Analysis

Media round-up: The IPCC synthesis report

  • 04 Nov 2014, 16:54
  • Robert McSweeney & Rosamund Pearce

Rajendra Pachauri on Sky News

On Sunday the Intergovernmental Panel on Climate Change (IPCC) published its synthesis report, which summarises the findings of three huge assessment reports. It prompted a flurry of media coverage. Here are some selected highlights.

Broadcast media

  • BBC News discusses the "controversial" recommendation that fossil fuels should be phased out by the end of the century - "a huge undertaking". Since every attempt to negotiate a new climate treaty has failed, and with Paris on the horizon, the BBC asks: "has anything really changed?"

  • With the "glacial" pace of the UN negotiating process,  Channel 4 news asks: can we adapt fast enough? Professor Joanna Haigh argues that climate change has not dropped of the agenda, discusses geoengineering versus preventative measures, and the value of the political process.

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  • In The IPCC report: why it matters, the BBC debates why another report was needed right now. Scientists believe that political leaders are in the process to agree a new climate deal - and they want to give them the most succinct report for this - "It may be the runt of the litter in size, but in political terms, it could turn out to be a real heavyweight".

  • In Climate change action will cost, the BBC broadcasts Ban Ki-moon's speech at the launch of the report.

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Untangling greenhouse gas emissions highlights the importance of carbon dioxide

  • 03 Nov 2014, 20:38
  • Robert McSweeney

Power Plant Emissions | Shutterstock

Efforts to limit climate change should focus on reducing emissions of carbon dioxide over any other greenhouse gas or air pollutant, a new study finds.

Short-lived

You might find you hear about efforts to cut carbon dioxide more than any other greenhouse gas (GHG). This is because carbon dioxide makes the biggest contribution of any of the gases emitted from human activities.

We emit more carbon dioxide than any other GHG, and once in the atmosphere it can stay there for centuries.

But there is also a group of 'short-lived' gases and pollutants that have an important warming effect. These include methane, ozone, hydrofluorocarbons (HFCs) and black carbon (soot).

A recent report by the UN Environment Programme (UNEP) recommended that reducing atmospheric concentration of these gases could "slow the rate of near-term climate change", alongside other benefits such as improving air quality and public health.

Now a study, published in the Proceedings of the National Academy of Sciences, looks at the long-term impact on global temperatures of reducing short-lived gases. And the results suggest that carbon dioxide should remain central to GHG emission cuts.

Influence

Many GHGs and pollutants are emitted from the same sources. Burning coal, for example, releases carbon dioxide, nitrous oxides and black carbon. Cutting coal use to reduce emissions of one gas would mean a reduction in the others as well.

These overlaps between gases and pollutants are significant. For example, 70 per cent of black carbon emissions are related to energy use, such as burning diesel in cars or biomass for cookstoves.

The study looks at the impact on global temperatures of cutting these short-lived gases with, and without, similar reductions in carbon dioxide.

In a scenario of 'no carbon dioxide mitigation', global temperatures would rise by over five degrees by 2100, but cutting emissions of methane, HFCs and black carbon would reduce this rise by around 0.9°C.

However, when carbon dioxide mitigation was included and global temperatures only rose by just over two degrees, the influence of reducing the other pollutants reduced to around 0.5°C. You can see the difference in the figure below.

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Carbon Brief’s guide to the Intergovernmental Panel on Climate Change’s fifth assessment report

  • 03 Nov 2014, 09:45
  • Carbon Brief staff

Night earth | Shutterstock

The Intergovernmental Panel on Climate Change (IPCC) has just completed a major review of global climate research - its fifth assessment report (AR5).

The report is split into three sections. The first two instalments cover the science and impacts of climate change. The third part looks at policies to cut global greenhouse gas emissions. The IPCC also produces a synthesis report, drawing all the research together.

We've covered each instalment in detail. Here's a catalogue of Carbon Brief's summaries, guides, and analyses of the IPCC's fifth assessment report.

Working group 1: The science

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The IPCC’s untapped resource: the frequently asked questions

  • 03 Nov 2014, 09:41
  • Robert McSweeney

Answers | Shutterstock

This Sunday, the Intergovernmental Panel on Climate Change (IPCC) will publish its latest Synthesis Report, a non-technical summary of three huge Assessments Reports.

But there is another easily-accessible IPCC resource that has already been published and is often overlooked: the IPCC's Frequently Asked Questions.

So what information does an FAQ written by the world's top climate scientists provide?

Here are some of the questions they cover:

- FAQ 1.1: If understanding of the climate system has increased, why hasn't the range of temperature projections been reduced?

- FAQ 2.1: How do we know the world has warmed?

- FAQ 2.2: Have there been any changes in climate extremes?

