Loon stratospheric balloons confirm wind data from Aeolus

ESA's novel Aeolus satellite reliably measures wind speed also in higher air layers and thus in a region of the atmosphere where other direct global wind measurements are relatively sparse. This is the result of a study for which data from the satellite were compared with wind observations from stratospheric balloons. Stratospheric balloons would provide highly accurate data on the horizontal wind speed and are therefore also suitable for the validation of future satellite missions. Future wind satellites should increase the vertical resolution to better resolve gravity waves in the tropics, writes the team of researchers from the Leibniz Institute for Tropospheric Research (TROPOS), the European Space Agency (ESA), the European Centre for Medium-Range Weather Forecasts (ECMWF), the University of Hamburg and the Google company Loon. The study has now been published in the Quarterly Journal of the Royal Meteorological Society.

The quality of numerical weather prediction models and thus of weather forecasts depends heavily on the available data. In recent decades, a global observation system has therefore been built up which also includes wind profiles from weather balloons, aircraft data or wind profiler radar systems. However, most of this data comes from the densely populated northern hemisphere. In the southern hemisphere, over the oceans and especially in the tropics, the network of direct measurements is still relatively sparse.

The launch of the European Space Agency's (ESA) first wind satellite Aeolus on 22 August 2018 was therefore a major step towards global wind measurements. This novel satellite has a powerful laser on board, the Atmospheric Laser Doppler Instrument (ALADIN). ALADIN is the first Doppler wind lidar in space to provide profiles of horizontal wind speed from the Earth's surface or from the top of thick clouds up to a height of about 30 km on a global scale. To do this, the satellite emits short ultraviolet laser pulses as it orbits the Earth. A small part of these light pulses is scattered back to the satellite by air molecules, aerosols and clouds and collected and processed in the detector there. For one circumnavigation of the globe Aeolus takes 90 minutes, within a week the satellite collects wind data around the entire globe. This data is assimilated by weather forecasting centres around the world to improve their forecasts. Since there have been no comparable satellite missions so far, the data are checked particularly critically and compared with other wind measurements.

A study recently published used data from 229 stratospheric balloons of the Loon project between July 2019 and December 2020 from tropical Latin America, Atlantic Ocean, Africa and Indian Ocean for comparison. Loon was a commercial project that had provided remote regions with internet access via helium balloons in the stratosphere. The balloons, which were about 12 metres in diameter, acted as floating mobile phone stations at altitudes of 16 to 20 kilometres above the ground. For maintaining the network, the balloons had to automatically correct the wind direction by changing the altitude. This created an extensive data set on wind speeds in these atmospheric layers, which partially fills the gap in wind data at this altitude in the global observation system. The Loon project was discontinued in 2021 for economic reasons, but a highly interesting data set remains for atmospheric research.

"Our analysis confirms that the Aeolus satellite provides almost bias-free wind measurements in the upper troposphere and lower stratosphere. In contrast, the current ECWMF weather model systematically underestimates the wind speed there by about 1 metre per second, which could be demonstrated by the Aeolus and Loon data. These results are important to better understand dynamical processes in the upper troposphere and lower stratosphere and to further improve the weather models," emphasises Dr. Sebastian Bley from TROPOS, who worked for the study at ESA in Frascati, Italy. Another recommendation of the researchers is to carry out more vertical measurements to be able to provide more wind information in the atmospheric layers. This could further improve the accuracy of upcoming wind satellites. In addition to wind speed, Aeolus also provides information about aerosols and clouds, but only via a portion of the backscattered light. "We hope that future wind missions will also be able to measure depolarisation, the rotation of light when it is reflected. That would be a milestone because the satellite could then also provide more information about aerosols," explains Bley.

Aeolus was developed as an explorer mission with an expected lifetime of 3 years to demonstrate the technology of a Doppler wind lidar in space. However, expectations have been exceeded and Aeolus has now been providing valuable data for over 4 years. The wind data are now used in the weather forecasts of several weather services throughout Europe, such as the German Weather Service (DWD), and have been convincing due to their positive influence on the quality of weather forecasts. The way forward for the follow-on mission Aeolus-2 has been recently decided in the ESA ministerial and will be jointly developed by ESA and EUMETSAT.

In September, researchers from the USA had integrated Aeolus data into the hurricane model (HWRF) of the US weather and oceanography agency NOAA on a trial basis in order to better predict tropical storms. Their conclusion is that the use of Aeolus wind data is most effective where there are no reconnaissance flights into the hurricanes and could therefore have the greatest positive impact on tropical cyclone forecasting in the Pacific and Indian Oceans.

