Analysis

Air pollution and climate change could mean 50 per cent more people going hungry by 2050, new study finds

  • 30 Jul 2014, 12:20
  • Roz Pidcock

The combination of rising temperatures and air pollution could substantially damage crop growth in the next 40 years, according to a new paper. And if emissions stay as high as they are now, the number of people who don't get enough food could grow by half by the middle of the century.

Burning question

Feeding the world's rapidly growing population is a serious concern.

Research shows  rising temperatures are likely to lead to lower crop yields. Other work suggests air pollution might reduce the amount of food produced worldwide. But nobody has considered both effects together, say the paper's authors.

The two effects are closely related as warmer temperatures increase the production of ozone in the atmosphere, the paper explains. 

The  new study looks at global yields of the four principle food crops - wheat, rice, corn and soybean - and how they're expected to change by 2050 under different levels of future emissions.

Together, these provide nearly  60 per cent of all the calories consumed by humans worldwide.

Global losses

The maps below show some of the results.

The top panel shows an optimistic scenario in which greenhouse gases stabilise at 630 parts per million (ppm) by 2100. For reference, we're at about 400 ppm now.

The team compared this with what might happen if greenhouse gases continue to rise as rapidly as they are now. That's the bottom panel.

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Does British belief in climate change really go up and down? A look at 14 polls

  • 29 Jul 2014, 15:30
  • Ros Donald

Newspapers love to cover surveys that show  belief in climate change has  risen or fallen. But how much can polls really tell us about what the UK public believes when it comes to climate change? We surveyed 14 polls to try and understand what's happening. 

We looked at polls by the  Guardian, the Sunday Times, the  Department of Energy and Climate Change (DECC),  Carbon Brief ( twice), the  UK Energy Research Council (UKERC) and Ipsos Mori.  

The polls were released between 2009 and 2014, but UKERC's poll includes earlier results from surveys in 2005 2010 and  2012

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UK Parliament says IPCC report is an "unambiguous picture of a climate that is being dangerously destabilised"

  • 29 Jul 2014, 00:01
  • Roz Pidcock

A group of MPs has today released a report examining the work of the Intergovernmental Panel on Climate Change (IPCC) - the UN body tasked with assessing the state of climate change science. The report concludes that the IPCC presents "a clear and unambiguous picture of a climate that is being dangerously destabilised."

The report from the House of Commons Energy and Climate Change (ECC) committee completes a nine-month long investigation, during which a number of witnesses were called on to give evidence on the robustness of the IPCC's workings and conclusions.

The inquiry came mid-way through the publication of a series reports on climate change released by the IPCC over the course of a year.

Minutes released with the report show efforts by two climate skeptic MPs - Graham Stringer and Peter Lilley - to change the report to conclude that the work of the IPCC was unsound in various ways. But the committee rejected the changes - finding no cause for concern with the way the IPCC operates or the conclusions it reaches.

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Scientists lambast The Australian for misleading article on deep ocean cooling

  • 28 Jul 2014, 13:50
  • Roz Pidcock

An article in Friday's  The Australian suggested brand new research by two eminent oceanographers casts doubt on scientific understanding of global warming. But the authors of the research have taken the newspaper to task for its coverage of their work.

The research by Carl Wunsch from Harvard University and Patrick Heimbach from MIT found temperatures seem to be falling in parts of the very deep ocean, known as 'the abyss'.

In a piece headline headlined "Puzzle of deep ocean cooling", journalist Graham Lloyd of the Australian interpreted the new research for readers:

"The deep oceans have been cooling for the past two decades and [so] it is not possible to say whether changes in ocean heat adequately explain the "pause" in global warming".

But the authors think Lloyd's article is misleading. In an  letter to the editor in today's edition of the Australian, they say:

"The article by Graham Lloyd will likely leave a mis-impression with many of your readers concerning the substance of our paper."

Wunsch tells us Lloyd's article "cherrypicks" statements from their paper and "misses some key points".

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Have satellites overestimated Antarctic sea ice growth?

  • 22 Jul 2014, 15:30
  • Roz Pidcock

It's puzzling why Antarctic sea ice seems to be growing while earth's other icy expanses are shrinking as temperatures rise.

Now new research questions whether there has been much of a rise in Antarctic sea ice after all. The paper suggests the small but significant growth scientists thought had occurred since 1979 could be little more than a "spurious artifact" of how satellite data is interpreted.

But other polar scientists tell us the implications of the new findings" are very limited indeed" and they're confident Antarctic sea ice is still growing.

Bucking the trend

Scientists know ice is being lost from both the Greenland and Antarctic ice sheets. They also know the amount of sea ice in the Arctic is rapidly decreasing.

But satellite data suggest the amount of sea ice around Antarctica has been growing since 1979. A report from the Intergovernmental Panel on Climate Change (IPCC) last year put the size of the increase at  1.5 per cent on average per decade.

For comparison, that's about a third of the rate of sea ice retreat in the Arctic. A  new paper just published in journal The Cryosphere explains the puzzle this poses for scientists:

"[T]here has been substantial interest in the trend in Antarctic sea ice extent … primarily because of the observed asymmetry between increasing ice extent in the Antarctic and rapidly diminishing ice extent in the Arctic, and the inability of current climate models to capture this."

The new paper raises an interesting point. It notes that the growth in Antarctic sea ice in the latest IPCC report is much bigger than suggested in the previous one in 2007. The authors say:

"[The 2007 report] reported the trend in Antarctic sea ice extent to be small and statistically indistinguishable from zero".

