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Ian Plimer’s ‘Heaven + Earth’ — Checking the Claims - page 46 / 64





46 / 64


Verschuren et al. [2000] is cited by Plimer when saying ‘the rise of great Zimbabwe co-

incided with the beginning of the dry little ice age while a warm pulse in the 15th and 16th centuries created the conditions for mixed farming in the highveld. nother warm an wet period at the end of the 18th century contributed to the spread of maize, increased

populations and more military action .’ The actual wording by [Verschuren et al., 2000] is ’equatorial east

frica was generally

drier than today during the Mediaeval Warm Period (MWP; , D 1000 to 1270), and that fairly wet conditions during the Little Ice ge (LI ; , D 1270 – 1850) were interrupted around D 1380 – 1420, 1560 – 1620 and 1760 – 1840 by episodes of persistent aridity more severe than any recorded drought of the twentieth century. ’

274 These temperature reconstructions from China show swings of up to ±1C either side of the 2000 year mean, and no indication of a Roman warming 2 to 6 degrees warmer than present.

278 Daniels and Knox [2005] look at alluvial deposits on the US Great Plains. They do not obtain any temperature data, but conclude that the drought at the time of the MWP may be an analogue for potential changes from 21st century warming.


281 ‘The Ontario forests have ... not returned to the diversity and productivity of the Medieval warming.’ Indeed — Campbell and Mc ndrews [1993] note that ‘the wild forest of Southern Ontario, now largely cleared, is no longer a major carbon reserve ...’

The main results of reference 281 (repeated as reference 286) are model simulations.

Some of the references confirm the widely accepted view of MWP to LI North tlantic area, e.g.

change in the

350 Lassen et al. [2004] analyses fjord sediments off Greenland, identifying changes, particu- larly from MPW to LI as potential contributions to loss of Norse settlements.

Twentieth century

In spite of the importance of current changes, this section of Heaven + Earth only cites two references:

368 Plimer correctly quotes this reference as saying ‘climate sensitivity greater than 1.5C has been a robust feature of the Earth’s climate over the last 420 million years.’ This is in accord with mainstream climate science and totally contradicts the main thrust of Plimer’s book.

369 Mann et al. [1998] are cited (incorrectly as noted below) primarily as a lead-in to the following section.


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