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Palau's Rock Islands harbor heat-resistant corals

Ocean warming is driving an increase in the frequency and severity of marine heatwaves, causing untold damage to coral reefs. Tropical corals, which live in symbiosis with tiny single celled algae, are sensitive to high temperatures, and exhibit a stress response called bleaching when the ocean gets too hot. In the last 4 decades, marine heatwaves have caused widespread bleaching, and killed millions of corals. Because of this, a global search is underway for reefs that can withstand the heat stress, survive future warming, and act as sources of heat-tolerant coral larvae to replenish affected areas both naturally and through restoration.

Now, scientists studying reefs in Palau, an archipelago in the western tropical Pacific, have identified genetic subgroups of a common coral species that exhibit remarkable tolerance to the extreme heat associated with marine heatwaves. Further, the scientists found evidence that larvae from these corals are traveling from their birthing grounds deep in Palau's lagoons, to the outer reef, where they survive and grow, and maintain their heat tolerance.

Understanding both the underlying mechanisms that facilitate heat tolerance of these corals, as well as the dispersal capabilities of their larvae will go a long way toward enhancing coral reef conservation and restoration efforts in the 21st century ocean, according to scientists at the Woods Hole Oceanographic Institution (WHOI) who led the research.

In Palau's main lagoon, a network of very ancient, fossilized reefs has been uplifted to form a series of mountains known as the Rock Islands. These formations slow water flow in and around them, creating localized environments in which the water temperatures are consistently higher than other areas of Palau's reefs.

Scientists sampled the keystone coral species Porites lobata (lobe coral) across Palau, including the Rock Islands. They took skeletal biopsies and examined the cores for stress bands, which are telltale signs of bleaching, a stress response corals have to high temperatures. They found corals from the Rock Islands bleached less during the intense 1998 heatwave than corals from other areas of the reef, indicating enhanced thermal tolerance.

Scientists then investigated the genetics of the corals and discovered four distinct lineages within the same species. Within the warmer Rock Islands, certain lineages, designated as "LB" and "RD" lineages, were much more common. The scientists were able to match the genetics of each coral with its own bleaching history and found that fewer individuals from the "LB" and "RD" lineages bleached during 1998, indicating enhanced thermal tolerance.

Remarkably, the scientists found the LB lineage was not restricted to the Rock Islands. They found some LB colonies also living on the cooler outer reefs. An examination of the bleaching histories of these colonies again revealed fewer stress bands, indicating that they maintained the thermal tolerance characteristic of their relatives in the Rock Islands.

"This suggests that the Rock Islands provide naturally tolerant larvae to neighboring areas," the scientists write in the paper titled "Palau's warmest reefs harbor thermally tolerant corals that thrive across different habitats," published in Communications Biology, a journal published by Nature. "Finding and protecting such sources of thermally-tolerant corals is key to reef survival under 21st century climate change."

"As oceans worldwide continue to warm, corals derived from extreme habitats will be at a competitive advantage and may enable the survival of otherwise vulnerable reefs," the authors continue. "Identifying and safeguarding natural breeding grounds of environmentally tolerant corals that can thrive under future climate conditions will be fundamental to the persistence of coral reef ecosystems worldwide in the coming decades."

"We found that some of Palau's reefs with the highest temperatures have corals that are more tolerant than one would expect," said the paper's lead author Hanny Rivera, a graduate of the MIT-WHOI Joint Program. Rivera, who conducted this work as part of her Ph.D. and postdoctoral research, is currently an associate director of business development at Ginko Bioworks. "In addition, they are genetically distinct from the same corals found in other parts of Palau, which suggests that there has been natural selection for hardier corals in these regions.."

Paper co-author Michael Fox added that the study is particularly exciting because it combines coral genetics with historical records of bleaching preserved in their skeletons to shed light on how corals from extreme habitats with high temperature tolerance can be dispersed across a reefscape. "This integrated perspective is essential for improving projections of coral communities in a warming ocean," said Fox, who was a postdoctoral scholar at WHOI during the research for this paper. He currently is an assistant research professor in the Red Sea Research Center at King Abdullah University of Science and Technology in Thuwal, Saudi Arabia.

