A science presenter, writer, speaker & former TV host; author of The Skeptic's Handbook (over 200,000 copies distributed & available in 15 languages).


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Now that was “climate change” 8200 years ago — California lashed by 150 years of storms

Don’t tell me that cold is nice and the climate was ever ideal

A few scientists thought that the climate was stable and well behaved during the Holocene until we invented coal power and the Ford Model T and everything fell apart “unprecedentedly”.

But 8200 years ago things apparently got pretty wild. See the GISP graph below where there was a three degree fall in temperatures suddenly (circled in red below). A new study found that at the same time China and California also cooled. Strangely, this cooling effect probably did not produce calm, happy days for the Californians at the time. Instead it looks like they got 150 years of intense winter storms and a lot of wet weather.

UPDATE: This graph shows the ice-core data up until 1855. The last 150 years (1705 to 1855) are highlighted in red to show the warming as the Earth began coming out of the LIA. Obviously that red line would continue up further if it was drawn to the present.

Looks like real climate change….

The reason for the sudden snap is possibly that a couple of massive glacial lakes in North East America collapsed and suddenly drained out [...]

Dinosaurs wiped out by … Darkness and Cold

Now this is climate change. If you can believe this study, wow:

“In the tropics, annual mean temperature fell from 27 to 5 degrees Celsius”

And we worry about a warming of one degree in a century.

“It became cold, I mean, really cold,” says Brugger. Global annual mean surface air temperature dropped by at least 26 degrees Celsius. The dinosaurs were used to living in a lush climate. After the asteroid’s impact, the annual average temperature was below freezing point for about 3 years. Evidently, the ice caps expanded. Even in the tropics, annual mean temperatures went from 27 degrees to mere 5 degrees. “The long-term cooling caused by the sulfate aerosols was much more important for the mass extinction than the dust that stays in the atmosphere for only a relatively short time. It was also more important than local events like the extreme heat close to the impact, wildfires or tsunamis,” says co-author Georg Feulner who leads the research team at PIK. It took the climate about 30 years to recover, the scientists found.

The real threats are not fertilizer and balmy weather, but rocks from space, and cold, cold, cold…

How the [...]

The message from boreholes

There have been suggestions that Jo Nova might be trying to hide or ignore the most recent boreholes graph from Huang et al. So here it is. This is the last 2,000 years according to 6000 boreholes, with the last 100 years also using the “instrumental record” which gives us that hockey-stick uptick at the end. Below I explain the pros and cons of this study and update my thoughts.

Huang and Pollack 2008: Their latest boreholes published study


A borehole sounds like a bit-of-a-stretch as a proxy. How could we tell if the world was warmer in 1066 by drilling a hole in the ground? Yes, fair point. But what makes boreholes useful is that they are global and there is a lot of data: specifically 6,000 holes all over the world.

I’ve been looking at boreholes in more detail, analyzing them in the light of newer proxies. When all the evidence is considered, boreholes turn out be not-much-use at giving us meaningful numbers in degrees C, and in my opinion, not-too-hot at telling us the “when” of an event either. Too much depends on assumptions.

But what are they good for is that, when combined with [...]