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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Where is the evidence for the dangerous positive feedback in the Vostok Ice Cores?

Vostok, Antarctica, Photo: Michael Studinger 2001

It appears the warming of the 20th Century has been done before.  It’s just business as usual for the planet.

Frank Lansner has been hard at work again, and we’ve been discussing the Vostok ice cores. This time Lansner was looking to see if the current warming trend was unusual, and if there was evidence to support the high climate sensitivities the models suggest. As it happens, most of those high climate sensitivities that the models “estimate” come not from carbon dioxide directly, but from the feedbacks (the way the planet responds to any small change in temperature).

The models assume the net feedbacks are positive. These same feedbacks ought to have been working 100,000 years ago, and if so, there should be some hint of it in the ice cores. Lansner has been hunting for large swings in temperature during the periods when Earth was at a similar temperature to present day conditions — but what he finds is that the current claimed rise of 0.7 degrees C over the last century, even if it were true (and not exaggerated by thermometer [...]

Ice Core evidence — where is carbon’s “major effect”?

The ice cores are often lauded as evidence of the effects of carbon dioxide. Frank Lansner asks a pointed question and goes hunting to find any effects that can be attributed to carbon.

Where is the data that actually shows a strong and important warming effect of CO2? If CO2 has this strong warming effect, would not nature reflect this in data?

He has collected together the data from the last four warm spells (the nice interglacials between all the long ice ages) into one average “peak”. The common pattern of the rise and fall has already been recorded in many scientific papers. Orbital changes trigger the temperatures to rise first and about 800 years later (thanks to the oceans releasing CO2), carbon dioxide levels begin to climb. At the end of a patch of several thousand warm years, temperatures begin to fall, and thousands of years later the carbon dioxide levels slowly decline. No one is really contesting this order of things any more. What is contested is that those who feel carbon is a major driver estimate that the carbon dioxide unleashed by the warming then causes major amplification or [...]

Great Debate Part III & IV – Glikson accidentally vindicates the skeptics!

UPDATED Part IV: Andrew Glikson replies below.

I am impressed that Glikson replied politely, rose above any ad hominem or authority based arguments, and focused on the science and the evidence. This kind of exchange is exceedingly rare, and it made it well worth continuing. Links to Part I and II are at the end. Round 4 was copied from comments up to the post.

Depending on flawed models

by Joanne Nova

May 11, 2010

For a sentence, I almost think Dr Glikson gets it. Yes, it’s a quantitative question: Will we warm by half a measly degree or 3.5 degrees? It’s not about the direct CO2 effect (all of one paltry degree by itself), it’s the feedbacks—the humidity, clouds, lapse rates and other factors that amplify (or not) the initial minor effect of carbon.

Decades ago, the catastrophe-crowd made guesses about the feedbacks—but they were wrong. Instead of amplifying carbon’s effect two-fold (or more!) the feedbacks dampen it.

Dr Glikson has no reply. He makes no comment at all about Lindzen [1], Spencer[2] or Douglass[3] and their three peer reviewed, independent, empirical papers showing that the climate models are exaggerating the warming by [...]

The big picture: 65 million years of temperature swings

Greenland Interglacial Temperatures – last 10,000 years. Are we headed for an ice age? (See below for more detail.)

David Lappi is a geologist from Alaska who has sent in a set of beautiful graphs–including an especially prosaic one of the last 10,000 years in Greenland–that he put together himself (and which I’ve copied here at the top).

If you wonder where today’s temperature fits in with the grand scheme of time on Earth since the dinosaurs were wiped out, here’s the history. We start with the whole 65 million years, then zoom in, and zoom in again to the last 12,000 from both ends of the world. What’s obvious is that in terms of homo sapiens history, things are warm now (because we’re not in an ice age). But, in terms of homo sapiens civilization, things are cooler than usual, and appear to be cooling.

Then again, since T-rex & Co. vanished, it’s been one long slide down the thermometer, and our current “record heatwave” is far cooler than normal. The dinosaurs would have scoffed at us: “What? You think this is warm?”

With so much volatility in the graphs, anyone could play “pick a trend” and depending [...]

Carbon rises 800 years after temperatures

Ice cores reveal that CO2 levels rise and fall hundreds of years after temperatures change

In 1985, ice cores extracted from Greenland revealed temperatures and CO2 levels going back 150,000 years. Temperature and CO2 seemed locked together. It was a turning point—the “greenhouse effect” captured attention. But, in 1999 it became clear that carbon dioxide rose and fell after temperatures did. By 2003, we had better data showing the lag was 800 ± 200 years. CO2 was in the back seat.