Polar bears unlikely to adapt to longer summers

More time stranded on land means greater risk of starvation for polar bears, a new study indicates.

During three summer weeks, 20 polar bears closely observed by scientists tried different strategies to maintain energy reserves, including resting, scavenging and foraging.

Yet nearly all of them lost weight rapidly: on average around 1 kilogram, or 2.2 pounds, per day.

Some have speculated that polar bears might adapt to the longer ice-free seasons due to climate warming by acting like their grizzly bear relatives and either rest or eat terrestrial food.

The polar bears in this study tried versions of both strategies -- with little success.

"Neither strategy will allow polar bears to exist on land beyond a certain amount of time. Even those bears that were foraging lost body weight at the same rate as those that laid down," said Charles Robbins, director of the Washington State University Bear Center and co-author of the study in the journal Nature Communications.

"Polar bears are not grizzly bears wearing white coats. They're very, very different."

Usually larger than grizzly bears, adult male polar bears can reach 10 feet in length and weigh 1,500 pounds compared to grizzly bears' 8 feet and 800 pounds.

To maintain that great mass, polar bears rely on the energy-rich fat of seals, which they best catch on the ice.

Little has been known about polar bear energy expenditure and behavior when confined to land, so researchers used collars with video cameras and GPS to track polar bears summering in the western Hudson Bay region of Manitoba, Canada.

They wanted to see what the specialized ice-hunters ate and did during the extended time on land when their preferred seal prey was out of reach.

The researchers also weighed the bears before and after the observation period and measured their energy expenditures.

"We found a real diversity of bear behaviors, and as a result, we saw a diverse range of energy expenditures," said lead author Anthony Pagano, research wildlife biologist with the U.S. Geological Survey Polar Bear Research Program and former WSU post-doctoral researcher.

Many of the adult male polar bears simply laid down to conserve energy, burning calories at rates similar to hibernation.

Others, actively searched for food, consuming bird and caribou carcasses as well as berries, kelp and grasses.

In all, the researchers found a five-fold range in energy expenditure from an adult male that rested 98% of the time to the most active who clocked 330 kilometers (205 miles). Some adult females spent as much as 40% of their time foraging.

Yet all that activity didn't pay off.

"The terrestrial foods did give them some energetic benefit, but ultimately, the bears had to spend more energy to access those resources," said Pagano.

Three polar bears went for long swims -- one swimming 175 kilometers (about 110 miles) across the bay.

Two found carcasses in the water, a beluga and a seal, but neither bear could feed on their finds while swimming nor bring them back to land.

Only one bear out of the 20 gained weight after stumbling across a dead marine mammal on land.

The study focused on the southern-most extent of polar bear range in the western Hudson Bay, where climate warming is likely impacting the bears at a faster rate than other Arctic regions.

The polar bear population in the area has already declined by an estimated 30% since 1987.

This study indicates that polar bears across the Arctic are at risk of starvation as the ice-free period continues to grow.

"As polar bears are forced on land earlier, it cuts into the period that they normally acquire the majority of the energy they need to survive," said Pagano.

"With increased land use, the expectation is that we'll likely see increases in starvation, particularly with adolescents and females with cubs."

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Microbial awakening restructures high-latitude food webs as permafrost thaws

Alaska is on the front lines of climate change, experiencing some of the fastest rates of warming of any place in the world. And when temperatures rise in the state's interior -- a vast high-latitude region spanning 113 million acres -- permafrost there not only thaws, releasing significant amounts of its stored carbon back into the atmosphere where it further accelerates rising temperatures, but it decays. This decomposition has the potential to infuse above- and belowground food webs with carbon, which can affect energy flow between these critical ecological linkages and affect the species they support.

One of these species is the tundra vole, one of four Arctic or boreal forest animals that Philip Manlick, a research wildlife biologist with the USDA Forest Service Pacific Northwest Research Station in Juneau, Alaska, examined as part of his new study published today in the journal Nature Climate Change. Along with collaborators from the University of New Mexico and the University of Texas at Austin, Manlick used a novel technique to quantify the impacts of climate change on energy flow and carbon fluxes between plant-supported aboveground, or green, food webs and microbe-driven belowground, or brown, food webs using two species of vole, a shrew, and a spider as windows into the complex worlds.

"Understanding how energy moves through food webs helps us understand how ecosystems function and how animals might respond to stressors like climate change," Manlick said. "In Arctic and boreal ecosystems, it's well known that the climate is warming, permafrost is melting, and microbes are flourishing. But we know very little about the impacts of this process on terrestrial food webs and the animals they support."

A Novel Technique With Promise

The novel technique at the heart of the study involved measuring unique carbon isotope "fingerprints" in essential amino acids that only plants, bacteria, and fungi can produce. Animals can only acquire these molecules through their diets. This allowed these essential amino acids to serve as a biomarker that helped the researchers track how carbon was moving between green and brown food webs, which, ultimately, helped them detect changes.