The Palau research is directly related to the Super Reefs initiative WHOI launched with The Nature Conservancy and Stanford University to locate coral communities that can withstand marine heat waves, and work with local communities and governments to protect them.

"This work is the scientific basis for the Super Reefs initiative," said paper co-author Anne Cohen, a scientist at WHOI and Rivera's advisor on the study. "The Palau research demonstrates that Super Reefs exist and also provides actionable science knowledge that can be used to support their protection."

Cohen noted that there are other coral reefs, not just in Palau, where coral communities have not bleached as severely as scientists predicted based on the levels of thermal stress. "When we find the coral communities that are heat-tolerant or bleaching-resistant, and we protect them from other stresses that can kill them -- like dynamiting, overfishing, or coastal development -- they will produce millions of larvae that will travel on the currents, outside of their places of origin as we see on Palau, and they will repopulate reefs that have been devastated by heatwaves," she said. "Nature is amazing. Our job with the Super Reefs initiative is to protect these thermally resilient reefs and let nature do the rest."

Rivera added she is in awe of the immense appreciation, respect, and stewardship that the Palauan people have for their environment.

"They have been one of the pioneering countries in promoting marine conservation and ecological protection. It is wonderful to know that these special reefs are in such good hands," Rivera said. "It is my greatest hope that our research will further support the Palauan people in their efforts to maintain a healthy marine ecosystem."

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Men may not 'perceive' domestic tasks as needing doing in the same way as women, philosophers argue

Philosophers seeking to answer questions around inequality in household labour and the invisibility of women's work in the home have proposed a new theory -- that men and women are trained by society to see different possibilities for action in the same domestic environment.

They say a view called "affordance theory" -- that we experience objects and situations as having actions implicitly attached -- underwrites the age-old gender disparity when it comes to the myriad mundane tasks of daily home maintenance.

For example, women may look at a surface and see an implied action -- 'to be wiped' -- whereas men may just observe a crumb-covered countertop.

The philosophers believe these deep-seated gender divides in domestic perception can be altered through societal interventions such as extended paternal leave, which will encourage men to build up mental associations for household tasks.

Writing in the journal Philosophy and Phenomenological Research, they argue that available data -- particularly data gathered during the pandemic -- suggest two questions require explanation.

One is "disparity": despite economic and cultural gains, why do women continue to shoulder the vast majority of housework and childcare? The other is "invisibility": why do so many men believe domestic work to be more equally distributed than in fact it is?

"Many point to the performance of traditional gender roles, along with various economic factors such as women taking flexible work for childcare reasons," said Dr Tom McClelland, from Cambridge University's Department of History and Philosophy of Science.

"Yet the fact that stark inequalities in domestic tasks persisted during the pandemic, when most couples were trapped inside, and that many men continued to be oblivious of this imbalance, means this is not the full story."

McClelland and co-author Prof Paulina Sliwa argue that unequal divisions of labour in the home -- and the inability of men to identify said labour -- is best explained through the psychological notion of "affordances": the idea that we perceive things as inviting or "affording" particular actions.

"This is not just looking at the shape and size of a tree and then surmising you can climb it, but actually seeing a particular tree as climbable, or seeing a cup as drink-from-able," said Sliwa, recently of Cambridge's philosophy faculty and now at the University of Vienna.

"Neuroscience has shown that perceiving an affordance can trigger neural processes preparing you for physical action. This can range from a slight urge to overwhelming compulsion, but it often takes mental effort not to act on an affordance."

There are dramatic differences in "affordance perception" between individuals. One person sees a tree as climbable where another does not. Objects offer a vast array of affordances -- one could see a spatula as an egg-frying tool or a rhythmic instrument -- and a spectrum of sensitivity towards them.

"If we apply affordance perception to the domestic environment and assume it is gendered, it goes a long way to answering both questions of disparity and invisibility," said McClelland.

According to the philosophers, when a woman enters a kitchen she is more likely to perceive the "affordances" for particular domestic tasks -- she sees the dishes as 'to be washed' or a fridge as 'to be stocked'.

A man may simply observe dishes in a sink, or a half-empty fridge, but without perceiving the affordance or experiencing the corresponding mental "tug." Over time, these little differences add up to significant disparities in who does what.

"Affordances pull on your attention," said Sliwa. "Tasks may irritate the perceiver until done, or distract them from other plans. If resisted, it can create a felt tension."

"This puts women in a catch-22 situation: either inequality of labour or inequality of cognitive load."

