To what climate are we adapting?

VIEWPOINT Mike Hulme

Moves to adapt our society for a changing climate may have focused rather too much on long-term scenarios and not enough on how to cope with weather and short-term variability, argues Mike Hulme. He says the past two British summers show the dangers of this overemphasis on laudable long-sightedness.

Are we giving too much weight to the anthropogenic 'signal' of global warming whilst ignoring the natural 'noise' of climate?

This year's British summer has again failed to meet many of our expectations.

As reported by the Daily Telegraph at the end of August: "Summer is all but over. We are entitled to ask: what summer? For the second year running we have been denied anything worthy of the name."

Rainfall was more than 50 percent above average; sunshine levels were well below average, with August being particularly gloomy.

The average temperature was a fraction above the 1961-90 mean, although this was disguised by cooler days offsetting warmer nights.

Is this the British summer climate to which we are being told we need to adapt?

The Mayor of London's office has just published its first ever climate change adaptation strategy in which the risks of increasing summer heatwaves and droughts compete with those of more frequent winter flooding. Both scenarios demand the attention of Boris Johnson and his urban planners.

In a couple of months time, the government - through the UK Climate Impacts Programme - will launch (with much publicity and scientific acclaim) a new set of climate scenarios called UKCIP08 for the nation until the year 2100.

They will be the first national scenarios that offer probabilities about how future climate may change.

'Eye off the storm'

As we think more carefully about how we live with our climate and how we can improve our preparedness for future weather, are we over-emphasising long-term prospects over shorter-term realities?

Are we paying too much attention to uncertain long-term climate predictions - dominated by greenhouse gas-driven global warming - whilst taking our eye off the more immediate weather futures which will determine the significance of climate for society over the next years and decades?

Climate adaptation is at a crossroads between the long- and short-term

Using the jargon of climate science, are we giving too much weight to the anthropogenic "signal" of global warming whilst ignoring the natural "noise" of climate?

Individuals, communities and societies have always wanted to know what the future weather will be; whether for managing the cultivation of land or the building of homes through to preparing for social rituals or communal celebrations.

Since the middle of the 19th Century, scientific weather forecasting has been evolving. Current forecasts are able to predict weather three days ahead. These forecasts are as skilful, and contain more detail, as next-day forecasts 40 years ago.

We are better prepared and better adapted to avoid weather risks, such as storms at sea, and to grasp opportunities (eg transport management) than any previous generation.

Paralleling these developments, we have in the last 10 to 15 years also been urged to start bringing long-term climate predictions - scenarios for 2050 and 2100 linked to global warming and derived from climate models - into our adaptation planning.

This is particularly needed for infrastructure projects which have a long life-span.

Balancing act

But are these long-term climate scenarios alone what we most urgently need to improve society's adaptation to weather and climate - to avoid risks and to grasp opportunities?

The projection of drier, warmer summers can seem wide of the mark

Weather forecasts offer easily demonstrable and quantified skill. But climate scenarios for the year 2050 cannot be tested against observations; we have to rely on our faith in the underlying climate models.

This faith is tested when we endure summers like those of 2007 and 2008. All long-term climate scenarios suggest British summers will become drier; if we now start adapting for drier summers what happens to farmers, businesses and tourists when we have two successive very wet summers?

All long-term scenarios also suggest heatwaves, such as the one in August 2003, will become more frequent, even the norm, by 2050. How does adapting to this prospect improve our ability to survive cool, gloomy weeks like those we had in 2008?

We will never know empirically on any useful timescale whether or not we have accurate climate predictions for 2050. Yet even if they do prove accurate, if our shorter-term forewarning of daily weather to decadal climate is poor, we may end up just as maladapted and just as exposed to weather risks as if we had ignored global warming entirely.

Two extremes

Scientists have recently begun to tackle seasonal to decadal climate forecasting, time-scales in which natural variability ("noise") is more important than global warming ("signal"). Yet for now, these forecasts remain primitive and of limited skill.

So we remain caught between the two extremes of what science can foretell of future weather: daily forecasts with known skill and value, and centennial scenarios of unknown skill based on (good) faith.