"Scientists often argue about the importance of animals to ecosystem processes like carbon cycling, but when they eat resources from different food webs, they move carbon between storage pools," Manlick said. "In the future, we think this tool can be used to trace the fate of carbon through food webs to understand the functional roles of animals in ecosystem functions, like nutrient cycling."

The study analyzed bone collagen from museum specimens of tundra and red-backed voles and masked shrews from the Bonanza Creek Experimental Forest near Fairbanks, Alaska, in 1990 and 2021, a sample that represented animals exposed to long-term climate warming. To study the effects of short-term climate warming on animals, the researchers sampled Arctic wolf spiders near Toolik Lake, Alaska. Some of the spiders were gathered as controls and others were exposed to 2 °C warming in outdoor compartmentalized habitats called "mesocosms" in which the scientists could increase temperature on a micro scale to simulate climate warming.

At just over 12,000 acres, and encompassing interior forest and flood-plain habitats, Bonanza Creek Experimental Forest is an ideal site for studying the impacts of climate change on boreal forests and food webs because it provides a long-term record of change in interior Alaska. It was established by the USDA Forest Service 60 years ago and has been a National Science Foundation Long-term Ecological Research site since 1987. For Manlick, the site offers an opportunity to study how these boreal forest changes are affecting the animals living there and how the animals, themselves, affect forest processes through foraging and food web dynamics.

Significant Shift in Energy Source

Through their isotope analyses, Manlick and his colleagues detected significant changes in carbon assimilation in the mammals -- notably a shift from plant-based food webs to fungal-based food webs. In other words, fungi replaced plants as the main energy source -- with small mammals, like the shrews, assimilating up to 90 percent of their total carbon intake from fungal carbon, a more than 40-percent increase over historical specimens.

The same was true for the Arctic wolf spiders. They, too, shifted from plant-based to fungal-based food webs as the main source of their energy, assimilating more than 50 percent brown carbon under warming conditions, compared to 26 percent at control sites.

"Our study presents clear evidence that climate warming alters carbon flow and food web dynamics among aboveground consumers in Arctic tundra and boreal forest ecosystems -- across species, ecosystems, and long- and short-term warming scenarios," Manlick said. "And we show that these changes are the consequence of a change from predominantly green, plant-based food webs to brown, microbe-based food webs."

What's behind the shift?

The scientists suspect brown carbon is being transferred to aboveground consumers, like the mammals and spiders, in a series of predation events known as trophic pathways. Increased warming results in increased decomposition in both permafrost on the tundra and in boreal forests; fungi feed on this decomposing plant matter and are, in turn, consumed by arthropods, mites, and earthworms that transfer the fungal carbon upward in the food web where they, in turn, are consumed by the voles, shrews, and spiders.

"Climate warming significantly alters the flow of energy through food webs, such that animals who were historically supported by plant-based food webs are now supported by fungal-based food webs derived from belowground decomposition," Manlick said.

Animals Can Alter Carbon Cycling

Manlick and his colleagues' work underscores that animals serve as a crucial link between green and brown food webs; it also shows that climate warming alters this link across species in the Arctic and in boreal forests. The potential implications of these climate-induced shifts are greater than the small size of these species might imply.

"Shifts in these interactions can have indirect effects on nutrient cycling and ecosystem function," Manlick said.

For example, if voles are getting more of their energy from belowground sources, they may be consuming fewer plants, which could increase carbon storage in aboveground ecosystems.

"Much of the current work in high latitudes has focused on 'Arctic greening,' or the idea that climate warming is leading to more plant growth and greener ecosystems. We found the exact opposite pattern -- food webs are 'browning,'" he said.

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Groundwater depletion rates in India could triple in coming decades as climate warms, study shows

A new University of Michigan-led study finds that farmers in India have adapted to warming temperatures by intensifying the withdrawal of groundwater used for irrigation. If the trend continues, the rate of groundwater loss could triple by 2080, further threatening India's food and water security.

Reduced water availability in India due to groundwater depletion and climate change could threaten the livelihoods of more than one-third of the country's 1.4 billion residents and has global implications. India recently overtook China to become the world's most populous nation and is the second-largest global producer of common cereal grains including rice and wheat.

"We find that farmers are already increasing irrigation use in response to warming temperatures, an adaptation strategy that has not been accounted for in previous projections of groundwater depletion in India," said study senior author Meha Jain, assistant professor at U-M's School for Environment and Sustainability. "This is of concern, given that India is the world's largest consumer of groundwater and is a critical resource for the regional and global food supply."

The lead author is Nishan Bhattarai of the Department of Geography and Environmental Sustainability at the University of Oklahoma, formerly a postdoctoral researcher in Jain's U-M lab.

The study, scheduled for online publication Sept. 1 in the journal Science Advances, analyzed historical data on groundwater levels, climate and crop water stress to look for recent changes in withdrawal rates due to warming. The researchers also used temperature and precipitation projections from 10 climate models to estimate future rates of groundwater loss across India.

Previous studies have focused on the individual effects of climate change and groundwater depletion on crop production in India. Those studies did not account for farmer decision-making, including how farmers may adapt to changing climate through changes in irrigation decisions.

