Published at 2020, July 7th
A new study published in Nature Climate Change suggests the South Pole has warmed 3 times faster than the rest of planet Earth over the last 3 decades. Much of this warming is connected to climate cycles happening thousands of miles away in the tropics.
Global Mean Surface Temperatures: The South Pole as an Outlier
The global mean surface air temperature (SAT) has been increasing
since at least the 1880s. But from 1970 onwards, the degree of warming rose from the average rate of 0.05 °C decade-1 to 0.15–0.20 °C decade−1.
Nonetheless, climate trends are subject to spatial heterogeneity and there are often regional trends that greatly differ from the global mean. A broad diagnosis of the drivers of such extreme fluctuations in temperature is essential to better understand how greenhouse gases impact variations like this one.
In polar regions, warming SAT can be partially explained by positive ice-albedo effects, while regional cooling can be induced by stratospheric ozone depletion and extreme decadal variability. But in Antarctica – a temperature fluctuation case study, there are other factors in the equation too.
Antarctica and the South Pole: the Same Region, Different Temperature Behaviors
The study published in Nature Climate Change was led by Kyle Clem of Victoria University of Wellington in New Zealand. The scientists involved studied surface air temperatures at the world’s southernmost weather observatory: the Amundsen-Scott station – located in the remote and high-altitude continental interior of the South Pole.
The changes between the global surface air temperature mean and Antarctica’s mean are particularly intriguing. Over the 2nd half of the 20th century, West Antarctica and the Antarctic Peninsula warmed more than twice as fast as the global average. However, the South Pole was actually cooling until the 1980s and only after this period the region started warming substantially.
More precisely, the scientists found that between 1989 and 2018, the South Pole had warmed by about 1.8 degrees Celsius at a rate of +0.6 degrees Celcius per decade – that’s 3 times the global average. They provide some answers that seek to explain such changes.
Natural Climate Cycles Led to Temperature Increases in the South Pole
Specific events like the one in the South Pole are affected by natural and anthropogenic climate change – the scientific community imagined. However, the individual contribution of each factor was not, up to this point, very well understood.
The study led by Kyle Clem found that the strong warming over the Antarctic interior during the last 30 years was mainly driven by the tropics. It looks like ocean temperatures in the Antarctic region are largely regulated by a natural climate cycle known as the Interdecadal Pacific Oscillation (IPO).
This cycle takes western Pacific temperatures to swing back and forth between warm and cool phases every couple of decades. So when the ocean is warmer, it interacts differently with the atmosphere – and these atmospheric changes transport more warm air south into Antarctica.
Scientists suggest these atmospheric changes along Antarctica’s coast are an important mechanism driving climate anomalies in its interior. But according to an article published by the Ohio University staff, Clem and Fogt (Ohio University professor) believe these warming trends were unlikely the exclusive result of natural climate change alone.
Human-Caused Emissions Likely Linked to Temperatures Increases in Antarctica and the South Pole
Despite not being the dominant driver, the researchers suggest that human-caused warming likely contributed to the trends observed at the South Pole in recent decades.
Despite the fact that the highest monthly reading ever recorded of carbon dioxide concentration – 417 parts per million – having been registered in May 2020, this year’s emissions are likely to decrease. This is the result of all the economic and social changes caused by the new coronavirus pandemic.
This study was an important step in better understanding of how the Antarctic region is influenced by both natural phenomena and human behaviors.