Protecting the Arctic

Written evidence from the Met Office

1. The Met Office is an acknowledged world-leading science organisation. As part of the DECC/Defra funded Met Office Hadley Centre Climate Programme, the Met Office conducts research on the Arctic region, both in terms of monitoring long-term changes and improving weather and climate predictions through improved understanding and modelling of Arctic processes.

2. The loss of Arctic sea ice has implications locally within the Arctic, as well as potential impacts on European and global climate. The Met Office is actively engaged with the NERC community on Arctic research and is currently collaborating on three (out of the five) current projects funded as part of NERC’s Arctic research programme. We have also set up a Joint (Met Office – NERC) Sea Ice Modelling Programme which will lead to further development of models of Arctic sea ice.

3. Perhaps the most dramatic indicator of Arctic climate in recent years has been the summer extent of Arctic sea ice observed from space. The extent of Arctic sea ice has been gradually declining since satellite records began thirty years ago and has been shown to be partly attributable to human influence.

4. Climate models project the Arctic will become ice-free during summer at some point this century – though likely not before 2040. Individual climate models are capable of capturing the observed decline in sea ice extent although, as a group, they tend to predict a slower decline than observed. Some models also capture year-to-year variability of similar magnitude to that seen in observations.

5. In September 2007, sea ice extent reached an all-time low, raising the question of whether the sea ice is likely to melt more quickly than has been projected. There is, however, no evidence to support claims that this represents an exponential acceleration in the decline. Indeed, modelling evidence suggests that Arctic sea ice loss would be broadly reversible if the underlying warming were reversed. Reducing uncertainty in model projections of Arctic sea ice requires a combination of increased and better observations and an increased ability to better represent Arctic processes in climate models.

6. The Met Office provides operational attribution reports to DECC throughout the summer melting season on the state of Arctic sea ice – including alerts on the likely date of the minimum sea ice extent in September. Forecasting summer Arctic sea ice months ahead is a developing capability. Predictions of future sea surface temperature and ice extent on these timescales are generated at the Met Office using the CICE model which was developed at Los Alamos National Laboratory in the US. Predictions are made based on recent observations of sea ice extent, together with computer simulations of key processes in the atmosphere and ocean. However, in order to provide robust advice on when narrow shipping routes (especially in the Northwest passage) will be ice-free, computing capacity to run our models at higher resolution will be required.

7. At the end of February 2012, the Met Office Hadley Centre Climate Programme completed a report commissioned by DECC and Defra on the Assessment of possibility and impact of rapid climate change in the Arctic. The report provides a comprehensive review of the current availability of observations in the Arctic; describes the models and mechanisms for Arctic sea ice projections; assesses the possibility of rapid change in Arctic sea ice and its potential impacts; and includes a chapter on further work in this field. The report will be published and publicly available in the next few months.

8 March 2012

Prepared 20th March 2012