The new study takes into account the fact that warmer temperatures may increase water demand from stressed crops, which in turn may lead to increased irrigation by farmers.

"Using our model estimates, we project that under a business-as-usual scenario, warming temperatures may triple groundwater depletion rates in the future and expand groundwater depletion hotspots to include south and central India," Bhattarai said.

"Without policies and interventions to conserve groundwater, we find that warming temperatures will likely amplify India's already existing groundwater depletion problem, further challenging India's food and water security in the face of climate change."

Previous studies found that climate change could decrease the yield of staple Indian crops by up to 20% by mid-century. At the same time, the country's groundwater is being depleted at an alarming rate, primarily because of water withdrawal for irrigation.

For the newly published study, the researchers developed a dataset that contains groundwater depths from thousands of wells across India, high-resolution satellite observations that measured crop water stress, and temperature and precipitation records.

Most climate models call for increased temperature, increased monsoon (June through September) precipitation and decreased winter precipitation in India over the coming decades. The U-M-led research team found that warming temperatures coupled with declining winter precipitation more than offset added groundwater recharge from increased monsoon precipitation, resulting in accelerated groundwater declines.

Across various climate-change scenarios, their estimates of groundwater-level declines between 2041 and 2080 were more than three times current depletion rates, on average.

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Climate: Lessons from the latest global warming

56 million years ago, the Earth experienced one of the largest and most rapid climate warming events in its history: the Paleocene-Eocene Thermal Maximum (PETM), which has similarities to current and future warming. This episode saw global temperatures rise by 5-8°C. It was marked by an increase in the seasonality of rainfalls, which led to the movement of large quantities of clay into the ocean, making it uninhabitable for certain living species. This scenario could be repeated today. This is what a team from the University of Geneva (UNIGE) has revealed, thanks to the analysis of sediments taken from the deep waters of the Gulf of Mexico. These results can be found in the journal Geology.

The Paleocene-Eocene Thermal Maximum (PETM), which occurred 56 million years ago, is the largest and most rapid climatic disturbance of the Cenozoic era (65.5 million years ago to the present day). Exceptional both in terms of its amplitude (5-8°C increase) and its suddenness (5,000 years, a very short time on a geological scale), this episode was marked by a warming of temperatures on a global scale. It lasted for about 200 000 years and led to numerous marine and terrestrial extinctions.

It would have been caused by a high concentration of carbon dioxide -- the famous CO2 -- and methane in the atmosphere, two powerful greenhouse gases. As is the case currently, these gases may have been released by several phenomena, certainly in combination: the release of methane hydrates trapped on the seabed, the sudden and significant melting of the permafrost, and the injection of magma into the organic sediments of the western edge of Norway. The origin of these processes is still under debate. The impact of a meteorite and/or the effects of intense volcanic activity in the depths of the North Atlantic could be responsible.

A geological ''archive'' of unprecedented quality

Because of the many similarities between the PETM and the current warming, the geological remains of this period are being closely studied by scientists. A team from the UNIGE is now reporting new elements. ''The objective of our study was to investigate the influence of these climatic changes on sedimentary systems, i.e. on the processes of sediment formation and deposition, and to understand how these changes could have been transmitted from the atmosphere to the depths of the ocean,'' explains Lucas Vimpere, a post-doctoral scholar at the Section of Earth and Environmental Sciences of the UNIGE's Faculty of Science and first author of the study.

The researchers analysed sediments taken from more than 8km deep in the Gulf of Mexico. This basin acts as a giant ''sink'' into which material eroded and transported from the North American continent over millions of years is discharged. ''For reasons of cost and infrastructure, the sediments used to study the PETM are generally taken from shallow marine or continental environments. Thanks to the collaboration of an oil company, we were able to obtain a sample of unprecedented quality, without any alteration'', says the researcher. The 543-metre-long core contains a 180-metre-thick PETM sedimentary record, making it the most complete geological ''archive'' of this period in the world.

More clay on the ocean floor

The UNIGE scientists found that it was composed first of a large layer of clay and then of a layer of sand, a counter-intuitive result. ''At the time of the PETM, we thought that there had been more precipitation, and therefore more erosion, and that large quantities of sand had then been transported first by the fluvial systems into the oceans. However, thanks to our sample, we were able to determine that it was the clays and not the sands that were transported in the first instance'', explains Sébastien Castelltort, full professor at the Earth and Environmental Sciences Section of the UNIGE Faculty of Science, and last author of the study.

This established that the period was not marked by an increase in the annual rate of precipitation but by an increase in its seasonality and intensity. ''This resulted in increased mobility of the river channels -- the deepest areas of a river -- which in turn transported large quantities of fluvial clays deposited on the adjacent alluvial plains to the ocean depths. We can now consider the presence of clay in deep basins as a marker of increased rainfall seasonality,'' says Lucas Vimpere. The phenomenon has led to an increase in ocean turbidity that is harmful to marine life, especially corals.

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River longer than the Thames beneath Antarctic ice sheet could affect ice loss

An unexpected river under the Antarctic ice sheet affects the flow and melting of ice, potentially accelerating ice loss as the climate warms.

