Arctic amplification refers to the phenomenon where the Arctic region experiences a more rapid rate of warming compared to the global average. While climate change is impacting temperatures across the globe, the changes are more pronounced in the Arctic area due to a variety of changes in weather systems, sea ice coverage, and ocean circulation.
Who first introduced the concept of Arctic amplification?
The understanding that global climate change would be most pronounced in the polar regions was first proposed by Swedish scientist and Nobel prize winner Svante Arrhenius. In 1896 Arrhenius proposed that variations in the levels of carbon dioxide in Earth’s atmosphere could influence the planet’s surface temperatures and those temperature changes would be most pronounced in regions closer to the poles.
Why is climate change more pronounced in the Arctic regions?
There are several reasons as for why scientists believe that the effects of climate change are more pronounced in the arctic regions, many of which are interrelated.
Decline in sea ice and the albedo effect
Climate change leads to changes in the Arctic’s albedo feedback, or reflectivity, of the Arctic surface. Ice and snow have high albedo and reflect most of the sunlight that falls on them. As they melt due to rising temperatures, darker surfaces like ocean water and land are exposed. These surfaces have a lower albedo, meaning they absorb more sunlight, which leads to further warming and melting in a feedback loop.
Aerosols like black carbon (soot and dust) can land on snow and ice, reducing their albedo and thus their ability to reflect sunlight. This darkening of the surface can lead to increased absorption of heat and further melting of ice and snow in the region,
Atmospheric Circulation
The differential warming between the Arctic and lower latitudes affects atmospheric circulation patterns, such as the jet stream. A weaker temperature gradient between the Arctic and the mid-latitudes can lead to a more meandering and slower-moving jet stream. This altered air circulation can lead to prolonged weather patterns, such as heatwaves, which can exacerbate Arctic warming.
Ocean Currents
Changes in ocean circulation patterns can also contribute to Arctic amplification. Warmer water from lower latitudes may be transported into the Arctic, contributing to ice melt and a warming local environment.
Cloud Cover
The nature and extent of cloud cover in the Arctic can also influence temperatures. Clouds can have both a warming and cooling effect, depending on various factors such as their altitude, thickness, and composition. NASA researchers have combined CALIPSO-CloudSAT satellite observations to show that summer cloud cover does not slow down the rate of warming in the Arctic. That same research, however, showed an increase in fall cloud cover in the Arctic. Increased cloud cover during the fall and winter months serves as a blanket, trapping in heat that has accumulated in the Earth’s surface and oceans in the Arctic over the summer.
Influx of warmth from the tropics
Thunderstorms are more prevalent in the tropics which move heat from the Earth’s surface at the equator to higher atmospheric levels. Global wind patterns then carry this heat toward higher latitudes. This frequent transfer of heat from the tropics helps to offset warming near the equator while contributing to increased warming in the Arctic.
Loss of Insulating Snow Cover
Snow acts as an insulator, preventing the release of heat from the ground. As snow cover diminishes, the ground loses more heat to the atmosphere, contributing to warming.
Using ground and satellite data to map Arctic amplification
This global map created by NASA compares how much hotter or colder areas of the world are compared to averages spanning from 1951 to 1980. The data to create this map came from GISS surface temperature analysis data which combines in situ data from more that 20,000 weather stations, ships, and buoys.
The map below visualizes the temperature deviations worldwide for 2022 from the 1951-1980 average for each region of the world. 2022 is a year that ranks as the fifth warmest in recorded history. Arctic amplification is visible in the map with dark red areas in the northern polar regions.
Mapping Arctic amplification with satellite data
Scientists are using remotely sensed data from Earth observation satellites to not only map Arctic amplification but also to track and study the global phenomenon that affect Arctic amplification.
Satellite tracking of Arctic sea ice
The European Space Agency‘s CryoSat and Copernicus Sentinel-3 satellites have altimeters that can measure the thickness of Arctic sea ice. By accurately measuring the elevation of the ice surface in relation to the ocean level, scientists can calculate both the thickness and volume of Arctic sea ice.
A decline in sea ice has been linked to increased freshwater in the ocean that triggers changes in the Atlantic Meridional Overturning Circulation (AMOC) that helps to regulate global climate. When sea water turns into ice, it becomes fresh ice and leaves behind salty water. This salty water is colder and heavier than the rest of the sea water, so it sinks deep into the ocean. This sinking action helps move water around the world as part of global ocean thermohaline circulation.
The decline in sea ice, which has a high albedo which means more sunlight is reflected, is replaced by open water. The darker water absorbs more heat from sunlight, further contributing to ocean warming.
Satellite data is also being used to measure surface temperature, albedo, and atmospheric composition, all factors that can affect climate conditions in the Arctic and contribute to accelerated warming in this area.
References
Arrhenius, S. (1896). XXXI. On the influence of carbonic acid in the air upon the temperature of the ground. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 41(251), 237-276.
Arrhenius, S., & Holden, E. S. (1897). On the influence of carbonic acid in the air upon the temperature of the earth. Publications of the Astronomical Society of the Pacific, 9(54), 14-24. https://www.jstor.org/stable/40670917
Candanosa, R. M. (2016, June 5). New insights into the role of clouds in Arctic climate change. Climate Change: Vital Signs of the Planet – NASA. https://climate.nasa.gov/news/2449/new-insights-into-the-role-of-clouds-in-arctic-climate-change/
Esau, I., Pettersson, L. H., Cancet, M., Chapron, B., Chernokulsky, A., Donlon, C., … & Johannesen, J. A. (2023). The Arctic Amplification and Its Impact: A Synthesis through Satellite Observations. Remote Sensing, 15(5), 1354. https://doi.org/10.3390/rs15051354
Satellites provide crucial insights into Arctic amplification. (2023, May 24). European Space Agency. https://www.esa.int/Applications/Observing_the_Earth/Space_for_our_climate/Satellites_provide_crucial_insights_into_Arctic_amplification
World of change: Global temperatures. (2020, January 29). NASA Earth Observatory. https://earthobservatory.nasa.gov/world-of-change/global-temperatures