This gender-based split in affordance perception could have a number of root causes, say philosophers. Social cues encourage actions in certain environments, often given by adults when we are very young children. Our visual systems update based on what we encounter most frequently.

"Social norms shape the affordances we perceive, so it would be surprising if gender norms do not do the same," said McClelland.

"Some skills are explicitly gendered, such cleaning or grooming, and girls are expected to do more domestic chores than boys. This trains their ways of seeing the domestic environment, to see a counter as 'to be wiped'."

The "gendered affordance perception hypothesis" is not about absolving men say Sliwa and McClelland. Despite a deficit in affordance perception in the home, a man can easily notice what needs doing by thinking rather than seeing. Nor should sensitivity to domestic affordances in women be equated with natural affinity for housework.

"We can change how we perceive the world through continued conscious effort and habit cultivation," said McClelland. "Men should be encouraged to resist gendered norms by improving their sensitivity to domestic task affordances.

"A man might adopt a resolution to sweep for crumbs every time he waits for the kettle to boil, for example. Not only would this help them to do the tasks they don't see, it would gradually retrain their perception so they start to see the affordance in the future."

Collective efforts to change social norms require policy-level interventions, argue the philosophers. For example, shared parental leave gives fathers the opportunity to become more sensitive to caring-task affordances.

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Shedding light on the origin of complex life forms

How did the complex organisms on Earth arise? This is one of the big open questions in biology. A collaboration between the working groups of Christa Schleper at the University of Vienna and Martin Pilhofer at ETH Zurich has come a step closer to the answer. The researchers succeeded in cultivating a special archaeon and characterizing it more precisely using microscopic methods. This member of the Asgard archaea exhibits unique cellular characteristics and may represent an evolutionary "missing link" to more complex life forms such as animals and plants. The study was recently published in the journal Nature.

All life forms on earth are divided into three major domains: eukaryotes, bacteria and archaea. Eukaryotes include the groups of animals, plants and fungi. Their cells are usually much larger and, at first glance, more complex than the cells of bacteria and archaea. The genetic material of eukaryotes, for example, is packaged in a cell nucleus and the cells also have a large number of other compartments. Cell shape and transport within the eukaryotic cell are also based on an extensive cytoskeleton. But how did the evolutionary leap to such complex eukaryotic cells come about?

Most current models assume that archaea and bacteria played a central role in the evolution of eukaryotes. A eukaryotic primordial cell is believed to have evolved from a close symbiosis between archaea and bacteria about two billion years ago. In 2015, genomic studies of deep-sea environmental samples discovered the group of the so-called "Asgard archaea," which in the tree of life represent the closest relatives of eukaryotes. The first images of Asgard cells were published in 2020 from enrichment cultures by a Japanese group.

Asgard archaea cultivated from marine sediments

Christa Schleper's working group at the University of Vienna has now succeeded for the first time in cultivating a representative of this group in higher concentrations. It comes from marine sediments on the coast of Piran, Slovenia, but is also an inhabitant of Vienna, for example in the bank sediments of the Danube. Because of its growth to high cell densities, this representative can be studied particularly well. "It was very tricky and laborious to obtain this extremely sensitive organism in a stable culture in the laboratory," reports Thiago Rodrigues-Oliveira, postdoc in the Archaea working group at the University of Vienna and one of the first authors of the study.

Asgard archaea have a complex cell shape with an extensive cytoskeleton

The remarkable success of the Viennese group to cultivate a highly enriched Asgard representative finally allowed a more detailed examination of the cells by microscopy. The ETH researchers in Martin Pilhofer's group used a modern cryo-electron microscope to take pictures of shock-frozen cells. "This method enables a three-dimensional insight into the internal cellular structures," explains Pilhofer. "The cells consist of round cell bodies with thin, sometimes very long cell extensions. These tentacle-like structures sometimes even seem to connect different cell bodies with each other," says Florian Wollweber, who spent months tracking down the cells under the microscope. The cells also contain an extensive network of actin filaments thought to be unique to eukaryotic cells. This suggests that extensive cytoskeletal structures arose in archaea before the appearance of the first eukaryotes and fuels evolutionary theories around this important and spectacular event in the history of life.

