Analysis

Dispelling myths and silently shaping progress: What consensus means to climate scientists

  • 23 Jun 2014, 10:45
  • Roz Pidcock

In the 2000s, the question of how strong agreement is among climate scientists that climate change is happening and that it's human-caused began to gain prominence.

few papers sought to  answer the question using various different approaches, ultimately pinning the level of consensus at around 97 or 98 per cent.

Last year, a study by University of Queensland climate scientist and founder of the Skeptical Science website, John Cook, revisited consensus on climate change within the scientific literature.

The researchers examined 12,000 studies. Similar to other studies, Cook et al.  concluded that 97 per cent of the papers that expressed a position on the causes of climate change pointed to human activity as the main driver.

The study received a lot of media coverage at the time, ranking 11th among new science papers receiving the most attention online in 2012, and even earning a mention from the US president. But it's alsoprompted some heated discussion.

Most recently, economics professor Richard Tol published a  critique of the paper in the journal Energy Policy. Tol takes no issue with the paper's conclusion about an overwhelming scientific consensus in the literature. Instead, the crux of his argument is with specifics of the methodology.

Consensus is complicated. And reducing a complex question to a simple number is going to be fraught. So why do it? We asked climate scientists what consensus means to them, if it can be measured and how they use consensus in their own work.

Why measure consensus?

Climate scientists overwhelmingly agree that recent warming is being driven by human activity rather than by naturally occurring processes. That's typically what people mean when they talk about a 'scientific consensus' on climate change.

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El Niño: How human history helped shape modern climate prediction

  • 18 Jun 2014, 12:00
  • Roz Pidcock

In the early 1500s, every few years Peruvian fisherman started noticing warmer seawater diminishing their anchovy catch, and farmers on land recorded more rain falling than usual.

Ever since then, the development of human society has been closely intertwined with the global climate pattern known as the El Niño Southern Oscillation (ENSO), and the effect it has on farming, food, water and public health.

A new study takes a historical look at the climate phenomena, and charts how society's need to better prepare for El Niño has paved the way for modern climate prediction.

An age old fascination

Every five years or so, a change in the winds causes a shift to warmer than normal ocean temperatures in the  equatorial Pacific Ocean. This shift is known as El Niño, and it has a counterpart, La Niña, which leads to  cooler than normal ocean temperatures.

Combined, the two phases together are known as the El Niño Southern Oscillation (ENSO), and are responsible for most of the fluctuations in global weather we see from one year to the next.

ENSO

Sea surface temperature during El Niño (left) and La Niña (right). Red and blue show warmer and cooler temperatures than the long term average. [Credit: Steve Albers, NOAA]

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New Met Office forecast predicts heavier summer downpours with climate change

  • 01 Jun 2014, 18:00
  • Roz Pidcock

Get set for more intense downpours as scientists say climate change is making heavy rainfall in summer more likely - at least in the southern part of the UK.

The Met Office's new forecast is a scientific first, taking a fresh approach to the notoriously difficult problem of forecasting climate change for such a small region. So how confident are the scientists in the prediction?

It's raining, it's pouring

The new Met Office study predicts extreme summer rainfall will become more frequent in the UK as the climate warms.

The team, including scientists from the University of Newcastle, estimates that by 2100 we'll see the sort of rainfall that leads to flash flooding - that's more than 28 millimetres of rain falling in one hour - five times as often as we are now.

Boscastle _pa

Intense summer rainfall led to devastating floods in Boscastle in 2004, and will get more common with climate change, according to a new Met Office forecast.

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Making waves: New science points to storminess as reason for Antarctic sea ice growth

  • 28 May 2014, 18:00
  • Roz Pidcock

Rob Johnson

The size of ocean waves could be the "missing science" behind why Antarctic sea ice is growing, say the authors of a new research paper.  But as climate change bites, the destructive power of high winds and big waves could lead to sea ice retreat at both ends of the globe, the paper warns.

Over the course of a year, the amount of sea ice in both poles waxes and wanes with the seasons, reaching a low at the end of the summer. But there are also bigger changes afoot.

