years.

''For instance, these messages can take the form of an unfounded questioning of the scientific consensus or an overestimation of the socio-financial burden of climate policies,'' explains Tobia Spampatti, a PhD Student and Teaching and Research Assistant in the Consumer Decision and Sustainable Behavior Lab (CDSB Lab) at the Faculty of Psychology and Educational Sciences and at the Swiss Center for Affective Sciences of the UNIGE.

Many psychological factors

This phenomenon weakens the support of a part of the population for climate policies.

To combat this, Tobia Spampatti and researchers from the UNIGE developed a theoretical framework to describe the formation and updating of (anti)scientific information.

This framework, built on previous theoretical takes on the psychology of misinformation (Philippe Mueller et al. and Ulrich Ecker et al. in 2022), takes into account the source of the message, its content, its recipients, and the psychological factors that can influence their processing.

This theoretical framework aims to identify the entry points for disinformation to access a person's ''psyche'', and can be used to intervene and block, or encourage, people to accept information.

''As individuals, we do not process scientific messages as neutral receivers of information, but by weighing them up against our prior beliefs, desired outcomes, emotional ties and socio-cultural and ideological backgrounds.

Depending on the configuration of these psychological factors, anti-scientific beliefs can be amplified and become resistant to correction,'' explains Tobia Spampatti, first author of the study.

Six preventive strategies put to the test

On this basis, the researchers developed six psychological intervention strategies aimed at preventing climate disinformation from affecting people's climate-related beliefs and behaviors.

They were tested on 6,816 participants in twelve different countries.

Each strategy was linked to a particular theme (scientific consensus, trust in climate scientists, transparent communication, moralizing climate action, accuracy, positive emotions towards climate action). The participants were divided into eight groups: six subjected to one of these strategies, one to disinformation without prevention, and a control group.

The ''trust in climate scientists'' group, for example, received verified information demonstrating the credibility of IPCC scientists.

The "transparent communication" group, meanwhile, was presented with information on both the advantages and the disadvantages of climate mitigation actions.

Each group was then exposed to twenty pieces of false or biased information, ten on climate science and ten on climate policy.

The UNIGE scientists then measured their impact after these preventive interventions by asking the participants about their feelings regarding climate mitigation actions.

Low preventive effect

''We found that the protective effect of our strategies is small and disappears after the second exposure to disinformation.

Climate disinformation used in this study has a negative influence on people's belief in climate change and their sustainable behaviour'', says Tobias Brosch, Associate Professor in the CDSB Lab at the Faculty of Psychology and Educational Sciences and at the Swiss Center for Affective Sciences in the UNIGE, and final author of the study.

''Disinformation is therefore extremely persuasive, seemingly more so than scientific information.

Only the 'accuracy' group, who were asked to think in depth about the accuracy of the information they encountered online, showed a slight advantage''.

Read more at Science Daily

Commitments needed to solve aviation's impact on our climate

Concerted efforts and commitments are needed to solve the complex trade-offs involved in reducing the impact of aviation on the climate, according to new research.

Non-CO2 emissions from aircraft -- largely of nitrogen oxides, soot and water vapour -- are known to add to global warming effects alongside the aviation sector's other CO2 emissions.

Soot triggers the formation of contrails and 'contrail cirrus', which are line-shaped clouds produced by aircraft engine exhaust.

This causes an increase in high clouds that can warm the Earth's atmosphere.

In a comprehensive assessment of the potential solutions to limit the non-CO2 emissions produced by aircraft, scientists warn there is 'no silver bullet' and a committed and co-ordinated effort from a range of stakeholders is urgently required.

The research, published today (November 28) in the Royal Society for Chemistry's journal Environmental Science: Atmospheres, outlines aviation's non-CO2 effects on the atmosphere, both in terms of climate and air quality, and how these may change in the future, as well as the effects of future technologies and fuels.

The findings are the result of a two-year study by Manchester Metropolitan University, the University of Oxford, the University of Reading and Imperial College London.

David Lee, Professor in Atmospheric Science at Manchester Metropolitan, said: "What we highlight is the inherent uncertainties that remain in some of these very complex effects on climate from non-CO2 emissions.

"More importantly, reducing the impact of emissions on the climate is not straightforward as practically all routes forward with conventional liquid hydrocarbon fuels involve 'trade-offs', mostly at the expense of emitting more CO2, whether it be technological or operational efforts.

"These trade-offs and uncertainties mean that there are no simple silver bullets or low-hanging fruit to solve the problem. What is often forgotten is, that while the non-CO2 climate impacts of, for example, an individual flight are short lived, a substantial proportion of the emitted CO2 persists for a very long time, literally tens of millennia. This means it is a difficult balancing act if reducing non-CO2 emissions leads to an increase in CO2 emissions."

Professor Keith Shine, Regius Professor of Meteorology and Climate Science at the University of Reading, is an author of the new paper.

He said: "Given the many uncertainties in the size of aviation non-CO2 climate effects, it is premature to adopt any strategy that aims to decrease non-CO2 climate effects but, at the same time, risks increasing CO2 emissions. We must be mindful that aviation affects local air quality as well as climate. Sometimes measures that improve one will be to the detriment of the other."

