Different Dynamics, Global Impact:
Climate change is happening faster and in a dramatically more visible way in the Earth’s cryosphere – the
regions of the globe covered in ice and snow, seasonally or year-round – than anywhere else on earth. Global changes
in climate are exaggerated here: especially at the poles, where average temperature has risen at over twice the global mean
in the Arctic and on the Antarctic Peninsula. The Himalayas store more freshwater ice and snow than any
region outside the poles, nearly 10% of the global total. The dynamics and history of these huge mountain
glaciers remain less well-understood in some ways than those at the poles; but experiences of accelerated melting and flash
flooding there have begun to mount as well.
Research increasingly shows that the forces driving warming in the cryosphere are different, and sometimes directly
opposite in action, to those drivers in less reflective areas of the globe. Black carbon in the atmosphere
for example may actually prove cooling in some weather conditions because it gathers water molecules that as clouds reflect
heat away from earth – but not over white surfaces where the clouds appear dark; and definitely not once that same dark
BC deposits out onto that ice and snow. Other short-lived pollutants, especially ozone and methane, appear
to have a magnified impact in the Arctic as well. Studies of the impact of these pollutants have barely
begun in other cryosphere regions, and the need is urgent for accelerated research and exchanges with Arctic scientists studying
these impacts.
And what happens in the cryosphere has its main human and environmental impact well outside these regions, making it
a challenge for international policymakers to address with sufficient urgency. Although only 4 million
people live in the Arctic region, 40 million in the Himalayas, and none (permanently) on Antarctica, the changes there will
affect hundreds of millions across the globe, among them some of the worlds’ poorest populations. A
sea level rise of just 1 meter will impact nearly 150 million people today living at or below that level, over 100 million
of these in Asia.
Perhaps of greatest significance, as permafrost and seabed thaw, they have the potential to release carbon (as both
methane and CO2) equal to the same amount currently in the atmosphere today. As a greenhouse gas twenty
times more powerful than CO2, such a methane release over a relatively short time period could rapidly accelerate warming.
Also, as ice and snow disappear at the poles (in particular, summer Arctic sea ice), the earth’s reflectivity
changes, leading to greater overall warming.
Finally, the timescale faced by the cryosphere is also different from that of the globe as a whole. Although
climate scientists have begun to focus on earlier and earlier timelines for a peak in CO2, for the cryosphere this timeline
is even further accelerated. Facing a loss of summer sea ice well before 2050 (and perhaps by 2013), and
disappearance of many land glaciers even earlier; climate policies aimed at the end of this century simply cannot occur quickly
enough. More so than the rest of the globe, the cryosphere is on a near-term timeline of at most decades,
rather than centuries. It requires measures that will act far more rapidly.
