Increasing air temperatures have driven dramatic changes in the Arctic for the last 47 years, according to a new study by scientists in Europe and the U.S.
“The Arctic biophysical system is now clearly trending away from its 20th century state, with implications not only within but beyond the Arctic,” said Jason Box, a research professor at the Geological Survey of Denmark and Greenland and lead author of the study, in a statement.
“Several of the climate indicators exhibit a statistical correlation with air temperature or precipitation,” said Box. “This reinforces the notion that increasing air temperatures and precipitation are drivers of major changes in the Arctic system.”
To create such a comprehensive report, the authors compiled records of observations of nine key indicators from 1971 to 2017: air temperature, permafrost, hydroclimatology, snow cover, sea ice, land ice, wildfires, tundra and terrestrial ecosystems, and carbon cycling.
A climate indicator illustrates the state of a climate-related system and the different key components therein. Sea ice extent, for example, summarizes the effects of changing temperature, winds, ocean heat and other variables over time.
All the indicators used in the report point to a warming climate and a fundamental change in the Arctic.
According to the study, annual average air temperatures in the Arctic increased 2.9 degrees Celsius from 1971 to 2017, at 2.4 times the rate of increase of the Northern Hemisphere average. Temperatures during the cold season from October to May increased by 3.1 degrees Celsius, the largest increase by season, at 2.8 times the corresponding rate of increase of the Northern Hemisphere. Air temperatures during the Arctic’s warm season, from June to September, also increased 1.8 degrees Celsius, at 1.7 times the rate of increase of the Northern Hemisphere summer.
The temperature increase has caused a cascade of effects within different Arctic systems. These include a shortened period of flowering and pollination for plant species; timing mismatch between plant flowering and pollinators; increased plant vulnerability to insect disturbance; increased shrub biomass; increased wildfire ignitions by lightning; and shifting animal distribution and demographics.
RAPID CHANGES FOR ARCTIC COMMUNITIES
“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,” said Andy Mahoney, an expert in sea ice geophysics at the University of Alaska Fairbanks who is not part of the study.
Mahoney has worked alongside indigenous communities in the Arctic to collect data and preserve local traditional knowledge about sea ice. He noted that socioeconomic indicators were absent from the study. “The study’s recommendations do not include the incorporation of local and indigenous knowledge in identifying and supplying other potential indicators, and this strikes me a notable absence,” he said.
Roughly 4 million people live in the Arctic, including indigenous peoples, recent transplants, hunters and herders, and city dwellers.
“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,” said Mahoney.
“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,” said Mahoney. “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.”
Because air temperatures over the Arctic are increasing faster than air temperatures over the rest of the world, weather patterns across Europe, North America and Asia are becoming more persistent, leading to extreme weather conditions.
Past studies have shown that increasing air temperatures have also caused the global ocean circulation to slow. Box said that this disruption can further destabilize climate, causing cooling across northwestern Europe and more intense storms.
The study’s authors hope that these indicator-based observations could provide a foundation for the research that is needed to address the gaps in knowledge and to support a more integrated understanding of the Arctic region and its role in the global dynamics of the earth’s biogeophysical systems.