Aviation is responsible for around 2.5% of the global CO2 emissions caused by human activity.

However, due to the amount non-CO2 emissions it produces, it is responsible for around 3.5% of change in the energy balance of the atmosphere -- known as radiative forcing -- or around 4% of the increase in global mean temperatures.

The sector is difficult to decarbonise because of its strong dependence on fossil kerosene -- jet fuel -- and the long timescales involved in developing new aircraft and replacing older fleets.

Given the aviation sector's strong growth after the COVID-19 pandemic, this contribution to climate change is set to increase, when other sectors are battling to reduce emissions.

In the latest assessment researchers argue for more work to be performed on the complex trade-offs in order to urgently search for solutions.

This difficulty has recently been recognised by the UK government which, through the Natural Environment Research Council (NERC), has announced a £10 million research programme to help inform policy decisions in this area.

Read more at Science Daily

'Not dead yet': Experts identify interventions that could rescue 1.5°C

To meet the goals of the Paris Agreement and limit global heating to 1.5°C, global annual emissions will need to drop radically over the coming decades. Today [22 Nov], a new paper from climate economists at the University of Oxford says that this goal could still be within our reach. They identify key "sensitive intervention points" that could unlock significant progress towards the Paris Agreement with the least risk and highest impact. These include:

• Investing in clean energy technologies with consistent cost declines
• Enacting central bank policies to reduce the value of polluting assets
• Improving climate-related financial risk disclosure.

'This is not to suggest that reaching the Paris goals will be straightforward, or easy, but like Achilles' heel, our research points to the areas that could have an outsized impact,' says lead author Dr Penny Mealy, associate at the Institute for New Economic Thinking, University of Oxford.

'We need climate policies which are pragmatic and practical, designed with an understanding of where the economy and technologies are capable of quickly transforming our economies for the better.

These are those policy areas. This is how we design policy for 1.5°C,' affirms co-author Dr Pete Barbrook-Johnson of the Smith School of Enterprise and the Environment.

The research also highlights the areas where interventions will be more difficult and less impactful, including nuclear fission, which would be slow to roll out and could have unintended consequences; and carbon capture and storage, which presents both high barriers and risks.

To reach their conclusions, the authors devised a new framework for identifying sensitive intervention points, or SIPs, that have the characteristics necessary to radically decarbonize our global economy.

SIPs include critical tipping points -- like renewable energy becoming cheaper than coal; critical points in networks -- like powerful political figures or important technologies, and critical points in time or "windows of opportunity" that might prime the existing systems for change, such as the Covid-19 pandemic.

These intervention points must be assessed by the ease with which they can be implemented, their impact potential, and the potential for creating risks.

The authors stress that, while the framework is highly applicable to climate change, it could also be applied to solving other economic and social problems.

The ratings provided for each SIP intervention were applied subjectively based on discussions with experts, literature research, and modelling.

The framework can and should be applied regularly to reassess priorities as new data and insights become available, the authors say.

Read more at Science Daily

Diverse forests hold huge carbon potential, as long as we cut emissions

Research results published in the journal, Nature, show that realistic global forest carbon potential is approximately 226 Gigatonnes (Gt) of carbon. The study, which involved hundreds of scientists around the world, highlights the critical importance of forest conservation, restoration, and sustainable management in moving towards international climate and biodiversity targets. The researchers stress that this potential can be achieved by incentivizing community-driven efforts to promote biodiversity.

The forest carbon potential has been a highly controversial topic. Four years ago, a study published in the journal Science found that the restoration of forests could capture over 200 Gt of carbon -- which could draw down approximately 30 percent of excess anthropogenic carbon. While this study elevated a discussion about the role of nature in fighting climate change, it also raised concerns around the adverse environmental impacts of mass tree plantations, carbon offsetting schemes, and greenwashing. While some scientific studies have supported the scale of this finding, others argued that this forest carbon estimate could be up to 4 or 5 times too high.

To address this controversial topic an international team of hundreds of researchers led by the Crowther Lab at ETH Zurich joined forces to build an integrated assessment using a comprehensive range of approaches, including vast ground-sourced data and satellite datasets.

Achieving forest carbon potential

Due to ongoing deforestation, the total amount of carbon stored in forests is ~328 Gt below its natural state. Of course, much of this land is used for extensive human development including urban and agricultural land. However, outside of those areas, researchers found that forests could capture approximately 226 Gt C in regions with a low human footprint if they were allowed to recover. Approximately 61 percent of this potential can be achieved by protecting existing forests, so that they can recover to maturity. The remaining 39 percent can be achieved by reconnecting fragmented forest landscapes through sustainable ecosystem management and restoration.

"Most of the world's forests are highly degraded. In fact, many people have never been in one of the few old growth forests that remain on Earth," said Lidong Mo, a lead author of the study. "To restore global biodiversity, ending deforestation must be a top priority."

