The enormous expanse of bright ice cover on the Arctic Ocean is our planet’s most important air-conditioning system. Much of the sun’s energy reaching the Arctic Ocean is reflected back into space by the sea ice. But in areas where the ice has melted, the dark ocean absorbs most of the sun’s energy, adding significant heat to Earth’s climate system. As atmospheric concentrations of carbon dioxide continue to rise and Arctic temperatures consequently climb, scientists project the Arctic Ocean will be essentially ice free for a portion of each summer within just a few decades, perhaps sooner.
Vanishing Arctic sea ice is one of the most obvious and ominous indicators that man-made climate change is already having far-reaching repercussions. Indigenous Arctic people whose way of life is intimately connected to the ice are confronting serious threats to their primary food resources, their safety and their traditional culture. And Arctic species dependent on sea ice for essential life functions — from ice algae and zooplankton to fish, seabirds, seals, walruses and polar bears — are also being adversely affected. Some are unlikely to survive over the long term if the ice vanishes.
Meanwhile, warming-induced changes in the characteristics of Arctic sea ice are causing alterations of atmospheric chemistry that are likely to increase toxic mercury in ecosystems, threatening the Arctic web of life as well as people who rely on it for food. And ocean acidification, exacerbated by sea-ice loss, will eventually impair crucial shell-building and skeleton-constructing capacities of numerous creatures. Their resulting decline will have devastating ripple effects throughout the entire marine food web.
Weather across northern hemisphere temperate regions will be influenced in potentially dangerous ways by the effects of sea-ice loss and rising Arctic temperatures on large-scale atmospheric circulation patterns. Extreme weather events, including severe droughts, devastating floods and hazardous heat waves, are projected to become more common as a consequence.
And as disappearance of sea ice continues to push Arctic temperatures higher, melting of the Greenland ice sheet will worsen, escalating sea-level rise worldwide.
Relentlessly climbing Arctic temperatures will eventually thaw permafrost throughout the Far North. Collapse of the defrosting ground will cause widespread and costly damage to infrastructure. Ultimately, decomposing organic material in previously frozen soils will emit huge additional quantities of CO2 and methane, causing substantial additional global warming.
Dwindling Arctic sea ice is a portentous warning that we are confronted by a rapidly developing planetary crisis. The longer we wait to address the underlying human causes of climate change, the worse the problem and resulting impacts will be. Our narrow window of opportunity to avert unimaginable harm is rapidly shrinking along with the Arctic sea ice.