Met Office submission to the Northern Ireland Assembly Environment Committee:
Inquiry into Climate Change

Introduction

1. The Met Office has a world-leading standing: because of its scientific excellence in both Numerical Weather Prediction and Climate Research and because - uniquely - both activities are carried out within one organisation using a single modelling suite. This combination of scientific expertise and operational capability means that the Met Office can provide “seamless” prediction - on timescales from an hour to 100 years - and is uniquely placed to understand how short or medium term forecasting and warning services can be used to manage some of the impacts of climate change.

2. Scientists from the Met Office’s Hadley Centre made a significant contribution to the Intergovernmental Panel on Climate Change (IPCC) 4 th assessment report and to the internationally recognised UK Stern review on the economics of climate change.

Climate Change is a reality

3. Climate change is real and getting worse. The earth is already nearly 0.8ºC warmer than it was in around 1900. Without large and rapid global emissions reductions it is very likely that global warming will exceed 2ºC over the coming decades.

4. The present day concentration of the main man-made greenhouse gas, CO 2, is already around 380 ppm. Other greenhouse gases add an equivalent CO 2 of around 70 ppm. Some estimates suggest that greenhouse gases would have to be stabilised at or below 500 ppm CO 2-eq to give a good chance of limiting eventual global temperature rises to between 2 and 3 ºC above pre-industrial levels. The Met Office Hadley Centre models warn that an even lower level of 450 ppm would most likely be required. Even if we can limit global warming to between 2 and 3 ºC, and local changes may be considerably larger over most of the globe, there will be significant changes in the world’s climate, some of which may be irreversible.

Uncertainties in Climate Change

5. Although there is now a clear consensus on the reality of anthropogenic climate change there is a great deal of uncertainty in local detail particularly in relation to extreme weather events.

6. Detail in local predictions are limited because:

• Temperature changes are comparatively easy to predict, currently other parameters – such as cloud and wind – are subject to much greater uncertainty;
• Regional predictions can be subject to considerable uncertainty. For example for northern parts of the UK different climate models do not agree on the sign of summer rainfall changes. This results in wide range of predicted outcomes for many climate variables such as rain and wind. For some variables, this will make the predictions difficult to use for planning purposes;
• Computer limitations mean that climate predictions are generated at relatively coarse resolutions that do not represent important weather features, such as intense storms, as well as current weather forecast models;

7. Climate models are not suitable for assessing low frequency, high impact extreme events, for example 1 in 50 or 100 year events. It is not yet clear how far UKCP scenarios can be pushed in terms of assessing such extremes, though guidance is being developed for the release in April 2009. Given known model deficiencies in representing a range of important modes of climate variability,  it is unlikely that they will be suitable for assessing the risk of extremes with periods of 1 in 20 years or greater.

8. Uncertainties in climate predictions are driven by several factors, including

• Climate sensitivity: the response of the climate to change in concentrations of greenhouse gases and aerosols;
• Carbon cycle: how climate effects the natural uptake of carbon;
• Regionalisation of climate response;
• Uncertainties in emissions pathways;
• Natural variability.

9. UKCP09 will, for the first time, provide estimates of the probability of a particular level of future change for a given weather variable – unlike UKCIP02 which only provided a single ‘most likely’ prediction. The estimation of uncertainty across a range of parameters is particularly valuable as, for example, predictions for temperature are likely to be significantly more reliable than for precipitation, wind and cloud.

10. There are good scientific reasons to believe that significant progress can be made over the next 5-10 years, to provide more reliable predictions at local scales, with reduced (and better quantified) uncertainties. However, achieving this will require a coordinated science programme, bringing together climate scientists across the UK and abroad, together with significantly enhanced supercomputing capacity.

11. Legislation should therefore remain as flexible as possible to accommodate increased understanding. Correct interpretation of the UKCP reports is vital to any future mitigation and adaptation strategies; the Met Office is well placed to support the Northern Ireland Assembly’s understanding of this work, and how it can best be applied in directing future policy and planning.

Mitigation and Adaptation

12. Fundamental to all strategic planning should be an understanding of the uncertainties of climate change and of the impact of mitigation activities on adaptation plans. If mitigation actions are themselves dependent on climate change (eg: implementation of some renewable energy sources, or non-fossil fuel energy sources such as nuclear) then the associated infrastructure (eg: siting of power stations) should take future climate changes and impacts into consideration.

13. The use of return periods for critical weather events in planning is useful in putting these into historical perspective. With climate change playing an increasing role in the evolution of current and future weather patterns, the use of return periods should not be used to predict the future likelihood of occurrence. Simply put, the past is no longer an adequate guide to the future.

14. Whatever emissions scenarios are realised over the next few decades, ‘inertia’ in climate system means that the extent of global warming is likely to remain broadly constant across the scenarios over the next 30 years. Consequently, a significant amount of adaptation will be required by both the public and private sector.

15. The time periods of 2020, 2050 and 2100 should all be considered if changes over these time periods affect decisions eg: on the development of infrastructure. In the near term (2020 or before), natural climate variability should be taken into account in addition to human-caused climate change.

16. Decadal forecasting techniques are being developed by the Met Office Hadley Centre to assist with decision-making affected by climate change on these timescales. In the longer term, the main driver of change is expected to be human-caused emissions of greenhouse gases. Again, climate modelling by the Met Office Hadley Centre can assist with that, including regional climate modelling such as that provided for UKCP09

17. Policy and adaptation planning requires an in-depth scientific understanding of future trends and risks. To be successful, early and coordinated intervention requires a sound understanding of the impacts of climate change and the impact of both the proposed adaptation and the impact of ongoing mitigation activities.

18. Adaptation must be seen as an ongoing requirement, not a single alteration or adjustment. Strategy must be flexible enough to accommodate increased understanding of climate change impacts. Key to adaptation is understanding the likely extent of future climate change, including the effects of mitigation, on the rate of change. In turn, the key to greater understanding of how climate change will evolve is to ensure we continue to align the advances in technology and in science to better model the global climate system. Future predictions will improve only if model complexity and model resolution improves in line with advances in the supporting science.

19. The Met Office is a world leading organisation, both in the field of weather forecasting and climate prediction which supports the UK’s high profile policy role on climate change issues. Scientists from the Met Office’s Hadley Centre made a significant contribution to the Intergovernmental Panel on Climate Change (IPCC) assessment reports and to the internationally recognised UK Stern review on the economics of climate change. We are at the forefront of world leading climate research, funnelling data from diverse natural sciences into climate prediction models that will produce, for example, the UKCP09 projections.

20. This, and our commitment to provide the best advice to science based policy, means we remain well placed to provide the guidance needed by the Northern Ireland Assembly to ensure policy remains flexible enough to react to increased understanding of climate change impacts, and that actions realise the greatest benefits as well mitigating the highest risks.