Climate science

Climate change set to increase extreme weather risk to UK population

  • 27 Nov 2014, 00:01
  • Robert McSweeney

The risk of heatwaves hitting the UK will increase ten-fold by 2100 if we don't cut greenhouse gas emissions, according to a new study of how climate change will affect extreme weather.  The UK will also be more at risk from flooding and drought says the new report, published by the Royal Society.

But the report also finds there are ways to prepare ourselves for what's to come, with a mix of large-scale engineering and natural measures to adapt to climate change making it possible to manage some climate risks.

Rising risks

The study uses climate models to estimate how the frequency of floods, droughts and heatwaves will change worldwide by the end of the century. It assumes population rises to around nine billion globally by 2100, and overlays projections of population growth to map where in the world the most people will be at risk from extreme weather.

Perhaps unsurprisingly, places with high populations tend to have more people at risk from climate extremes. For the UK, the combined effects of climate and population changes will increase the risk of exposure to heatwaves by a factor of more than 10 by the end of the century, the report says.

If we don't cut emissions, the risk of exposure to floods in the UK will increase four and a half times by the end of the century, and the risk of drought three times.

The risks posed by heatwaves grow particularly rapidly because older people who are more at risk from extreme heat will make up a larger chunk of global population by the end of the century, the report says.

The study produced maps which show how exposure to extreme weather will change. The areas of dark red show the greatest increase in people exposed to risk - in India, southeast Asia, parts of central Africa and western Europe.

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Scientists dig deep into earth's history for clues to El Niño past, present and future

  • 26 Nov 2014, 18:00
  • Roz Pidcock

The Pacific weather phenomenon known as El Niño has attracted a lot of attention this year as forecasters have puzzled over its 'will it or won't it' behaviour.

In May, scientists were confidently predicting a  90 per cent chance of an El Niño materialising by the end of the year. But it's proved elusive, with the odds of even a weak event dropping to 58 per cent earlier this month.

El Niño brings extreme rainfall to some parts of the world and drought to others. So predicting when one will make an appearance and how big the effects will be is important.

A new study just published in Nature uses a diverse array of different data sources, from corals to computer modelling, to unravel what's been driving changes in El Niño over the past 21,000 years.

Pinning down this  enigmatic phenomenon is tricky, the study concludes. But there's reason to believe climate change could lead to stronger El Niño's in the future, say the scientists.

El Niño and climate-readiness

Every five years or so, a change in the winds causes a shift to warmer than normal ocean temperatures in the  equatorial Pacific Ocean - a phenomena known as El Niño.

Together, El Niño and its cooler counterpart La Niña are known as the El Niño Southern Oscillation (ENSO). Cycling between the two phases is responsible for much of the variation we see in global climate from one year to the next.

Knowing if and how climate change will affect El Niño and La Niña is an important scientific question, says Professor Kim Cobb, co-author on today's paper. She  told us recently:

"Preparing for large swings in temperature and rainfall is critical to adaptation strategies, especially if such variability will increase in the future."

In theory, human-caused warming could increase the strength of ENSO events, Cobb continues:

"It is important to remember that climate change is much more than "global warming" … Because ENSO involves feedbacks between the wind strength, ocean temperature, and circulation, a change in any related climate parameter would arguably have some effect on ENSO strength".

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Remote-controlled submarines reveal Antarctic sea ice is thicker than previously thought

  • 24 Nov 2014, 16:14
  • Robert McSweeney

New research sees scientists using remote-controlled submarines to create 3D maps of Antarctic sea ice. And the results suggest sea ice is thicker than previously thought.

The area covered by Antarctic sea ice appears to be slightly growing each year, the reasons for which are proving hard to pin down. Today's research adds another dimension to unravelling the complex goings-on around the South Pole.

Measuring ice thickness isn't easy

Scientists have been monitoring changes at Earth's poles for decades now. But the harsh conditions of the Antarctic make it difficult to get good measurements of the sea ice that surrounds the vast continent.

How and why Antarctic sea ice thickness is changing "remains one of the great unknowns in the climate system," says Dr Ted Maksym of the Woods Hole Oceanographic Institution (WHOI) in Massachusetts.

While satellites are very good at measuring the extent, or area, of sea ice covering the ocean, they struggle when it comes to ice thickness. Satellite measurements can't distinguish between ice and the snow lying on top of it, which makes it harder for scientists get accurate readings of its true depth.

Scientists can also make estimates of thickness from visual observations or by drilling into the ice itself. But these approaches are hampered by thick sea ice during winter and spring, which prevents ships from accessing parts of the Antarctic coast.

To overcome these limitations, Dr Maksym and his colleagues deployed 'Autonomous Underwater Vehicles (AUVs)', which are specially-designed unmanned submarines that measure ice thickness to within 10 centimetres.

The data from these submarines, published in  Nature Geoscience, suggests that Antarctic sea ice is thicker than previously thought.

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