With Temperatures Rising, Can Animals Survive the Heat Stress?

A growing number of studies show that warming temperatures are increasing mortality in creatures ranging from birds in the Mojave Desert, to mammals in Australia, to bumblebees in North America. Researchers warn that heat stress could become a major factor in future extinctions.

Populations of the American kestrel (above) and other birds are declining in the Mojave Desert as temperatures rise. SHUTTERSTOCK

n the early 20th century, pioneering naturalist Joseph Grinnell and his team studied the flora and fauna of California, conducting meticulous surveys across large swaths of the state, including the Mojave Desert. They collected 100,000 specimens and took 74,000 pages of field notes, creating an invaluable baseline against which to measure long-term change.

Several years ago, a research team from the Grinnell Resurvey Project at the University of California, Berkeley set out to find how desert birds had fared over the last century. The changes were profound. In a study published last fall, the team found that on average temperatures in the desert had increased 3.6 degrees Fahrenheit, making one of the world’s hottest places even hotter.

They also found that nearly a third of the 135 bird species present a century ago are far less common today and not nearly as widespread. The “heat stress associated with climate change” is the culprit, the study concluded, because desert birds need more water to keep cool, but it is not available.

“We often think that climate change may cause a mass mortality event in the future, but this study tells us that the change in climate that has already occurred is too hot and in certain areas, animals can’t tolerate the warming and drying that has already occurred,” said Eric Riddell, a physiological ecologist and the lead author.

The effects of heat stress on organisms trying to survive outside the temperature envelope they evolved in is becoming evident.

The impacts of a hotter world are no longer off in the future — they have already arrived. As the planet grows warmer, the effects of heat stress on organisms trying to survive outside the temperature envelope they evolved in is becoming increasingly evident. From insects to coral reefs to biodiversity across entire ecosystems, researchers are chronicling the serious impacts of heat stress as temperatures break records. And several leading scientists believe we are underestimating the impacts, even as the heat ramps up.

The period from 2015 to 2019 was the warmest five-year period on record, according to a new report from the World Meteorological Association, and the just-finished decade was the hottest since record-keeping began. Last summer across Europe numerous high temperature records were broken, and the “frequency, intensity, and duration of heat waves are all expected to increase,” according to a recent paper. Marine heat waves are occurring four or five times more frequently than in the 1980s, according to another recent study.

Australia has been ground zero for recent extreme heat waves. Heat waves have occurred for centuries across the dry continent, but of the 39 known ones, 35 have taken place since 1994. This past summer was the second-hottest on record and the country is projected to warm faster than the global average, rising 4 degrees Celsius (7 degrees F) by 2100. Australia set a new record high in 2019 of 107.4 degrees F, which was an average of highs across the country. The individual record-high temperature was 121 degrees F in 2019 in Port Augusta.

One of the best-studied heat events in Australia took place in 2011 and shows how devastating the effects of extreme heat can be, on both terrestrial and marine ecosystems. The exceptional temperatures, a 2018 paper concluded, caused “rapid, diverse, and broad scale” changes and “triggered abrupt, synchronous … ecological disruptions, including mortality, demographic shifts, and altered species distributions.” The paper said that tree die-off and coral bleaching occurred simultaneously in response to the heat wave and “were accompanied by terrestrial plant mortality, seagrass and kelp loss, population crash of an endangered terrestrial bird species [Carnaby’s black cockatoo], plummeting breeding success in marine penguins, and outbreaks of terrestrial wood-boring insects.”

This cascade of events led the team of researchers to conclude that “the extent of ecological vulnerability to projected increases in heat waves is underestimated.”

Other recent events show the disparate impacts of extreme heat. In November 2018, the temperature in northern Australia soared to 107 degrees and stayed there for days. Endangered spectacled flying foxes — 2-pound animals with 5-foot wing spans — were overwhelmed. They tried to cool off by fanning themselves with their wings and panting, but that fell far short. In the end, some 23,000 of the endangered animals fell out of trees and died. The heat also killed fish, wild horses, and camels.

In 2014, an Australian heat wave killed more than 45,000 bats of various species. In some places fire trucks were deployed to spray and cool off dying bats.

Last month, the U.S. National Oceanic and Atmospheric Administration (NOAA) predicted that this year would bring the third major coral bleaching event to the Great Barrier Reef in five years because of heat waves. Coral bleaching occurs when high sea temperatures cause the living corals to expel the symbiotic algae on which the corals depend.

Experts say extreme temperatures are the catalyst for a growing number of local extinctions.