Since 1979, the Arctic has been losing sea ice at a rate of about  four per cent per decade. At the opposite end of the earth, Antarctic sea ice is increasing by about  1.5 per cent per decade.

Scientists are confident climate change is driving Arctic sea ice loss. But it's not clear what's causing Antarctic sea ice to increase.

A new study, just published in the journal Nature, suggests an explanation. Changes in wave patterns could be closely linked to what's happening at both poles, the study says.

Storms, waves and sea ice

Sea ice floats on top of the polar oceans. The area covered by ice grows in winter and melts or 'retreats' in summer as the amount of heat from the sun changes.

Scientists have long suspected waves generated by stormy weather can break up sea ice, causing it to retreat faster. A combination of high temperatures and stormy conditions is thought to be behind the record low amount of Arctic sea ice seen in September 2012.

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Enabling the messenger: How can the IPCC get its message across to the public?

  • 23 May 2014, 13:30
  • Ros Donald

cazstar

The pages of the Intergovernmental Panel on Climate Change (IPCC)'s new reports tells a range of compelling stories about the huge changes humans and our environment face as the planet warms. 

Trouble is, these narratives are couched in fairly inaccessible language.

We look at two new pieces of research aimed at analysing the way the IPCC communicates and improving the panel's rapport with the public.

Bringing the IPCC to life

For its new  report, 'Science & stories: Bringing the IPCC to life', communications group Climate Outreach & Information Network (COIN) interviewed 16 communications experts from UK media organisations and NGOs.

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Mail Online overplays new study with claims melting glaciers could partly ‘cancel out' global warming

  • 22 May 2014, 14:50
  • Roz Pidcock

Today's  Mail Online reports on a new study suggesting melting ice sheets could have an upside for Arctic ecosystems, by boosting plant growth.

As a potential way to capture carbon dioxide, the Mail Online's headline suggests the findings could represent "another positive effect of global warming". The authors take a more cautious view, however, saying such conclusions are "outside the scope" of the paper.

Unfortunately, it's seems likely the Mail Online's headline was inspired by the University of Bristol  press release, entitled 'Iron from melting ice sheets may help buffer global warming', though the rest of the release doesn't do much to back up that statement.

The full paper is freely available, so you can have a read for yourself  here.

A rush of iron

The Mail Online story stems from  research published in Nature Communications. The study looks at the consequences of melting Greenland and Antarctic glaciers for polar ecosystems.

Every year in summer, glacial "outbursts" send thousands of litres of meltwater gushing into the ocean every second. This releases iron previously locked up in the ice, the paper explains.

The Arctic, Southern Ocean and parts of the North Atlantic are low in iron - an essential nutrient for plant growth. The new paper suggests a seasonal iron boost from melting glaciers stimulates plants to grow, drawing more carbon dioxide out of the air.

The scientists estimate the Greenland ice sheet releases 400,000 to 2.5 million tonnes of iron each year. In Antarctica, it's likely to be less - about 60,000 to 100,000 tonnes, they estimate.

Together, the combined mass of iron is equivalent to about 125 Eiffel Towers or 3,000 Boeing 747s added to the ocean each year, the  press release notes.

The scientists' estimates are based on measurements from the Leverett glacier in Southwest Greenland. Since the glacier is representative of more than 75 per cent of the continent, the team scaled their findings up to get an estimate for the whole ice sheet.

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Ice picks: Five pieces of ice news revealing earth’s ice cover is in serious decline

  • 20 May 2014, 17:00
  • Roz Pidcock

Melting ice has filled the newspapers over the past couple of weeks, with a deluge of new research into how the planet's ice cover is being altered by climate change making the headlines.

Coming just a few days after research showing West Antarctic glaciers are in irreversible collapse, today's news that Antarctic ice melt has doubled in a decade was widely covered.

We've taken a look at several new papers that highlight the speed at which earth's vast ice sheets, glaciers and ice caps are diminishing. Put them all together, and it makes for a stark picture.