The dataset revealed that biodiversity accounts for approximately half of the global forest productivity. As such, the researchers highlighted that, to achieve the full carbon potential, restoration efforts should include a natural diversity of species. In addition, sustainable agricultural, forestry, and restoration practices that promote biodiversity have the greatest potential for carbon capture.

Redefining restoration

The authors stress that responsible restoration is a fundamentally social endeavour. It includes countless actions such as conservation, natural regeneration, rewilding, silviculture, agroforestry, and all other community-driven efforts to promote biodiversity. It requires equitable development, driven by policies that prioritize the rights of local communities and Indigenous people.

"We need to redefine what restoration means to many people," said Thomas Crowther, the senior author of the paper and a professor at ETH Zurich. "Restoration is not about mass tree plantations to offset carbon emissions. Restoration means directing the flow of wealth towards millions of local communities, Indigenous populations, and farmers that promote biodiversity across the globe. Only when healthy biodiversity is the preferred choice for local communities will we get long-term carbon capture as a biproduct."

The researchers conclude that ecologically responsible forest restoration does not include the conversion of other ecosystems that would not naturally contain forests. "Global restoration is not only about trees," said Constantin Zohner, a senior researcher at ETH Zurich. "We have to protect natural biodiversity in all ecosystems including grasslands, peatlands, and wetlands that are equally essential for life on Earth."

Nature for climate

This study brings to light the critical importance of natural, diverse forests in contributing to 30 percent of carbon drawdown potential. However, forests cannot be a substitute for cutting fossil fuel emissions. If emissions continue to rise, the study warns, then on-going droughts, fires, and warming will threaten forests and limit their ability to absorb carbon.

Read more at Science Daily

Southern Alaska's national forests key to meeting climate, conservation goals

Analyses of U.S. national forests led by Oregon State University scientists shows that increased protections for two Alaskan forests is a key to meeting climate and biodiversity goals.

In a paper published in AGU Advances, OSU College of Forestry researchers make the case that greater conservation efforts in the Tongass and Chugach national forests in southern Alaska are crucial because of their landscape integrity, high carbon stocks and wildlife habitat extent.

"More thoroughly safeguarding those forests from industrial development would contribute significantly to climate change mitigation and species adaptation in the face of the severe ecological disruption that's expected to occur over the next few decades as the climate rapidly gets warmer," said Oregon State's Bev Law, who co-led the study.

At 16.7 million acres, the Tongass is America's largest national forest. The Chugach is the second-largest at just under 7 million acres.

Not only are they the biggest national forests, they are the most intact, Law said, and provide habitat for iconic, keystone species such as the bald eagle, brown bear and gray wolf.

"Those forests are also cool and wet, with carbon stocks that are only minimally affected by wildfire, stocks that are likely to increase as the climate changes," she said. "Protecting the Tongass and Chugach is a high priority if we want to have a chance to attain global goals relating to climate and diversity of species."

Law and collaborators in the College of Forestry teamed up with researchers at Southern Oregon University, the Woodwell Climate Research Center and EcoSpatial Services L.L.C. to look at 152 national forests and compare them in terms of carbon density and accumulation, total biomass carbon stocks, habitat for eagles, bears and wolves, and landscape integrity -- defined as degree of modification by humans.

The authors report that almost 31% of all high-landscape-integrity area found in national forests -- areas with minimal or no human modification -- is in the Tongass and Chugach, at 25.3% and 5.6%, respectively.

Those forests also combine to account for nearly half of all bald eagle habitat available in national forests, 37% of brown bear habitat and 18% of gray wolf habitat -- no other location has more than 4% of the total wolf habitat found in the U.S. inventory of national forests. All three species were once widespread and abundant across much of North America.

"Forests play an incredibly important part in trying to mitigate climate change and support biodiversity," Law said. "For six decades, ecosystems on land have annually been removing roughly 30% of all the carbon dioxide humans have been putting into the atmosphere, and forests do most of that work. But intact forests with high carbon density and high biodiversity are disappearing at a frightening pace, lost to agriculture, logging and other industries, and development."

In addition to sequestering carbon and providing wildlife habitat, intact forests provide a range of ecosystem services, including helping to keep water clean, the authors note. And in the quest to establish nature-based climate solutions, public lands have outsized importance because they are more likely than private lands to afford more stable carbon storage.

Still, at present, federal forest lands are caught up in a numbers game, and conservation has some ground to make up on the scoreboard, Law said.

"National forests account for 76% of all federal forest land, but logging and other industrial activities are allowed throughout most of that, with only about 19% classified as reserved in one way or another from timber production," she said. "That means there is a substantial gap between current preservation and the preservation targets for protecting biodiversity and carbon stocks."

Ramping up protection in the Alaskan forests offers a big opportunity for closing that gap, the authors point out. Right now, 35% of the Tongass is protected at the two highest levels as categorized by the U.S. Geological Survey and the International Union for Conservation of Nature, and 57.6% of the Chugach.

"Those two forests have historically been wetter and cooler than most national forests, and over the next 100 years they are projected to have much larger increases in precipitation and much lower increases in maximum temperatures," Law said. "Combined with a relatively low occurrence of wildfire, that makes preserving these forests in their intact state highly possible -- if there is the political will to take bold action."