Research on impacts to the natural world from increasing temperatures is still in its early stages. But David Breshears — a University of Arizona professor of ecology and an expert in forests and climate change, is deeply worried. “First you get drought, on top of that the average temperature is going up, and on top of that a heatwave occurs,” said Breshears, who co-authored the 2018 heat wave paper. “Do extremes matter? You better believe they do, and it’s scary and getting scarier.”

Extreme temperatures — as opposed to warmer average temperatures — are the catalyst for a growing number of local extinctions, experts say. A recent study looked at 538 plant and animal species at 581 sites around the world that had been previously surveyed. The goal was to understand what aspect of climate change was the most serious threat to biodiversity. Researchers found that 44 percent of the species at the sites had gone locally extinct, and that the culprit was an increase in the temperature of the hottest days of the year.

John J. Wiens, an evolutionary ecologist at the University of Arizona and a co-author of that study, said this research creates a model that allows scientists to estimate at what temperatures species around the world will not be able to take the heat anymore. “We can estimate the global extinction for each species,” he said. He estimated that if there is moderate global warming, 16 percent of all species would be lost; if there’s more severe warming, 30 percent could be lost. “The big picture is that one in three species could go extinct over the next 50 years,” Wiens said.

Part of what dictates whether species will survive is their physiology and habits. Birds pant to cool off, exhaling air and water. The hotter they get, the more water they need to expel. The mourning dove, for example, requires 10 to 30 percent more water to keep cool than it did a century ago, according to the Grinnell Resurvey Project.

Insect or animal-eating birds, which get their water from their prey, are even worse off. The Mojave Desert study found that if water needs increase by 30 percent, larger birds need to catch 60 to 70 bugs more per day to satisfy their water needs, which has an energetic cost. That’s why avian carnivores in the desert — including the kestrel, prairie falcon and turkey vulture — have declined along with insectivores such as gnatcatchers and mountain chickadees. All told, the increasing need for water has led to a 43 percent decline in species richness, the Grinnell Resurvey Project concluded.

Birds suffer more than other animals. “They have high exposure to climate change,” said Riddell. “They are diurnal and exposed to the hottest part of the day. Small mammals live underground and are generally nocturnal.” Insects are small and can take advantage of smaller habitat niches.

“If current trends continue, we’ll see more declines in the desert birds,” Riddell said. “Even desert specialists are struggling to live in this environment that they are supposedly well adapted for.”

Some insects in some places have taken a heat hit as well. A recent study found that the number of areas that native bumblebees occupy has plummeted 46 percent in North America and 17 percent in Europe compared to surveys taken from 1901 to 1974. Those bee-less areas were also places with a high degree of climate variation, especially higher temperatures. “Climate change is related to the growing extinction risk that animals are facing around the world,” lead author Peter Soroye said, because of “hotter and more frequent extremes in temperatures.”

“As you crank up the heat, the time it takes to kill trees is less and less,” says one researcher.

At the same time, an increase in temperatures is also expected to boost some insect populations — including those that eat crops. A 2018 study predicted that could have a serious detrimental impact on world food supplies. “Warmer temperatures increase insect metabolic rates exponentially,” said Chris Deutsch, a professor of oceanography at the University of Washington, who led the team. “Second, with the exception of the tropics, warmer temperatures will increase the reproductive rates of insects. You have more insects and they’re eating more.”

Warmer temperatures are already causing major damage to the world’s forests. As temperatures warm, trees become less resilient and die-offs become more frequent — as much as five times more so. “If the climate warms a little more, things don’t get a little different, they get very different,” said Henry Adams, a plant biologist at Oklahoma State University and co-author of a recent paper on the topic. “You get an acceleration in the rate of mortality. As you crank up the heat, the time it takes to kill trees is less and less.”

Warmer temperatures, in other words, make droughts more deadly.

And there is concern that warmer temperatures will also keep burned forests from re-growing and that those ecosystems will instead transform into grasslands or shrub ecosystems.

Part of the reason is that, in the American West, fires are becoming bigger and hotter and more frequent, which kills the mother trees needed to drop seeds and regenerate the forest. Extreme heat then reduces seedling survival. “The hotter, drier climate is making it more difficult for trees to regenerate on sites to which a lot of these conifers were suited,” said Craig Allen, a research ecologist with the U.S. Geological Survey in New Mexico. “Parts of the landscape are becoming less available” to regrowth.

This trend is especially important because forests are a significant carbon sink. For 30 years, nearly 100 institutions studied 565 tropical forests in Africa and the Amazon to understand their role in taking up and sequestering atmospheric carbon dioxide, which helps mitigate climate warming.

