Skip to main content

Climate Change: Arctic

Volume 488: debated on Tuesday 24 February 2009

To ask the Secretary of State for Energy and Climate Change what research his Department has conducted into the scale of polar icepack melting in the Northwest Passage. (255188)

My Department funds the Met Office Hadley Centre (MOHC), through its Integrated Climate Programme with joint funding from the MOD and DEFRA, to monitor, understand and predict climate change; this research includes incorporating sea ice into global climate models to ensure best possible predictions on melting of Arctic sea ice. We also liaise with other research groups in the U.K. and internationally on this topic.

The Northwest Passage temporarily became fully open and navigable in summer 2007, for first time in recorded history, due to the record low extent (September average area: 4.28 million sq km) of Arctic sea ice melt. The same situation occurred in summer 2008, when the sea ice area (4.67 million sq km) was at its second lowest on record. Satellite monitoring data since 1979, available from the US National Snow and ice Data Centre (NSIDC) shows there has been a long-term decline in the extent of summer Arctic sea ice and that this decline has accelerated over the last decade; the long-term downward trend of around 10 per cent. per decade can be linked to human emissions of greenhouse gases and aerosols. It is not yet clear if the much larger summer ice melt in the last two years is an acceleration of this long term trend or a short term variation around it. Recent analysis by the MOHC suggests that changes as large as the observed record low in 2007 can indeed result from natural year-to-year variability around the longer term downward trend; this provides confidence in the ability of the MOHC’s climate model to simulate changes in the area of Arctic sea ice and its continuing decline. However, it is evident that climate models show a wide range of future predicted rates of sea ice decline. Whilst the IPCC’s Fourth Assessment Report suggested the Arctic would be largely free of summer ice by 2100, many more recent models predict this will happen much sooner—by the middle of this century or even earlier; several experts suggest there may possibly be no summer sea ice by the mid 2010s.

Satellite and other records also show a long-term decline in the average thickness and age of Arctic sea ice over recent decades. For example, scientists from University College London recently reported that the thickness of the ice was significantly lower (by an average of 10 per cent.) during the winter of 2007-08 than during the previous five winters, indicating that the total volume of sea ice has decreased significantly. Though based only on satellite data (which are not ideal for measuring sea ice thickness), this result confirms previous evidence of decreasing sea ice thickness over the past three decades from US and UK submarine sonar measurements.

The retreat of Arctic sea ice has geo-political implications, with the Northwest Passage becoming increasingly ice free and fully open to shipping. There are other important implications; by reducing the reflectivity (albedo) of the Earth’s surface, it increases the amount of solar radiation that the surface absorbs, thereby accelerating warming. Temperatures have already risen almost twice as quickly in the Arctic as in the rest of the world over the past 100 years. Sea ice retreat also has significant impacts on Arctic ecosystems, as many organisms (including certain species of fish) depend on its presence for survival. DECC is continuing to seek updated assessments of Arctic sea ice conditions and impacts from UK and international experts.