Read more at Science Daily

How salt from the Caribbean affects our climate

The distribution of salt by ocean currents plays a crucial role in regulating the global climate. This is what researchers from Dalhousie University in Canada, GEOMAR Helmholtz Centre for Ocean Research Kiel, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) and MARUM -- Center for Marine Environmental Sciences at the University of Bremen have found in a new study. They studied natural climate anomalies, including the so-called Little Ice Age. This cold period from the 15th to the mid-19th century led to poor harvests, famine and disease in Europe. Although the Little Ice Age is one of the most studied periods in recent history, the underlying climatic mechanisms remain controversial.

"Looking at recent, natural climate anomalies helps to understand the processes and mechanisms that human-induced global warming may trigger," says Dr Anastasia Zhuravleva, lead author of the study. She was a PhD student at GEOMAR and received the Annette Barthelt Prize for her dissertation in 2019. She then worked as a post-doctoral researcher at GEOMAR and Dalhousie University, where the study was completed.

"Researchers often consider an increase in sea ice extent and desalination in the subpolar North Atlantic as possible triggers for past cold periods, but processes in the tropical Atlantic appear to be equally important," says Dr Zhuravleva. "In fact, in contrast to the northern and mid-latitudes, there is little information on these recent climate events from the subtropical-tropical Atlantic and their impact on regions in the Northern Hemisphere," adds Dr Henning Bauch, paleoclimatologist at AWI and GEOMAR, co-initiator and co-author of the study. "This is where our research comes in."

So, what happened in the tropical Atlantic during historical climate anomalies, and how might potential changes there have affected ocean circulation and climate much further north? To answer these questions, the team worked on a sediment profile from the southern Caribbean and reconstructed the salinity and temperature of the surface water over the last 1700 years. Among other things, the researchers determined the isotopic and elemental composition of the calcareous shells of plankton.

The results show a cooling of about 1°C during the Little Ice Age. "It is a significant temperature change for this region," says Dr Mahyar Mohtadi, co-author of the study and head of the Low Latitude Climate Variability group at MARUM. "Particularly noteworthy is the occurrence of another pronounced cooling for the 8th-9th centuries. Colder temperatures in the otherwise warm tropical ocean led to lower regional rainfall, which coincided with severe droughts in the Yucatan Peninsula and the decline of the Classic Maya culture."

In addition, the researchers found that the cold climate anomalies in the subpolar North Atlantic and Europe were accompanied by weaker ocean circulation and increased salinity in the Caribbean. "Advection, or the movement of tropical salt to high northern latitudes, is essential for maintaining high surface densities in the subpolar North Atlantic. This is a prerequisite for the overall stability of the large-scale ocean circulation, including the transfer of warm Gulf Stream water, which is responsible for our mild temperatures in Europe," says Dr Bauch.

The data on the historical past thus allow a reconstruction of the connection across the North Atlantic. Initial cooling can be caused by volcanic eruptions, low solar activity and feedbacks between sea ice and the ocean in the north. The new study provides evidence that a decrease in salt movement to high northern latitudes will amplify and prolong these climate events. Conversely, the slow movement of positive salinity anomalies from the tropics will eventually increase the density at the surface of the subpolar North Atlantic. This may favour the northward transport of heat by ocean currents, resulting in milder temperatures over Europe and North America.

"Such a salinity feedback is known from models and has been assumed for the Little Ice Age. However, in the absence of tropical ocean data, these assumptions have been based on less direct precipitation records," says Dr Zhuravleva.

Read more at Science Daily

Window to avoid 1.5°C of warming will close before 2030 if emissions are not reduced

Without rapid carbon dioxide emission reductions, the world has a 50% chance of locking in 1.5°C of warming before 2030, according to a study led by Imperial College London researchers.

The study, published today in Nature Climate Change, is the most up-to-date and comprehensive analysis of the global carbon budget. The carbon budget is an estimate of the amount of carbon dioxide emissions that can be emitted while keeping global warming below certain temperature limits.

The Paris Agreement aims to limit global temperature increase to well below 2°C above preindustrial levels and pursue efforts to limit it to 1.5°C. The remaining carbon budget is commonly used to assess global progress against these targets.

The new study estimates that for a 50% chance of limiting warming to 1.5°C, there are less than 250 gigatonnes of carbon dioxide left in the global carbon budget.

The researchers warn that if carbon dioxide emissions remain at 2022 levels of about 40 gigatonnes per year, the carbon budget will be exhausted by around 2029, committing the world to warming of 1.5°C above preindustrial levels.

The finding means the budget is less than previously calculated and has approximately halved since 2020 due to the continued increase of global greenhouse gas emissions, caused primarily from the burning of fossil fuels as well as an improved estimate of the cooling effect of aerosols, which are decreasing globally due to measures to improve air quality and reduce emissions.

Dr Robin Lamboll, research fellow at the Centre for Environmental Policy at Imperial College London, and the lead author of the study, said: "Our finding confirms what we already know -- we're not doing nearly enough to keep warming below 1.5°C.

