Thawing permafrost can lead to loss of terrain, like in this image where part of the coast along Drew Point, Alaska, has collapsed into the ocean.
Scientists are turning to a combination of data collected from the air, land and space to get a better picture of how climate change is affecting the frozen regions of the planet. pure.
Trapped in Earth’s permafrost – the ground remains frozen for at least two years – are untold amounts of greenhouse gases, bacteria and chemicals, including the now-banned pesticide DDT. . As the planet warms, the permafrost is thawing at an increasing rate, and scientists face a host of uncertainties as they try to determine the potential effects of the thaw.
ONE paper published earlier this year in Nature Reviews Earth & Environment reviewed the current state of permafrost research. As well as highlighting the conclusions about permafrost thaw, the paper focuses on how researchers are looking to address the questions surrounding it.
Infrastructure has been affected: The melting permafrost has led to huge sinkholes, toppled telephone poles, damaged roads and runways, and toppled trees. Less noticeable was what was trapped in the permafrost mixed with soil, ice, and dead organic matter. The study looked at how chemicals such as DDT and bacteria – some of which have been frozen for thousands, if not millions of years – can be released out of thawed permafrost.
Then there’s the impact of thawing permafrost on the planet’s carbon: The Arctic permafrost alone contains an estimated 1.7 trillion tons of carbon, including methane and carbon dioxide. That’s about 51 times the amount of carbon the world emitted as fossil fuel emissions in 2019. The plant matter frozen in the permafrost doesn’t decompose, but as the permafrost melts, The bacteria in the dead plant material begin to break down the matter, releasing carbon into the air.
“Current models predict that we should see a carbon pulse that resolves,” said Kimberley Miner, a climate researcher at NASA’s Jet Propulsion Laboratory in Southern California and lead author of the study. from the permafrost into the atmosphere within the next hundred years. paper. But the key details – such as the amount, specific source and timing of the carbon emissions – are still unclear.
The worst case scenario is if all the carbon dioxide and methane are released in a very short time, such as a few years. Another scenario involves a gradual release of carbon. With more information, scientists hope to better understand the likelihood of either scenario.
Although the review paper finds that the Earth’s polar regions are warming the fastest, increasing carbon emissions could lead to drier or wetter conditions in the Arctic remains unclear. clear. What is more certain is that changes in the North and South Poles will shift to lower latitudes. Earth’s polar regions help stabilize the planet’s climate. They help promote heat transfer from the equator to higher latitudes, leading to atmospheric circulation that powers jet and other currents. The warmer, permafrost-free Arctic could have unpredictable consequences for Earth’s weather and climate.
Integrated approach
To understand the effects of thawing, scientists are increasingly turning to integrating Observing the earth from the ground, air and space – techniques outlined in the paper. Each method has its advantages and disadvantages.
For example, ground-based measurements provide accurate monitoring of changes in a local area, while aerial and space-based measurements can cover large areas. Ground- and aerial measurements focus on the specific time at which they were collected, while satellites continuously track the Earth – although they may be limited by things like coverage of the Earth. clouds, time of day or last of the satellite mission.
It is hoped that using measurements from a combination of multiple platforms will help scientists create a more complete picture of changes at the poles, where permafrost thaws fastest.
Miner is working with colleagues on the ground to characterize microorganisms frozen in the permafrost, while others are using airborne instruments to measure greenhouse gas emissions. greenhouse effect like methane. Besides, overhead and satellite missions can help pinpoint emissions hot spots in permafrost regions.
There are also satellite missions in the pipeline that will provide carbon emissions data with higher resolution. The ESA (European Space Agency) Copernicus Hyperspectral Imaging Mission will map changes in land cover and help monitor soil properties and water quality. From NASA Surface biology and geology (SBG) mission will also use satellite-based imaging spectroscopy to collect data on study areas including plants and their health; changes to the land associated with events such as landslides and volcanic eruptions; and snow and ice accumulation, melting, and luminosity (related to the amount of heat reflected back into space).
SBG is the focus area for one of several future Earth science missions that make up NASA’s Earth System Observatory. Together, these satellites will provide a holistic, 3D view of Earth, from its surface through the atmosphere. They will provide information on topics including climate change, natural disasters, hurricanes, water availability and agriculture.
“Everybody is racing as fast as they can to understand what is happening at the poles,” Miner said. “The better we understand, the better prepared we are for the future.”
Jane J. Lee / Andrew Wang
Jet Propulsion Laboratory, Pasadena, Calif.
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