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Raymond T. Pierrehumbert

6 Dec 2004 by raypierre

Pierrehumbert Portrait
Raymond Pierrehumbert is the Louis Block Professor in Geophysical Sciences at the University of Chicago, having earlier served on the atmospheric science faculties of MIT and Princeton. He is principally interested in the formulation of idealized models which can be brought to bear on fundamental phenomena governing present and past climates of the Earth and other planets. His recent research interests have included water vapor feedback, baroclinic instability, the Neoproterozoic Snowball Earth, the climate of Early Mars, and methane hydrological cycles on Titan. He has been director of the Climate Systems Center, a US National Science Foundation Information Technology Research project aimed at bringing modern software design techniques to the problem of climate simulation. He has also collaborated with David Archer on the University of Chicago’s global warming curriculum.

He received an A.B. degree in Physics from Harvard, was then a Knox Fellow in the Department of Applied Mathematics and Theoretical Physics at Cambridge University, and completed his PhD on hydrodynamic stability theory at MIT, in the Department of Aeronautics and Astronautics. He was a lead author of the IPCC Third Assessment Report, and a co-author of the National Research Council study on abrupt climate change. He is a Fellow of the American Geophysical Union.

Pierrehumbert is the author of the textbook Principles of Planetary Climate, available from Cambridge University Press.

More information about his research, including a complete publication list, can be found here.

Filed Under: Contributor Bio's, Extras

The Arctic Climate Impact Assessment

5 Dec 2004 by Stefan

In early November 2004 the results of the Arctic Climate Impact Assessment (ACIA) were published, a uniquely detailed regional study compiled by 300 scientists over 3 years. The study describes the ongoing climate change in the Arctic and its consequences: rising temperatures, loss of sea ice, unprecedented melting of the Greenland ice sheet, and many impacts on ecosystems, animals and people. The ACIA is the first comprehensively researched, fully referenced, and independently reviewed evaluation of arctic climate change and its impacts for the region and for the world.

Sadly, in recent years we have become accustomed to a ritual in which the publication of each new result on anthropogenic climate change is greeted by a flurry of activity from industry-funded lobby groups, think tanks and PR professionals, who try to discredit the science and confuse the public about global warming.

[Read more…] about The Arctic Climate Impact Assessment

Filed Under: Arctic and Antarctic, Climate Science, Paleoclimate

The Arctic Climate Impact Assessment II

5 Dec 2004 by Gavin

Another apparent ‘refutation’ appears in a CNS news story (a right-wing internet news service). The piece is predominantly an interview with Pat Michaels and other less prominent skeptics. We take their scientific points one at a time:

[Read more…] about The Arctic Climate Impact Assessment II

Filed Under: Arctic and Antarctic, Climate Science

The Arctic Climate Impact Assessment III

5 Dec 2004 by Gavin

Does the ACIA overstate the problem of ozone depletion? The overview report states that the “stratospheric ozone layer over the Arctic is not expected to improve significantly for at least a few decades”. This is partly because CFC concentrations (that enhance stratospheric ozone destruction) are only expected to decrease slowly as a function of restrictions imposed by the Montreal Protocol and subsequent amendments. Another factor is the fact that stratospheric temperatures are generally cooling as greenhouse gases increase (see MSU Temperature Record, also Why does the stratosphere cool when the troposphere warms?). Due to the temperature dependence on the rates of chemical reactions involving ozone, cooler temperatures also lead to more ozone destruction. Stratospheric temperatures, particularly near the pole are also significantly influenced by dynamical changes, and in particular, the strength of the [Read more…] about The Arctic Climate Impact Assessment III

Filed Under: Arctic and Antarctic, Climate modelling, Climate Science

Temperature Variations in Past Centuries and the so-called "Hockey Stick"

4 Dec 2004 by mike

Translations: (Français)

Instrumental data describing large-scale surface temperature changes are only available for roughly the past 150 years. Estimates of surface temperature changes further back in time must therefore make use of the few long available instrumental records or historical documents and natural archives or ‘climate proxy’ indicators, such as tree rings, corals, ice cores and lake sediments, and historical documents to reconstruct patterns of past surface temperature change. Due to the paucity of data in the Southern Hemisphere, recent studies have emphasized the reconstruction of Northern Hemisphere (NH) mean, rather than global mean temperatures over roughly the past 1000 years.

