Polar vortex: did warming bring the chill to US?

Extreme events like this may become frequent, say experts

 
By Vibha Varshney
Last Updated: Thursday 17 September 2015

Small islands getting submerged because of rising sea levels are no longer the poster images of climate change. North America and eastern Europe have replaced them. Since January 2, parts of North America and eastern Europe are experiencing extreme cold weather, at places the temperatures have fallen below -50 degree centigrade.

The dip in temperature is a result of an unbalanced Arctic polar vortex, the mass of cold air that generally circulates over the North Pole. The polar vortex keeps the cold air caged in the area. If the vortex weakens, the cold air can escape and reach Canada and subsequently enter the US and eastern Europe. If this air meets the jet stream—winds from the Pacific Ocean which carry moisture—it can result in heavy snow.

Is global warming responsible?

It is being hypothesised that the weakening of polar vortex is a result of global warming. Warming leads to melting of polar ice during summer months. The melting ice warms the Arctic Ocean and the heat is radiated back to the atmosphere. In the absence of global warming, there used to be a substantial difference between the temperatures at the poles and in the mid latitudes. But because of rising temperatures, the Arctic region is warming twice as rapidly as the mid latitudes. The reduction of temperature difference between the two areas results in a change of path of the cold winds which then move southwards. As more and more ice melts in the coming years, more such events can be expected. But very little research on this is available as ice melting is a recent phenomenon. In fact, the IPCC (Intergovernmental Panel on Climate Change) report says that the polar vortex is expected to become smaller in the coming years.

This time, US is the victim

The extreme weather has the US government reiterating the reality of climate change. In a blog on the website of the White House, the scientific adviser to the president of the US said that while a single weather episode cannot prove or disprove climate change, this is part of a pattern and more extreme events such as these can be expected. A blog on the website says, “… there’s reason to believe may become more frequent in a world that’s getting warmer, on average, because of greenhouse-gas pollution.”

It is just that the US is not willing to take steps to reduce the carbon dioxide emissions. The cold winds have brought the US economy to a standstill. But now, the bad boys are the victims. Will the country now come forward to take responsibility for its actions? Just 6.6 per cent of the world population in North America contributes to 28.1 per cent of polluting emissions.

I. Per capita emissions in 2010 and Per capita cumulative emissions from 1971-2010*

  PER CAPITA EMISSIONS: 2010 PER CAPITA CUMULATIVE EMISSIONS: 1971-2010
ASIA 3.8 83.0
EUROPE 7.0 292.9
AFRICA 0.9 22.1
NORTH AMERICA 14.0 508.6
SOUTH AMERICA 2.4 58.3
OCENIA 15.4 434.0
WORLD 4.3 120.1



It is being said that the worst of the event is already over. During the weekend, it is expected that most of the affected areas would experience average or above average temperatures.

But extreme events have become a reality in today's world. Sea level rise, tropical cyclones and floods are likely to affect poor people in Asia (see infographics).

Sea level rise

image

The graphic shows that the Asian population is most exposed to sea level rise and Asia will bear the brunt of sea level rise in the future, with over 80 million people being affected in 2030

Tropical cyclones

imge

The average number of people exposed to tropical cyclones per year globally would increase by 11.6 per cent from 2010 to 2030 from population growth only. In relative terms, Africa has the largest percentage increase in physical exposure to tropical cyclones. In absolute terms, Asia has more than 90 per cent of the global population exposed to tropical cyclones

Floods

image

About 800 million people are currently living in flood-prone areas, and about 70 million people currently living in flood-prone areas are, on average, exposed to floods each year. Population growth will continue to increase this exposure, more so in Asia than anywhere else

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