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Slow surface warming since 1998 is “not exceptional”, say scientists

  • 21 Jul 2014, 19:30
  • Roz Pidcock

Scientists know greenhouse gases are causing the world to warm. But an interesting question is why warming at earth's surface speeds up and slows down.

new paper shows surface temperature "slowdowns" like we're experiencing now aren't unusual - and capturing the timing of natural ups and down in the climate is key to predicting them.

But as a  second paper explains, the planet as a whole has warmed up in the last decade even as surface temperature rise has been sluggish.

Model mismatch

Temperatures are rising due to long term greenhouse gas warming. But natural variability causes temperatures to go up and down from one year to the next.

Natural variability can at least partly explain slower surface warming in the last 15 years, the Intergovernmental Panel on Climate Change (IPCC)  concluded in its latest report. Recent evidence  points to changes in the  Pacific causing the deep oceans to absorb more heat.

But most climate models didn't predict the slowdown. And as a  new paper in Nature Climate Change explains, some parts of the media have argued that since models don't replicate recent temperatures, we shouldn't trust their predictions for future warming.

But the paper, lead by Australian climate scientist Dr James Risbey, finds that 15 years of temperatures rising slower than models predict "does not constitute evidence against the fidelity" of models in general. Let's take a closer look at why not.

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Typhoon Haiyan, record-breaking CO2 levels, rising seas and more: five measures of the state of the climate in 2013

  • 18 Jul 2014, 17:00
  • Ros Donald

Atmospheric carbon dioxide levels broke modern records last year - and 2013 was one of the warmest years on record according to four major datasets. Sea levels continue to rise, and the oceans are getting warmer. The US National Oceanic and Atmospheric Administration's State of the Climate, 2013 is a reminder of the many changes the world is experiencing. 

The State of the Climate report, published by the Bulletin of the American Meteorological Society, is a different beast to the Intergovernmental Panel on Climate Change's (IPCC) fifth assessment report. Both reports assemble multiple datasets to give a picture of the changes the planet is experiencing, but NOAA's annual climate checkup doesn't try to answer why certain events have occurred. Instead, it focuses on building a detailed picture year on year, chronicling the shifting state of the physical climate system. 

NOAA has also created a  summary that pulls out the report's most striking results. We've picked five measures that help form this picture along with NOAA's explanation of why they matter. 

 

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Climate change spells bad news for reindeer, say experts

  • 17 Jul 2014, 11:40
  • Roz Pidcock

If you look at one corner of the Arctic, you might conclude climate change means reindeer are better off. But those that benefit are likely to be the exception rather than the rule, say scientists.

Overall, warming is leading to loss of habitat, food and declining reindeer populations.

Svalbard reindeer

According to an article in yesterday's  Times, reindeer numbers are growing on the Norwegian islands of Svalbard.

The piece is based on data from scientists at the Arctic University of Norway, who have monitored reindeer populations in Adventdalen Valley on Spitsbergen, Svalbard's main island, since 1979.

The new research suggests the reindeer of Svalbard may be doing OK out of climate change, as melting ice reveals new grazing territory. But this is the latest estimate from one group of researchers, and not all scientists are as confident of such a rosy picture.

Getting a handle on reindeer numbers in these vast and remote landscapes is difficult. This Smithsonian  feature from March explores researcher Steve Albon's efforts to monitor reindeers in Svalbard, where he says the impact of climate change is not yet well understood.

Reindeer in decline

Svalbard is just one part of the Arctic where reindeer live. And the picture looks very different in some other parts.

Reindeer _map _ABT2010

How reindeer populations are faring across the Arctic. Green is increasing, red is decreasing and orange is unknown. Source:  Arctic Biodiversity Trends 2010

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The future of coal in China, India, Australia, the US, EU, and UK

  • 16 Jul 2014, 13:00
  • Mat Hope

CC: Bobak

Have reports of coal's demise been greatly exaggerated? It depends which part of the world you look at.

Global coal use has grown significantly over the last decade, with global demand increasing 60 per cent between 1990 and 2011, according to research body the International Energy Agency (IEA). With some countries implementing climate policies to limit the use of polluting fuels, some commentators are predicting  coal's imminent demise.

Bp Global Coal Consumption

Source:  BP Statistical Review of World Energy

That's probably premature. While some European countries are ramping up renewables, shutting coal plants and closing mines, other parts of the world are planning an extraction frenzy to feed emerging economies' seemingly insatiable energy demand.

Here's a quick guide to coal's prospects around the world.

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Arctic summer sea ice is disappearing fast, but can we rescue it?

  • 14 Jul 2014, 15:30
  • Roz Pidcock

Diminishing Arctic sea ice is perhaps the most iconic consequence of climate change. And there's a good chance we'll lose it in summer before too long if emissions stay high, according to a new paper. But its demise is not a foregone conclusion - with a swift peak and decline in greenhouse gases we could still reverse that trend, the scientists say.

Losing ice

Arctic sea ice cover is declining by about  four per cent per decade. But the seasonal low in summer is shrinking particularly quickly, at more like 11.5 per cent per decade.

At the other end of the planet, Antarctic sea ice is growing - but much slower than it's being lost in the Arctic. We've written more about global sea ice loss  here.

AR5_summer _Arctic _sea _ice _extent

Arctic sea ice summer extent has decreased by between 9.4 to 13.6% per decade. Source: IPCC 5th Assessment Report,  Summary for Policymakers

 

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