The 460km-long river is revealed in a new study, which details how it collects water at the base of the Antarctic ice sheet from an area the size of Germany and France combined. Its discovery shows the base of the ice sheet has more active water flow than previously thought, which could make it more susceptible to changes in climate.

The discovery was made by researchers at Imperial College London, the University of Waterloo, Canada, Universiti Malaysia Terengganu, and Newcastle University, with the details published today in Nature Geoscience.

Co-author Professor Martin Siegert, from the Grantham Institute at Imperial College London, said: "When we first discovered lakes beneath the Antarctic ice a couple of decades ago, we thought they were isolated from each other. Now we are starting to understand there are whole systems down there, interconnected by vast river networks, just as they might be if there weren't thousands of metres of ice on top of them.

"The region where this study is based holds enough ice to raise the sea level globally by 4.3m. How much of this ice melts, and how quickly, is linked to how slippery the base of the ice is. The newly discovered river system could strongly influence this process."

Water can appear beneath ice sheets in two main ways: from surface meltwater running down through deep crevasses, or by melting at the base, caused by the natural heat of the Earth and friction as the ice moves over land.

However, the ice sheets around the north and south poles have different characteristics. In Greenland, the surface experiences strong melting over the summer months, where immense amounts of water channel down through deep crevasses called moulins.

In Antarctica, however, the surface doesn't melt in sufficient quantities to create moulins, as the summers are still too cold. It was thought this meant that there was relatively little water at the base of the Antarctic ice sheets.

The new discovery turns this idea on its head, showing there is sufficient water from basal melt alone to create huge river systems under kilometres-thick ice.

The discovery was made through a combination of airborne radar surveys that allow researchers to look beneath the ice and modelling of the ice sheet hydrology. The team focussed on a largely inaccessible and understudied area that includes ice from both the East and West Antarctic Ice Sheets and reaches the Weddell Sea.

That such a large system could be undiscovered until now is testament to how much we still need to learn about the continent, says lead researcher Dr Christine Dow from the University of Waterloo.

She said: "From satellite measurements we know which regions of Antarctica are losing ice, and how much, but we don't necessarily know why. This discovery could be a missing link in our models. We could be hugely underestimating how quickly the system will melt by not accounting for the influence of these river systems.

"Only by knowing why ice is being lost can we make models and predictions of how the ice will react in the future under further global heating, and how much this could raise global sea levels."

For example, the newly discovered river emerges into the sea beneath a floating ice shelf - where a glacier extending out from the land is buoyant enough to begin floating on the ocean water. The freshwater from the river however churns up warmer water towards the bottom of the ice shelf, melting it from below.

Co-author Dr Neil Ross, from the University of Newcastle, said: "Previous studies have looked at the interaction between the edges of ice sheets and ocean water to determine what melting looks like. However, the discovery of a river that reaches hundreds of kilometres inland driving some of these processes shows that we cannot understand the ice melt fully without considering the whole system: ice sheet, ocean, and freshwater."

The existence of large under-ice rivers also needs to be taken into account when predicting the possible consequences of climate change in the region. For example, if summers warm enough to cause enough surface melt that the water reaches the base of the ice sheet, it could have large effects on the river systems, potentially tipping Antarctica to a Greenland-like state, where ice loss is much faster.

There are also potential feedback loops that would accelerate ice loss. For example, if the ice starts to flow faster as water accumulated at the base, then this will increase friction where the ice runs over dry land, which could increase the amount of basal melting and water produced.

Read more at Science Daily

A window of opportunity for methane to slip by nature's filters

Warmer oceans can lead to large amounts of methane being released from the seabeds, which may amplify climate warming. A new study develops a method to understand the role of microorganisms in increasing emissions of methane from seabeds.

Vast reservoirs of the potent greenhouse gas methane are stored beneath the sea in a solid ice-like combination with water. This solid is known as methane hydrate. For over three decades, various concerns have been raised that warming the seafloor may cause this methane to be rapidly released, perhaps even reaching the atmosphere where it would cause further climate warming. Happily, this methane hydrate is mostly located beneath the seafloor and under hundreds of meters of seawater. Even if warming melts this methane hydrate and releases methane gas, the natural microbial filters present in the seafloor were expected to destroy most of the methane before it ever reaches the open seawater.

However, there have been some gaps in our knowledge of the relevant seafloor processes. In particular, can seafloor warming be rapid enough that methane hydrate could melt so fast that the released methane would overwhelm and ultimately bypass the natural microbial filters? "The microbial filter layer in the sediment -- we call it the 'sulfate-methane transition', where methane is removed -- is somewhat delicate," explains Assistant Professor Christian Stranne at the Department of Geological Sciences, Stockholm University. "The filter layer takes many years to form and reach peak methane-consuming efficiency. The filter is a living thing, made of microorganisms that consume methane under anaerobic (no-oxygen) conditions. The filter also moves up and down within the sediment, depending on the rate at which methane is reaching it."

