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Weather or not to change?

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Architects are always told to accommodate potential climate changes. Here we challenge the environmental assumptions

The Foundation for the Built Environment (FBE) report Potential Implications of Climate Change in the Built Environment offers a range of adaptation strategies. Rising sea levels, changing rainfall patterns and increasing mean wind speed, it is claimed, 'will have a significant impact on the built environment during this century'. The report 'is intended to help all sectors of the construction and finance industries to consider the implications on their business and the UK economy as a whole. . . Planning can help avoid problems from floods, coastal erosion and shortage of water resources.

Design can minimise wind damage, subsidence in clay soils, dampness from rain penetration and weather damage to materials.'

Attempts to plan for, and adapt to, changes in the environment are, of course, eminently sensible. The foundation's report puts forward a number of suggestions: 'It would seem likely that the predicted climate change scenario will require foundations for new domestic buildings to be deeper than they are currently.'

Also '. . . roofs, guttering and local infrastructure will need to be designed to cope with greater volumes of water', as a result of driving rain. Rising temperatures will require the provision of 'good natural ventilation where air pollution allows'.

However, the problem with the report (as with many discussions about global warming) is that the projected changes in the UK climate - in this case based on scenarios put forward by the UK Climate Impact Programme (UKCIP)- are more akin to doomsday prophecies than scientific predictions. So, for instance, we are told that in the south of England the probability of a scorching August, as in 1997, will increase from 1 in 50 years to 1 in 2.5 years by 2080; we will apparently see a 6 per cent increase in average wind speed, which is likely to cause damage to one million buildings at a cost of between £1 billion and £2 billion; dry summers in the south of England could cause a 50 to 100 per cent increase in subsidence claims at a cost of between £200 million and £300 million; and driving rain is likely to increase by 33 per cent in London and the Home Counties in the autumn and winter - affecting up to seven million dwellings. There are even warnings about the indirect impact of global warming. 'Problems with summer overheating of buildings may lead to increased window opening in an effort to improve ventilation, ' the FBE report states.

Apparently, global warming may lead to more opportunist burglaries.

What are these projected changes really based on? Is this merely crystal ball gazing? Or could climatology be said to be able to give us a fairly reliable picture of what the UK climate will be like in 50 or 100 years time?

In the document Design within a Climate of Change, Professor Peter Smith, RIBA vice-president for sustainable development, asserts that 'the next few decades are likely to witness an unprecedented rate of change across a range of areas which affect architects'. Professor Smith does acknowledge that 'there are still those who argue that the current phase of global warming is nothing more than an episode in the natural pattern of climatic fluctuations to which the earth has been subjected for at least the 300,000 years of paleo-climatic record', but that does not stop him.

The fact is that the scenarios put forward by the FBE and Professor Smith are based not on scientific evidence but statistical extrapolations. The mathematical models used are based on assumptions about a number of complex and interconnected factors - many that are still not sufficiently understood. The Intergovernmental Panel on Climate Change (IPCC) explicitly admits a lack of knowledge about a number of factors - including solar variation, volcanic eruptions, sea-ice dynamics, ocean heat transport and water vapour - thought to affect global climate. In fact, the panel's range of estimated temperature increases has widened rather than narrowed in the past few years.

In 1995 it forecast that that the Earth would warm by between 1.5degreesC and 3.5degreesC over the next 100 years. In its most recent report, Climate Change 2001: The Scientific Basis, the range has widened to between 1.4degreesC and 5.8degreesC. The margins of error given in relation to its many predictions are huge, due to the uncertainties of the science that goes into the computer models that make the calculations.

Piers Corbyn of Weather Action, a company that provides long-term forecasts to UK industry, claims the IPCC has underestimated some of the indirect effects of the sun on the Earth's climate. 'Particles and magnetic effects from the sun are the decisive influence that controls world temperatures, ' he says, 'not carbon dioxide emissions. The levels of CO 2are governed by global temperatures which are governed by particles from the sun.'

Nature produces large quantities of CO 2, but also reabsorbs CO 2.'The add-on effect of man is like having a bath full of water with the tap on full and the plug open', says Corbyn. 'If you add a little more water - like pouring a cup of tea in there - all you get is a slight increase in the water level. And that is all man has contributed to Earth's CO 2levels.'

According to the global warming sceptic Professor Philip Stott, from the University of London: 'The IPCC models and correlations are not new; they are recycled 'old hat'. . . computer models present various 'stories' or scenarios and people should not see them as outcomes that are bound to happen. There are over 40 such stories; inevitably, of course, the media selects the very worst storyline. It seems that the FBE has done the same: selecting the UKCIP98 'MediumHigh' climate change scenario.'

Similarly Professor Smith asks: 'In the light of all the evidence of the extremely eventful history of the Earth, are the changes we are now seeing out of character with changes in the past? Individually these changes can be attributed to natural causes, but the question is this: is the accumulation of anomalous events itself so unusual as to lay the finger of blame on humans?'He concludes that it is, adding: 'There is a marked increase in the incidence and severity ofstorms. One of the most reliable indicators of this is the escalating amount being paid out by insurance companies.' This, however, is not very convincing (see graph above).

But is there a 'marked increase' in storm activity? 'There is an important distinction between hazard and vulnerability, ' explains Lord Hunt, former director-general and chief executive of the Meteorological Office. 'Hazard is the actual phenomenon and vulnerability is the effect on the community. So if you have the same level of storms but everybody lives on floodplains or the coast, the weather is the same but there is a much bigger insurance loss. So, by comparison, although there's been a small change in the hazard, there is a huge change in the vulnerability.'

Research conducted at the Benfield Greig Hazard Research Centre, across the corridor from Lord Hunt, shows that tropical cyclones have, if anything, decreased in the northern hemisphere in the 1990s - despite it being the warmest decade on record (that is, the warmest decade since instrumental records in 1861).

In The Weather of Britain, the late Robin Stirling also put paid to the assertion that Britain's weather is more extreme. Britain has experienced significant changes in temperature levels. Going back a few hundred years, the Little Ice Age in the northern hemisphere brought a cooler climate to Britain, with temperatures in London at times falling to -40degreesC and ice several feet thick covering parts of the Thames. In Roman times, Britain's climate may even have been three or four degrees warmer than today.

So there is no consensus on the vital question of how much the Earth will warm this century. Nor do we know what effect temperature increases may have on the climate of the globe, nor the extent to which sea levels may rise. Some of the recommendations made by the FBE - not to build on flood plains or on areas vulnerable to coastal erosion - may make a lot of sense. But much of the report reads more like a doom-mongering prophecy than a discerning aid to architects.

Dr Helene Guldberg teaches at the Open University FBE Report 2 Potential Implications of Climate Change in the Built Environment, by Hilary Graves and Mark Phillipson, is available from CRC on tel 020 7505 6622

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