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Copenhagen number crunch

Olive Heffernan

It’s clear that the Copenhagen Accord agreed to at last month’s UN talks doesn’t promise to do nearly enough to address the climate problem. But how far does it fall short?

The commitments to emissions reductions, which will be included in the Accord by the end of January (but can already be surprised from national pledges), would allow warming to reach at least 3°C above pre-industrial levels, according to the best available science (and according to a leaked UN document). And the financing to help the world’s most vulnerable adapt to climate change will only cover impacts resulting from 1.5°C of warming. The Copenhagen Accord thus leaves a 1.5°C gap of climate change unaccounted for – in other words, between the 1.5°C of change that we’ll have adapted to and the 3°C we’ll experience, there will be unavoided impacts, writes Martin Parry of the Grantham Institute and Centre for Environmental Policy at Imperial College London over on Nature Reports Climate Change.

Some sectors will, of course, be worse hit by unavoided impacts than others. The food and health sectors, for example, might be able to adapt and thus avoid impacts of up to a 1.5 °C rise by 2030, the water sector up to a 2°C rise by 2050 and coasts up to a 2.5 °C rise by 2080. But for ecosystems, many climate impacts simply cannot be avoided whatever the scale of funding available.

The ‘1.5C gap’ and its unavoided impacts are nicely illustrated in the figure below.

parry 2010.jpg

Caption: Schematic shows the 1.5 °C gap of unavoided impacts likely to result from current international commitments to adaptation funding and mitigation, as laid out in the Copenhagen Accord. The global climate impacts are taken from the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.

The full commentary is available here [free access].


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    Roger Pielke, Jr. said:

    Among other conceptual problems with this graph it has a significant error.

    The Figure says that the X-axis refers to “global mean change from pre-industrial temperature.” However, the IPCC Figure, which is identical in other respects, says that the axis represents “global mean temperature change relative to 1980-1999.”

    Thus, if global temperatures were 1 degree above preindustrial by 1990, then the stated 1.5 degree “gap” in the figure is really a 2.5 degree “gap.”

    Of course the deeper problem here is trying to represent climate impacts on society and ecosystems in terms of a global temperature average, while ignoring societal and ecological changes on the same time scales.

    The error in the figure simply helps to point out that this exercise makes little sense.

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    martin parry said:

    Thanks for the pointer that there was a labelling error in this Figure.

    The corrected figure has now been posted.

    This gives the temperature scale both against pre-industrial (at the top), which was correct in the original; and against present-day (at the bottom)which was inadvertantly omitted in the original. The 1.5 deg C gap reported in the paper remains unchanged since it referred to pre-industrial.

    Full details about how the impacts were scaled against global temperature, with caveats, are given in Table TS3 of the Technical Summary of the IPCC WGII Assessment (ref 7)

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