April 13, 2013
Researchers Predict Sea Ice-Free Arctic Summers By 2050
April Flowers for redOrbit.com — Your Universe Online
The question of ice-free summers in the Arctic, for most scientists, is not "if," but "when." A new study by two National Oceanic and Atmospheric Administration (NOAA) scientists says that "when" is coming sooner than many thought.
Already, the Arctic has experienced a loss of thick, multi-year ice, with last September´s extent being less than half the average of 1979-2000.
The scientists, James Overland of NOAA´s Pacific Marine Environmental Laboratory and Muyin Wang of the Joint Institute for the Study of Atmosphere and Ocean at the University of Washington, say that the Arctic summers will be ice-free by 2050, and possibly within the next twenty years. The study, published online in the journal Geophysical Research Letters, looked at three methods of predicting when the Arctic will have nearly ice-free summers.
“Rapid Arctic sea ice loss is probably the most visible indicator of global climate change; it leads to shifts in ecosystems and economic access, and potentially impacts weather throughout the northern hemisphere,” said Overland. “Increased physical understanding of rapid Arctic climate shifts and improved models are needed that give a more detailed picture and timing of what to expect so we can better prepare and adapt to such changes. Early loss of Arctic sea ice gives immediacy to the issue of climate change.”
“There is no one perfect way to predict summer sea ice loss in the Arctic,” said Wang. “So we looked at three approaches that result in widely different dates, but all three suggest nearly sea ice-free summers in the Arctic before the middle of this century.”
The scientists stress the term "nearly" ice-free is important to remember, as they expect some sea ice to remain north of the Canadian Archipelago and Greenland.
The three approaches -- "trendsetters," "stochasters" and "modelers" -- give estimates that range from 2020 to 2040 for ice-free summers using different methods.
Trendsetters use data from observed ice trends that show the total amount of sea ice has decreased rapidly over the previous decade. This approach estimates a nearly ice-free Arctic summer by 2020.
The stochasters method assumes randomly-timed, multiple large sea ice loss events in the future — much like those that happened in 2007 and 2012. According to this approach, several more events are needed to reach a nearly ice-free summer. It estimates the timing to be about 2030, but with a large uncertainty in that hypothesis.
The third approach, the modelers method, uses the large collection of global climate model results to predict atmosphere, ocean, land, and sea ice conditions over time. The earliest possible loss of sea ice, according to this method, is around 2040 as greenhouse gas concentrations increase and the Arctic warms. The average timing of sea ice loss in this compilation of models is closer to 2060, however. Overland and Wang caution there are several reasons to consider that this median timing of the models may be too slow.
“Some people may interpret this to mean that models are not useful. Quite the opposite,” said Overland. “Models are based on chemical and physical climate processes and we need better models for the Arctic as the importance of that region continues to grow.”
The timing for future sea ice loss will be within the first half of the 21st century, the authors say, taking the range of dates from the various approaches together. There is a possibility of major loss within a decade or two, as well. Wang notes none of the approaches see the polar ice cap remaining intact in the long run, despite their different estimates.
USA Today reports the summer ice sheet disappearance will lead to cascading effects throughout the Arctic food chain. Everything from plankton to polar bears will be affected. Concerns over landslides caused by melting permafrost and other land effects are mixed with geopolitical jousting over navigation and mining rights already.
There are disagreements among the scientific community about the effects of climate change, according to Bloomberg. Environment America, a collaboration of environmental advocacy organizations, claims everything from Hurricane Sandy, to last year's drought in the Midwest, and the wildfires that swept through Colorado and the West, were the result of greenhouse gas-aggravated climate change. NOAA, however, released a separate study saying last year's drought was not related to "human-induced climate change," but rather a freak occurrence caused by the lack of moist air streaming northward from the Gulf of Mexico.