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Climate
Science references
Yumashev, D., et al. (2019). "Climate
policy implications of nonlinear decline of Arctic land permafrost and
other cryosphere elements." Nature Communications 10(1): 1900.
Arctic feedbacks accelerate climate change
through carbon releases from thawing permafrost and higher solar
absorption from reductions in the surface albedo, following loss of sea
ice and land snow. Here, we include dynamic emulators of complex
physical models in the integrated assessment model PAGE-ICE to explore
nonlinear transitions in the Arctic feedbacks and their subsequent
impacts on the global climate and economy under the Paris Agreement
scenarios. The permafrost feedback is increasingly positive in warmer
climates, while the albedo feedback weakens as the ice and snow melt.
Combined, these two factors lead to significant increases in the mean
discounted economic effect of climate change: +4.0% ($24.8 trillion)
under the 1.5 °C scenario, +5.5% ($33.8 trillion) under the 2 °C
scenario, and +4.8% ($66.9 trillion) under mitigation levels consistent
with the current national pledges. Considering the nonlinear Arctic
feedbacks makes the 1.5 °C target marginally more economically
attractive than the 2 °C target, although both are statistically
equivalent.
Wadham, J. L., et al. (2019). "Ice sheets
matter for the global carbon cycle." Nature Communications 10(1): 3567.
The cycling of carbon on Earth exerts a
fundamental influence upon the greenhouse gas content of the atmosphere,
and hence global climate over millennia. Until recently, ice sheets were
viewed as inert components of this cycle and largely disregarded in
global models. Research in the past decade has transformed this view,
demonstrating the existence of uniquely adapted microbial communities,
high rates of biogeochemical/physical weathering in ice sheets and
storage and cycling of organic carbon (>104 Pg C) and nutrients. Here we
assess the active role of ice sheets in the global carbon cycle and
potential ramifications of enhanced melt and ice discharge in a warming
world.
Stein, R., et al. (2017). "Arctic Ocean
sea ice cover during the penultimate glacial and the last interglacial."
Nature Communications 8(1): 373.
Coinciding with global warming, Arctic sea ice
has rapidly decreased during the last four decades and climate scenarios
suggest that sea ice may completely disappear during summer within the
next about 50–100 years. Here we produce Arctic sea ice biomarker proxy
records for the penultimate glacial (Marine Isotope Stage 6) and the
subsequent last interglacial (Marine Isotope Stage 5e). The latter is a
time interval when the high latitudes were significantly warmer than
today. We document that even under such warmer climate conditions, sea
ice existed in the central Arctic Ocean during summer, whereas sea ice
was significantly reduced along the Barents Sea continental margin
influenced by Atlantic Water inflow. Our proxy reconstruction of the
last interglacial sea ice cover is supported by climate simulations,
although some proxy data/model inconsistencies still exist. During late
Marine Isotope Stage 6, polynya-type conditions occurred off the major
ice sheets along the northern Barents and East Siberian continental
margins, contradicting a giant Marine Isotope Stage 6 ice shelf that
covered the entire Arctic Ocean.
Sources & Further
reading
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