How do we prepare the 2012 London Olympics to be well adapted to British summer climate?

We do need to consider the latter in guiding long-term infrastructure design, but an over-reliance on such scenarios to dominate our adaptation thinking and planning carries three dangers.

Long-term climate scenarios may prove to be inaccurate (we have poor means of knowing for sure).

Second, even if they do prove accurate on the time-scale of 50 to 100 years, they may be all but useless for foretelling the climate of the next one to 10 years.

This is linked to the third danger, which is about the social psychology of weather expectations.

Constant public talk of presaged late-century climate will alter public expectations of near-term climate, which - as we have seen these last two years - will continue to yield weather of very different character to that offered by our 2050s scenarios.

To use a specific example: how do we prepare the 2012 London Olympics to be well adapted to British summer climate?

Do we take a 2050 climate change scenario - heatwaves, droughts and all - and assume this will best describe the summer of 2012?

Do we use one of the new experimental decadal forecasts that suggests we may see little warming and maybe wetter summers over the next decade?

Or do we make sure that the Olympics are prepared to cope with whatever the summer of 2012 turns out like - whether the blazing heat of 1995 or the gloom of 2008?

There is an irony here. At the same time as the new national UKCIP08 scenarios offer us more detailed information than ever before about the climate of 2050 - for example, probabilities of hourly rainfall at 1km resolution - so climate science is increasingly emphasising that our weather from months to a decade or two ahead will be dominated by natural variability which we poorly understand and struggle to predict.

The coming decade will yield the familiar mixture of British weather: heat, cold, wind, rain and drought.

Yes, let us use such foresight as science can offer us about the longer term; but effective adaptation to weather and climate variability and management of public expectations of future weather demand more than merely this.

Premature locking of our infrastructure and our social psychology into the dimly presaged but overly precise climate of the late 21st Century maybe as risky as pretending we are still living with the climate of the 20th Century.

Mike Hulme is a professor in the School of Environmental Sciences at the University of East Anglia (UEA), and was the founding director of the Tyndall Centre for Climate Change Research

The Green Room is a series of opinion article on environmental topics running weekly on the BBC News website

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Do you agree with Professor Mike Hulme? Are we focusing too much on long-term climate scenarios at the expense of the short-term? Are weather-dependent sectors, like tourism and agriculture, well served by climate projections? Or are we expecting too much from climate scientists?

I think you are more than right that Britain should eb focusing on the now rather than a century ahead. I think it is interesting t note though that the future of heatwaves was predicted and now global warming led climatologists are saying the increased rainfall is a product of global warming.

I prefer the explaination meteorologists tend to give prosed most suitably in this extract, 'Weather is a flip of the coin, an infniate number of variables from the sun to a birds wing effect our weather. Like the flip of a coin there is always uncertainty, always doubt and always an intrinsic randomness. Sometimes you get good weather, sometimes we get bad weather, it's happneed throughout earths history.'
Oli, York

Is this part of the unavoidable row back from the Gore-ite hysteria ? Climate may be changing, and it may not. It may be man made and it may not. CO2 concentrations are high and rising but they've been higher without anthropogenic forcing. There has been no measurable increase in average global temperatures since 1998. The key point is that if the IPCC projections are right and we do all the armageddon-like things (including 50,000+ windmills) suggested we will merely delay the achievement of unrestricted CO2 levels from 2100 to 2106. Mike Hulme is quite right to question whether we are doing the right things. Alleviation may well make much more sense than prevention and at a fraction of the cost. The World is not going to burst into flames, nor are sea levels going to rise more than a few inches at most, if at all. We need the sort of sense of proportion which Mr Hulme is bringing to the debate at last.
Jim Corbett, Cork, Ireland

So long as there is uncertainty over decadal and centenial variations in average weather conditions it is important that those who make such forecasts explain how they do it. Explanations must be such that the careful reader of any background can grasp them.