"The remaining budget is now so small that minor changes in our understanding of the world can result in large proportional changes to the budget. However, estimates point to less than a decade of emissions at current levels.

"The lack of progress on emissions reduction means that we can be ever more certain that the window for keeping warming to safe levels is rapidly closing."

Dr Joeri Rogelj, Director of Research at the Grantham Institute and Professor of Climate Science & Policy at the Centre for Environmental Policy at Imperial College London, said: "This carbon budget update is both expected and fully consistent with the latest UN Climate Report.

"That report from 2021 already highlighted that there was a one in three chance that the remaining carbon budget for 1.5°C could be as small as our study now reports.

"This shows the importance of not simply looking at central estimates, but also considering the uncertainty surrounding them."

The study also found that the carbon budget for a 50% chance of limiting warming to 2°C is approximately 1,200 gigatonnes, meaning that if carbon dioxide emissions continue at current levels, the central 2°C budget will be exhausted by 2046.

There has been much uncertainty in calculating the remaining carbon budget, due to the influence of other factors, including warming from gasses other than carbon dioxide and the ongoing effects of emissions that are not accounted for in models.

The new researchused an updated dataset and improved climate modelling compared to other recent estimates, published in June, characterising these uncertainties and increasing confidence around the remaining carbon budget estimates.

The strengthened methodology also gave new insights into the importance of the potential responses of the climate system to achieving net zero.

'Net zero' refers to achieving an overall balance between global emissions produced and emissions removed from the atmosphere.

According to the modelling results in the study, there are still large uncertainties in the way various parts of the climate system will respond in the years just before net zero is achieved.

It is possible that the climate will continue warming due to effects such as melting ice, the release of methane, and changes in ocean circulation.

However, carbon sinks such as increased vegetation growth could also absorb large amounts of carbon dioxide leading to a cooling of global temperatures before net zero is achieved.

Dr Lamboll says these uncertainties further highlight the urgent need to rapidly cut emissions. "At this stage, our best guess is that the opposing warming and cooling will approximately cancel each other out after we reach net zero.

"However, it's only when we only when we cut emissions and get closer to net zero that we will be able to see what the longer-term heating and cooling adjustments will look like.

Read more at Science Daily

Raining cats and dogs: Global precipitation patterns a driver for animal diversity

Since the HMS Beagle arrived in the Galapagos with Charles Darwin to meet a fateful family of finches, ecologists have struggled to understand a particularly perplexing question: Why is there a ridiculous abundance of species some places on earth and a scarcity in others? What factors, exactly, drive animal diversity?

With access to a mammoth set of global-scale climate data and a novel strategy, a team from the Department of Watershed Sciences in Quinney College of Natural Resources and the Ecology Center identified several factors to help answer this fundamental ecological question. They discovered that what an animal eats (and how that interacts with climate) shapes Earth's diversity.

The work was recently published in the high-impact journal Ecology Letters.

"Historically studies looking at the distribution of species across Earth's latitudinal gradient have overlooked the role of trophic ecology -- how what animals eat impacts where they are found," said Trisha Atwood, author on the study from the Department of Watershed Sciences and the Ecology Center. "This new work shows that predators, omnivores and herbivores are not randomly scattered across the globe. There are patterns to where we find these groups of animals."

Certain locations have an unexpected abundance of meat-eating predators -- parts of Africa, Europe and Greenland. Herbivores are common in cooler areas, and omnivores tend to be more dominant in warm places. Two key factors emerged as crucial in shaping these patterns: precipitation and plant growth.

Precipitation patterns across time play a big role in determining where different groups of mammals thrive, Atwood said. Geographical areas where precipitation varies by season, without being too extreme, had the highest levels of mammal diversity.

"Keep in mind that we aren't talking about the total amount of rain," said Jaron Adkins, lead author on the research. "If you imagine ecosystems around the world on a scale of precipitation and season, certain places in Utah and the Amazon rainforest fall on one end with low variability -- they have steady levels of precipitation throughout the year. Other regions, like southern California, have really high variability, getting about 75 percent of the annual precipitation between December and March."

But the sweet spot for predators and herbivores fell in a middle zone between the two extremes, he said. Places like Madagascar, where precipitation patterns had an equal split between a wet season and a dry one (six months each), had the ideal ecological cocktail for promoting conditions for these two groups. Omnivore diversity tends to thrive in places with very stable climates.

The second important factor connected with mammal diversity the work uncovered was a measure of the amount of plant growth in an area, measured as "gross primary productivity."

"It makes intuitive sense for plant-eating animals to benefit from plant growth," Adkins said.

But this measure actually impacted carnivores most, according to the research. The strong relationship between predators and plant growth highlights the importance of an abundance of plants on an entire food chain's structural integrity.

"It was surprising that this factor was more important for predators than omnivores and herbivores," Atwood said. "Why this is remains a mystery."

Although evolutionary processes are ultimately responsible for spurring differences in species, climate conditions can impact related factors -- rates of evolutionary change, extinction and animal dispersal -- influencing species and trait-based richness, according to the research.

