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More on the IPCC’s leaked climate report: A roundup of media reactions

  • 22 Aug 2013, 17:30
  • Roz Pidcock

There's a major new report on the state of the climate due next month from the Intergovernmental Panel on Climate Change.

This week has seen a sneak preview of some of the findings after journalists got their hands on a leaked summary. Here's a rundown of what the papers had to say.

What's been leaked?

Every five or six years, the Intergovernmental Panel on Climate Change (IPCC) produces an in-depth assessment of the state of research in all areas of climate science, from rainfall patterns to polar ice. It's not new science as such, but a mega-summary of the state of the scientific literature on climate.

The fifth version of the IPCC's report is due to be published in three parts, starting next month. The first part of the report is nearing the end of an involved process of review by experts and governments worldwide and is not yet in the public domain.

But a summary intended for policymakers appears to have been leaked to journalists, and Alister Doyle from  Reuters broke the story first last week.

Clear on the causes of warming

Like a number of  others that followed, the Reuters piece focuses on how new tools and ways to analyse data mean scientists are more confident about how and why the climate is changing than in the last report six years ago.

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Climate models predict hard times ahead for global food production

  • 21 Aug 2013, 12:50
  • Freya Roberts

Sourced under creative commons

Global food production is set to take a hit in the coming decades, new research predicts.

As rising greenhouse gas emissions drive changes in rainfall patterns, river flows and temperatures, the availability of food may decline, it says.

What's more, with less to go around, food prices look set to rise while welfare standards fall.

Less food, more expensive

The  research, published in the journal Climatic Change, shows that under both optimistic and pessimistic scenarios of future emissions, the many effects of climate change could together cause food production to fall 0.5 per cent by the end of this decade, and 2.3 per cent by the 2050s.

As a result of the decrease in food production, the price of food is set to rise, the paper says. By midcentury, staple foods like cereal grains, sugar cane and wheat are expected to be around 40 per cent more expensive than they would be in a world without climate change.

Fruit and vegetable prices are expected to be 30 per cent by in a climate changed world in 2050, while the cost of rice is likely to be almost 20 per cent higher than it otherwise would be.

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UK flood fund underestimates number of homes at risk

  • 19 Aug 2013, 16:50
  • Freya Roberts

Sourced under creative commons

Building homes and businesses in flood prone areas might be more costly in the future than government expects, according to a new report.

A policy paper published today by the London School of Economics says the government's new insurance scheme has seriously underestimated the cost of future floods in the UK. The scheme's failing, according to the research, is that it doesn't factor in the rising number of homes at risk of flooding as a result of climate change.

Fortunately though, a separate new research paper does just that - estimating how the cost of flooding might scale with climate change.

The UK picture

Flooding is one of the biggest  natural threats in the UK, and it's set to become even more of a problem in the future. Climate change is predicted to  raise the risk of flooding through heavier rainfall and sea level rise, while the ongoing development of floodplains means that when it does flood there's more to lose.

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Heat wave spread can be curbed with carbon cuts

  • 15 Aug 2013, 06:45
  • Freya Roberts

Heat waves will become increasingly widespread and severe as the planet warms, a new study warns.

By 2040, exceptionally warm summer months will become commonplace for a fifth of the world, it says, with potentially serious effects for humans and the environment. But how much heatwaves affect the planet after 2040 depends on whether greenhouse gas emissions can be aggressively curbed. Without carbon cuts, heat waves will continue to become more severe and widespread, the study says.

More heatwaves

One consequence of a warming planet is that heatwaves will become a more common. In the last decade alone there have been a number of record breaking heat waves. Some of them, like the European heatwave of 2003, have been made more  likely by climate change.

The new research suggests that in the future more of the earth's surface will be affected by heatwaves as temperatures continue to rise. To reach that conclusion, the scientists used climate models to look at how much of the world would experience exceptionally warm summer months, which are a useful proxy for the concept of a heatwave. Long-lasting heat waves, which are well captured by this measurement, are the ones which have the greatest impact on society too, making them important to study.

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A vicious cycle: Could droughts and storms make climate change worse?

  • 14 Aug 2013, 18:30
  • Roz Pidcock

With climate change expected to bring more heatwaves, violent storms and heavy rainfall, the impact on human society is likely to be significant. As if we didn't have enough to adapt to, a new paper suggests extreme weather could further contribute to rising carbon dioxide levels by reducing how much carbon plants draw out of the air.

Growing plants take carbon dioxide out of the atmosphere and store it as living plant matter. The world's ecosystems have absorbed about a third of the  carbon dioxide humans have put into the atmosphere through  fossil fuel burning. In effect, by reducing the amount of carbon dioxide in the atmosphere, plants keep global temperature below what it might otherwise be.

The new Nature review  paper suggests extreme weather events - especially heatwaves, droughts and fires - weaken ecosystems' ability to act as a buffer against climate change. And the situation is likely to worsen as temperatures rise further and extreme events become more frequent or more severe, the authors say.

Carbon losses

The scorching  heatwave in central Europe in 2003 gave scientists a chance to look closely at how water scarcity affects the amount of carbon dioxide forests take up. And the results suggested the consequences are much more serious than first thought.

