Article**: Oceans and Wetlands.
A new study led by Brown University, published in Geophysical Research Letters, has revealed the actual atmospheric methane emissions of Arctic lakes and wetlands. These lakes and wetlands are the main sources of natural gas production, but they remain largely unmapped.
Source: Green Society, Ocean and Wetland).
Methane is about 25 times more capable of trapping heat in the atmosphere than carbon dioxide. This makes it crucial to track methane emissions, especially in the Arctic, which is now the fastest-warming region for global warming.
The lake is the second largest natural methane after wetlands**. The researchers assessed the relative importance of three insufficiently constrained parameters that were known to be the "double counts" of lake methane estimation errors: lake area distribution, lake aquatic vegetation, and wetlands. The researchers used the latest available high-resolution data to estimate the total area of mapped and unmapped lakes and to make the first estimates of aquatic vegetation in Arctic Ocean lakes. The Arctic accounts for 40% of the world's lake area. The study found that small lakes that were not mapped, especially those with an area of less than 0001 square kilometers of ponds account for only 3% of methane emissions. Although vegetated areas, known emission hotspots, cover 8% of Arctic lakes, their impacts are offset by the potential wetland double-counting that still exists in the estimates. These findings can help reduce uncertainty by comparing the relative effects of lake area, lake aquatic vegetation, and wetland double-counting, and indicate that previous emission estimates were too high. New maps, based on abundant high-resolution data from existing satellites, could unambiguously reveal the size of small lakes on a global scale.
Using NASA's high-resolution satellite and aerial imagery, the researchers used this technology to overcome obstacles created by the region's vast area and large number of natural formations, which are the main source of methane production. They made new estimates and found that these unmapped lakes were not major sources of methane emissions. According to the study, small, unmapped lakes do not contribute about 40% of the region's methane emissions, but only about 3%.
The project began as a search for hidden lakes in the Arctic, but changed as researchers examined the data more closely. The work, which combined high-resolution aerial data with a global map of lakes in the Arctic, also uncovered some unexpected results.
For example, this work shows that many large and small lakes are still double-counted as wetlands. This double-count yielded an estimate of methane emissions in the region, but given the new findings of the reduction in the number of small unmapped lakes, the researchers believe the problem is smaller than previously thought.
Another unexpected result appeared on Fang **. In the field of methane modeling, there are two widely held lines of thought. One is a "bottom-up" estimate, which models methane emissions against a map of the Earth, as the study did. Another approach is "top-down" estimation, which models methane based on atmospheric measurements.
Source: Green Society, Ocean and Wetland).
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3.citation: a closer look at the effects of lake area, aquatic vegetation, and double‐counted wetlands on pan‐arctic lake methane emissions estimates, geophysical research letters (2023). doi: 10.1029/2023gl104825