Future insights through the new model organism

"Our new organism, called Lokiarchaeum ossiferum, has great potential to provide further groundbreaking insights into the early evolution of eukaryotes," comments microbiologist Christa Schleper. "It has taken six long years to obtain a stable and highly enriched culture, but now we can use this experience to perform many biochemical studies and to cultivate other Asgard archaea as well." In addition, the scientists can now use the new imaging methods developed at ETH to investigate, for example, the close interactions between Asgard archaea and their bacterial partners. Basic cell biological processes such as cell division can also be studied in the future in order to shed light on the evolutionary origin of these mechanisms in eukaryotes.

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ESPRESSO and CARMENES discover two potentially habitable exo-Earths around a star near the sun

An international scientific team led by researchers at the Instituto de Astrofísica de Canarias (IAC) has discovered the presence of two planets with Earth-like masses in orbit around the star GJ 1002, a red dwarf not far from the Solar System. Both planets are in the habitability zone of the star.

"Nature seems bent on showing us that Earth-like planets are very common. With these two we now know 7 in planetary systems quite near to the Sun," explains Alejandro Suárez Mascareño, an IAC researcher, who is the first author of the study accepted for publication in Astronomy & Astrophysics.

The newly discovered planets orbit the star GJ 1002, which is at a distance of less than 16 light years from the Solar System. Both of them have masses similar to that of the Earth, and they are in the habitability zone of their star. GJ 1002b, the inner of the two, takes little more than 10 days to complete an orbit around the star, while GJ 1002c needs a little over 21 days. "GJ 1002 is a red dwarf star, with barely one eighth the mass of the Sun. It is quite a cool, faint star. This means that its habitability zone is very close to the star," explains Vera María Passegger, a co-author of the article and an IAC researcher.

The proximity of the star to our Solar System implies that the two planets, especially GJ 1002c, are excellent candidates for the characterization of their atmospheres based either on their reflected light, or on their thermal emission. "The future ANDES spectrograph for the ELT telescope at ESO in which the IAC is participating, could study the presence of oxygen in the atmosphere of GJ 1002c," notes Jonay I. González Hernández, an IAC researcher who is a co-author of the article. In addition, both planets satisfy the characteristics needed for them to be objectives for the future LIFE mission, which is presently in a study phase.

The discovery was made during a collaboration between the consortia of the two instruments ESPRESSO and CARMENES. GJ 1002 was observed by CARMENES between 2017 and 2019, and by ESPRESSO between 2019 and 2021. "Because of its low temperature the visible light from GJ 1002 is too faint to measure its variations in velocity with the majority of spectrographs," says Ignasi Ribas, researcher at the Institute of Space Sciences (ICE-CSIC) and director of the Institut d'Estudis Espacials de Catalunya (IEEC). CARMENES has a sensitivity over a wide range of near infrared wavelengths which is superior to those of other spectrographs aimed at detecting variations in the velocities of stars, and this allowed it to study GJ 1002, from the 3.5m telescope at Calar Alto observatory.

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New cause of melting Antarctic ice shelves

Researchers have discovered a process that can contribute to the melting of ice shelves in the Antarctic.

An international team of scientists found that adjacent ice shelves play a role in causing instability in others downstream.

The study, led by the University of East Anglia in the UK, also identified that a small ocean gyre -- a system of circulating ocean currents -- next to the Thwaites Ice Shelf can impact the amount of glacial-meltwater flowing beneath it. When that gyre is weaker, more warm water can access the areas beneath the ice shelf, causing it to melt.

The Thwaites Ice Shelf is one of the biggest ice shelves in West Antarctica and buttresses the eastern side of the Thwaites Glacier, which has been retreating rapidly over the last 20 years and is the largest contributor to global sea-level rise among Antarctic glaciers.

Using a unique dataset collected by sensors installed beneath the Thwaites Ice Shelf -- which has also thinned and weakened significantly in recent decades -- the researchers observed that the shallow layers of the ocean underneath it warmed considerably during the period from January 2020 to March 2021.

Most of this warming was driven by waters with a high volume of glacial meltwater originating from the Pine Island Ice Shelf, further east, flowing into the area beneath the Thwaites Ice Shelf.

The glacial meltwater mixes with saltwater when the ocean melts the base of ice shelves and can form a buoyant layer of water that is warmer than the surrounding waters. This lighter, relatively fresher and warmer water brings heat that melts the base of the Thwaites Ice Shelf.

Lead author Dr Tiago Dotto, of the Centre for Ocean and Atmospheric Sciences at UEA, said: "We have identified another process that could impact the stability of ice shelves, revealing the importance of local ocean circulation and sea-ice.

