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Arctic Melt: What Will It Mean For The Planet?

Following 'Arctic Melt: Will There Be A New Arms Race?', a look at the wider environmental problems associated with rapid Arctic warming.

It might not exactly be the storyline of the Hollywood movie 'The Day After Tomorrow', but there could still be very serious effects from melting ice in the Arctic.

Countries around the region are vying for resources opened up by reducing ice, and Britain is getting to grips with the political and military implications.

But scientists are pointing out that, access to resources aside, the meltwater pouring into the North Atlantic could have grave consequences for the planet that have not previously been considered - some of which are already in motion. 

The reason for this is that the AMOC, or Atlantic meridional overturning circulation, could be severely affected.

global warming

This system works like a conveyor belt, with warmer water floating along the surface and then sinking as it nears or enters the Arctic and cools.

As more warm water comes in behind it, the cold water is pushed down and away from the Arctic, forming a giant loop that wraps around the globe.

This pattern of ocean currents brings warm water to Europe and is an integral part of Earth's climate.

But when fresh water is introduced through melting ice, this equation changes.

That’s because the salt in seawater makes it denser, facilitating its sinking when it cools.

Fresh (non-salty) meltwater dilutes and reduces the amount of salt water, and risks sabotaging the whole system.

The climate scientist-run site Realclimate.org has pointed out that, in fact, the fresh water introduced into the North Atlantic from the Arctic melt is already affecting the climate.

RealClimate.org
Changes to global temperature - a warming trend, except near the Arctic (image: Rahmstorf et al, Nature Climate Change 2015)

While the average temperature elsewhere has gone up, the northernmost part of the Atlantic has cooled. This, RealClimate says, has been discussed as a possible consequence of global warming since the 1980s:

"Evidence is mounting that the long-feared circulation decline is already well underway".

James Hansen of Columbia University has said that in future decades, if the meltwater causes the AMOC to shut down entirely, it would "drive superstorms stronger than any in modern times" and that "all hell will break loose in the North Atlantic and neighbouring lands":

"If we let ice melt from Greenland to fully shut down the AMOC... it will be permanent, as far as the public is concerned. It may take several centuries for AMOC to get moving again. However, superstorms will not be the most important consequence of global warming if it continues to grow. The most important effect will be sea level rise".

In fact, some sea level rise has already been recorded

But, despite the long-term trends for less ice in the Arctic, there have been considerable fluctuations, year by year, in Arctic ice. Could climate scientists be mistaken?

In October of 2016, the Telegraph pointed out that there was more ice in the region then than there had been during the same season in 2012. This was despite predictions that the region could have become seasonally ice-free by that point.

When comparing year-by-year ice in the Arctic, comparisons are made at identical points in the calendar because ice levels fluctuate by season. Arctic ice peaks in volume in March, and, having been warmed all summer, is always at its lowest point around September and October.

The side-by-side National Snow and Ice images above show very clearly that there was more ice cover in September 2016 than there had been in 2012.

But while this disproves the prediction made by Professors Peter Wadhams, of Cambridge University, and Wieslaw Maslowski, of the Naval Postgraduate School, in Monterey, California, of a 2016 seasonally ice-free Arctic, it does not debunk a longer-term warming trend.

The Telegraph article did also quote other scientists, such as Dr Ed Hawkins of the University of Reading, who said that Wadhams and Maslowski's incorrect forecast aside, the overall trend is definitely for declining sea ice:

"As global temperatures rise, we will see a continuing decline in Arctic sea ice extent, although this will happen somewhat erratically, rather like a ball bouncing down a bumpy hill".

To avoid being misled by two isolated annual comparisons, the Met Office advises only using long-term data. Indeed, a look at ice levels for other years shows the downward trend in Arctic sea ice very clearly.

Snapshots of Arctic ice levels, with 1979 in blue, 2012 in green, and 2016 in red

Clicking on each year's ice level line, from 1979 to 2016, this graph illustrates brilliantly both the short-term fluctuations between sea ice cover from year to year and the long-term trend of overall declining sea ice in the region.

But establishing just whether, and to what extent, global warming is occurring in the Arctic is only one part of global warming research and planning.

The consequences both in the Arctic and elsewhere are also crucial considerations. Indeed, droughts either caused or exacerbated by climate change are thought to have played a role in sparking the Syrian civil war

Whether the immediate issue of access to new resources in the Arctic is resolved quickly or not, global warming is likely to prove a continuing concern for defence planners in the coming decades.

More: 'Military Experts: Global Warming Could Spark 'Epic' Humanitarian Crisis'