Soon afterwards, scientists from eight different countries launched an international project to investigate the connection between extreme events and the carbon cycle.

The impacts of extreme weather can be pretty immediate if vast swathes of vegetation are killed off by drought or wildfire and stop taking up carbon dioxide, say the authors. But there are less obvious effects that take a while to appear. Changes in temperature or rainfall extremes can make trees and plants less resistant to pests and diseases, for example.

While most of these impacts are relatively well known, the  new paper is the first to put a figure on how much less carbon dioxide ecosystems absorb as a result of extreme events.

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Cutting methane and soot alone is no quick fix for climate

  • 12 Aug 2013, 20:35
  • Freya Roberts

Mining coal in China

A new study says focusing efforts on cutting emissions of short-lived pollutants like methane and soot won't offer us a quick fix for climate change.  

Even using all known measures to curb emissions of these short lived pollutants, the new modelling suggests that by 2050, global temperatures would only be 0.16 degrees Celsius lower than in a world without any climate policies.

Climate policies which tackle a range of greenhouse gases including carbon dioxide remain the best way to slow temperature rise this century, the new research concludes.

Short, sharp bursts

Carbon dioxide is the main cause of current climate change. Once released, it stays in the atmosphere for more than a thousand years, warming the planet.

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The BBC discusses changes in the sun - and why they don’t mean an ice age is on the way

  • 09 Aug 2013, 12:15
  • Roz Pidcock

Could changes deep within in the sun soon see us skating on a frozen-over Thames? The question of the sun's role in climate change - and the prospect of an icy future - pops up in the media from time to time.

This morning, it was the BBC's turn on the Today Programme. The slot did a pretty good job of explaining that although changes in the sun have affected climate in the past, greenhouse gases are now the dominant factor driving temperatures up.

The programme's topic was the imminent  flip in the sun's magnetic field, the force responsible for driving sunspot activity. Steve Tobias, professor of maths at Leeds University, explained how this switch happens about every 11 years, when the sun's output is at the highest point in a natural cycle.

Asked whether the sun's waxing and waning contributes to climate change. Professor Tobias explained:

"It does feed in but it's a very small effect. The sun's total irradiance actually varies by a fraction of a percent, so the direct forcing is very small … it may have indirect effects for the climate but I think I should stress current global warming trends are not really due to changes in the sun's activity."

Presenter Justin Webb pressed a bit more, saying "but years ago the sun created an ice age, didn't it?"

The simple answer is yes. But as Tobias explained, human activity is now the main driver climate change, not the sun - a mistake that has led some parts of the media to suggest we're headed for a ' mini ice age'. Here's a closer look at what the sun has to do with our climate.

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What makes ice sheets grow and shrink?

  • 08 Aug 2013, 10:40
  • Freya Roberts

A new look at how the earth freezes and thaws suggests that while colder glacial periods in earth's history are triggered by changes in the planet's orbit, it takes climate feedbacks to give a full picture of why the planet freezes and thaws every hundred millennia.

The last million years

Earth has cycled between glacial and interglacial periods roughly every 100,000 years out of the past million. When the climate cools, vast ice sheets grow slowly from the north pole towards the equator, burying much of North America, Europe and Asia. When earth warms again, these continent-sized ice sheets melt quickly and retreat towards the poles.

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Reflections on a changing Arctic: Less ice means faster warming

  • 04 Aug 2013, 18:20
  • Roz Pidcock

The Arctic is intricately linked to earth's climate. As Arctic sea ice declines, the effects are being felt far beyond the Arctic region. Now a new study shows how losing sea ice means the top of the planet is absorbing more heat than it did just three decades ago - and it makes for a sobering read.

Scientists have noticed big changes in the Arctic since satellites started observing earth from space, thirty years ago. The area covered by sea ice is getting smaller and the ice is getting thinner, due largely to  rising global temperature.

The loss is most noticeable at the end of summer, when sea ice shrinks to a minimum, as part of its seasonal cycle. In September 2012, Arctic sea ice reached its lowest extent since satellite records began.

Knock-on effects

Losing sea ice has  knock on effects for climate. One of the most direct consequences is that losing sea ice changes something scientists call albedo. Albedo is a measure of how well the earth's surface reflects sunlight.

Snow-covered sea ice has a high albedo, reflecting up to 85 per cent of sunlight. As the area covered by ice and snow gets smaller, sunlight that would have been reflected is  absorbed by open water instead, warming it up.

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Knock-on effects for wildlife as the Arctic loses ice

  • 01 Aug 2013, 19:30
  • Freya Roberts

Credit: Eric Post

The climate impacts of retreating Arctic sea ice are reasonably well  known. But it's not just a global issue, it's also an ecological one. A new review article in the journal Science examines the effect of climate change in the Arctic on the plants, animals and ecosystems of the region.

Temperatures in the Arctic have risen  twice as fast as the global average in recent decades. Sea ice cover is in long term decline. In the summer of 2012, sea ice reached its lowest level since satellite records began in 1979.

Scientists agree that the decline will have  consequences for the climate, extra heating and possible changes to weather patterns. But, as the new review article explores, the loss of sea ice and warming oceans will have an impact on the Arctic's wildlife too.

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