"Circumpolar Deep Water, a warm variety of Antarctic waters, is a key player in melting the base of ice shelves. However, in this study, we show that a great amount of heat at shallow layers beneath one ice shelf can be provided by waters originating from other melting ice shelves nearby.

"Therefore, what happens to one ice shelf, can impact the adjacent ice shelf, and so on.

This process is important for regions of high ice shelf melting such as the Amundsen Sea because one ice shelf sits next to the other, and the export of heat from one ice shelf can reach the next one through the ocean circulation."

Dr Dotto added: "These atmosphere-sea-ice-ocean interactions are important because they can prolong warm periods beneath ice shelves by allowing warm and meltwater-enriched water to enter adjacent ice-shelf cavities.

"Gyres potentially existing in other regions around Antarctica may also cause a greater number of ice shelves to be prone to intense basal melting associated with prolonged warm conditions, and as a result further contribute to global sea-level rise."

In January 2020 colleagues from the US drilled holes in the ice and installed sensors monitoring temperature, salinity and ocean current beneath the Thwaites Ice Shelf.

For more than a year these sensors sent, via satellite, the data used to identify the ocean variations, for example how the temperature and meltwater content varied. From these observations, the researchers suspected that the excess of heat could not have originated locally at the Thwaites Ice Shelf because they did not see strong melting at the sites where the sensors were installed.

By combining the information with computer simulations to identify the origin of this heat, they found that the water that leaves the Pine Island Ice Shelf can access the areas beneath Thwaites Ice Shelf.

The mechanism that explains how these waters access the Thwaites Ice Shelf was identified by using model simulations and data collected by tags attached to seals. They both showed that a gyre near the Thwaites Ice Shelf weakens in winter, which allows more heat to reach shallow areas beneath the ice shelf.

Satellite images also showed that the Southern Hemisphere summer season of 2020/2021 was unusual because it had a high concentration of sea ice in regions near the Thwaites Ice Shelf.

Drawing on the simulations and previous research, the team hypothesised that the gyre was even weaker, so the excess of meltwater from adjacent ice shelves could not be moved away from that region by the currents and instead entered the Thwaites Ice Shelf.

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Climate impacts are increasing; textbooks aren't keeping pace

A new study from North Carolina State University finds that biology textbooks have done a poor job of incorporating material related to climate change. For example, the study found that most textbooks published in the 2010s included less information about climate change than they did in the previous decade -- despite significant advances in our understanding of how climate change is influencing ecosystems and the environment.

"In short, we found biology textbooks are failing to share adequate information about climate change, which is a generation-defining topic in the life sciences," says Jennifer Landin, corresponding author of the study and an associate professor of biological sciences at NC State. "These books are the baseline texts for helping students understand the science of life on Earth, yet they are providing very little information about a phenomenon that is having a profound impact on habitats, ecosystems, agriculture -- almost every aspect of life on Earth."

For the study, researchers analyzed coverage of climate change in 57 college biology textbooks published between 1970 and 2019. The researchers found that climate coverage has varied substantially over those five decades.

Prior to 1990, textbooks had a median of fewer than 10 sentences addressing climate change. In the 1990s, the median length of climate content was 30 sentences. The median length of climate content rose to 52 sentences in the 2000s, which is not surprising given the amount of emerging research into climate change and its impacts. However, the researchers found that the amount of climate coverage in textbooks actually declined in the 2010s -- dropping to a median of 45 sentences.

In addition to length, the nature of the content has also changed substantially over time. For example, sentences dedicated to actionable solutions to climate change peaked in the 1990s at more than 15% of the climate content. However, in more recent decades, actionable solutions make up only about 3% of the climate content.

"One of the most troubling findings was that textbooks are devoting substantially less space to addressing climate solutions now than they did in the 1990s -- even as they focus more on the effects of climate change," Landin says. "That suggests to students that nothing can be done, which is both wildly misleading and contributes to a sense of fatalism regarding climate change."

In addition, the position of climate change sections keeps moving further back in the books, from the last 15% of the overall text in the 1970s to the last 2.5% of the text in the 2010s.

"This is important because most instructors present textbook content in order, which means topics at the end of the book are often skipped," Landin says.

"However, it's not all bad news," Landin adds. "Textbooks in the 2000s and 2010s began including a wider variety of climate-relevant information, such as how climate is affecting species distributions, which can help students understand the various impacts of climate change.

