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Q & A: What’s El Niño - and why does it matter that scientists say one is on the way?

  • 24 Apr 2014, 12:50
  • Roz Pidcock

Forecasters worldwide are issuing alerts. Later this year, we're likely to be in the midst of an El Niño - a phenomenon driving severe weather worldwide. So when can we expect it to kick in, and what will the consequences be for global temperature? Find this and more in our quick Q & A.

What is an El Niño?

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.

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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IPCC review of farming and forests leaves key questions about effect on climate change "unresolved"

  • 17 Apr 2014, 12:15
  • Robin Webster

The rate at which we're chopping down the world's forests is declining - and in future, crops and newly planted forests could help prevent more climate change, according to the UN.

But uncertainties surrounding how we measure emissions, and what changing temperatures will mean for the world's forests, mean it's hard to be sure this is a good news story.

Emissions from farming, deforestation and other land use are going down, and are expected to continue doing so in the future. By the end of the century, humanity could use the land as a carbon sink, rather than a source of emissions, according to the Panel on Climate Change (IPCC)'s latest  report

It sounds like one piece of good news among  gloomy predictions from the IPCC. But human land use is only one part of a complex picture. 

Climate change could lead to forests  drying out, releasing more carbon dioxide in the atmosphere. And using trees, crops and plants as a source of energy instead of fossil fuels could also lead to more forest destruction.  

Declining emissions

Agriculture, forestry and other land use account for about a quarter (24 per cent) of man-made greenhouse gas emissions. Most of these emissions come from deforestation, changes to the soil and livestock farming.

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Degrees of change: the IPCC’s projections for future temperature rise

  • 15 Apr 2014, 12:00
  • Robin Webster

Many governments are trying to reduce greenhouse gas emissions. But unless policymakers raise their ambition significantly, temperatures are likely to rise beyond safe levels. We examine the pathways that could take us towards a two degrees temperature rise by the end of the century - or considerably higher. 

On Sunday, the Intergovernmental Panel on Climate Change (IPCC) released the last in a series of three reports, which together assess the physical evidence that climate change is happening, the  expected impacts over the course of this century and what would need to happen to curb the rise in greenhouse gases.

Embedded in the reports are the scientists' predictions for how high temperatures are likely to rise this century - and what that's likely to mean for ecosystems and societies around the world. 

Comparing scenarios 

The IPCC bases its projections for future temperature rise on two different techniques. 

First, the IPCC has created its own storylines, or scenarios, describing how high temperatures are likely to rise in the future and what that might mean. The scenarios vary according to different predictions for how societies develop and how much effort we make to reduce greenhouse gas emissions over the course of this century.

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Climate fixes and Plan Bs: The IPCC’s guide to staying below two degrees of global warming

  • 14 Apr 2014, 13:10
  • Roz Pidcock

Cutting emissions, ramping up renewable energy, adapting to a new way of life and sucking carbon dioxide out of the air: recent reports from the Intergovernmental Panel on Climate Change (IPCC) appear to offer a number of ways to limit the scale and seriousness of climate change.

Which are the real climate solutions, and which are pretty risky bets? Here's what the IPCC says about what will and won't work when it comes to fixing the climate.

The two degree target

What we can do to curb the  impacts of climate change is the topic of the  third in a series of recent reports from the IPCC. But when we talk about limiting climate change, what do we really mean?

The idea that we should avoid "dangerous" interference with the climate has been around for a while. But at the UN climate summit in  Cancun in 2010, governments made the goal of keeping warming to no more two degrees Celsius above pre-industrial levels an official target.

The world has already warmed by 0.85 degrees over the industrial period and if emissions stay high, we're on course for more like three to five degrees by 2100, the IPCC  noted in its September report.

In other words, without efforts to reduce warming, we're set to fall a long way short of the target.

RCP2.6-8.0

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Media reaction: The Intergovernmental Panel on Climate Change's big climate mitigation report

  • 14 Apr 2014, 12:50
  • Mat Hope

While many were still engulfed in their duvets recovering from the night before, the UN spent Sunday morning launching a big report on strategies to tackle climate change. The report was the third instalment of the Intergovernmental Panel on Climate Change's (IPCC) major review of the most up-to-date climate change research.

If you've been too busy to catch up on the swathes of media coverage since then, have no fear - we've speed-read it all for you:

International cooperation

A significant proportion of the media focused on the report's message that there is still time for countries to act to avoid the worst impacts of climate change - but only if they work together.

  • The  Financial Times said the IPCC was sure there is "still time to save the world". It quotes one of the report's co-chairs, Ottmar Edenhofer, saying the report carried "a message of hope"  that tackling climate change "can be done".
  • Doing so would mean cutting emissions "by up to 70% by 2050 if it is to prevent global temperatures rising by more than two degrees", the  Sunday Times reports. The IPCC's research shows "stabilising climate is humanity's biggest challenge", it adds.
  • Newswire  Agence France Presse described the report's findings as a "wake up call" for governments. It said the IPCC identifies a 15-year window in which countries' will be able to act to avoid the worst impacts of climate change.
  • That means "governments must do more" to address rising emissions, the Washington Post argues. Countries must work together to lower emissions by 40 to 70 percent, according to the IPCC's findings, it said.
  • Taking a slightly different angle, the  Independent on Sunday was the only major UK newspaper to focus on the consequences of inaction. Unless the world acts soon, the IPCC says emissions could reach a level "that could reap devastating effects on the planet", the newspaper reports.

