26TH MAY 2004

Douglas V. Hoyt is a solar physicist and climatologist who worked for more than thirty years as a research scientist in the field. He has worked at NOAA, NCAR, Sacramento Peak Observatory, the World Radiation Center, Research and Data Systems, and Raytheon where was a Senior Scientist. He has conducted research on issues related to climate change, changes in solar irradiance on all time scales, and the sun-climate connection. His most recent publication is the book "The Role of the Sun in Climate Change" . He has published nearly 100 scientific papers on solar irradiance variations, the greenhouse effect, atmospheric transmission, aerosols, cloud cover, sunshine, radiative transfer, radiometers, solar activity, sunspot structure, sunspot decay rates, and the history of solar observations.

He has received no funding from any fossil fuel entity or government entity. His work is influenced only by the data and the study of the scientific literature.

He has recently published


a detailed and up-to-date survey on Climate Science which offers a challenge to that promoted by the IPCC. It is available on>

The well-known IPCC TAR conclusions are: “Climate sensitivity is likely to be in the range of 1.5 to 4.5°C. …The climate sensitivity is the equilibrium response of global surface temperature to a doubling of equivalent CO2 concentration. The range of estimates arises from uncertainties in the climate models and their internal feedbacks, particularly those related to clouds and related processes.

In contrast, Hoyt shows that:

* most empirical determinations of climate sensitivity place it somewhere between 0.07 and 0.26 C/W/m2

* recent published work shows that the sum total of all feedbacks is negative

* the upper limit on warming due to a doubling of carbon dioxide is 0.7 C and it is probably much less.

In addition to these carefully argued conclusions he tackles many other inaccuracies in the IPCC results.So far the IPCC scientists have not had the courage to reply to his criticisms.

He gives many references and links, and it is quite a struggle to go through all of them. Good hunting!


Warwick Hughes is a New Zealand-born graduate in geology from Auckland University who has worked in Australia for many years and has carried out pioneering research on surface temperature measurement. Much of this is to be found, plus important general information, and links to other sites, on his website at

I owe him a debt for his help in  my early work on the greenhouse effect, and he has now generously offered to put the best of these newsletters on his website. I will be updating and editing them, so if you want the latest news see his site.

Vincent Gray
75 Silverstream Road
Crofton Downs
Wellington 6004
New Zealand
Phone/Fax (064) 4 9735939
"It's not the things you don't know that fool you.
It's the things you do know that ain't so"
Josh Billings