- FAQ 3.1: Is the ocean warming?

- FAQ 3.2: Is there evidence for changes in the Earth's water cycle? 

- FAQ 3.3: How does anthropogenic ocean acidification relate to climate change?

- FAQ 4.1: How is sea-ice changing in the Arctic and Antarctic? 

- FAQ 4.2: Are glaciers in mountain regions disappearing?

- FAQ 5.1: Is the Sun a major driver of recent changes in climate? 

- FAQ 5.2: How unusual is the current sea level rate of change?

- FAQ 6.1: Could rapid release of methane and carbon dioxide from thawing permafrost or ocean warming substantially increase warming? 

- FAQ 6.2: What happens to carbon dioxide after it is emitted into the atmosphere? 

- FAQ 7.1: How do clouds affect climate and climate change?

- FAQ 7.2: How do aerosols affect climate and climate change?

- FAQ 7.3: Could geoengineering counteract climate change and what side effects might occur?

- FAQ 8.1: How important Is water vapour to climate change?

- FAQ 8.2: Do improvements in air quality have an effect on climate change?

- FAQ 9.1: Are climate models getting better, and how would we know? 

- FAQ 10.1: Climate is always changing. How do we determine the causes of observed changes?

- FAQ 10.2: When will human influences on climate become obvious on local scales?- FAQ 11.1: If you cannot predict the weather next month, how can you predict climate for the coming decade?

- FAQ 11.2: How do volcanic eruptions affect climate and our ability to predict climate?

- FAQ 12.1: Why are so many models and scenarios used to project climate change?

- FAQ 12.2: How will the Earth's water cycle change? 

- FAQ 12.3: What would happen to future climate if we stopped emissions today? 

- FAQ 13.1: Why does local sea level change differ from the global average? 

- FAQ 13.2: Will the Greenland and Antarctic ice sheets contribute to sea level change over the rest of the century?

- FAQ 14.1: How is climate change affecting monsoons?

- FAQ 14.2: How are future projections in regional climate related to projections of global means?

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Rising temperatures will delay disease reduction in China, study shows

  • 02 Nov 2014, 18:01
  • Robert McSweeney

Child washing hands | Shutterstock

Efforts to reduce water-related diseases in China will be hampered by climate change, a new study finds.

Despite continued improvement in access to clean water and sanitation across China, rising temperatures could set back progress in reducing infectious diseases by as much as seven years by 2030.

Warmer temperatures

According to the UN, China has made significant progress on reducing water-related diseases in recent years. It has already met its Millennium Development Goal to halve the number of people without access to safe drinking water.

Recent decades have seen a huge drop in cases of water-related diseases in the country. Between 1990 and 2010 deaths from diarrheal diseases fell by 94 per cent. Malaria and Japanese encephalitis, both spread by mosquitoes that breed in water, fell by over 60 per cent and over 80 per cent, respectively .

However, a study published in Nature Climate Change suggests further progress on water-related diseases will be stunted by climate change.

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Briefing: What's new and interesting in the IPCC synthesis report

  • 02 Nov 2014, 10:00
  • Roz Pidcock

Clouds farmland | Shutterstock

The world has received the clearest message yet on how humans are changing the climate. Delegates from 195 countries gathered in Copenhagen this week to add their seal of approval to a 100-page "synthesis report". It's the final instalment in a four-part series from the UN's Intergovernmental Panel on Climate Change (IPCC).

The synthesis report condenses the IPCC's three other major reports on different aspects of climate change into one concise document. While that means some parts of it may sound familiar, there are some new and different sections as well. Here's our assessment of what's new, as well as a look at the report's main conclusions.

Warming continues unabated

Evidence that the climate is warming is unequivocal, the IPCC says. Each of the last three decades has been warmer than any previous one since 1850, and the world has warmed by about 0.85 degrees since then.

Today's report explains how the rate of surface warming varies from decade to decade, noting that warming since 1998 has been a third to half of the average since the 1950s. But, it adds:

"Even with this reduction in surface warming trend, the climate system has very likely continued to accumulate heat since 1998".

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The IPCC synthesis report: A summary for everyone

  • 02 Nov 2014, 10:00
  • Roz Pidcock

Daniel Julie

Today marks the release of an important document in the climate science world.

At 10 am this morning, the group of experts tasked by the United Nations with assessing the state of the climate released a major report on how and why it is changing, as well as what we can do about it.

Covering everything from declining sea ice to harnessing energy from the wind, the 100-page document has been hailed as an  essential "handbook" on climate change.

It connects the dots between three reports released by the Intergovernmental Panel on Climate Change (IPCC) over the past year, each looking at a different aspect of climate change.

