Natural cycles and global warming combine for higher rainfall

Posted by judy


The world is facing a trend that is unlikely to put a smile on many faces, as global warming and natural weather cycles combine to create wetter and wetter weather.

In the UK, this reached new heights in 2012, when the wettest summer for a century was recorded, complete with substantial flooding in some areas, and landslides caused by waterlogged soil.

According to the Met Office, the evidence suggests that this was a natural event, created by normal variations of climate and weather conditions. However, that does not mean that global warming and manmade climate change are not also shaping rainfall figures – particularly in certain parts of the world.

The vapour conundrum

As temperatures rise, you might expect that the weather would tend towards the classic ‘summer day’ with clear blue skies and low humidity. But in fact, the opposite is the case, as warmer temperatures allow more standing water to evaporate, increasing the amount of water vapour in the atmosphere and allowing more clouds to form as a result.

This in turn means more rain, putting extra strain on rainwater systems the world over.

While the UK’s 2012 floods were due to natural causes, at the far side of the world evidence is already accumulating that links heavier rainfall with manmade global warming and CO2 emissions. Back at home, should we be worried? The answer seems to be yes.

‘Substantial’ risks to the UK

A further Met Office report published in September 2013 contradicts a widely held belief about the impact of climate change on the UK. While many people think that global warming would cause the Gulf Stream – the current of warm water coming from the mid-Atlantic, which keeps the UK’s climate relatively temperate – to stop flowing, the Met Office says this would not lead to the country getting colder overall.

Rather, the direct effects of global warming would more than make up for any cooling due to the cessation of the Gulf Stream. This suggests that, in the years ahead, the UK’s already infamously unpredictable weather is likely to simply get wetter and wilder.

For the country’s straining rainwater guttering, that could prove to be the tipping point; but it’s not all bad.

Taming the drains

If higher rainfall demands better drainage, then the UK has a rare chance to tame its drainage problems once and for all. Better understanding of permeable surfaces and the importance of allowing water to enter the subsurface of streets, driveways, pavements and gardens are already combining to give us renewed control over surface runoff water.

Green roofs are helping to tackle both the concern of carbon emissions in urban environments, and reducing the amount of rainwater that runs directly off of the roof during a brief downpour. And investment into better drainage and sewerage systems has the potential to carry that surface runoff away safely, without it accumulating to a dangerous degree above ground.

Together, this broad approach to a global problem is allowing the UK to adapt to climatic conditions – and hopefully avoid any further major floods in the years to come.

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