The extent
of sea ice cover in Arctic was much less than it is today between four and five million years ago.
Koch, F., Wiens, D., Euler, G., Wilson, T., Nyblade, A., Aster, R., Huerta, A., Anandakrishnan, S., 2012, Tracking the Effect
of Sea Ice Cover on Microseismic Noise Using Two Seismic Arrays in Antarctica, Proc.
«Because these plants are photosynthetic, it's not surprising to find that as the
amount of sea ice cover declined, the amount of [photosynthesis] increased,» says biological oceanographer Kevin Arrigo of Stanford University's School of Earth Sciences, who led an effort to use the MODIS (Moderate Resolution Imaging Spectroradiometer) devices on NASA's Terra and Aqua satellites to determine changes in phytoplankton growth.
Koch, F., Wiens, D., Euler, G., Nyblade, A., Anandakrishnan, S., Huerta, A., Wilson, T., Aster, R., Tracking the
Effect of Sea Ice Cover on Microseismic Noise Using Two Seismic Arrays in Antarctica, Seismol.
Jaiser, R., Dethloff, K., Handorf, D., Rinke, A. & Cohen, J. Impact
of sea ice cover changes on the Northern Hemisphere atmospheric winter circulation.
Impact of sea ice cover changes on the Northern Hemisphere atmospheric winter circulation — Jaiser et al (2012) doi: 10.3402 / tellusa.v64i0.11595
Contrary to a report published by US researchers, this warmth did not result in the
thinning of the sea ice cover in some regions over the course of the winter.
«Past and
future of sea ice cover in the Arctic: Despite the high temperatures, geologists and climate researchers find evidence that there was sea ice at the North Pole during the last interglacial.»
The
area of sea ice covering the Arctic ocean even stopped growing and started shrinking in the Barents Sea for a brief period in November.
Scientists from NASA and the University of Washington used observations from NASA's Ice, Cloud and land Elevation Satellite (ICESat) to make the first Arctic Ocean basin - wide estimate of the thickness and
volume of sea ice cover.
The rapid
disappearance of sea ice cover can have consequences that are felt all over the Northern Hemisphere, due to the effects it has on atmospheric patterns.
Unprecedented warm temperatures lead to the loss of more than
half of the sea ice cover in the Bering Sea in two weeks, resulting in record lows for Arctic Ocean sea ice extent for the month of February.
In a new paper, researchers conclude that changes in sensible heat transfer and evaporation fluxes — in response to strong regional trends in the air - surface temperature contrast related to the changing
character of the sea ice cover — are becoming increasingly consequential to Arctic climate variability and change.
Intervals of sustained low extent
of sea ice cover occurred before AD 1200, and may be coincident with the so - called Medieval Warm Optimum (roughly AD 800 — 1300) attested in numerous Northern Hemisphere proxy records18, but the pre-industrial minimum occurred before, at about AD 640 (T3 in Fig. 3).
The former is defined as the areal
sum of sea ice covering the ocean (sea ice + open ocean), whereas the latter «area» definition counts only sea ice covering a fraction of the ocean (sea ice only).
In late August, just 1.58 million square
miles of sea ice covered the Arctic Ocean, the smallest such area ever observed by NASA satellites since the space agency began monitoring the Earth's polar ice caps 30 years ago.
The 2017 Arctic Report Card stated that ice is shrinking faster compared with the prior 500 years, and that «observations in 2017 continue to indicate that the Arctic environmental system has reached a «new normal», characterized by long - term losses in the extent and
thickness of the sea ice cover, the extent and duration of the winter snow cover and the mass of ice in the Greenland Ice Sheet and Arctic glaciers, and warming sea surface and permafrost temperatures.»
On Sunday, the total
amount of sea ice covering the Arctic Ocean was 1.58 million square miles, the smallest size ever observed by NASA satellites since the space agency began monitoring earth's polar ice caps 30 years ago.
Koch, F., Wiens, D., Euler, G., Aster, R., Nyblade, A., Anandakrishnan, S., Huerta, A., Wilson, T., Tracking the
effect of sea ice cover on microseismic noise using two seismic arrays in Antarctica, Eos Trans.
«Arctic Ice in «Death Spiral» with additional heating due to global warming, the
extent of sea ice cover has gotten smaller and smaller over the summers since the 1980s.
The
loss of sea ice cover (dominated by extent and only slightly influenced by thickness) allows for a change in the heat fluxes between ocean and atmosphere (heat absorbed by the ocean in summer is released back to the atmosphere, growing heat transfer in the colder months as decades pass).
As winter, supposedly, descends onto the North Pole, warm weather has persisted in the Arctic for weeks on end, while the amount
of sea ice covering the world's northernmost ocean has hit lows never seen before for this time of year.