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We desperately need to predict what climate change is doing to UK rainfall
Recent floods can’t be directly attributed to global warming but it’s still vital we refine our projections of what the future holds
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The devastation caused by intense rainfall events and associated flooding of properties over Christmas and the new year must have been dreadful for those affected.
So the very last thing that needs to be heard at the moment is a set of pompous statements implying this might be due to manmade climate change. What would this achieve? Nobody wants to hear the message “it’s your fault”, and it is almost certainly not completely true anyway.
At the same time, we do know that the composition of the atmosphere is changing, and predominantly with a ramping-up of carbon dioxide. The resulting warming will adjust the patterns of surface temperatures of the oceans, and change the yearly extent of sea-ice nearer the Earth’s poles. Many detailed simulations are starting to confirm that this then affects storm directions and rainfall patterns in the UK.
It is correct to state, almost as a mantra, that no single period of storm events can be attributed to climate change. There always have been extreme intense rainfall occurrences and there always have been floods.
What the meteorological research community is working hard to determine is the amount to which their frequency is changing. To answer this, there is continuous assessment of all available archived weather measurements. In parallel, an additional analysis is made using the best available weather forecast models, but artificially driving these computer models with different prescribed atmospheric carbon dioxide levels.
What patterns then emerge from such a set of computer simulations when forced with past carbon dioxide concentrations? Do they tally with measurements? Once we see agreement for decades past, we can trust the same models far more to predict the future, corresponding to higher carbon dioxide measurements than present. Surprisingly, there is reason to believe that for some parts of the world, extreme events are starting to occur less often.
There is real hope in the UK that the combination of the advanced Met Office climate models, assessed in collaboration with our research centres and key university departments, are starting to make rigorous assessments of expected change. In particular, by supplying refined estimates for how the probabilities of major storm events happening might change over the coming decades. That information will be critical for adaptation planning, including how to make our infrastructure more robust.
Hence there is a pressure too on those who undertake ‘impacts calculations’ – for a given rainfall strength and duration, what are the consequences for safety, property and transport? Can we further improve estimates of soil moisture, river flow response and risk of landslides? There is a compelling argument that even should expected frequency changes be relatively small, there is still a duty to protect society as best as possible from the impacts of peaks in rainfall. With population growth and much more travel by society, inevitably larger numbers of people will be affected by extreme weather.
It feels as if these days, people now just switch off when hearing any discussion of climate change and its implications. There are many reasons for this, and some are no doubt very valid.
There was a period of time when even researchers working in this scientific area felt there was an over-emphasis on the concern, and to which a backlash would occur. But it is still worth remembering that even with the current “lull” in warming, averaged at the decadal timescale, the last decade has been the warmest on record.
Unfortunately there is compelling evidence such warming will start to climb again and most likely will change the hydrological cycle. Hence there remains a desperate need for refinement of projections as to how rainfall patterns might evolve in to the future.
It is this knowledge that will enable society to have a calm and considered discussion, allowing the UK and elsewhere to plan ahead. Such planning will need to optimise available adaptation funds, in a way to maximise safety and resilience should the weather events witnessed over recent weeks become more commonplace.
• Dr Chris Huntingford is a climate modeller at the UK Centre for Ecology and Hydrology
Recent floods can’t be directly attributed to global warming but it’s still vital we refine our projections of what the future holds
The devastation caused by intense rainfall events and associated flooding of properties over Christmas and the new year must have been dreadful for those affected.
So the very last thing that needs to be heard at the moment is a set of pompous statements implying this might be due to manmade climate change. What would this achieve? Nobody wants to hear the message “it’s your fault”, and it is almost certainly not completely true anyway.
At the same time, we do know that the composition of the atmosphere is changing, and predominantly with a ramping-up of carbon dioxide. The resulting warming will adjust the patterns of surface temperatures of the oceans, and change the yearly extent of sea-ice nearer the Earth’s poles. Many detailed simulations are starting to confirm that this then affects storm directions and rainfall patterns in the UK.
It is correct to state, almost as a mantra, that no single period of storm events can be attributed to climate change. There always have been extreme intense rainfall occurrences and there always have been floods.
What the meteorological research community is working hard to determine is the amount to which their frequency is changing. To answer this, there is continuous assessment of all available archived weather measurements. In parallel, an additional analysis is made using the best available weather forecast models, but artificially driving these computer models with different prescribed atmospheric carbon dioxide levels.
What patterns then emerge from such a set of computer simulations when forced with past carbon dioxide concentrations? Do they tally with measurements? Once we see agreement for decades past, we can trust the same models far more to predict the future, corresponding to higher carbon dioxide measurements than present. Surprisingly, there is reason to believe that for some parts of the world, extreme events are starting to occur less often.
There is real hope in the UK that the combination of the advanced Met Office climate models, assessed in collaboration with our research centres and key university departments, are starting to make rigorous assessments of expected change. In particular, by supplying refined estimates for how the probabilities of major storm events happening might change over the coming decades. That information will be critical for adaptation planning, including how to make our infrastructure more robust.
Hence there is a pressure too on those who undertake ‘impacts calculations’ – for a given rainfall strength and duration, what are the consequences for safety, property and transport? Can we further improve estimates of soil moisture, river flow response and risk of landslides? There is a compelling argument that even should expected frequency changes be relatively small, there is still a duty to protect society as best as possible from the impacts of peaks in rainfall. With population growth and much more travel by society, inevitably larger numbers of people will be affected by extreme weather.
It feels as if these days, people now just switch off when hearing any discussion of climate change and its implications. There are many reasons for this, and some are no doubt very valid.
There was a period of time when even researchers working in this scientific area felt there was an over-emphasis on the concern, and to which a backlash would occur. But it is still worth remembering that even with the current “lull” in warming, averaged at the decadal timescale, the last decade has been the warmest on record.
Unfortunately there is compelling evidence such warming will start to climb again and most likely will change the hydrological cycle. Hence there remains a desperate need for refinement of projections as to how rainfall patterns might evolve in to the future.
It is this knowledge that will enable society to have a calm and considered discussion, allowing the UK and elsewhere to plan ahead. Such planning will need to optimise available adaptation funds, in a way to maximise safety and resilience should the weather events witnessed over recent weeks become more commonplace.
• Dr Chris Huntingford is a climate modeller at the UK Centre for Ecology and Hydrology