Climate science

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

  • 31 Oct 2014, 13:45
  • Simon Evans

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

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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