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Heart health tip for older adults in 2023: Step it up a bit

The evidence-based health benefits of walking continue to accumulate, according to ongoing research by a University of Massachusetts Amherst physical activity epidemiologist, who leads an international consortium known as the Steps for Health Collaborative.

Findings from the latest study led by Amanda Paluch, assistant professor of kinesiology in the School of Public Health and Health Sciences, show that older adults who walked between 6,000 and 9,000 steps per day had a 40-50% reduced risk of a cardiovascular event, such as a heart attack or stroke, compared to those who walked 2,000 steps per day.

"We found for adults over 60, there was a strikingly lower risk of a cardiovascular event or disease over an average follow-up of six years," says Paluch, whose team's research was published this week in the journal Circulation. "When accumulating more steps per day, there was a progressively lower risk."

Earlier this year, research by Paluch and the Steps for Health Collaborative showed that more movement, even below the highly touted but unscientific "10,000 steps per day," was associated with longevity benefits. The meta-analysis of 15 studies involving nearly 50,000 people from four continents found that walking between 6,000 and 8,000 steps per day was linked with a lower risk of death from all causes among older adults.

Following those findings, Paluch and team wanted to tackle the less-charted territory of steps per day and cardiovascular disease. The results were similar, in terms of the most beneficial range of steps.

While there appears to be a continual additional benefit for those who walk more than 6,000 steps, Paluch says, encouraging the least-active older adults to take more steps is perhaps the most important public health message.

"The people who are the least active have the most to gain," she says. "For those who are at 2,000 or 3,000 steps a day, doing a little bit more can mean a lot for their heart health. If you're at 6,000 steps, getting to 7,000 and then to 8,000 also is beneficial, it's just a smaller, incremental improvement."

The meta-analysis of eight studies involved more than 20,000 people from the U.S. and 42 other countries. For younger adults, no link between steps per day and cardiovascular risk was detected.

"This is because cardiovascular disease is a disease of aging and often doesn't come to fruition until we're at older ages," says Paluch, whose project was supported by the Centers for Disease Control and Prevention (CDC). "You're not going to see many people develop cardiovascular disease after six years of follow-up in young to middle adulthood."

Future research involving younger adults and steps per day would focus on the precursors of cardiovascular disease, including high blood pressure, obesity and type 2 diabetes. "Those conditions develop in younger adults and are important for early prevention," Paluch says.

Four of the eight studies the researchers analyzed included data about walking intensity, or how fast the steps were taken. "We're interpreting these results with caution, but we did not find any striking association with walking intensity," she says. "There was no additional benefit with how fast you're walking, beyond the total number of steps that you accumulated."

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Common food dye can trigger inflammatory bowel diseases, animal study suggests

Long-term consumption of Allura Red food dye can be a potential trigger of inflammatory bowel diseases (IBDs), Crohn's disease and ulcerative colitis, says McMaster University's Waliul Khan. Researchers using experimental animal models of IBD found that continual exposure to Allura Red AC harms gut health and promotes inflammation.

The dye directly disrupts gut barrier function and increases the production of serotonin, a hormone/neurotransmitter found in the gut, which subsequently alters gut microbiota composition leading to increased susceptibility to colitis.

Khan said Allura Red (also called FD&C Red 40 and Food Red 17), is a common ingredient in candies, soft drinks, dairy products and some cereals. The dye is used to add colour and texture to foodstuffs, often to attract children.

The use of synthetic food dyes such as Allura Red has increased significantly over the last several decades, but there has been little earlier study of these dyes' effects on gut health. Khan and his team published their findings in Nature Communications. Yun Han (Eric) Kwon, who recently completed PhD in Khan's laboratory, is first author.

"This study demonstrates significant harmful effects of Allura Red on gut health and identifies gut serotonin as a critical factor mediating these effects. These findings have important implication in the prevention and management of gut inflammation," said Khan, the study's senior author, a professor of the Department of Pathology and Molecular Medicine and a principal investigator of Farncombe Family Digestive Health Research Institute.

"What we have found is striking and alarming, as this common synthetic food dye is a possible dietary trigger for IBDs. This research is a significant advance in alerting the public on the potential harms of food dyes that we consume daily," he said.

"The literature suggests that the consumption of Allura Red also affects certain allergies, immune disorders and behavioural problems in children, such as attention deficit hyperactivity disorder."

