Two degree limit: a dangerous way to think about climate change?


Photo by Flickr user Eladesor

The idea that any warming up to two degrees is ‘safe’ has shaped not just discussions on climate change, but the process of international negotiations. The Campaign against Climate Change has always tried to be clear that significant harm will take place well before this, and that we must consider the risk of triggering positive feedbacks such as the release of methane from Arctic melt.

A new paper by Christopher Shaw of the University of Sussex explores why the two degree concept has taken such a firm hold. It presents a challenge for all NGOs including the Campaign against Climate Change. Are we succumbing to ‘pragmatism’ and failing to challenge sufficiently strongly an emissions path that will lead to dangerous climate change?

The research found that the two degree ‘dangerous limit’ to climate change is unchallenged in tabloid papers and only rarely in broadsheets.

A typical example is given as a Guardian editorial (shared with 56 ‘major’ newspapers in 45 European countries) before the Copenhagen negotiations: “The science is complex but the facts are clear. The world needs to take steps to limit temperature rises to 2C.”

Very occasionally, broadsheets report views that challenge this, for example the demands of the Least Developed Countries bloc at the UN for a 1.5 degrees limit, protesting the dire human consequences of allowing the global average temperature to rise by up to 2 degrees.

NGOs’ campaign materials and statements have an important role in shaping public opinion on climate change. Like news reports, these generally rely on the use of anonymous expertise, for example describing two degrees as a target ‘determined on the basis of the science’ (Tearfund, 2007) or the opinion of ‘many scientists’ (Only Planet, 2007), something that ‘scientists warn’ (WWF, 2006) we must avoid.

To a more informed audience, for example in popular science books and in speeches, experts give a more realistic view. The following are extracts from interviews carried out for the research:

A prominent climate scientist was at pains to point out it was not him who came up with the two degree idea:
“It is one certain people in the UK and EU have come up with and broadly we acknowledge it, and most of us are aware that this is going to kill people elsewhere in the world but they are a long way away, they’re poor and they’re generally black and we don’t care.”

A politician “closely connected with environmental policy”, admitted politicians using the limit in their arguments were engaged in a conscious act of ‘deceit’, both self deceit and a deceit of the public, because the science simply did not support the claim that warming would not become dangerous until two degrees.

It was argued by campaigners and scientists attempting to influence policy that a simple message was important in communicating both with policymakers and with the public. Without a fixed limit there is nothing ‘to aim for; “you are trying to have some sort of policy
impact, so you have to be fairly pragmatic about the targets you are using”

In the real world, the Arctic is melting dramatically at just 0.8 degrees of warming, losing about 4/5 of its summer sea ice volume over the last three decades. And the 2 degrees concept has not been effective in keeping emissions down to stay within that limit: current political ambition would put us on course for a horrendous 4 degree temperature rise by the end of the century.

One organisation that has take a different approach to communicating limits is (350ppm is an estimate of the safe limit of CO2 parts per million in the atmosphere – compared to today’s approximately 400ppm and rising).

So is it time to stop talking about 2 degrees, with the measure of (false) security it brings?

Christopher Shaw warns:

"We face a critical juncture in the climate change story. There is a growing realization that the two degree idea has failed – failed to slow the increase in emissions of CO2, and failed to prevent dangerous climate change. The search has begun for alternative ways of framing climate policy. It is vital that such deliberations do not take place behind the locked doors of conference rooms in powerful institutions. Instead, people must be given the information that will allow them share their opinion on the most important question of all – how much climate change is too much?"

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