The newest scientific survey of global warming’s impacts in the Arctic describe a climate, a landscape and an ecology that are not so much evolving as falling apart.
As sea ice continues to decline and the terrestrial seasons of hard freeze and snow cover grow shorter, the world above 60 degrees north latitude is getting rainier, cloudier and more humid. (Bill McKibben, commenting on the findings, coined a word to summarize these converging effects as “slushifying.”) But that’s just the tip of the … you know.
The permafrost season is shrinking, too, undermining forests as well as buildings and infrastructure; in combination with rising sea levels, it’s accelerating coastal erosion.
The pace of glacial melt is rising, and together with heavier rainfall is flushing more nutrients into marine ecosystems, modifying water chemistry and, eventually, food webs. Some important fisheries appear to be threatened as habitats lose the conditions necessary for spawning.
Growing seasons on the tundra are shifting around, but not in an orderly way; flowering cycles of plants are both earlier and shorter, falling out of sync with pollinators. Forests, notably, are becoming more vulnerable to insect infestations, as well as faster growth in the shrubby understory, both of which can make wildfires more frequent and more severe. Oh, and fire-starting lightning strikes seem to be on the rise.
Many of these impacts are not new discoveries, of course. What distinguishes this project, whose findings were published last week in Environmental Research Letters, is its comprehensive analysis of how all of these factors are linked together — and of their aggregate impact.
The paper is the work of an international team of two dozen scientists with Jason Box, of the Geological Survey of Denmark and Greenland, in the lead author’s role. And they are agreed on this point:
The key driver of change across all nine interrelated indicators — air temperature, permafrost, hydroclimatology, snow cover, sea ice, land ice, wildfires, tundra and terrestrial ecosystems, and carbon cycling — is air temperature.
That’s rising across the Arctic, just as it is worldwide — only faster, because corresponding changes in sea ice, snow cover and other temperature-driven influences create feedbacks that become part of the so-called Arctic amplification.
Twice the hemisphere’s warming
Based on temperature records from 1971 through 2017, the data show an increase in year-long average temperature of 2.70 C. (just under 50 F.), which is 2.4 times the rise for the entire Northern Hemisphere.
Winters are warming faster than summers in the Arctic; looking just at the “cold season” from October to May, temperatures rose 3.10 C, or 2.8 times as much as for the hemisphere.
As for the future, the research simply notes that there’s little likelihood that the world’s temperature trend is likely to change much, and that the pace of some key impacts has been accelerating since the 1980s and 1990s. Thus the conclusion:
The Arctic biophysical system is now clearly trending away from its previous state and into a period of unprecedented change, with implications not only within but also beyond the Arctic.
Among the impacts beyond the Arctic: disruptions of ocean circulation patterns, like those that caused last year’s horrific heatwave across northern Europe, and an increase in the frequency and severity of weather extremes, including major storms, for the upper latitudes.
The paper is fairly silent in addressing, at least directly, the impact on human communities across the Arctic; it calls for further research on “socioeconomic indicators,” whose “development has lagged the compilation of physical and biological factors.”
However, co-author Jim Overland of the National Oceanic and Atmospheric Administration had seemed to have Alaskan fisheries in mind when he spoke with Inside Climate News about a “domino effect” of declining sea ice and warming temperatures on the Bering Sea:
“In the past, you had sea ice growing in the fall, with northerly winds that helped grow ice. Now, with the delay of Arctic-wide freeze-up, you don’t have the pre-conditioning for the Bering freeze-up.”
‘A state we’ve never seen before’
Combined with unusual storm systems, you can get these off-the-charts changes in the Bering Sea,” said Overland. … “Last year, with no sea ice and no pool of deep, cold water, pollock were found in the north Bering Sea where they don’t usually go. The question was if they will they spawn in the new location or not, and it doesn’t seem that they did,” he said.
“When this happens two years in a row, it becomes really important. The Bering Sea is now in a state we’ve never seen before.”
Andy Mahoney of the University of Alaska Fairbanks, a geophysicist who has studied sea ice patterns and their importance to indigenous communities in the Arctic, shared his thoughts on the Box paper’s implications with a newsletter of the Global Landscapes Forum, which noted that “roughly 4 million people live in the Arctic, including indigenous peoples, recent transplants, hunters and herders, and city dwellers.”
Almost all of the changes described in the paper, including warming air temperatures, thawing permafrost, retreating sea ice, increased river discharge, and changes in the arrival of migratory species have direct impacts on the residents of Arctic communities, particularly those near the coast.
If [the study’s authors] were to consider metrics such as the cost of maintaining or relocating infrastructure, they would likely find that these are strongly correlated with rates of coastal erosion and permafrost thaw.
Rapid environmental change such as loss of sea ice as a hunting platform and bigger waves during the open water season is also affecting traditional subsistence activities in indigenous communities throughout the Arctic. But it is far from clear if these impacts outweigh those from other socioeconomic factors that are also changing, such as fuel prices, wildlife regulations, industrial activity and pressure to participate in the wage economy.
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The full paper, “Key indicators of Arctic climate change: 1971-2017,” can read without charge here.