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Not just another climate report: main messages from the UN report on tackling emissions

  • 13 Apr 2014, 14:15
  • Robin Webster

If we're going to curb the rise in greenhouse gas emissions, the world's governments need to co-operate - and they're running out of time to do it. That's one of the top-line messages from the Intergovernmental Panel on Climate Change (IPCC)'s latest mega-report into current and future greenhouse gas emissions. 

Today's report is the last in a series of three from the IPCC. The first two summarised the physical evidence base for climate change and its potential  impacts on ecosystems and human societies. Now the organisation is looking at what's likely to happen to greenhouse gas emissions over the course of this century - and what possibilities there are for reversing the upwards trend. 

The full report runs to thousands of pages, providing an overview of all the research in the area. In order to complete it, the scientists assessed more than 1200 scenarios for how the future might unfold from different studies. The report's  summary is slightly more digestible, at just 33 pages. Here's our run-down of its key points. 

Emissions rising

Between 2000 and 2010, greenhouse gas emissions grew at 2.2 per cent a year -  a faster rate of increase than over the previous three decades. Human-caused emissions were "the highest in human history" in the first decade of this century, the IPCC says. 

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How to read the Intergovernmental Panel on Climate Change’s reports

  • 13 Apr 2014, 10:02
  • Mat Hope

Picdream

The UN's three new climate reports are thousands of pages long and contain a huge amount of detail on topics as diverse as flood risk to bioenergy. So how do you stop them from becoming the world's best-researched doorstop? Here's our guide to navigating the reports.

Three reports

Three publications make up the Intergovernmental Panel on Climate Change's (IPCC) comprehensive review of climate change research, known as the Fifth Assessment Report (or AR5). As they're such big pieces of work, the IPCC only produces a new assessment report every five or six years.

So where do you start? First, make sure you're reading the right document.

Screen Shot 2014-04-13 At 10.16.38

Responsibility for writing the reports is shared across three sets of scientists, known as Working Groups (sometimes referred to as WGs).

The WG1 report was released last September, WG2 came out yesterday, and WG3 is due in a week's time.

The Working Group 1 report looks at the physical scientific aspects of the climate system and climate change. Working Group 2 is tasked with assessing the impacts of climate change, and options for adapting to it. Working Group 3 tries to work out how policymakers can reduce global greenhouse gas emissions, and curb climate change.

In addition to each of the working group's reports is a synthesis report which brings together all of the IPCC's research.

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What’s mitigation? A short and straightforward summary of the IPCC’s latest report

  • 13 Apr 2014, 10:00
  • Carbon Brief Staff

Today an international group of hundreds of climate scientists released a  report on how nations can act to limit climate change.

The three-part report from the Intergovernmental Panel on Climate Change (IPCC) assesses the current state of climate change science. The organisation has just published the final part of the report, looking at how the world can cut carbon dioxide emissions.

Carbon dioxide is a greenhouse gas, meaning it traps heat in the atmosphere. Scientists now understand that this warming is changing the climate.

The first instalment of the IPCC's report, released last September, says scientists are more sure than ever - 95 per cent certain - that humans are causing extra warming in the oceans, land and atmosphere. As a result, snow and ice is melting and sea levels are rising.

Scientists now know much more about the risks the world faces as the climate changes, too. The IPCC says climate change is already contributing to problems like flooding, disruption to farming and food supply and species migration and extinction.

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Regional changes, global effects: an interview with IPCC Arctic specialist Jan-Gunnar Winther

  • 09 Apr 2014, 10:30
  • Ros Donald

Climate change is affecting the Arctic further and faster than any other part of the world. Carbon Brief speaks to Intergovermental Panel on Climate Change (IPCC) lead author Jan-Gunnar Winther about how the new report from the UN panel on the impacts of climate change relates to this highly sensitive region. 

What are the three main messages in the IPCC report concerning the Arctic?

First, it's important to stress that climate change with an anthropogenic component is having a greater effect in the Arctic than in other parts of the world, according to the report.

Second, it shows that we now have quite substantial knowledge that change in the Arctic region is having an effect on weather and climate in the northern hemisphere. We now know that regional changes - particularly in the Arctic - can have global effects.

And third, the report indicates that climate models have so far failed to give us accurate projections for the future of the Arctic. Over the past 20 years, they have systematically underestimated the rate of change in the Arctic. For example, the reduction in summer sea ice extent and thickness has been far beyond that predicted by models.

We must be aware that the future could bring yet more surprises in the region.

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IPCC report: Climate change and the things people care about

  • 07 Apr 2014, 12:00
  • Professor Neil Adger

No place is immune to the impacts of climate change. This is the principal message from the latest Intergovernmental Panel on Climate Change (IPCC) report. The impacts of climate change will be felt in individual places such as in back gardens, homes, fields and cities and will likely make us feel less safe and secure. 

For the first time the IPCC examines in detail the impacts of climate change on well-being across the report, with a cluster of chapters on the topics of  health, human  security, and  poverty

Human security encapsulates the notion of the vital core of human lives and the ability of people to have freedom and the capacity to live with dignity. Human security has direct material elements, such as life and livelihood, but also elements of cultural expression and identity.

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