| / English Dictionary |
PERMAFROST
| Pronunciation (US): |  | (GB): | |
I. (noun)
Sense 1
Meaning:
Ground that is permanently frozen
Classified under:
Nouns denoting natural objects (not man-made)
Hypernyms ("permafrost" is a kind of...):
ground; land; soil (material in the top layer of the surface of the earth in which plants can grow (especially with reference to its quality or use))
Context examples:
New research counters a widely-held scientific view that thawing permafrost uniformly accelerates atmospheric warming, indicating instead that certain Arctic lakes store more greenhouse gases than they emit into the atmosphere.
(Certain Arctic lakes store more greenhouse gases than they release, NSF)
As rising Arctic air temperatures cause permafrost to thaw, the organic material decomposes and releases its carbon to the atmosphere in the form of the greenhouse gases carbon dioxide and methane.
(Far Northern Permafrost May Unleash Carbon Within Decades, NASA)
The study focuses on thermokarst lakes, which occur as permafrost thaws and creates surface depressions that fill with melted fresh water, converting what was previously frozen land into lakes.
(Certain Arctic lakes store more greenhouse gases than they release, NSF)
The study found that warmer, more southerly permafrost regions will not become a carbon source until the end of the 22nd century, even though they are thawing now.
(Far Northern Permafrost May Unleash Carbon Within Decades, NASA)
Through its data collection, the study expanded the circumpolar peat carbon pool estimate for permafrost regions by more than 50 percent.
(Certain Arctic lakes store more greenhouse gases than they release, NSF)
Permafrost in the coldest northern Arctic — formerly thought to be at least temporarily shielded from global warming by its extreme environment — will thaw enough to become a permanent source of carbon to the atmosphere in this century, with the peak transition occurring in 40 to 60 years, according to a new NASA-led study.
(Far Northern Permafrost May Unleash Carbon Within Decades, NASA)
The new permafrost formation then stores a large amount of carbon processed in and under thermokarst lakes, as well as the peat that formed after lake drainage.
(Certain Arctic lakes store more greenhouse gases than they release, NSF)
As roughly 30 percent of global permafrost carbon is concentrated within 7 percent of the permafrost region in Alaska, Canada and Siberia, this study's findings also renew scientific interest in how carbon uptake by thermokarst lakes offsets greenhouse gas emissions.
(Certain Arctic lakes store more greenhouse gases than they release, NSF)
They found that high rates of carbon accumulation in lake sediments were stimulated by several factors, including thermokarst erosion and deposition of terrestrial organic matter, nutrient release from thawing permafrost that stimulated lake productivity, and by slow decomposition in cold, anoxic lake bottoms.
(Certain Arctic lakes store more greenhouse gases than they release, NSF)
Using published data from the circumpolar Arctic, their own new field observations of Siberian permafrost and thermokarsts, radiocarbon dating, atmospheric modeling and spatial analyses, the research team studied how thawing permafrost is affecting climate change and greenhouse gas emissions.
(Certain Arctic lakes store more greenhouse gases than they release, NSF)
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