Totting up the risks

Greenhouse gas emissions from humans are the highest in history, the first in the series of reports told us last year. Greenhouse gases trap heat in the atmosphere. Carbon dioxide and other greenhouse gases are released when we burn fossil fuels like coal, oil and gas.

As a result the oceans, land and atmosphere are warming, snow and ice cover is melting, our weather is getting more extreme and sea levels are rising.

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Why the IPCC synthesis report is necessary but not sufficient to secure a response to climate change

  • 31 Oct 2014, 13:45
  • Simon Evans

Factory chimneys | Shutterstock

On Sunday 2nd November, the Intergovernmental Panel on Climate Change (IPCC) will publish its latest synthesis report, distilling the latest knowledge on what UN chief Ban Ki-Moon has  called the greatest threat ever faced by humanity.

The synthesis report will wrap up the IPCC's fifth assessment (AR5) of climate change. It draws together information from the IPCC's reports on the science of climate change, climate impacts and the  ways climate risks can be addressed.

It takes a mammoth collective effort on the part of scientists, economists and policymakers to produce these IPCC reports. Is it worth it?

We've collected a range of views on the need for, and wider significance of, the IPCC's work. These suggest it remains a necessary but not sufficient part of the job of addressing climate change.

The synthesis report is necessary

Does the world need an IPCC, asks former IPCC chair and former scientific adviser to the UK government Bob Watson. "My answer would be absolutely yes," he says. "I think it's critically important the IPCC does routinely report back on what we know."

The synthesis report collects together scientific opinion on the technical and socio-economic aspects of the causes of climate change, the risks it poses and the options for adaptation and mitigation. It is unique in taking such a wide ranging and considered view of climate.

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Nitrous oxide emissions could double by 2050, study finds

  • 28 Oct 2014, 17:42
  • Robert McSweeney

Emissions of nitrous oxide could double by the middle of the century if left unchecked, a new study finds. And nitrous oxide is the third biggest contributor to manmade climate warming. So should we be worried?

Laughing gas

Most people know nitrous oxide as 'laughing gas', used as a mild anaesthetic by doctors and dentists. But it is also a powerful greenhouse gas.

Nitrous oxide is the third-largest contributor to the manmade greenhouse effect, after carbon dioxide and methane.

A new study, published in the journal Environmental Research Letters, brings together all the projections for future nitrous oxide emissions from different researchers. The results show that on average emissions will increase 83 per cent by 2050, if we carry on with business as usual.

The study also looks at how emissions might be curbed between now and the middle of the century. If 'moderate' attempts are made, the study finds, nitrous oxides would still increase by around 26 per cent. But emissions could reduce by as much as 22 per cent if we really get our act together.

All the projections were made using a starting point of 2005. This means the researchers are able to see how actual nitrous oxide emissions in recent years compare to the different scenarios. And the bad news is that we're currently on the business-as-usual path, the researchers say.

Human activities

Bacteria release nitrous oxide naturally by breaking down nitrogen in the soil and oceans. Total emissions from natural sources are currently around twice those of emissions from human activities.

But while natural emissions have not changed significantly since the industrial revolution, manmade emissions have. This increase has caused nitrous oxide concentrations in the atmosphere to rise steadily since the the mid-19th century, as shown below.

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New study strengthens link between Arctic sea-ice loss and extreme winters

  • 26 Oct 2014, 19:11
  • Robert McSweeney

Winter scene in Russia | Shutterstock

Declining Arctic sea-ice has made severe winters across central Asia twice as likely, new research shows. The paper is the latest in a series linking very cold winters in the northern hemisphere to rapidly increasing temperatures in the Arctic.

But the long-term picture suggests these cold winters might only be a temporary feature before further warming takes hold.

Arctic amplification

Temperatures in the Arctic are increasing almost twice as fast as the global average. This is known as Arctic amplification. As Arctic sea-ice shrinks, energy from the sun that would have been reflected away by sea-ice is instead absorbed by the ocean.

Arctic amplification has been linked with very cold winters in mid-latitude regions of the northern hemisphere. The UK, the US and Canada have all experienced extreme winters in recent years. Just last year, for example, the UK had its second-coldest March since records began, prompting the Met Office to call a rapid response meeting of experts to get to grips with whether melting Arctic sea-ice could be affecting British weather.

The new study, published in Nature Geoscience, suggests the likelihood of severe winters in central Asia has doubled over the past decade. This vast region includes southern Russia, Mongolia, Kazakhstan, and northern China. And it's the Arctic that's driving the changes once again, the authors say.

Pronounced change

The study finds that almost all of the very cold winters in central Asia during the past decade have coincided with particularly warm conditions in the Arctic.

The paper points to sea ice loss in the Barents Sea and the Kara Sea as the cause. These sit to the north of Scandinavia and Russia and to the south of the Arctic Ocean, as shown in the map below.

 

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