University of Illinois Department of Atmospheric Sciences
The loss of Arctic summer sea ice is accelerating, and the perennial sea ice loss is increasing.
The big burning questions on the loss of Arctic summer sea ice albedo are:
(1) How much will this increase the rate of warming?
(2) What will the impacts be?
There is little published science to answer these vital questions. Research by David Lawrence (NCAR) tells us that the summer sea ice loss would increase the rate of warming of the whole Arctic region more than three and half times.
Though scientists say the Arctic summer sea ice is the air conditioner of the entire northern hemisphere and the climate of the hemisphere will be changed, there is nothing to tell us how and by how much.
What is Arctic albedo?
Arctic albedo is the amount of solar radiation reflected from
a surface, often expressed as a percentage (EPA).
Sources of Arctic Albedo and decline
o Arctic sea ice extent or more accurately net area
o Sea ice condition (puddles etc)
o Sea ice thickness to a significant degree,
o Greenland ice sheet surface
o Arctic Far North snow cover
o Arctic tundra (replacement by forest)
o Replacement of exposed permafrost surface by wetlands (deep water has a very high albedo)
The significance of Arctic sea ice albedo loss by melting was kwon by 1960 Arctic research.
Alll of the above are losing albedo because of rapid melting in the summer due to rapid Arctic warming.
The catastrophic dangers of Arctic albedo loss
o Arctic ampliification (of global warming)
o Boost the loss of Greenland and glacial land ice.
o Increase Boreal and tundra fires.
o Boost the Arctic GHG emissions amplifying feedbacks
o Destabilize the seasonal weather climate of the tremperate NH
o Increase NH extreme heat and drought.
The rate of decline of NH snow and of summer sea ice is exceeding the models to a large degree since 2000, indicating assessment should now put extrapolation of trends ahead of models.
Arctic and Far North albedo have a large cooling effect on the Arctic region mid-high northern latitudes and ieven to the tropics to some extent, as the NASA 2002 Terra satellite global albedo image suggests.
Scientists call the Arctic summer sea ice, the air conditioner of the entire northern hemisphere. It is therefore vital to N hemisphere and hence world food security.
By keeping permafrost frozen it keeps the planet's largest store of carbon mainly as methane safe.
Light surfaces reflect heat energy well, while dark surfaces are poor reflectors and absorb heat energy well.
The percentage of incoming solar energy that is reflected back out to space by a surface is its albedo. Albedo is expressed in a scale of 0 to 1.0. An albedo of 1 would reflect 100% of solar energy.
Snow has the very highest albedo and open water the very lowest.
A loss of 1% of planetary albedo is about equivalent to 2X CO2 (Flanner).
On average, the Earth absorbs about 70% of the solar flux, while the remaining 30% reflects back to space without ever entering Earth's energy cycle (30% albedo). Of the total 340 W/m2 (watts per square metre) incoming of solar radiation at the top of the Earth's atmosphere, 107 W/m2 is reflected back. 77 W/m2 is reflected by clouds and by the atmosphere, and the rest is reflected back into space from Earth's surface.
Dark-coloured land and ocean surfaces (covering approximately 70% of the Earth) are strongly absorptive and contribute to warming, reflecting only 10-20% of the incoming solar energy
Snow and ice surfaces (only about 10% of Earth's surface) have a high albedo (85-90%), meaning they are very good reflectors of incoming solar radiation. Snow has an even higher albedo than sea ice, and therefore thick sea ice covered with snow reflects as much as 90 per cent of the incoming solar radiation (NSIDC).
As the Arctic warms and the sea ice melts, dark open water (along with exposed land) replaces white ice and snow. The exposed water and land have a lower albedo, or a lower reflectivity. As a result, more solar radiation is absorbed at the surface, which amplifies the Arctic warming. This is the ice-albedo positive feedback effect.
How large is the Arctic albedo effect?
A drop of as little as 0.01 in Earth’s albedo would have a major warming influence on climate — roughly equal to the effect of doubling the amount of carbon dioxide in the atmosphere, which would cause Earth to retain an additional 3.4 watts of energy for every square meter of surface area (NASA).
Just recently, the total albedo loss from sea ice and snow loss of the Arctic/subarctic region has doubled the estimates.
"Results show that the globally and annually averaged radiative forcing caused by the observed loss of sea ice in the Arctic between 1979 and 2007 is approximately 0.1 W/m2; a complete removal of Arctic sea ice results in a forcing of about 0.7 W/m2, while a more realistic ice-free summer scenario (no ice for 1 month and decreased ice at all other times of the year) results in a forcing of about 0.3 W/m2, similar to present-day anthropogenic forcing caused by halocarbons" Hudson, 2011.
over the last 30 years cryospheric feedback is almost twice as strong as what models have simulated. The implication is that Earth's climate may be more sensitive to increases in atmospheric carbon dioxide and other perturbations than models predict. "We find that cyrospheric cooling declined by 0.45 W m-2 from 1979 to 2008, with nearly equal contributions from changes in land snow cover and sea ice. On average, the Northern Hemisphere now absorbs about 100 PetaWatts more solar energy because of changes in snow and ice cover. 100 PetaWatts is seven-fold greater than all the energy humans use in a year.
Arctic snow cover shows sharp decline
Arctic albedo since 1980
The loss of thick old ice results in less abedo from the new thinner ice cover. Albedo evolution of seasonal Arctic sea ice 2012.
2014 NASA Arctic sea ice surface darkening faster
workshop (Sept 2013
Observational determination of albedo decrease caused by vanishing Arctic sea ice = globally 25% higher than CO2 caused global warming.
2014 NAP Linkages Between Arctic Warming and Mid-Latitude Weather Patterns: Summary of a Workshop 2013
March 2014 J. Stroeve New data confirms Arctic ice trends: Ice-free season getting longer by five days per decade. The amounts of energy involved is equivalent to several times the energy released by the atom bomb at Hiroshima for every square kilometre of the Arctic ocean.
2013 retreat of sea ice is diminishing Earth's albedo, or reflectivity, considerably faster than previously estimated
April 2013 Aku Riihelä Observed changes in the albedo of the Arctic sea-ice zone for the period 1982–2009
2 min VIDEO scientist
AGW Observer Papers on ice-albedo feedback