The latest data and images released by the U.S. National Snow and Ice Data Center reveal that the rate of Arctic sea ice decline currently shatters all previous records. In August, the sea ice melted at about twice the normal rate, NSIDC scientists said. The extent of the melt may become even larger as the melt continues into September.
While previous low ice levels could be attributed to weather anomalies, as was the case in 2007, the latest data indicate a larger trend in climate change consistent with global warming predictions. Counting this year, the six years with the lowest sea ice coverage on record all occurred in the last six years.
A glance at the satellite image below shows a drastic reduction in sea ice from previous longstanding levels. According to NSIDC scientist Julienne Stroeve, the typical sea ice coverage measured in the 1980’s was approximately 7 million square kilometers. Today’s measurement of sea ice coverage is approximately 4 million square kilometers.
While the levels of Arctic sea ice may seem a distant concern, the consequences of its retreat will touch us all in the form of extreme weather – prolonged heat waves and ensuing droughts and wildfires, harsher cold spells and heavier rain events. Rising temperatures resulting from diminished sea ice levels can influence prevailing weather patterns carried by atmospheric flows, or jet streams. Arctic melt has the effect of slowing down these jet streams which makes weather events, such as droughts or rainfalls, persist longer.
The Arctic warming trend has resulted in larger swaths of open water, which in turn absorbs more heat and makes the ice thinner. The thinner melts easier and is broken up by storms more easily than thicker ice. This loop is accelerating the loss of sea ice as the Arctic moves towards ice-free summers.
The dramatic loss of sea ice does not mean sea levels will rise significantly, at least in the short term, since floating ice displaces the same amount of water when melted. As sea ice melts, however, its reflective white surface is replaced by a heat absorbing blue surface which increases sea surface temperatures and further accelerates regional warming. These conditions may lead to the melting of major land-based ice sheets which would result in sea level rise. As an example, this summer the Greenland ice sheet experienced its largest thaw in 40 years, with melt on 97 percent of its surface.
Central to the debate about climate change is the effect, or ‘contribution’, of greenhouse gases attributed to human activity. In the new study, published in the journal Geophysical Research Letters, Stroeve’s research team analyzed multiple computer climate models to determine the extent to which global warming is responsible for the increasing shrinkage of Arctic sea ice. Her team determined that human activity accounts for some 60 percent of the observed rate of decline since 1979, with the rest due to natural climate variability.
While researchers study the changing state of Arctic sea ice, it remains to be seen what impact this new data has on the national climate change dialogue, which has been relegated to the background during the runup to the Presidential elections. Hopefully this event can be a tipping point towards awareness and acceptance of climate change and its impact the planet. Climate change skeptics, however, reason that a melting Arctic can benefit mankind. As the ice shrinks, new areas will be open to oil exploitation. Never mind that the added burden of fossil fuel emissions from the new found oil speeds the process of climate change – there is so much money to be made!
This week, Royal Dutch Shell’s drill ship, the Noble Discoverer, took advantage of reduced sea ice and started sailing from Alaska’s Dutch Harbor to the Chukchi Sea, in anticipation of final federal approval for oil exploration activities there.