Forecasters often produce probability scatter graphs, showing how likely is a 10% increase in fog in the next 50 years for example. (fog during the 2012 javelin competition might influence the outcome! and would ceratinly influence TV revenues). But these scatter graphs are unconvincing if the method by which they arrive at these statistics remains unclear; how much does the fog forecast depend on the degree of the predicted increase in ocean plankton activity for example? How do the forecasters account for non-linear feedback mechanisms e.g. release of methane from tundra? If this was wrong by 10% how much would it affect the fog forecast? And so on.

This really matters to those who must make political judgements and economic decisions. It is not enough that public opinion can be swayed by a popular movement. Choices will be guided by the degree of confidence in the method and how much the answers vary with assumptions.

Pro and contra commentators alike fail to communicate openly about the weaknesses of their postures. The latest IPCC report is a step in the right direction but when some of their predictions turn out to be wrong, is the reader able to say "so what" and know what the complete answer will be?

Andrew Auty, Oxford

Mike Hulme said;

"Long-term climate scenarios may prove to be inaccurate (we have poor means of knowing for sure)."

And Mr Henderson has responded by saying; "The contras will love that one. Hasn't Mike Hulme learned anything from the way Channel 4 and papers like the Daily Mail distort the science on climate change?"

Let me paraphrase that response.

Mr Henderson dislikes the public being told facts that are inconvenient to those who promote the agenda of global warmers. The Channel 4 programme titled 'The Great Global Warming Swindle' reported such inconvenient facts, and an Ofcom investigation resolved that the program did not "materially mislead". Mike Hulme stated another demonstrable fact that is an inconvenient truth for those who promote the agenda of global warmers. So, Mr Henderson says Mike Hulme should not have mentioned that fact.

Richard S Courtney
Richard S Courtney, Falmouth

Jay Furneaux - I thought the Medieval Warm Period was supposed to have been deleted from history as inappropriate for the cultural needs of the present generation?
Thomas Goodey, Cuxton-upon-Medway, Kent, ENGLAND

As much as change is the only certainty, the only certainty about climate change is increased climatic variability. Hard enough for people in developed and resourced economies like the UK; absolute devastation for people already on the ecological edge, like so many in Africa. Adaptation planning must deal with all the likely extremes, not just the most probable ones.
Pierre du Plessis, Windhoek, Namibia

I have to agree with Professor Hulme. There is far to much we don't understand about the climate and how it changes to reliably make any predictions for the future. I see on a daily basis the arguments of why we must change our habits to reduce CO2 for the greater good, but what I don't see is convincing evidence to back this up. There is evidence that humans are changing the world, but the true effects are not really quantifiable, and certainly, we don't have all the answers on CO2 induced global warming. As has been shown many times in the past, human power over this planet is minute compared to the power of mother nature. I'm glad that Professor Hulme, as an evironmental researcher, has asked us to consider that we don't yet know it all when it comes to climate science. It makes a refreshing change from the usual politically motivated crowds.
Paul Shanahan, MAnchester

And then there is the wildcard of another Pinatubo type volcanic explosion. Several summers I was hoping to enjoy in Southern New Zealand got ruined by that. Harder to predict, we might be able to predict on a short term that any given volcano will blow, but we are poor at telling how big the eruption will be.
muscleguy, Dundee, Scotland

It may be mistaken to assume that future climate and consequent weather will be consistently one thing or another. I imagine long-term models are looking at trends, within which there will be variability. The Little Ice Age wasn't uniformly cold for example and the Medieval Warm Period had prolonged cold spells. For many regions what will be most important will be if they get more or less rainfall overall; or if the pattern of rainfall changes - more dry days interspersed with heavy downpours and flash floods for example. If warmer air holds more moisture I'd have thought it likely that summers would see more thunderstorms and rainfall. And our climate is also influenced by the jet stream and changes in ocean temperatures that may be difficult to predict. Effective rainfall capture in preparation for prolonged dryer periods would seem the best preparation.
Jay Furneaux, UK

"Long-term climate scenarios may prove to be inaccurate (we have poor means of knowing for sure)." The contras will love that one. Hasn't Mike Hulme learned anything from the way Channel 4 and papers like the Daily Mail distort the science on climate change?
M r Henderson, London, UK