In a new study, just published in Communications Earth and Environment, Stranne and colleagues from Stockholm University and Linnaeus University have combined a new model of the biological behaviour and vertical movements of this microbial filter with existing models of seafloor sediments' physical behaviour. The physical parts of the model include processes such as how cracks form and methane can move up thorough the sediment after methane hydrates melt.

Christian Stranne explains: "Imagine that the amount of methane rising through the sediment suddenly increases, as might happen if methane hydrate begins to melt faster. It can take decades for the filter to adjust itself to consume methane at the new rate. Our new study shows that during the time that the filter is not reestablished, substantial methane can leak past the filter, and into the ocean water."

Despite this "window of opportunity," methane from melting hydrates that reaches the seawater faces further methane-destroying processes. These processes make it nearly impossible for substantial methane from methane hydrate melting to reach the atmosphere. However, methods as demonstrated in this study can be applied to other regions where seafloor-released methane is much shallower and is more likely to reach the atmosphere, such as the Arctic continental shelves, according to Christian Stranne.

"Methane hydrates are a massive storehouse of carbon, so it remains important to understand how they interact with ocean changes, and potentially, the atmosphere, over long and, in the case of our study, rather short timescales. We now know that there is indeed a possible process for melting methane hydrates to temporarily bypass what was previously thought to be a strong filter in the sediment," says Christian Stranne.

The warming rate is, however, of great importance: "Our results suggest that if our oceans warm at a pace significantly lower than 1 °C per 100 years, the filter can keep up with the pace and remain highly efficient. Unfortunately, we see higher warming rates than that in some of our oceans."

Read more at Science Daily

Fjords emit as much methane as all the deep oceans globally

During heavy storms, the normally stratified layers of water in ocean fjords get mixed, which leads to oxygenation of the fjord floor. But these storm events also result in a spike in methane emissions from fjords to the atmosphere.

Researchers from the University of Gothenburg have estimated that the total emissions of this climate-warming gas are as great from fjords as from all the deep ocean areas in the world put together.

The world's fjords were created when the inland ice receded, and are a relatively rare natural feature, constituting only 0.13 per cent of all the oceans on Earth. However, according to researchers from the University of Gothenburg, emissions of methane from the surface of fjords are comparable to the emissions of this gas from global deep oceans which account for 84 per cent of the global sea surface area. These results were presented in an article in the science journal Limnology and Oceanography Letters.

"It's been known for some time that many fjords have anoxic environments closest to the bottom and that methane forms in the bottom sediment. Usually, only a small portion of this gas ever reaches the atmosphere because it gets broken down as it ascends through the more oxygen-rich waters closer to the surface. But in our research, we recorded large emissions of methane when the water in the fjord was mixed during storm events, for example," says Stefano Bonaglia, researcher in marine geochemistry at the Department of Marine Sciences at the University of Gothenburg.

Anoxic environments produce methane

Detecting and budgeting methane emissions to the atmosphere is essential to be able to model the future climate. Researchers estimate that methane emissions cause about 30 per cent of the greenhouse effect. The contribution of the oceans to methane emissions is budgeted as significantly smaller than from land areas. But human activity has increased eutrophication in coastal areas, and this has created larger areas of anoxic waters on the sea floor. This is particularly apparent in fjords, and although they constitute only 0.13 per cent of the global sea surface area, they account for about half of all methane emissions to the atmosphere.

"This is because in fjords, carbon-rich sediment is deposited from marine plants and animals as well as from materials entering the fjords from the surrounding land via streams that flow into them. As fjords are relatively protected from ocean currents, the water tends to remain stratified in layers at different temperatures and with different concentrations of salt and oxygen. The layers closest to the fjord floor are anoxic regions where methane gas forms as the material in the sediment decomposes," says Stefano Bonaglia.

Agriculture drives eutrophication

The researchers from the University of Gothenburg studied By Fjord near Uddevalla during the period 2009-2021 and conducted field studies to measure methane production in the fjord. By Fjord is hypoxic and affected by eutrophication. The Bäve River flows into the fjord, bringing with it high concentrations of nutrients from agriculture in the region. It was clear that during mixing events in the fjord, emissions of methane to the atmosphere rose. During these events, anoxic water from the bottom is lifted rapidly to the surface, taking the methane with it, which can then be emitted into the atmosphere.

1 million tonnes methane

"The methane emissions were high, and American researchers have seen the same types of events in fjords in Canada. We estimate that emissions from all the world's fjords are of the same magnitude -- around 1 Teragram (Tg) or 1 million tonnes per year -- as the budgeted emissions from global deep oceans. This is because the distance from the bottom to the surface of a fjord is much shorter than in deep oceans. This results in more organic matter being deposited in the sediment, and not enough time for the methane to be broken down on its way up to the surface," says Stefano Bonaglia, and adds that if climate change leads to more extreme weather events, methane emissions may rise, but only up to a certain point.

Read more at Science Daily

Climate change could spark the next pandemic, new study finds

As Earth's climate continues to warm, researchers predict wild animals will be forced to relocate their habitats -- likely to regions with large human populations -- dramatically increasing the risk of a viral jump to humans that could lead to the next pandemic.

