Human-induced global warming alone can’t be blamed for the Arctic meltdown over the last couple of decades and natural variability is also to be blamed, a new study has claimed.
Researchers at University of California, Santa Barbara, led by climate scientists Qinghua Ding published a paper in the journal Nature Climate Change wherein they have blamed wind swings and other natural variations alongside human activity-induced global warming for the rapid decline in sea ice at the Arctic over the last couple of decades.
The team notes that although the greenhouses gases have a big impact on the sea ice cover at the Arctic, around 30-50 per cent of ice loss is due to the natural swings caused over the span of past 20 to 30 years. Scientists found that changes in the tropical Pacific Ocean have led to creation of “hot spot” over Greenland and the Canadian Arctic and this effectively has boosted warming in that region.
The hot spot is a large region of higher pressure where air is squeezed together so it becomes warmer and can hold more moisture, both of which bring more heat to the sea ice below. The new paper focuses specifically on what this atmospheric circulation means for Arctic sea ice in September, when the ocean reaches its maximum area of open water.
Ding and his team have developed a sea ice experimental model that includes the climate variations also along with the impact of the greenhouses gases. In this model it has been found out that the wind patterns, which then creates a shift in wind pressure, thus causing a substantial amount of sea ice loss.
According to Ding, tropical Pacific Ocean will drive the cycles causing ripple effects, generating atmospheric waves which will ultimately turn specific regions into higher or lower pressure modes causing a shift in temperature. Thus to predict the future impact on sea ice, both the components; natural variations and greenhouse gases effect is essential.
Scientists believe that the long-term natural variability in the region is most likely driven by the tropical Pacific Ocean, which have ripple effects, and atmospheric waves snake around the globe to create areas of higher and lower air pressure. Teasing apart the natural and human-caused parts of sea ice decline will help to predict future sea ice conditions in Arctic summer. Forecasting sea ice conditions is relevant for shipping, climate science, Arctic biology and even tourism. It also helps to understand why sea ice declines may be faster in some decades than others.