1. Antarctic ice melt is twice as fast as ten years ago

'Antarctic ice losses have DOUBLED in less than a decade with 159 billion tonnes of ice melting each year', reads today's Daily Mail headline. The Guardian opts for, 'Doubling of Antarctic ice loss revealed by European satellite'. The Times says 'Antarctic melt rate worries scientists'.

All three headlines stem from a paper published yesterday in Geophysical Research Letters, which finds the volume of ice melting into the ocean from Antarctica is twice as large the average between 1992 and 2011, now raising global sea levels by 0.45 millimetres a year.

Mc Millan Et Al ., (2014) Antractic _map

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How much are we willing to adapt to climate change, and where are the limits?

  • 20 May 2014, 13:30
  • Ros Donald

How much climate change can humans stand? That's the question policymakers should be asking themselves as they contemplate ways to adapt to climate change, according to an Intergovernmental Panel on Climate Change (IPCC) expert. 

Professor Frans Berkhout  was speaking at Exeter University's Transformational Climate Science. He coauthored a chapter for the IPCC entitled ' Adaptation, Opportunities, Constraints and Limits', which examined just how far it is possible to adapt to climate change. 

The authors used a  risk-based analysis to consider how we might adapt, or fail to adapt, to effects of climate change like sea level rise, crop depletion and extreme heat. Berkhout tells Carbon Brief: 

"We drew on a small literature that exists and tried to develop a risk-based framework for thinking about limits [to adaptation]. The Working Group 2 report regional and sectoral chapters did for the most part engage with this new concept, but the idea of limits is not very visible in the [report's] Summary for Policymakers and Technical Summary. I think this is because some of the ideas are still quite fresh." 

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New study links El Niño to poor crop harvests worldwide

  • 15 May 2014, 19:46
  • Roz Pidcock

For the first time, scientists have worked out how natural climate cycles El Niño and La Nina - the source of extreme weather fluctuations worldwide - affect global crop yields.

A new  paper out today in journal Nature Communications looks at the link between a natural climate fluctuation known as the El Nino Southern Oscillation (ENSO) and poor harvests of wheat, rice corn and soybeans which, taken together, provide nearly  60 per cent of all calories produced on croplands.

Natural fluctuations

Every five years or so, a change in the winds causes a shift to warmer than normal ocean temperatures in the equatorial Pacific Ocean - known as El Niño, or cooler than normal - known as La Niña, moving briefly back to normal in between.

Both phases together are known as the El Niño Southern Oscillation (ENSO), and are responsible for most of the fluctuations in global weather we see from one year to the next. The new research allows them to match the specific phase of the cycle to the impact on crop yields.

Professor Andy Challinor from Leeds University, who is a co-author of the new study, tells us the conclusions are a scientific first:

"It's been known for a long time that both El Niño and La Niña have different impacts in different parts of the world in terms of excess rainfall and drought, and that they have knock on effects for crops. What's not been done before is a global study of impacts on all major crops, right across the globe"

CropsA satellite image of sea surface height. A region of warm water characterises El Niño and raises sea level in the Pacific (shown in red). Image credit: NASA JPL (Jet Propulsion Laboratory)]

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Some key questions answered on the news West Antarctic glaciers are “collapsing"

  • 14 May 2014, 10:00
  • Roz Pidcock

Collapse, irreversible, unstoppable, catastrophic: Eye-catching words like these pepper recent media coverage of  two scientific  papers charting the demise of West Antarctic glaciers.

Both papers come to much the same conclusion - the region's glaciers are shrinking under the pressure of rising temperatures and will ultimately add several metres to sea levels worldwide.

The research prompted some dramatic headlines. The  Daily Mail's headline reads 'Nasa data reveals Antarctic ice sheet is melting at an 'unstoppable' speed' while The  Guardian says, 'West Antarctic ice sheet collapse has begun already'.

Are glaciers retreating or collapsing entirely? When does retreat become a collapse? Do scientists think we're heading for a collapse too? We've tried to answer some questions the coverage raises.

What's the West Antarctic ice sheet? Why is it important?

Antarctica Glaciers _WAIS

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