This link between climate change and viral transmission is described by an international research team led by scientists at Georgetown University and is published April 28 in Nature.

In their study, the scientists conducted the first comprehensive assessment of how climate change will restructure the global mammalian virome. The work focuses on geographic range shifts -- the journeys that species will undertake as they follow their habitats into new areas. As they encounter other mammals for the first time, the study projects they will share thousands of viruses.

They say these shifts bring greater opportunities for viruses like Ebola or coronaviruses to emerge in new areas, making them harder to track, and into new types of animals, making it easier for viruses to jump across a "stepping stone" species into humans.

"The closest analogy is actually the risks we see in the wildlife trade," says the study's lead author Colin Carlson, PhD, an assistant research professor at the Center for Global Health Science and Security at Georgetown University Medical Center. "We worry about markets because bringing unhealthy animals together in unnatural combinations creates opportunities for this stepwise process of emergence -- like how SARS jumped from bats to civets, then civets to people. But markets aren't special anymore; in a changing climate, that kind of process will be the reality in nature just about everywhere."

Of concern is that animal habitats will move disproportionately in the same places as human settlements, creating new hotspots of spillover risk. Much of this process may already be underway in today's 1.2 degrees warmer world, and efforts to reduce greenhouse gas emissions may not stop these events from unfolding.

An additional important finding is the impact rising temperatures will have on bats, which account for the majority of novel viral sharing. Their ability to fly will allow them to travel long distances, and share the most viruses. Because of their central role in viral emergence, the greatest impacts are projected in southeast Asia, a global hotspot of bat diversity.

"At every step," said Carlson, "our simulations have taken us by surprise. We've spent years double-checking those results, with different data and different assumptions, but the models always lead us to these conclusions. It's a really stunning example of just how well we can, actually, predict the future if we try."

As viruses start to jump between host species at unprecedented rates, the authors say that the impacts on conservation and human health could be stunning.

"This mechanism adds yet another layer to how climate change will threaten human and animal health," says the study's co-lead author Gregory Albery, PhD, a postdoctoral fellow in the Department of Biology in the Georgetown University College of Arts and Sciences.

"It's unclear exactly how these new viruses might affect the species involved, but it's likely that many of them will translate to new conservation risks and fuel the emergence of novel outbreaks in humans."

Altogether, the study suggests that climate change will become the biggest upstream risk factor for disease emergence -- exceeding higher-profile issues like deforestation, wildlife trade, and industrial agriculture. The authors say the solution is to pair wildlife disease surveillance with real-time studies of environmental change.

"When a Brazilian free-tailed bat makes it all the way to Appalachia, we should be invested in knowing what viruses are tagging along," says Carlson. "Trying to spot these host jumps in real-time is the only way we'll be able to prevent this process from leading to more spillovers and more pandemics."

"We're closer to predicting and preventing the next pandemic than ever," says Carlson. "This is a big step towards prediction -- now we have to start working on the harder half of the problem."

"The COVID-19 pandemic, and the previous spread of SARS, Ebola, and Zika, show how a virus jumping from animals to humans can have massive effects. To predict their jump to humans, we need to know about their spread among other animals," said Sam Scheiner, a program director with the U.S. National Science Foundation (NSF), which funded the research. "This research shows how animal movements and interactions due to a warming climate might increase the number of viruses jumping between species."

Read more at Science Daily

Greenland’s groundwater changes with thinning ice sheet

For more than a decade, a team of University of Montana researchers and students have studied the dynamics of the Greenland Ice Sheet as it responds to a warming climate. Department of Geosciences researchers Toby Meierbachtol and Joel Harper said water has always been central to their research.

"The water from melting of the ice can run off the surface to the ocean and contribute to sea level rise, it can refreeze in place and actually warm the ice, and it can even reach the bottom of the ice sheet and act as a sort of lubricant to make the ice slide quickly over its bed," Meierbachtol said. "The importance of water in controlling the response of Greenland to warming is hard to overstate."

But while much of their focus has been on the importance of water in controlling processes occurring on the ice sheet, their most recent research findings have flipped the order of their thinking.

As outlined in their recent article in Nature Geoscience, Meierbachtol, Harper and an international team of researchers discovered that changes to the ice sheet have an immediate impact on the groundwater underlying the Greenland island, an area larger than the state of Alaska.

"We have been focused on water's impacts on ice sheet change," said Harper. "But our most recent findings show that changes in the ice sheet have a real impact on Arctic hydrology -- specifically the massive groundwater system extending under the ice sheet."

This latest revelation occurred thanks to a marriage of drilling techniques, with international collaborators boring an angled hole 650 meters through bedrock underneath a Greenland glacier to measure groundwater conditions deep under the ice sheet. Meanwhile, UM and University of Wyoming researchers drilled 32 holes from atop the glacier, through nearly a kilometer of ice, to measure water conditions at the interface between ice and bedrock, which forms an important boundary controlling groundwater flow below.

The system that UM has perfected over the years involves drilling with a combination of very hot water under high pressure typically for 12 or more hours at a time.