Animal diversity is rapidly declining in many ecosystems around the world through habitat loss and climate change. This has negative consequences for ecosystems. Forecasting how climate change will disrupt animal systems going forward is extremely important, Atwood said, and this research is a first step in better managing future conditions for animals around the world.

"Animal diversity can act as an alarm system for the stability of ecosystems," Atwood said. "Identifying the ecological mechanisms that help drive richness patterns provides insight for better managing and predicting how diversity could change under future climates."

Read more at Science Daily

Fewer but more intense tropical storms predicted over the Ganges and Mekong

Climate experts project a decline in the frequency of future tropical storms but an increase in their strength across the Ganges and Mekong basins allowing for better future planning.

The Newcastle University-led team focused on the Ganges and Mekong basins and evaluated the simulation of tropical storms. Their analyses show an increase in tropical storms frequency up until the early 2010s but that climate models project a frequency decline of over 50% on average across both basins by 2050.

In contrast, the results from high resolution climate models show an increase in the future intensity of tropical storms for both basins, with the largest increases for the most intense tropical storms.

These findings can be used to assess the future resilience of existing infrastructure systems to tropical storms across these densely populated basins.

The team, involving scientists from the Met Office and the University of Reading, published their findings in the journal Geophysical Research Letters. The scientists used European Union Horizon 2020 project PRIMAVERA models, which are available at up to 25 km resolution. They also employed two storm tracking algorithms, TRACK and TempExt.

Study lead author, Dr Haider Ali, of Newcastle University's School of Engineering, said: "Tropical storms are one of the world's most damaging natural hazards which result in colossal socioeconomic losses to life, infrastructure and property, especially in low-lying delta rivers basins like the Ganges and Mekong.

"Knowledge of changes to tropical storms activity under climate change can therefore be helpful in developing better disaster risk mitigation and for climate adaptation. Previous modelling studies have used coarse-resolution global climate models unable to capture key tropical storm characteristics.

"In this study, we used finer resolution models and two different tracking algorithms to resolve a part of this uncertainty."

Study author, Hayley Fowler, Professor of Climate Change Impacts, Newcastle University School of Engineering, added: "Our results are consistent with those found for tropical storms and Tropical Cyclones in the Atlantic Basin, where they also project an overall decline in frequency but an increase in the frequency of the most intense TCs. These systems cause massive impacts on society from high winds, rainfall and storm surges causing flooding. Quantifying these changes will allow us to better plan for future events."

Implications for Climate Adaptation Policies

The Ganges and Mekong basins are two significant river systems in Asia that play vital roles in the lives of millions of people living in the region. The basins are essential for agriculture, water supply, and transportation.

However, both the Ganges and Mekong basins are highly vulnerable to the impacts of climate change, including changes in precipitation patterns, extreme weather events, and sea-level rise.

Read more at Science Daily

A finer picture of global migration reveals complex patterns

While public discussions often focus on climate change driving people to emigrate, new research published in Nature Human Behaviour shows that net-migration patterns around the world are actually more strongly linked with socio-economic factors. The study also provides a new, high-resolution dataset of net-migration over the past two decades to inform policy-making and fuel further research.

'Our findings don't really match the narrative that's repeated by the public about climate-induced migration,' says Venla Niva, a postdoctoral researcher at Aalto University who was lead author of the study. 'When you look at the different factors together, the analysis shows that human development factors are more important drivers than climate.'

Societal factors override climate considerations

The research group, which included researchers from Aalto University, International Institute for Applied Systems Analysis and the University of Bologna, published similar research last year covering the period 1990-2000. The new analysis covers the past two decades, 2000-2019. The high-resolution dataset they prepared makes it possible to answer questions that can't be addressed with coarser data, such as national averages. 'There was a real need for a dataset like this, but it didn't exist. So we decided to make it ourselves,' says Niva. The new dataset is openly available and can be easily explored through an online interactive map.

The team combined birth and death rates with overall population growth to estimate net migration. The role of socio-economics and climate were incorporated through the Human Development Index (HDI) and the aridity index.

By starting with sub-national death and birth ratios and scaling them down to 10 km resolution, the researchers produced a net-migration dataset of unprecedented resolution. This makes it possible to address questions that can't be answered using national aggregates. 'Climate factors don't follow administrative boundaries, so data like this is needed if you want to study these patterns,' explains Niva.

The researchers found high levels of emigration in regions that were on the middle of the scale in both HDI and aridity, such as areas in Central America, northeast Brazil, Central Africa and southeast Asia. 'It's not the poorest of the poor who are fleeing environmental disasters or environmental changes. Migration is an adaptation method used by people who have the capacity to move,' says Niva.

By the same token, areas with a high HDI experienced positive net migration regardless of their climate condition. For example, regions in the Arabian Peninsula, North America, Australia, and the North Mediterranean are net receivers despite their aridity.

'Decision-makers should pay attention to this. Rather than focusing solely on border closures and combating migration, we should work to support and empower individuals in economically disadvantaged countries. That would help reduce the drivers that compel people to migrate in search of better opportunities,' says Matti Kummu, associate professor of global water and food issues at Aalto and senior author of the study.

