From	Michael E. Mann	Date	Thu, 02 Oct 2003 17:03:15 -0400
To	Phil Jones, Keith Briffa, Tim Osborn, Folland, Chris, Stott, Peter, David Viner - Climate Impacts LINK Project, Mike Hulme
Subject	Re:
For those of you who haven't seen it, this is Robert Matthews last article on the topic. Hence the fairly brusque tone taken... mike Middle Ages were warmer than today, say scientists By Robert Matthews, Science Correspondent (Filed: 06/04/2003) Claims that man-made pollution is causing "unprecedented" global warming have been seriously undermined by new research which shows that the Earth was warmer during the Middle Ages. From the outset of the global warming debate in the late 1980s, environmentalists have said that temperatures are rising higher and faster than ever before, leading some scientists to conclude that greenhouse gases from cars and power stations are causing these "record-breaking" global temperatures. Last year, scientists working for the UK Climate Impacts Programme said that global temperatures were "the hottest since records began" and added: "We are pretty sure that climate change due to human activity is here and it's accelerating." This announcement followed research published in 1998, when scientists at the Climatic Research Unit at the University of East Anglia declared that the 1990s had been hotter than any other period for 1,000 years. Such claims have now been sharply contradicted by the most comprehensive study yet of global temperature over the past 1,000 years. A review of more than 240 scientific studies has shown that today's temperatures are neither the warmest over the past millennium, nor are they producing the most extreme weather - in stark contrast to the claims of the environmentalists. The review, carried out by a team from Harvard University, examined the findings of studies of so-called "temperature proxies" such as tree rings, ice cores and historical accounts which allow scientists to estimate temperatures prevailing at sites around the world. The findings prove that the world experienced a Medieval Warm Period between the ninth and 14th centuries with global temperatures significantly higher even than today. They also confirm claims that a Little Ice Age set in around 1300, during which the world cooled dramatically. Since 1900, the world has begun to warm up again - but has still to reach the balmy temperatures of the Middle Ages. The timing of the end of the Little Ice Age is especially significant, as it implies that the records used by climate scientists date from a time when the Earth was relatively cold, thereby exaggerating the significance of today's temperature rise. According to the researchers, the evidence confirms suspicions that today's "unprecedented" temperatures are simply the result of examining temperature change over too short a period of time. The study, about to be published in the journal Energy and Environment, has been welcomed by sceptics of global warming, who say it puts the claims of environmentalists in proper context. Until now, suggestions that the Middle Ages were as warm as the 21st century had been largely anecdotal and were often challenged by believers in man-made global warming. Dr Philip Stott, the professor emeritus of bio-geography at the University of London, told The Telegraph: "What has been forgotten in all the discussion about global warming is a proper sense of history." According to Prof Stott, the evidence also undermines doom-laden predictions about the effect of higher global temperatures. "During the Medieval Warm Period, the world was warmer even than today, and history shows that it was a wonderful period of plenty for everyone." In contrast, said Prof Stott, severe famines and economic collapse followed the onset of the Little Ice Age around 1300. He said: "When the temperature started to drop, harvests failed and England's vine industry died. It makes one wonder why there is so much fear of warmth." The United Nation's Intergovernmental Panel on Climate Change (IPCC), the official voice of global warming research, has conceded the possibility that today's "record-breaking" temperatures may be at least partly caused by the Earth recovering from a relatively cold period in recent history. While the evidence for entirely natural changes in the Earth's temperature continues to grow, its causes still remain mysterious. Dr Simon Brown, the climate extremes research manager at the Meteorological Office at Bracknell, said that the present consensus among scientists on the IPCC was that the Medieval Warm Period could not be used to judge the significance of existing warming. Dr Brown said: "The conclusion that 20th century warming is not unusual relies on the assertion that the Medieval Warm Period was a global phenomenon. This is not the conclusion of IPCC." He added that there were also doubts about the reliability of temperature proxies such as tree rings: "They are not able to capture the recent warming of the last 50 years," he said. © Copyright of Telegraph Group Limited 2003. Terms & Conditions of reading. Commercial information. Privacy Policy. At 04:11 PM 10/2/2003 -0400, Michael E. Mann wrote: Dear Mr. Matthews, Unfortunately Phil Jones is travelling and will probably be unable to offer a separate reply. Since your comments involve work that is his as well, I have therefore taken the liberty of copying your inquiry and this reply to several of his British colleagues. The comparisons made in our paper are well explained therein, and your statements belie the clearly-stated qualifications in our conclusions with regard to separate analyses of the Northern Hemisphere, Southern Hemisphere, and globe. An objective reading of our manuscript would readily reveal that the comments you refer to are scurrilous. These comments have not been made by scientists in the peer-reviewed literature, but rather, on a website that, according to published accounts, is run by individuals sponsored by ExxonMobile corportation, hardly an objective source of information. Owing to pressures on my time, I will not be able to respond to any further inquiries from you. Given your extremely poor past record of reporting on climate change issues, however, I will leave you with some final words. Professional journalists I am used to dealing with do not rely upon un-peer-reviewed claims off internet sites for their sources of information. They rely instead on peer-reviewed scientific research, and mainstream, rather than fringe, scientific opinion. Sincerely, Michael E. Mann At 08:30 PM 10/2/2003 +0100, Robert Matthews wrote: Dear Professor Mann I'm putting together a piece on global warming, and I'll be making reference to your paper in Geophysical Research Letters with Prof Jones on "Global surface temperatures over the past two millennia". When the paper came out, some critics argued that the paper actually showed that there have been three periods in the last 2000 years which were warmer than today (one just prior to AD 700, one just after, and one just prior to AD 1000). They also claimed that the paper could only conclude that current temperatures were warmer if one compared the proxy data with other data sets. (For an example of these arguments, see: [1]http://www.co2science.org/journal/2003/v6n34c4.htm) I'd be very interested to include your rebuttals to these arguments in the piece I'm doing. I must admit to being confused by why proxy data should be compared to instrumental data for the last part of the data-set. Shouldn't the comparison be a consistent one throughout ? With many thanks for your patience with this Robert Matthews ---------------------------------------------------------------------- Robert Matthews Science Correspondent, The Sunday Telegraph C/o: 47 Victoria Road, Oxford, OX2 7QF Email: [2]r.matthews@physics.org Homepage: [3]www.ncrg.aston.ac.uk/People/ Tel: (+44)(0)1865 514 004 / Mob: 0790-651 9126 ---------------------------------------------------------------------- ______________________________________________________________ Professor Michael E. Mann Department of Environmental Sciences, Clark Hall University of Virginia Charlottesville, VA 22903 _______________________________________________________________________ e-mail: mann@virginia.edu Phone: (434) 924-7770 FAX: (434) 982-2137 [4]http://www.evsc.virginia.edu/faculty/people/mann.shtml ______________________________________________________________ Professor Michael E. Mann Department of Environmental Sciences, Clark Hall University of Virginia Charlottesville, VA 22903 _______________________________________________________________________ e-mail: mann@virginia.edu Phone: (434) 924-7770 FAX: (434) 982-2137 [5]http://www.evsc.virginia.edu/faculty/people/mann.shtml References 1. http://www.co2science.org/journal/2003/v6n34c4.htm 2. mailto:r.matthews@physics.org 3. http://www.ncrg.aston.ac.uk/People/ 4. http://www.evsc.virginia.edu/faculty/people/mann.shtml 5. http://www.evsc.virginia.edu/faculty/people/mann.shtml