Humiliating dirt can pack a sudden climatic fist, according to a new study published Wednesday in the journal Nature. An experiment heating the earth under a tropical rain forest to mimic the temperatures expected in the coming decades found that warmer soils emitted 55 percent more carbon dioxide to warm the planet than in nearby unarmed areas.
If the results apply across the tropics, much of the carbon stored underground could be released as the planet warms.
“The loss rate is huge,”; said Andrew Nottingham, an ecologist at the University of Edinburgh who led the study. “It’s a bad story in the news.”
The thin skin of the earth that covers most of our planet’s earth sells a lot of carbon – more, in total, than all the plants and atmosphere combined. That carbon feeds a host of bacteria and fungi, which build some of them into more microbes, while permeating the rest into the atmosphere as carbon dioxide. Many of these microbes grow more actively at warm temperatures, increasing their digestion and respiration rate.
The finding “is another example of why we should be more concerned” about the speed of global warming, said Eric Davidson, an environmental scientist at the College of Environmental Sciences at the University of Maryland School of Environmental Science in Frostburg who was not involved in the research.
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Updated August 12, 2020
Here’s what you need to know about the latest climate change news this week:
- Climate change leaders said the election of Kamala Harris as vice president signaled that Democrats would have a focus on environmental justice.
- This year is preparing to be one of the hottest ever and millions are already feeling the pain, but the agony of extreme heat is profoundly uneven across the globe.
- The EPA plans to lift controls on methane, a powerful greenhouse gas, in the latest move in the Trump administration’s ongoing effort to weaken environmental regulations.
In an effort to predict the future, ecologists began in the early 1990s by building appliances on artificial heating soils. Such experiments in soft and boreal forests have shown that carbon-rich soils almost always reduce carbon dioxide when heated. In 2016, a group of researchers estimated that, by 2050, lands could emit so much gas that warms the planet’s warming that it would be like increasing the carbon emissions of a new country the size of the United States.
But this study left the ever-warm mega-biodiversity tropics where a third of the earth’s carbon dwells. Understanding the fate of this carbon would require overcoming many obstacles to doing research in the tropics: humidity, storms, and a host of hungry animals that can charge a fee for research equipment – chewing on electrical wires or protective covers, for example. – and on the researchers themselves.
To understand the contributions of soils to climate change, the tropics “is a really important region” that “has not really been studied,” said Margaret Torn, an ecologist at Lawrence Berkeley Lab in California, who was not included in the study.
In 2014, Dr. Nottingham, then a postdoctoral fellow at the University of Edinburgh, traveled to Barro Colorado Island, a man-made island in the Panama Canal area that is home to the Smithsonian Institution of Tropical Research. He buried electrical wires in five circular plots at a depth of nearly four feet. For protection from wild elements and insects, he shielded the wires inside metal structures shaped like large spiders. The measurements were recorded inside weatherproof boxes.
“Our experiment was basically me as a postdoc doing things from a DIY store,” Dr Nottingham said.
The team encountered a number of hiccups, including weak electrical connections that exploded and cost the researchers nearly a year and much of their budget to repair. Beginning in November 2016, the electrical resistance of the wires began to warm the earth by almost 6 degrees Fahrenheit, within the interval from how much the tropics are projected to warm by the end of the century, according to current climate models. Other devices measured carbon dioxide emanating from both experimental plots and nearby plots that were not artificially heated as well as microbial activity on the plots.
An experiment heating global warming in Puerto Rico’s El Yunque National Forest was ignited two months ago but was collected by Category-5 hurricanes back in September 2017; the study team did not turn power back on for a year.
Results from the team of Dr. Nottingham are surprising: Over two years, warm soils explode 55 percent more carbon than control plots. “This is a very big answer,” said Dr. Torn, who runs a warm-up experiment in a California forest that reported a nearly 35 percent increase in carbon emissions after two years. “Oneshte is one of the greatest I have ever heard.”
If all the tropics were to behave similarly, researchers estimate that 65 billion metric tons of carbon would enter the atmosphere by 2100 – more than six times the annual emissions from all human-related sources.
The scale of the results to account for across the tropics is however complex. The soils on Barro Colorado Island are richer in nutrients than many others, such as those in most of the Amazon rainforest, Dr. noted. Davidson. This could make it easier for the Pannanian microbes to increase their activity. The microbial communities in African and Asian soils are very different from those in America, added Dr. Torn.
And while there is an agreement that climate models should treat land more realistically, how best to do so is unclear. The new study strikes a blow against simple theories that predict tropical soils will respond poorly to heat, said Kathe Todd-Brown, a soil scientist at the University of Florida at Gainesville who was not part of the research team. But to really take control of the problem, she said, modellers will need information on how microbes react to changes in soil moisture and nutrients in addition to temperature.
By warming the earth alone, the Barro Colorado Island experiment does not capture how plants would divide under warmer conditions, said Tana Wood, a U.S. Forest Service ecologist who is leading the Puerto Rican experiment. If plants were to photosynthesize more, for example, they could take in some of the carbon dioxide emitted by the soil, making the overall impact on the climate less severe. “This is only telling half the history of carbon,” she said. (Her team is warming both the ground and the air with infrared heat and measuring how plants and germs react.)
Dr. Torn said she was eager to see data for more than two years, which could reveal whether the carbon dioxide nuance is prolonged or short-lived. “In the life of a tropical forest, it is a very short time,” she noted.
Dr Nottingham has the funding to run the Panama project for at least another five years. But even two years has shown how critical it is to find ways to keep ecosystems intact, he said. “It makes you realize how lucky we have been to this point, to have a relatively stable climate.”