National averages mask local patterns

The granularity of the new dataset reveals complexities in migration patterns that are hidden when national data is used. 'In France and Italy, for example, there are really interesting differences between north and south, and in Spain there's an east-west difference. There are so many patterns that national experts could look into, and of course the reasons behind them might be different for each country,' says Kummu.

Unexpected patterns also showed up in urban-rural migration. 'There's a very common belief that urban areas are pulling the people from the rural areas, but that wasn't the case everywhere. For example, there are a lot of places for example in Europe where the opposite is true,' says Kummu. Migration from cities to rural areas was also evident in parts of Indonesia, Congo, Venezuela, and Pakistan, and when the analysis is done of the level of communities, the picture becomes even more complex.

'Overall, migration is more complex than people tend to think,' says Niva. 'Our findings contribute to the discussion of where and how migration is happening -- it's not actually a Eurocentric phenomenon, because most migration happens elsewhere in the world.'

Read more at Science Daily

New research explains 'Atlantification' of the Arctic Ocean

New research by an international team of scientists explains what's behind a stalled trend in Arctic Ocean sea ice loss since 2007. The findings indicate that stronger declines in sea ice will occur when an atmospheric feature known as the Arctic dipole reverses itself in its recurring cycle.

The many environmental responses to the Arctic dipole are described in a paper published online today in the journal Science. This analysis helps explain how North Atlantic water influences Arctic Ocean climate. Scientists call it Atlantification.

The research is led by professor Igor Polyakov of the University of Alaska Fairbanks College of Natural Science and Mathematics. He is also affiliated with the International Arctic Research Center at UAF.

Co-authors include Andrey V. Pnyushkov, research assistant professor at the International Arctic Research Center; Uma S. Bhatt, atmospheric sciences professor at the UAF Geophysical Institute and UAF College of Natural Science and Mathematics; and researchers from Massachusetts, Washington state, Norway, and Germany.

"This is a multidisciplinary view on what's going on in the Arctic and beyond," Polyakov said of the new research. "Our analysis covered the atmosphere, ocean, ice, changing continents and changing biology in response to climate change."

A wealth of data, including direct instrumental observations, reanalysis products and satellite information going back several decades, shows that the Arctic dipole alternates in an approximately 15-year cycle and that the system is probably at the end of the present regime.

In the Arctic dipole's present "positive" regime, which scientists say has been in place since 2007, high pressure is centered over the Canadian sector of the Arctic and produces clockwise winds. Low pressure is centered over the Siberian Arctic and features counterclockwise winds.

This wind pattern drives upper ocean currents, with year-round effects on regional air temperatures, atmosphere-ice-ocean heat exchanges, sea-ice drift and exports, and ecological consequences.

The authors write that, "Water exchanges between the Nordic seas and the Arctic Ocean are critically important for the state of the Arctic climate system" and that sea ice decline is "a true indicator of climate change."

In analyzing oceanic responses to the wind pattern since 2007, the researchers found decreased flow from the Atlantic Ocean into the Arctic Ocean through the Fram Strait east of Greenland, along with increased Atlantic flow into the Barents Sea, located north of Norway and western Russia.

The new research refers to these alternating changes in the Fram Strait and the Barents Sea as a "switchgear mechanism" caused by the Arctic dipole regimes.

The researchers also found that counterclockwise winds from the low-pressure region under the current positive Arctic dipole regime drive freshwater from Siberian rivers into the Canadian sector of the Arctic Ocean.

This westward movement of freshwater from 2007 to 2021 helped slow the overall loss of sea ice in the Arctic compared to 1992 through 2006. The freshwater layer's depth increased, making it too thick and stable to mix with the heavier saltwater below. The thick layer of freshwater prevents the warmer saltwater from melting sea ice from the bottom.

The authors write that the switchgear mechanism regulating inflows of sub-Arctic waters has "profound" impacts on marine life. It can lead to potentially more suitable living conditions for sub-Arctic boreal species near the eastern part of the Eurasian Basin, relative to its western part.

"We are beyond the peak of the currently positive Arctic dipole regime, and at any moment it could switch back again," Polyakov said. "This could have significant climatological repercussions, including a potentially faster pace of sea-ice loss across the entire Arctic and sub-Arctic climate systems."

Read more at Science Daily

Elephant ancestors´ teeth evolved in response to long term changes in diet and climate in Africa

A new study shows that the cheek teeth of proboscideans (elephants and their ancient relatives) evolved in response to dietary changes due to vegetation changes and climate change in East Africa during the last 26 million years.

The latest study about of proboscideans (elephants and their ancient relatives) from the University of Helsinki provides proof that some proboscideans started to adapt to locally grass-rich environments in East Africa first by changing their behavior and starting to feed more on grasses. This happened in some lineages of proboscideans, such as choerolophodonts, much earlier than has been thought until now, about 23 to 11 million years ago in parts of East Africa

Also, around 7 million years ago in the lake Turkana region, increasingly grass-rich diets of the earliest true elephants were associated with dryer and more grass-rich savanna environments than elsewhere in East Africa.