Khan said that IBDs are serious chronic inflammatory conditions of the human bowel that affect millions of people worldwide. While their exact causes are still not fully understood, studies have shown that dysregulated immune responses, genetic factors, gut microbiota imbalances, and environmental factors can trigger these conditions.

In recent years there has been significant progress in identifying susceptibility genes and understanding the role of the immune system and host microbiota in the pathogenesis of IBDs. However, similar advances in defining environmental risk factors have lagged, he said.

Khan said that environmental triggers for IBDs include the typical Western diet, which includes processed fats, red and processed meats, sugar and a lack of fibre. He added that the Western diet and processed food also includes large amounts of various additives and dyes.

He added that the study suggests a link between a commonly used food dye and IBDs and warrants further exploration between food dyes and IBDs at experimental, epidemiological and clinical levels.

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Early forests did not significantly change the atmospheric CO2

Scientists have discovered that the atmosphere contained far less CO2 than previously thought when forests emerged on our planet, the new study has important implications for understanding how land plants affect the climate.

The research has been led by the University of Copenhagen in collaboration with the University of Nottingham and alters 30 years of previous understanding. The study is published in Nature Communications.

Earth's continents were colonized by tall trees and forests about 385 million years ago. Before then, shallow shrub-like plants with vascular tissue, stems, shallow roots, and no flowers had invaded the land. Textbooks tell us that the atmosphere at that time had far higher CO2 levels than today and that an intense greenhouse effect led to a much warmer climate. The emergence of forests was previously thought to promote CO2 removal from the atmosphere, driving the Earth into a long cool period with ice cover at the poles.

Reconstructing atmospheric CO2 levels in the geological past is difficult and has previously relied on proxies that also depend on parameters that had to be assumed. Climate scientists agree that CO2 plays a crucial role in shaping Earth's climate both today and in the past. Therefore, a grand challenge for Earth scientist is to understand what has controlled the abundance CO2 in the atmosphere.

"We calibrated a mechanistic model for the gas-exchange between plant leaves and the ambient air to the oldest lineage of vascular land plants, namely clubmosses. With this approach, we could calculate the CO2 level in the air solely from observations made on the plant material," tells associate professor Tais W. Dahl from the Globe institute at University of Copenhagen, who led the study in collaboration with an international team of researchers from Germany, Saudi Arabia, UK, and USA.

The new method builds on three observations that can be made both in living plants and fossil plant tissue, including the ratio of two stable carbon isotopes and the size and density of stomata (pore openings) through which CO2 is taken up by the plant. The researchers calibrated the method in living clubmosses and found that this approach can accurately reproduce ambient CO2 levels in the greenhouse.

"The newly calibrated method to study CO2 levels from the geological record is superior to previous approaches that produce estimates with unbound error bars simply because they depend on parameters that cannot be independently constrained in the geological record," says Barry Lomax Professor at University of Nottingham and a co-author on the study.

The research team applied the method to some of the oldest vascular plant fossils that lived before and after trees evolved on our planet and discovered that the ratio of the two stable carbon isotopes, carbon-13 and carbon-12, is very similar to that of modern plants. Further, the stomata density and size were also very similar to that observed in their living descendants. These observations kickstarted a more thorough investigation of the early CO2 record.

Dahl and colleagues collected data from 66 fossils of three distinct species of club mosses found in 9 different localities worldwide 410 to 380 million years in age. In all cases, the atmospheric CO2 levels were only 30-70% higher (~525 -- 715 ppm) than today (~415 ppm). This is far lower than previously thought (2000-8000 ppm). Ppm stands for parts-per-million and is the unit used to measure carbon dioxide concentrations in air.

The team utilized a paleoclimate model to show that Earth was a temperate planet with mean tropical surface air temperatures of 24.1-24.6°C.

"We used a fully coupled atmosphere-ocean model to find that Earth had ice-covered poles when forests emerged. Yet, land plants could thrive in the tropical, subtropical and temperate zones," explains Georg Feulner from the Potsdam Institute for Climate in Germany, who co-authored the study.

The new study suggest that trees actually play an insignificant role on atmospheric CO2 levels over longer time scales because early trees had deeper root systems and produced more developed soils that are associated with lower nutrient loss. With more efficient nutrient recycling in soils, trees actually have a smaller weathering demand than the shallow shrub-like vegetation that came before them. This idea goes against previous thinking that trees with deeper root system promoted CO2 removal through enhanced chemical weathering and dissolution of silicate rocks.

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