A draft of the United Nations organisation’s fifth climate report (IPCC AR5), due to be completed 2014, has been leaked onto the internet.
The International Panel of Climate Change is a time-consuming voluntary process comprising three working groups, that produce the three blockbuster reports (on physics, impacts, and mitigation strategies respectively) every seven years. Although the process produces no new science, it is intended to faithfully reflect the state of play.
Although anyone could sign up to “review” the draft, anyone who did was forbidden from disclosing the contents. Skeptical climate blogger Alec Rawls signed up and waited until the second review round closed on November 30th, then posted the draft to his blog – which promptly buckled under the weight.
Rawls’ decision has won some support from surprising quarters. The New York Times Malthusian-in-residence Andy Revkin described the IPCC demands for secrecy as archaic.
What does it say, then? We shall refrain from cherry-picking all but the cherry-picked “Summary for Policy Makers”. There’s little change in the conclusion since AR4. Although only a small fraction of CO2 in the atmosphere is produced by human activity, and only half of that isn’t absorbed, this remaining component is the dominant factor in determining the climate, say IPCC authors.
“Globally, CO2 is the strongest driver of climate change compared to other changes in the atmospheric composition, and changes in surface conditions. Its relative contribution has further increased since the 1980s and by far outweighs the contributions from natural drivers.”
Computer models predict a 3°C rise over a hundred years, and they’re more sure than ever “that many changes, that are observed consistently across components of the climate system, are significant, unusual or unprecedented on time scales of decades to many hundreds of thousands of years.”
Dire predictions of an increase in violent weather aren’t justified however, according to the IPCC.
Rawls says he was motivated to leak the draft because of the IPCC’s refusal to accept any other solar factors other than irradiance, or ‘brightness’. The refusal is a fact, but results largely from the failure of the scientific community to explore such factors. The Svensmark hypothesis on cloud nucleation is at least acknowledged, for the first time.