Category Archive 'Medieval Warm Period'

05 Nov 2006

Debunking the UN’s Stern Report

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Christopher Moncton starts a series of two articles discussing the fallacies of the UN’s Stern Report on Climate Change.

First, the UN implies that carbon dioxide ended the last four ice ages. It displays two 450,000-year graphs: a sawtooth curve of temperature and a sawtooth of airborne CO2 that’s scaled to look similar. Usually, similar curves are superimposed for comparison. The UN didn’t do that. If it had, the truth would have shown: the changes in temperature preceded the changes in CO2 levels.

Next, the UN abolished the medieval warm period (the global warming at the end of the First Millennium AD). In 1995, David Deming, a geoscientist at the University of Oklahoma, had written an article reconstructing 150 years of North American temperatures from borehole data. He later wrote: “With the publication of the article in Science, I gained significant credibility in the community of scientists working on climate change. They thought I was one of them, someone who would pervert science in the service of social and political causes. One of them let his guard down. A major person working in the area of climate change and global warming sent me an astonishing email that said: ‘We have to get rid of the Medieval Warm Period.’ “…

Scores of scientific papers show that the medieval warm period was real, global and up to 3C warmer than now. Then, there were no glaciers in the tropical Andes: today they’re there. There were Viking farms in Greenland: now they’re under permafrost. There was little ice at the North Pole: a Chinese naval squadron sailed right round the Arctic in 1421 and found none.

The Antarctic, which holds 90 per cent of the world’s ice and nearly all its 160,000 glaciers, has cooled and gained ice-mass in the past 30 years, reversing a 6,000-year melting trend. Data from 6,000 boreholes worldwide show global temperatures were higher in the Middle Ages than now. And the snows of Kilimanjaro are vanishing not because summit temperature is rising (it isn’t) but because post-colonial deforestation has dried the air. Al Gore please note.

In some places it was also warmer than now in the Bronze Age and in Roman times. It wasn’t CO2 that caused those warm periods. It was the sun. So the UN adjusted the maths and all but extinguished the sun’s role in today’s warming. Here’s how:

• The UN dated its list of “forcings” (influences on temperature) from 1750, when the sun, and consequently air temperature, was almost as warm as now. But its start-date for the increase in world temperature was 1900, when the sun, and temperature, were much cooler.

• Every “forcing” produces “climate feedbacks” making temperature rise faster. For instance, as temperature rises in response to a forcing, the air carries more water vapour, the most important greenhouse gas; and polar ice melts, increasing heat absorption. Up goes the temperature again. The UN more than doubled the base forcings from greenhouse gases to allow for climate feedbacks. It didn’t do the same for the base solar forcing.

Two centuries ago, the astronomer William Herschel was reading Adam Smith’s Wealth of Nations when he noticed that quoted grain prices fell when the number of sunspots rose. Gales of laughter ensued, but he was right. At solar maxima, when the sun was at its hottest and sunspots showed, temperature was warmer, grain grew faster and prices fell. Such observations show that even small solar changes affect climate detectably. But recent solar changes have been big.

Read the whole thing.


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