"We practice and rehearse to make the operation flow smoothly," Harper said, noting they always include one to two undergraduate students on an expedition. "Everyone on the team has an important and specific role to fill."

After drilling the team installs sensors in the ice column and at the ice sheet bed to measure ice dynamics and water conditions as water flows under the ice to margin. Time is always of the essence because the cold ice freezes the hole shut in as little as two hours.

The dual drilling approach facilitated the first-ever measurements of groundwater response to a changing ice sheet, and the eight-year data record yielded some unexpected results.

"By studying areas that were covered by ice 10,000 years ago during the last ice age, the field has known that the huge mass and vast amounts of water from melting ice can impact the underlying groundwater," Meierbachtol said, "but the paradigm has been that the groundwater response to ice sheet change is long: thousands of years. What we've shown here is that the groundwater response to Greenland's change is immediate."

This new understanding could have important downstream implications for how Greenland's thinning impacts the Arctic, Harper said. The thinning ice could reduce the rate of groundwater flow to the ocean, changing the water temperature and salinity balance that is important for ocean circulation patterns.

"In thinking about the complex feedbacks that occur from Greenland's ongoing change, we as a field have really neglected the groundwater component because we thought it was more or less dormant over the decade to century timescales that are important for us as a society," Harper said. "But now we recognize that the groundwater system actually changes quite rapidly, and there are some compelling reasons for why this could really matter for the broader Arctic."

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A recent reversal in the response of western Greenland’s ice caps to climate change

Greenland may be best known for its enormous continental scale ice sheet that soars up to 3,000 meters above sea level, whose rapid melting is a leading contributor to global sea level rise. But surrounding this massive ice sheet, which covers 79% of the world's largest island, is Greenland's rugged coastline dotted with ice capped mountainous peaks. These peripheral glaciers and ice caps are now also undergoing severe melting due to anthropogenic (human-caused) warming. However, climate warming and the loss of these ice caps may not have always gone hand-in-hand.

New collaborative research from the Woods Hole Oceanographic Institution and five partner institutions (University of Arizona, University of Washington, Pennsylvania State University, Desert Research Institute and University of Bergen), published today in Nature Geoscience, reveals that during past periods glaciers and ice caps in coastal west Greenland experienced climate conditions much different than the interior of Greenland. Over the past 2,000 years, these ice caps endured periods of warming during which they grew larger rather than shrinking.

This novel study breaks down the climate history displayed in a core taken from an ice cap off Greenland's western coast. According to the study's researchers, while ice core drilling has been ongoing in Greenland since the mid-20th century, coastal ice core studies remain extremely limited, and these new findings are providing a new perspective on climate change compared to what scientists previously understood by using ice cores from the interior portions of the Greenland ice sheet alone.

"Glaciers and ice caps are unique high-resolution repositories of Earth's climate history, and ice core analysis allows scientists to examine how environmental changes -- like shifts in precipitation patterns and global warming -- affect rates of snowfall, melting, and in turn influence ice cap growth and retreat," said Sarah Das, Associate Scientist of Geology and Geophysics at WHOI. "Looking at differences in climate change recorded across several ice core records allows us to compare and contrast the climate history and ice response across different regions of the Arctic." However, during the course of this study, it also became clear that many of these coastal ice caps are now melting so substantially that these incredible archives are in great peril of disappearing forever.

Due to the challenging nature of studying and accessing these ice caps, this team was the first to do such work, centering their study, which began in 2015, around a core collected from the Nuussuaq Peninsula in Greenland. This single core offers insight into how coastal climate conditions and ice cap changes covaried during the last 2,000 years, due to tracked changes in its chemical composition and the amount of snowfall archived year after year in the core. Through their analysis, investigators found that during periods of past warming, ice caps were growing rather than melting, contradicting what we see in the present day.

"Currently, we know Greenland's ice caps are melting due to warming, further contributing to sea level rise. But, we have yet to explore how these ice caps have changed in the past due to changes in climate," said Matthew Osman, postdoctoral research associate at the University of Arizona and a 2019 graduate of the MIT-WHOI Joint program. "The findings of this study were a surprise because we see that there is an ongoing shift in the fundamental response of these ice caps to climate: today, they're disappearing, but in the past, within small degrees of warming, they actually tended to grow."

According to Das and Osman, this phenomenon happens because of a "tug-of-war" between what causes an ice cap to grow (increased precipitation) or recede (increased melting) during periods of warming. Today, scientists observe melting rates that are outpacing the rate of annual snowfall atop ice caps. However, in past centuries these ice caps would expand due to increased levels of precipitation brought about by warmer temperatures. The difference between the past and present is the severity of modern anthropogenic warming.

The team gathered this data by drilling through an ice cap on top of one of the higher peaks of the Nuussuaq Peninsula. The entire core, about 140 meters in length, took about a week to retrieve. They then brought the meter-long pieces of core to the National Science Foundation Ice Core Facility in Denver, Colorado, and stored at -20 degrees Celsius. The core pieces were then analyzed by their layers for melt features and trace chemistry at the Desert Research Institute in Reno, Nevada. By looking at different properties of the core's chemical content, such as parts per billion of lead and sulfur, investigators were able to accurately date the core by combining these measurements with a model of past glacier flow.