"This supports the hypothesis of such regions as "species-factories" where evolutionary adaptation to changing environmental conditions first centered around," says Juha Saarinen from the University of Helsinki, who led the research.

Feeding on grasses is more demanding on teeth than feeding on most other kinds of plants due to a high content of mineral grains called phytoliths in their leaves, causing heavy abrasion on teeth.

Nonetheless, during the Early and Middle Miocene the choerolophodont lineage of proboscideans were able to shift to more grass-rich diets with relatively modest changes in the morphology of their teeth.

Since about 10 million years ago, major changes in climate had a more profound effect on the evolution of proboscidean teeth in East Africa, especially the evolution of true elephants (Elephantidae) with highly specialized high-crowned, multi-ridged molar teeth.

"We were able to show that the strongest peaks of drying of the East African climate during the last 7 million years (for example about 4 and 2 million years ago) correspond with evolutionary bursts in the increase of tooth crown height and the number of ridges on the molar teeth, while these evolutionary changes did not reverse during periods of less harsh climatic conditions" says Saarinen.

"This supports earlier suggestions that adaptive traits in organisms are adaptations to extreme rather than average environmental conditions."

Comparing evidence of past vegetation and the diet of elephants during the last 7 million years also showed an increase of grasslands and increasing dominance of grass-feeding elephants with highly specialized teeth throughout that period in most parts of East Africa. However, during the last 100,000 years this situation changed probably because of drastic fluctuations in global climate and eventually only the dietarily more generalist modern African savanna elephant (Loxodonta africana) with less specialized teeth survived in East Africa. Ecological generalism might similarly explain the survival of Asian elephant (Elephas maximus) in Asia, while the African forest elephant (L. cyclotis) was able to find refuge in more forested parts of Central and Western Africa.

Read more at Science Daily

How a massive North Atlantic cooling event disrupted early human occupation in Europe

A new study published in the journal Science finds that around 1.12 million years ago a massive cooling event in the North Atlantic and corresponding shifts in climate, vegetation and food resources disrupted early human occupation of Europe.

The study published by an international group of scientists from the UK, South Korea and Spain presents observational and modelling evidence documenting that unprecedented climate stress changed the course of early human history.

Archaic humans, known as Homo erectus moved from Africa into central Eurasia around 1.8 million years. From there on they spread towards western Europe, reaching the Iberian peninsula around 1.5 million years ago (Ma). Experiencing initially rather mild climatic conditions, these groups eventually established a foothold in southern Europe, as documented by several dated fossils and stone tools from this period. But given the increasing intensity of glacial cycles in Europe from 1.2 Ma onwards, it remains unknown for how long early humans lived in this area and whether the occupation was interrupted by worsening climate conditions.

To better understand the environmental conditions, which early human species in Europe experienced, the team of pollen experts, oceanographers, climate modelers, archeologists, and anthropologists combined data of a deep ocean sediment cores from the eastern subtropical Atlantic with new supercomputer climate model and human habitat model simulations covering the period of the depopulation event.

Sieving through thousands of small plant pollen stored in the ocean sediment core and analyzing preserved temperature-sensitive organic compounds left by tiny algae, which lived over a million years ago, the scientists discovered that around 1.127 million years ago, the climate over the eastern North Atlantic and the adjacent land suddenly cooled by 7oC.

"This massive cooling marks one of the first terminal stadial events in the paleoclimatic record. It occurred during the last phase of a glacial cycle, when ice-sheets disintegrated, releasing large amounts of freshwater into the ocean, and causing ocean circulation changes and a southward expansion of sea ice," says Prof. Chronis Tzedakis from University College London (UCL), senior author of the study.

The pollen data extracted from the ocean sediment core further add to this scenario "Rivers and winds bring tiny pollen from the adjacent land to the ocean, where they sink and get deposited in the deep ocean. According to our ocean sediment core pollen analysis, the North Atlantic cooling event switched western European vegetation to an inhospitable semi-desert landscape.," adds Dr. Vasiliki Margari from UCL, lead author of the study.

To quantify how early humans may have reacted to such an unprecedented climate anomaly, scientists from the IBS Center for Climate Physics (ICCP) in South Korea, conducted new computer model simulations for this period. By adding glacial freshwater to the North Atlantic, Dr. Kyung-Sook Yun, and Ms. Hyuna Kim from the ICCP were able to reproduce key features of the terminal stadial event, such as the cooling and drying over southern Europe. "We then used this global climate model simulation as an input for a human habitat model, which determines whether certain environmental conditions were suitable for early Homo erectus or not. We found that over many areas of southern Europe, early human species such as Homo erectus would have not been able to survive" describes Prof. Axel Timmermann, Director of the ICCP at Pusan National University and co-corresponding author of the study.

Even though the cooling event only lasted for about 4,000 years, a lack of stone tools and human remains over the next 200,000 years further raises the possibility of a long-lasting hiatus in European occupation. Europe was again repopulated around 900 thousand years ago by a group that is often referred to as Homo antecessor. This group and its descendants were much more resilient, because they were able to adapt to the increasing intensity of glacial conditions over Europe.

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