[Read more…] about Temperature Variations in Past Centuries and the so-called "Hockey Stick"

Filed Under: Climate modelling, Climate Science, Greenhouse gases, Paleoclimate, Sun-earth connections

Myth vs. Fact Regarding the "Hockey Stick"

4 Dec 2004 by mike

Translations: (Español)

Numerous myths regarding the so-called "hockey stick" reconstruction of past temperatures, can be found on various non-peer reviewed websites, internet newsgroups and other non-scientific venues. The most widespread of these myths are debunked below:

[Read more…] about Myth vs. Fact Regarding the "Hockey Stick"

Filed Under: Paleoclimate

False Claims by McIntyre and McKitrick regarding the Mann et al. (1998) reconstruction

4 Dec 2004 by mike

A number of spurious criticisms regarding the Mann et al (1998) proxy-based temperature reconstruction have been made by two individuals McIntyre and McKitrick ( McIntyre works in the mining industry, while McKitrick is an economist). These criticisms are contained in two manuscripts (McIntyre and McKitrick 2003 and 2004–the latter manuscript was rejected by Nature; both are collectively henceforth referred to as “MM”). MM claim that the main features of the Mann et al (1998–henceforth MBH98) reconstruction, including the “hockey stick” shape of the reconstruction, are artifacts of a) the centering convention used by MBH98 in their Principal Components Analysis (PCA) of the North American International Tree Ring Data Bank (‘ITRDB’) data, b) the use of 4 infilled missing annual values (AD 1400-1403) in one tree-ring series (the ‘St. Anne’ Northern Treeline series), and c) the infilling of missing values in some proxy data between 1972 and 1980. Each of these claims are demonstrated to be false below. [Read more…] about False Claims by McIntyre and McKitrick regarding the Mann et al. (1998) reconstruction

Filed Under: Paleoclimate

Antarctic cooling, global warming?

3 Dec 2004 by Gavin

Translations: (Français)

by Eric Steig and Gavin Schmidt
Long term temperature data from the Southern Hemisphere are hard to find, and by the time you get to the Antarctic continent, the data are extremely sparse. Nonetheless, some patterns do emerge from the limited data available. The Antarctic Peninsula, site of the now-defunct Larsen-B ice shelf, has warmed substantially. On the other hand, the few stations on the continent and in the interior appear to have cooled slightly (Doran et al, 2002; GISTEMP). At first glance this seems to contradict the idea of “global” warming, but one needs to be careful before jumping to this conclusion.

[Read more…] about Antarctic cooling, global warming?

Filed Under: Arctic and Antarctic, Climate modelling, Climate Science, Greenhouse gases

What does the lag of CO2 behind temperature in ice cores tell us about global warming?

3 Dec 2004 by group

Translations: (Français)

This is an issue that is often misunderstood in the public sphere and media, so it is worth spending some time to explain it and clarify it. At least three careful ice core studies have shown that CO2 starts to rise about 800 years (600-1000 years) after Antarctic temperature during glacial terminations. These terminations are pronounced warming periods that mark the ends of the ice ages that happen every 100,000 years or so.

Does this prove that CO2 doesn’t cause global warming? The answer is no.

[Read more…] about What does the lag of CO2 behind temperature in ice cores tell us about global warming?

Filed Under: FAQ, Greenhouse gases, Paleoclimate

Michaels misquotes Hansen

2 Dec 2004 by Gavin

Pat Michaels (under the guise of the Greening Earth society) is particularly fond of misquoting Jim Hansen, director of the NASA GISS laboratory (and in the interests of full disclosure, GS’s boss).

Recently he claimed that Dr. Hansen has now come around to the ‘skeptics’ (i.e. Pat Michaels) way of thinking and suggests that they agree on the (small) amount of warming to be expected in the future. Michaels quotes Hansen from a 2001 PNAS paper:

[Read more…] about Michaels misquotes Hansen

Filed Under: Climate modelling, Greenhouse gases

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