What they found, in a paper published this month in the journal Nature, is that the uptake of CO2 in these forests peaked in the 1990s. By 2010, their ability to take up carbon had dropped by a third.

The cause was the growing number of dead trees in these forests, which were killed by higher temperatures, according to Wannes Hubau, who worked on the project as a post-doctoral researcher at the University of Leeds and who now works with the Royal Museum for Central Africa in Belgium.

“Our modeling of these factors shows a long-term future decline in the African [carbon] sink,” said Hubau, “and that the Amazonian sink will continue to rapidly weaken, which we predict to become a carbon source in the mid-2030s.” SOURCE

Scotland restores its peatlands to keep carbon in the ground

Often overlooked as critical carbon sinks, peatlands store at least twice as much carbon as forests. After years of degredation, Scotland has increased its ambition in restoring these important areas.

The burning Amazon rainforests, with their jaguars, monkeys and colourful birds, have grabbed global attention in a way the destruction of the world’s mossy peatlands never has.

Yet protecting the world’s peatlands, which store at least twice as much carbon as forests, is critical in the fight against climate change.

Peatlands, also known as bogs, are created when the remains of plants are submerged in waterlogged lands, turning them over time into peat with the plants’ carbon still stored inside. They cover around 3% of the world’s land and are found in 175 countries, mostly in northern Europe, North America and Southeast Asia.

Scotland has a particularly high coverage, with bogs amounting to 20% of it’s of land (roughly 1.7 million hectares) mainly in its lesser-populated north and western islands.

Decades of degradation

However the Scottish governmentestimates that roughly a third of the country’s total —  roughly 600,000 hectares —  have been degraded. Scotland’s peatlands, created mostly in areas left water-logged from the melting of Ice Age glaciers, lay untouched for thousands of years until farmers began to drain the land, building ditches so the water would run downhill into rivers.

While such ditches date back to Roman times in parts of Britain, their building intensified in Scotland in the 1950s with the advent of new machinery and government grants aimed at improving grazing.

Peatlands in Scotland cover roughly 20% of its land

Without the bogs’ acidic water there to preserve them, the dead plants in the peat start to degrade, releasing their carbon into the atmosphere as carbon dioxide. The degradation is sped up by the sun and wind they are exposed to without their water coverage.

Restoration plans

To correct past mistakes, landowners are being offered grants by the Scottish government to block the drainage ditches their predecessors were encouraged to dig. A total of €16.3 million ($18 million) has been madeavailable this year. The hope is that 50,000 hectares will have been restored by the end of 2020, and 250,000 hectares by 2030.

The restoration happens in two ways according to Andrew McBride, who works for Scottish Natural Heritage, the government agency responsible for handing out grants. It can either involve a ditch being filled in with peat from nearby, or a wooden dam being built inside the ditch to slow down the loss of water and spread it across the bog.

When the ditches are blocked, rainwater increases the water level, erosion stops and within two years, plants such as moss return. Within five to fifteen years, the bogs are back to fully functioning, McBride said.

Speed is key

“We want to do things as quickly as possible,” he told DW, “because obviously there’s a climate emergency.”

McBride says that landowners are often keen for restoration on their property as the farming benefits of drainage were not as great as previously thought. It only really improved the land right next to the bog, he says, adding that the drainage of ditches cause its own problems. On large estates, wandering sheep often fall into the ditches and can’t get out.

Peatlands can store up to twice as much carbon as forests.

Scotland is also trying to restore bogs by cutting down trees. In the 1980s, the UK government introduced tax incentives encouraging landowners to drain bogs to plant trees. This was a double hit —  first drainage dried the land and then the trees sucked out even more of the moisture.

Although the trees absorbed carbon as they grew, that didn’t cancel out the amount of carbon released into the atmosphere by the peatlands’ destruction.

Protests from conservationists eventually ended the tax incentives and now even the Scottish government agency Forestry and Land Scotland is aiming to transform2,500 hectares of forest back into peatland over five years.

The restoration happens in two ways according to Andrew McBride, who works for Scottish Natural Heritage, the government agency responsible for handing out grants. It can either involve a ditch being filled in with peat from nearby, or a wooden dam being built inside the ditch to slow down the loss of water and spread it across the bog.

When the ditches are blocked, rainwater increases the water level, erosion stops and within two years, plants such as moss return. Within five to fifteen years, the bogs are back to fully functioning, McBride said. MORE

Glacial rivers absorb carbon faster than rainforests, scientists find

‘Total surprise’ discovery overturns conventional understanding of rivers

 Ellesmere Island in Canada, where researchers collected meltwater samples. Photograph: Luke Copland

In the turbid, frigid waters roaring from the glaciers of Canada’s high Arctic, researchers have made a surprising discovery: for decades, the northern rivers secretly pulled carbon dioxide from the atmosphere at a rate faster than the Amazon rainforest.

