Global warming less than we thought

Don’t have time to look closely, but here’s a taste of good news.

*abridged* New research from Oxford University shows the rate of global warming has been lower over the past decade than it was previously.

The paper, “Energy budget constraints on climate response”, to be published online by Nature Geoscience, shows the estimated average climate sensitivity – or how much the globe will warm if carbon dioxide concentrations are doubled – is almost the same as the estimates based on data up to the year 2000.

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Simple arithmetic

For all of its apparent complexity, the threat of dangerous anthropogenic global warming (DAGW) formulated at the Rio Earth Summit in 1992 is based on a very simple assumption:

When X = 560, Y = ECS

where

X = atmospheric concentration of CO2e in parts-per-million
Y = the increase in temperature since pre-1880, in °C
ECS (Equilibrium Climate Sensitivity) = 1°C plus the ultimate net effect of feedbacks

X is taken from the Mauna Loa observatory and Y is provided by five published temperature series, neither being deeply controversial. The sole debatable element is ECS, the assessment of which is described in Wikipedia: Continue Reading →

Harder and harder to ignore

Professor Myles Allen -- will you ignore him?

Bishop Hill has an account — Lindzen at the Oxford Union — of the recent Oxford debate involving (mainly) Professors Richard Lindzen and Myles Allen. The latter comments (1.25pm):

“I was deeply embarrassed to be associated with Hasan’s ad hominem attacks on Dick Lindzen, in particular his going on about speaker fees and airline tickets. I thought this was going to be a discussion of climate science, and most of it seemed to be, as ever, about people and politics. As I hope I made clear when I had the chance, these were completely irrelevant to the discussion (and nothing he brought up seemed in any way exceptionable anyway) and that kind of attempt at personalising everything is just what is preventing a sensible discussion. I am very sorry that a visitor to Oxford was treated in this way.

On the science side, I’m happy to accept that studies comparing simple models with observations of the recent record, of which several have been published recently, suggest a climate sensitivity in the region of 2 degrees (although this isn’t the only line of evidence). But even a two degree sensitivity, if we do decide to burn all available fossil carbon, which would take concentrations well over 1000ppm, would be more than enough for 4+ degrees of warming. The real question, therefore, is whether 4+ degrees is OK. That’s what we need to be discussing, and unfortunately, because once again it was side-tracked onto irrelevancies, the debate didn’t go there.” (emphasis added)

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Insensitive climate

Barry Brill points out the warmists don’t seem pleased at the recent good news about climate sensitivity (a new paper says it’s not going to warm catastrophically). Could it be because the warmists cry only crocodile tears about the forecast disaster and they’re actually looking forward to it? (It lets them control us.) – Richard Treadgold

Whether the future level of Anthropogenic Global Warming is dangerous or catastrophic or merely interesting turns entirely on how “sensitive” the climate is to carbon dioxide emissions.

The key sensitivity measure is the increase in temperature resulting from a doubling of the CO2 atmospheric concentration of 280ppm that is said to have existed in pre-industrial times.

Laboratory experiments have shown that sensitivity should be about 1°C before feedbacks – but the net impact of positive and negative feedbacks is the subject of incessant debate. Sceptics generally say negatives (especially clouds) are dominant so that the final outcome falls back to about 0.4°C. The majority view is that positives (especially water vapour) drive the outcome up to 3-4°C, while some catastrophists see runaway warming up to 6°C or above.

There is no consensus.

The science is not settled. The debate is not over. Continue Reading →

Set phasers on stun

Spencer claims that climate sensitivity has been “grossly overestimated” because of confusion over cause and effect between cloud cover and temperature. All the computer models now wrongly treat cloud cover as a positive feedback, amplifying warming. But some clouds directly cause warming (a forcing) and are not the result of warming (a feedback). He gives details and says they’re having to fight to get it published. more…