Our directory of things of interest

University Directory

The Great Thaw: mapping Arctic sea ice thickness

  • Written by  Benjamin Hennig
  • Published in Mapping
The Great Thaw: mapping Arctic sea ice thickness Benjamin Hennig
06 Dec
2016
As Geographical takes a look at the geopolitical state of the Arctic, Benjamin Hennig maps current ice thickness at the top of the world

Sea ice can be described as frozen seawater floating on the surface of the polar oceans. It does not include icebergs or ice shelves, as these are originating from glaciers, rather than sea water. Sea ice becomes thickest and most widespread over the respective winter months in each hemisphere, covering the oceans around the Arctic and Antarctic with millions of square kilometres of ice. It melts when the seasons change, but in the Arctic large areas remain covered all year around, while Antarctic sea ice melts away over the summer in the southern hemisphere.

Sea ice in the Arctic has become of special interest of late, with research taking place on its role in regulating the global climate. It influences salinity of the ocean and affects the heat flux between the air and the ocean temperature. Sea ice also plays an important role in the polar ecosystems, most notably for marine mammals such as polar bears and seals.

From a human perspective, changes in the sea ice cover and resulting changes of important habitats have an impact on indigenous populations whose livelihoods are intertwined with the changing polar seasons and the existence of sea ice. It also affects the ability to navigate the polar oceans. Icebreakers are only capable of sailing through ice of a certain thickness. In recent years, the prospect of possible ice-free shipping routes through the northern seas during the summer period has become a serious prospect for shortening the distance between the Asian and European sea ports. Other economic factors are the natural resources in the Arctic Ocean which could become easier to access and exploit if sea ice concentrations are in decline due to global warming.

With its decline and changing patterns, sea ice might soon no longer be capable of protecting one of the last frontiers of human impact

While sea ice melts over the summer months, the winter period is crucial to building up the sea ice cover. This map shows the thickness of sea ice over the last northern hemisphere winter period, between the months of October 2015 and March 2016. Data used in this cartogram was measured by the CryoSat-2 satellite operated by the European Space Agency. CryoSat-2 is a sensor specialising in measuring the changes in the polar ice cover in both the Arctic and Antarctic region.

The cartogram distorts the Arctic Ocean by the total thickness of sea ice aggregated over the last winter. Using a regularly distributed raster grid, the cartogram transformation resizes each of the grid cells proportionally to the thickness of sea ice in that area. The map is centred on the North Pole, and the surrounding land area is included in the transformation for better orientation. Countries neighbouring the Arctic seas within the polar circle are labelled. The additional colour key highlights the maximum thickness of sea ice averaged for each grid cell area.

Arctic sea ice covers 14 to 16 million square kilometres in late winter. The cartogram shows the spatial patterns in the higher concentration of thicker sea ice towards the Canadian archipelago and the Greenlandic coast, while it appears much thinner along the Russian coast. It’s here that we might see possible future shipping routes, as the thinner ice cover over the winter period increases the chances of these areas becoming ice free over summer. At the moment it is estimated that the ice cover over summer decreases to about seven million square kilometres. Long-term trends also suggest that the median ice edge is in retreat, and that the thickness of sea ice in the Arctic is changing. A long-term study using other satellite observations recently found that ice thickness in the Arctic declined from an average of 3.59 metres in 1975 to 1.25 metres in 2012, which is a reduction of 65 per cent.

Changes in Arctic sea ice has begun to turn the region into an important area of economic interest for neighbouring nations. Claims over ownership of the Arctic waters (and resources) has already begun. With its decline and changing patterns, sea ice might soon no longer be capable of protecting one of the last frontiers of human impact.

Benjamin Hennig (@geoviews) is Assistant Professor in Geography, University of Iceland and Honorary Research Associate in the School of Geography and the Environment at the University of Oxford. He is also part of the Worldmapper project and is author of mapping blog www.viewsoftheworld.net

This was published in the December 2016 edition of Geographical magazine.

Related items

Geographical Week

Get the best of Geographical delivered straight to your inbox every Friday.

Subscribe to Geographical!

EDUCATION PARTNERS

Aberystwyth University University of Greenwich The University of Winchester

TRAVEL PARTNERS

Ponant

Silversea

Travel the Unknown

DOSSIERS

Like longer reads? Try our in-depth dossiers that provide a comprehensive view of each topic

  • The Human Game – Tackling football’s ‘slave trade’
    Few would argue with football’s position as the world’s number one sport. But as Mark Rowe discovers, this global popularity is masking a sinister...
    Essential oil?
    Palm oil is omnipresent in global consumption. But in many circles it is considered the scourge of the natural world, for the deforestation and habita...
    National Clean Air Day
    For National Clean Air Day, Geographical brings together stories about air pollution and the kind of solutions needed to tackle it ...
    The green dragon awakens
    China has achieved remarkable economic success following the principle of developing first and cleaning up later. But now the country with the world's...
    Mexico City: boom town
    Twenty years ago, Mexico City was considered the ultimate urban disaster. But, recent political and economic reforms have transformed it into a hub of...

MORE DOSSIERS

NEVER MISS A STORY - Follow Geographical on Social

Want to stay up to date with breaking Geographical stories? Join the thousands following us on Twitter, Facebook and Instagram and stay informed about the world.

More articles in PLACES...

Cities

As the planet urbanises, attention is turning towards the most…

Forests

Palm oil is omnipresent in global consumption. But in many…

Cities

A rising number of cruise ships and their ‘overlooked’ diesel…

Mapping

Benjamin Hennig charts the growth and impact of the world’s…

Deserts

Long-term studies reveal the Sahara desert has expanded substantially over…

Water

South America’s wealthiest economy is at a crossroads between environmental…

Forests

The European Court of Justice finds the logging of a…

Mountains

In this extract from his new book, Tides, mountain climber…

Cities

New data from the World Health Organization reveals that nine…

Water

In the wake of the water crisis in Flint, Michigan,…

Mapping

Benjamin Hennig maps out the global production and distribution levels…

Water

Millions of Americans are living in areas at high-risk of…

Mapping

New interactive maps combine precipitation and temperature to show climate…

Cities

Public transport in India could be on the verge of…

Water

To retrace the route of the fur voyageurs on the waterways…

Cities

IPCC Cities and Climate Change Conference: Alberta host dresses non-renewable…

Water

Increased carbon dioxide is affecting freshwater ecosystems

Forests

The latest laser scanning technology reveals new insights into the…

Forests

Deforestation is having an unexpected effect in the Amazon: fewer…

Forests

The iconic Douglas fir tree, familiar to fans of the…