Climate policy

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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Tackling global warming could slow global growth - by 0.06 per cent, IPCC predicts

  • 16 Apr 2014, 14:00
  • Mat Hope

Economists and policymakers have spent decades debating how much the world will have to pay to avoid the worst impacts of climate change, and whether it's worth the cost. A key finding in the UN's latest big climate report should help move that debate along: tackling climate change could slow economic growth by just 0.06 per cent a year, it says.

The Intergovernmental Panel on Climate Change (IPCC) released the third instalment of its review of latest climate change research last Sunday. While the first two instalments aimed to better define the climate change problem, the third report focuses on potential solutions - from ramping up wind and solar power, to halting deforestation.

But governments don't just want to know what they must do to avoid the worst impacts of climate change, they also want to know how much it will cost. So the IPCC's latest report spells out the choice: governments either pay a bit to curb emissions now, or risk much larger costs in the future.

Or, as IPCC co-chair Ottmar Edenhofer put it during the report's launch, "Climate policy isn't a free lunch but could be lunch [that's] worthwhile to buy".

Taking action is relatively cheap

In 1992, countries agreed they would curb emissions to prevent temperatures rising by more than two degrees above pre-industrial levels. 22 years on, after more than two decades of increasing emissions, that goal looks ever more ambitious.

So it may come as a surprise to find that the IPCC says the cost of keeping the pledge may be relatively low.

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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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