As US President Joe Biden prepares to sign historic climate change legislation, the Arctic reminds us that much more is needed to prevent catastrophic impacts.
Long considered the “canary in the coal mine” for climate change, the Arctic is warming faster than the globe as a whole. Now new research shows it’s heating up much faster than previously thought.
Multiple previous studies have found that due to a phenomenon known as Arctic amplification, the region is warming either twice, more than twice or even three times faster than the global average. But Finnish scientists, using several sets of observational data, found that over just over four decades, the actual rate of Arctic warming was almost four times faster.
Some parts of the region saw even more extreme Arctic amplification. For example, marine areas near Novaya Zemlya, a Russian archipelago in the Arctic Ocean, have experienced warming rates up to seven times faster than the global average.
“This is worrying because the Arctic contains sensitive and delicately balanced climate components that, if pushed too hard, will respond with global consequences,” says Jonathan Bamber, a scientist who studies Earth cryosphere using satellite data. Bamber, who was not involved in the research, discusses the findings in story on The Conversation.
Footsteps in the snow atop Longyearbreen Glacier in the Arctic Svalbard archipelago point metaphorically to a much warmer — and dangerous — future. (Credit: ©Tom Yulsman)
The carbon “time bomb”
One example of possible global consequences: a dramatic acceleration of global warming caused by melting permafrost in the Arctic. Such thawing can offer microbes a sumptuous feast of organic matter, causing them to produce large amounts of carbon dioxide and methane—the latter an extremely potent greenhouse gas.
The amount of carbon available for this process is beyond enormous. It is estimated that Earth’s permafrost currently stores about 1.6 trillion tons of carbon—more than twice the amount in the atmosphere today.
Needless to say, we cannot afford this carbon to make its way into the atmosphere.
This animation shows how the extent of Arctic permafrost, as well as sea ice, has changed between 1997 and 2019. Watch the darkest blue color recede and the lighter blue colors expand, revealing permafrost in decline. (Credit: ESA)
“If permafrost thaw accelerates, there is the potential for an irresistible positive feedback process, often referred to as a permafrost carbon time bomb,” says Bamber. This in turn would accelerate global warming, accelerating and greatly worsening impacts such as sea level rise and heat waves.
The sea ice connection
Shrinkage of the Arctic’s floating sea ice cap is believed to be a major cause of Arctic amplification. Sea ice reflects much of the sunlight that hits it, helping to preserve it Arctic temperatures frigid. But as the atmosphere has warmed from our greenhouse gas emissions, Arctic sea ice has shrunk significantly, exposing ever-larger swaths of ocean.
Unlike reflective ice, dark ocean waters eagerly absorb the sun’s energy and warm significantly during the summer. This delays freezing in the fall, allowing the accumulated summer heat to be released into the atmosphere.
Gaps in the sea ice off the west coast of Greenland leave dark, relatively warm waters exposed off the west coast of Greenland in this January 2018 aerial photo. (Credit: ©Tom Yulsman)
The more the climate warms, the more the sea ice melts. This leads to more warming, which causes even more ice shrinkage and even more warming—all in a positive feedback loop that largely explains the strengthening of the Arctic.
Why do previous analyzes based on observations give lower estimates of how much the Arctic has warmed? One possibility is differences in the way the analyzes were done. That’s another thing earlier estimates may simply be out of date due to continued Arctic warming.
What have the climate models shown?
Climate models have been able to simulate an increase in the Arctic. But the Finnish scientists found that the models simulated less amplification than actually occurred between 1979 and 2021. This was true even for the latest, most modern models.
As the researchers say, “climate models struggle to simulate [the] quadruple amplification ratio in the Arctic.”
2020 is the warmest year globally, according to NASA. This map shows how temperatures vary from the long-term average, revealing that some areas of the globe experienced more abnormal warmth than others during the year. The dark red tones at the top of the globe reveal that the Arctic is the warmest region of all, a result traced to the phenomenon known as Arctic Amplification. (Credit: NASA GISS)
Not that they don’t simulate it at all. It’s just that when models are run repeatedly, they almost never produce as high a degree of amplification. But they really rarely do.
Therefore, there may simply be nothing wrong with the models. Instead, a fourfold warming of the Arctic compared to the globe as a whole may simply be an extremely unlikely event that has unfortunately happened. Put another way, when pushed by our greenhouse gas emissions, the Arctic climate is actually most likely to have responded less aggressively than it actually did. But due to a very rare roll of the climatic dice — unlucky for us! — the warming is particularly strong.
Another possibility is that there really is a problem with the models – specifically, errors in how sensitive they are to climate forcing from greenhouse gases. There may also be problems in how they simulate the energy fluxes between the atmosphere, cryosphere and ocean.
This is not just an academic problem for researchers to grapple with. If the models do have problems, then they may not be giving as accurate a picture of how storm tracks may change as different parts of the Earth warm at different rates, and how that in turn may affect climate in different regions . Accurate predictions of these kinds of changes are important because they can help us prepare better.
How much will climate legislation help?
Three independent research groups have estimated that the Inflation Reduction Act, which President Biden will soon sign into law, will reduce US greenhouse gas emissions by about 40 percent by the end of this decade. That’s two-thirds of what the United States needs to meet its commitment under the Paris Agreement, an international treaty on climate change.
If this actually happens, it would be a remarkable achievement. But the United States still has a long way to go to eliminate its carbon dioxide emissions from the atmosphere by 2050. What’s more, scientists say all major economies must meet the same goal by midcentury if we want to keep the average global temperature rise of more than 1.5 degrees Celsius or 2.7 degrees Fahrenheit, above pre-industrial levels.
If the world passes this threshold, there are risks of much worse heat waves, wildfires, heat waves and more catastrophic climate impacts will increase significantly.