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Winds of change

Climate change will have a profound impact on the world over the next 50 years. Matthew Jones kicks off our environment special by looking at some of the effects, and asking what engineers can do to prepare.

South east Britain, August 2050. It has been an exceptionally hot, dry summer again. Tanned shoppers sip ice-cold drinks at street-side tables. Palm trees and vines have replaced conifers and hardy shrubs. Only the travel companies seem to be moaning because this year has seen another dip in holidays to the Mediterranean.

This is the positive image of climate change. But there is also a bleaker picture.

According to the Government-sponsored UK Climate Impacts Programme's latest report the global surface temperature is warming at a rate of 0.15degreesC a decade, and has been doing since the 1970s. If carbon dioxide and other greenhouse gas emissions continue to pour into the atmosphere through burning fossil fuels and the world's forests, this rate could rise to as much as 0.35degreesC a decade, and lead to a rise in global sea levels of up to 1cm a year.

Ex-Met Office chief executive Julian Hunt is a world authority on climate change. Now continuing his research as a professor of applied mathematics and theoretical physics at Cambridge University, he believes that the implications of global warming are going to be huge.

'We know in the case of tropical cyclones, for example, that a slight increase in the temperature of the sea significantly increases their intensity. There is a strong chance that the range and latitude of such storms may spread further north and south, and that would mean having to build bigger harbour facilities, higher sea defence walls and stronger buildings,' he says.

Many scientists are still reluctant to accept the need for action, arguing that climate fluctuations have happened naturally throughout the earth's history. But Hunt dismisses this line of reasoning and says it is time to face up to reality.

'Considering geological time periods is all well and good, but at a political and engineering level we need to operate on a much smaller time scale,' he says.

Major impacts of climate change are already being felt in some parts of the world. The land-locked Caspian sea has risen by more than 2m in the last 20 years, and by as much as 500mm in one year alone. According to the Institute of Atmospheric Physics in Moscow, changing wind patterns are causing evaporation from the sea to fall, while the rivers flowing into it have stayed at the same level.

Consultant Mouchel is now working on the design of a new multi-million pound breakwater needed to protect the oil industry port of Aktau in Kazakhstan.

'The very high rise in water level has meant the existing breakwater is a lot lower in the water and the quays themselves are more vulnerable to overtopping. We're looking at designing a much less permeable structure with a higher crest level,' says project manager John Mackowski.

Hunt - also chairman of the Royal Society and Royal Academy of Engineering Committee for Natural Disaster Reduction - says this is just one example of the problems facing the world, for which engineers need to start planning solutions now.

Better storm and flood warning systems will have to be put into place, new water resources will have to be constructed in areas which become drier, and cities will have to be re-designed with more vegetation and better natural ventilation to cope with the higher temperatures.

Hunt believes that whenever a piece of infrastructure or building is designed, engineers should be considering the possible

consequences of global warming. In vulnerable parts of the world this might mean designing wider roads with mass evacuation in mind, drainage systems which get storm water away more quickly, and buildings which can withstand repetitive flooding.

The latest thinking on how climate change will affect the UK over the next 50 years is that mean annual temperature could rise by as much as 2.3degreesC in the south east, and by 1.9degreesC in Scotland. Winters and autumns will become up to 13% wetter across the whole country, but summers are likely to get significantly drier, particularly in southern Britain. Average wind speeds are set to rise across the country, with storms and gales becoming more frequent. And sea levels could rise by as much as 630mm in western Scotland, and 830m in East Anglia.

How these changes will impact the built environment and construction industry practices is the subject of a year-long study being carried out by the BRE's Scottish laboratory. Project leader Dr Stephen Garvin says the consequences for civil engineering design codes are considerable.

'With all standards, codes and regulations which are affected by climate parameters, we have to start asking if the numbers we use are suitable any more,' he says.

For buildings and structures this may mean altering the design wind speeds which are used in the British Standards, both in terms of the maximum wind considered and the return period of violent gusts. More driving rain may mean altering design specifications to make buildings more waterproof, and increased soil shrinkage in the summer could require redesigning foundations to make them more resistant to damage.

BRE project scientist Mark Phillipson says climate change will also affect contractors.

'The weather will start to have a much bigger impact. The number of days when contractors can't use cranes or go up on scaffolding will increase, leading to more overruns. And the issue of storing materials on site may have to be changed, with more off-site fabrication and just-in-time delivery,' he says.

Wetter soils in the winter may mean that working in trenches becomes more hazardous. In the summer site staff will have to take more precautions against harmful ultra-violet rays, more care to ensure concrete is properly cured, and more powerful excavators may be needed to dig in hard-baked ground.

'The basic message is that things are going to get a lot harder for contractors,' says Garvin.

The BRE's research project comes to an end in March, but Garvin says more work will be needed to persuade the industry to take climate change seriously.

'One of the things that people don't fully appreciate is that most buildings and structures constructed now will be there for at least 60 years or more. Designing for climate change may cost more now, but it will definitely save money in the long run.'

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