Record-breaking Arctic ice melt - causes and implications

Image credit: NASA Goddard Space Flight Center.

NASA satelite pictures and a BBC News item on the latest data from the Norwegian Polar Institute (NPI) showed that the Arctic sea ice has thawed to record levels this year. It is well known that the Arctic ice thaws annually during the summer months, when the temperature is above freezing, and forms again in the winter, but lately more ice is melting each year and the floating ice is at its smallest since monitoring began more than 30 years ago. What are the causes and implications?

The line on the above image shows the average minimum extent from the period 1979-2010, as measured by satellites. NASA says that a 13% decline per decade in the minimum summertime extent of the sea ice has been observed over the last three decades. The thickness of the sea ice cover also continues to decline.

Scientist from NPI has been gathering and examining data from their Norway's Arctic research station at Ny-Alesund on Svalbard, since the beginning of the 1990s, using satellites and a range of different techniques, both old and new. They have seen a greater change than they could even imagine 20 or even 10 years ago, said their international director, Kim Holmen.

The BBC news article says: “the most cautious forecasts say that the Arctic might become ice-free in the summer by the 2080s or 2090s, but that recently many estimates for that scenario have been brought forward.”

The Causes

The main cause for the accelerated melting of Artic sea ice is global warming, which is caused mainly by greenhouse gases (GHG) emissions. In its report ‘State of the Climate: Global Analysis, July 2012’ the National Oceanic and Atmospheric Administration (NOAA) showed that the average combined global land and ocean surface temperature for July 2012 was 0.62°C above the 20th century average of 15.8°C, making this the fourth warmest July since records began in 1880. The global average land surface temperature for July 2012 was the third warmest on record, at 0.92°C above average. This figure was even higher (1.19°C) when considering the Northern Hemisphere separately.

Things can only get worse, it seems, if the outcome of the interim climate talks which concluded in Bangkok, Thailand, last Wednesday is anything to go by. According to various news reports from participant observers of the talks, none of the 190 nations involved in the talks made new commitments regarding emissions reduction, as promised in previous climate meetings.

An article from the Energy and Environment Management (EEM) webpage said that US negotiators "stunned” delegates when they called for any new climate treaty to be "flexible" and "dynamic" rather than legally binding. These climate talks in Bangkok were intended as a preparation for the major UN end-of-the-year climate change meeting, which this year will take place in Doha, Qatar, from 26 November to 7 December 2012.

A report by the UN Environment Programme (UNEP) showed that several rich nations will not meet their existing pledges to cut GHG emissions by the end of the decade and even if they did, GHG emissions would still be 20% above what is needed to keep global temperature increase below 2°C. This means stronger commitments from rich and developing nations is still very much needed, otherwise a 3.5°C temperature increase is more likely.

The Implications

The Norwegian researchers suggested that a large reduction in sea ice is likely to have an impact on the path of the jet stream (the high altitude wind that guides weather systems such as storms) and that these changes will be observed across and beyond Europe.

This happens because of the albedo effect, i.e. white surfaces such as a frozen Arctic sea has high albedo or reflecting power and reflect most of the sunlight reaching it, whereas darker surfaces such as deep water has lower reflecting power and absorbs more of the sunlight reaching it. This means when the Arctic is ice free it will absorb more sunlight and the warm sea in turn will influence wind systems and precipitation patterns.

Links to references

David Shukman’s coverage of the Arctic Sea thaw story on the BBC News online.

NASA satelite images of shrinking Arctic sea ice.

‘State of the Climate : Global Analysis, July 2012,’ from the  National Oceanic and Atmospheric Administration (NOAA).

Energy and Environment Management News article.

UNEP Emissions Gap Report.

The CABI internet resource Environmental Impact is a comprehensive source of bibliographic information  on climate change and other influences of humans on the biosphere, which also covers other aspects of man's damage to the environment such as pollution, deforestation, desertification and habitat loss.