The findings, published in the Proceedings of the National Academy of Sciences, flip the conventional understanding of rivers, which are largely viewed as sources of carbon emissions.

“It was a total surprise,” said Dr Kyra St Pierre, a biologist at the University of British Columbia and lead researcher on the project. “Given what we know about the rivers though … the findings are intuitive when you think about it. But we were initially very surprised to see what we did.”

The discovery came from time spent collecting meltwater samples on Ellesmere Island, in Canada’s Nunavut territory, where several glaciers flow into Lake Hazen. The team of researchers also gathered samples in the Rocky Mountains and Greenland.

“We have a pretty good understanding of the state of glaciers globally,” said St Pierre. “One thing we don’t know much about is the meltwaters and what happens when it … flows into rivers and downstream lakes.”

In temperate rivers, a bounty of organic material – plant life and fish – results in higher levels of decomposition, meaning the bodies of water emit a far greater amount of carbon dioxide into the atmosphere than they absorb.

But glacial rivers, with their milky appearance and silt-laden composition, are not very hospitable to aquatic life, leading to far less organic decay – and little carbon output.

At the same time, the fine sediment scraped from glaciers, including silicate and carbonate, when tossed along in the rushing waters, begins the geological process known as chemical weathering.

“As the rivers take up the particles, they start to mix within the water and within that water there are also gases, including carbon dioxide,” said St Pierre. “The mixing together creates these reactions and puts all these different particles together. That’s where we see that the net result is the sink of carbon dioxide.”

The research team discovered the effect of chemical weathering in removing carbon dioxide from the atmosphere extended as far away as 26 miles (42km) from the headwaters of the river.

This means that during high melt periods, glacial river water will absorb 40 times as much carbon as the Amazon rainforest.

“On a per-metre-squared basis, these rivers can consume a phenomenal amount of carbon dioxide,” said St Pierre. But their limited size means on a gross scale, they pull in far less than the sprawling Amazon. The team plan on sampling meltwaters in the Canadian Rockies, and expect to find similar results.

In a rapidly changing climate, the findings provide a surprisingly optimistic message: there are often unseen or underappreciated ways in which the planet regulates carbon emissions. “It shows just how little we know about these systems,” said St Pierre. MORE

The Cautious Case for Climate Optimism

Believing in a comfortable future for our planet probably means some giant carbon-sucking machines.

Photo-Illustration: Joe Darrow/Sven Schabbach/Getty Images

[Adapted from The Uninhabitable Earth, by David Wallace-Wells, to be published on February 19 by Tim Duggan Books, an imprint of Penguin Random House LLC. Copyright © 2019 by David Wallace-Wells.]

It’s not too late. In fact, it never will be. Whatever you may have read over the past year — as extreme weather brought a global heat wave and unprecedented wildfires burned through 1.6 million California acres and newspaper headlines declared, “Climate Change Is Here” — global warming is not binary. It is not a matter of “yes” or “no,” not a question of “fucked” or “not.” Instead, it is a problem that gets worse over time the longer we produce greenhouse gas, and can be made better if we choose to stop. Which means that no matter how hot it gets, no matter how fully climate change transforms the planet and the way we live on it, it will always be the case that the next decade could contain more warming, and more suffering, or less warming and less suffering. Just how much is up to us, and always will be.

…Since I first began writing about climate a few years ago, I’ve been asked often whether I see any reason for optimism. The thing is, I am optimistic. But optimism is always a matter of perspective, and mine is this: No one wants to believe disaster is coming, but those who look, do….Given only conventional methods of decarbonization (replacing dirty-energy sources like coal and oil with clean ones like wind and solar), this is probably our best-case scenario. It is also what is called — so often nowadays the phrase numbs the lips — “catastrophic warming.” A representative from the Marshall Islands spoke for many of the world’s island nations when he used another word to describe the meaning of two degrees: genocide.

….But this fall, the start-up incubator Y Combinator called for proposals in four areas, hoping to invest in companies that would suck carbon out of the atmosphere by expanding the reach of the ocean’s phytoplankton (which naturally absorb CO₂ in the ocean and turn it into oxygen) or reengineer it to do so more prolifically; by making the world’s rocks massive carbon sinks; by inventing new enzymes that would filter the air; and by flooding large areas of the world’s deserts with beds of algae engineered to absorb all that CO₂.

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