"These model estimates of ice cap flow, coupled with the actual ages that we have from this high precision chemistry, help us outline changes in ice cap growth over time. This method provides a new way of understanding past ice cap changes and how that is correlated with climate," said Das. "Because we're collecting a climate record from the coast, we're able to document for the first time that there were these large shifts in temperature, snowfall and melt over the last 2,000 years, showing much more variability than is observed in records from the interior of Greenland," Das added.

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The warming climate is causing animals to 'shapeshift'

Climate change is not only a human problem; animals have to adapt to it as well. Some "warm-blooded" animals are shapeshifting and getting larger beaks, legs, and ears to better regulate their body temperatures as the planet gets hotter. Bird researcher Sara Ryding of Deakin University in Australia describes these changes in a review published September 7th in the journal Trends in Ecology and Evolution.

"A lot of the time when climate change is discussed in mainstream media, people are asking 'can humans overcome this?', or 'what technology can solve this?'. It's high time we recognized that animals also have to adapt to these changes, but this is occurring over a far shorter timescale than would have occurred through most of evolutionary time," says Ryding (@zuuletc). "The climate change that we have created is heaping a whole lot of pressure on them, and while some species will adapt, others will not."

Ryding notes that climate change is a complex and multifaceted phenomenon that's been occurring progressively, so it is difficult to pinpoint just one cause of the shapeshifting. But these changes have been occurring across wide geographical regions and among a diverse array of species, so there is little in common apart from climate change.

Strong shapeshifting has particularly been reported in birds. Several species of Australian parrot have shown, on average, a 4%-10% increase in bill size since 1871, and this is positively correlated with the summer temperature each year. North American dark-eyed juncos, a type of small songbird, had a link between increased bill size and short-term temperature extremes in cold environments. There have also been reported changes in mammalian species. Researchers have reported tail length increases in wood mice and tail and leg size increases in masked shrews.

"The increases in appendage size we see so far are quite small -- less than 10% -- so the changes are unlikely to be immediately noticeable," says Ryding. "However, prominent appendages such as ears are predicted to increase -- so we might end up with a live-action Dumbo in the not-so-distant future."

Next, Ryding intends to investigate shapeshifting in Australian birds firsthand by 3D scanning museum bird specimens from the past 100 years. It will give her team a better understanding of which birds are changing appendage size due to climate change and why.

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Climate warming can influence fungal communities on oak leaves across the growing season

Climate warming plays a larger role than plant genes in influencing the number and identity of fungal species on oak leaves, especially in autumn. Recently published in the journal New Phytologist, this research by ecologists sheds light on how warming and tree genes affect the dynamics of fungal communities across the season.

"One of our major findings was that elevated temperature decreased the number of fungal species and changed their community composition, especially in the late season" says Maria Faticov, a researcher at the Department of Ecology, Environment and Plant Sciences (DEEP) at Stockholm University.

Plants host thousands of microscopic organisms and leaves are no exception. Leaves harbour a large diversity of microorganisms including fungi, bacteria and, less frequently, archaea. Fungi are among the most diverse groups of microorganisms living on leaves. Some of these microscopic fungi cause disease, others can promote plant growth and defend leaves against biotic and abiotic stresses, and still others play an important role in leaf senescence and decomposition.

Climate is one of the main factors influencing fungal development, either directly or indirectly, by triggering plant defences.

"From earlier studies, we know that the number of fungal species and their abundance change as leaves age and the season progresses from spring to autumn. What we do not know is what role climate warming and plant genetic variation play in shaping fungal communities across the growing season" says Ayco Tack, associate professor at the Department of Ecology, Environment and Plant Sciences, Stockholm University.

To answer this question, researchers took on a challenging project -- they built 6 identical cages in a field to the north of Stockholm, each cage the size of a small living room. Scientists put 132 young oak trees into the cages that represented 5 different genotypes. Half of the cages were heated from May to October using ceramic heaters. The remaining ones were left as control and did not have heaters in them. The temperature in the heated cages was increased by ca 2°C to mimic the global temperature increase predicted by scientists to occur by the end of the century. Researchers collected leaves in the early, middle and late growing season and used DNA sequencing to find out which fungi had colonised the leaves. This way they could compare the changes in fungal community structure between the control and warming treatment and also among oak genotypes.

"We observed that fungal community composition drastically changed from spring to autumn, with yeasts increasing in relative abundance and fungal pathogens decreasing. Interestingly, while experimental warming had a major impact on the fungal community, oak genotype explained only a minor part of the variation in the number of fungal species and their composition" says Maria Faticov.

These findings suggest that warming is one of the most important environmental factors shaping fungal community development during the growing season and emphasizes how profound the effects of ongoing climate change may be to plant health and ecosystem functioning.

Researchers did not link the observed change in fungal community structure under warming with plant health and ecosystem functioning. More detailed long-term experiments are needed to predict how changes in the fungal community under climate warming will influence the plants they live on and their surrounding environment.

Read more at Science Daily