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Hurricanes and Global Warming – Is There a Connection?

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Translations: (Français) (Español)

by Stefan Rahmstorf, Michael Mann, Rasmus Benestad, Gavin Schmidt, and William Connolley

On Monday August 29, Hurricane Katrina ravaged New Orleans, Louisiana and Missisippi, leaving a trail of destruction in her wake. It will be some time until the full toll of this hurricane can be assessed, but the devastating human and environmental impacts are already obvious.

Katrina was the most feared of all meteorological events, a major hurricane making landfall in a highly-populated low-lying region. In the wake of this devastation, many have questioned whether global warming may have contributed to this disaster. Could New Orleans be the first major U.S. city ravaged by human-caused climate change?

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Did the Sun hit record highs over the last few decades?

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Guest commentary by Raimund Muscheler

[note: this is a restore (8/8/05) of an article from August 3, 2005 that was accidentally deleted due to a technical glitch. Unfortunately, most of the comments could not be retrieved. We sincerely apologize to our readers!]

The solar influence on climate is a controversial topic in climate research (see previous posts here and here). The irradiance changes are assumed to be relatively small and the importance of potential amplifying mechanisms is still a matter of current debate. One reason for these uncertainties is that there are only approximately 25 years of satellite-based observations of the solar irradiance. Sunspot observations for the last 400 years clearly indicate that current levels of solar activity are very different from the state of the sun during the Maunder minimum (from approx. 1645 to 1715 AD) where almost no sunspots could be observed.
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Scientists respond to Barton

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by Gavin Schmidt and Stefan Rahmstorf

Many readers will be aware that three scientists (two of which are contributors to this site, Michael Mann and Ray Bradley) have received letters from Representative Joe Barton (Texas), Chairman of the House Energy and Commerce Committee specifically requesting information about their work on the ‘hockey stick’ papers (Mann et al (1998) and Mann et al (1999)) as well as an enormous amount of irrelevant material not connected to these studies.

Many in the scientific community would welcome any genuine interest in climate change from the committee, but the tone and content of these letters have alarmed many scientists and their professional organisations. In the words of Alan Leshner, CEO of the American Association for the Advancement of Science, the Barton letters “give the impression of a search for some basis on which to discredit these particular scientists and findings, rather than a search for understanding.” Other organisations and individual scientists have also expressed strong concerns: [Read more…] about Scientists respond to Barton

The Wall Street Journal vs. The Scientific Consensus

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Translations: (Español)

We are disappointed that the Wall Street Journal (WSJ) has chosen to yet again distort the science behind human-caused climate change and global warming in their recent editorial “Kyoto By Degrees” (6/21/05) (subscription required).

Last week, the U.S. National Academy of Sciences and 10 other leading world bodies expressed the consensus view that “there is now strong evidence that significant global warming is occurring” and that “It is likely that most of the warming in recent decades can be attributed to human activities”. And just last week, USA Today editorialized that “not only is the science in, it is also overwhelming”.

It is puzzling then that the WSJ editors could claim that “the scientific case….looks weaker all the time”.

While we resist commenting on policy matters (e.g. the relative merits of the Kyoto Protocol or the various bills before the US Senate), we will staunchly defend the science against distortions and misrepresentations, be they intentional or not. In this spirit, we respond here to the scientifically inaccurate or incorrect assertions made in the editorial.

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New contributor

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We welcome David Archer of the University of Chicago to the RealClimate team. David adds to our expertise in ocean and carbon cycle modelling and has already contributed a guest post, with more on the way. RealClimate actively solicits contributions from the wider climate science community and so if you’d like to help out, drop us a line.

Betting on climate change

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Translations: (Romanian) (Ukranian)

Guest contribution by James Annan of FRCGC/JAMSTEC.

“The more unpredictable the world, the more we rely on predictions” (Steve Rivkin). The uncertainty of an unknown future imposes costs and risks on us in many areas of life. A cereal-growing farmer risks a big financial loss if the price of grain is low at harvest time, and a livestock farmer may not be able to afford to feed his herd if the price of grain goes up. One way to reduce the risk is to hedge against it in a futures market. The two farmers can enter a forward contract, for one to deliver a set quantity of grain to the other for a fixed price at a future date. And indeed farmers do routinely use futures contracts to reduce their risks.

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How much of the recent CO2 increase is due to human activities?

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Translations: (Français)

Contributed by Corinne Le Quéré, University of East Anglia.

This question keeps coming back, although we know the answer very well: all of the recent CO2 increase in the atmosphere is due to human activities, in spite of the fact that both the oceans and the land biosphere respond to global warming. There is a lot of evidence to support this statement which has been explained in a previous posting here and in a letter in Physics Today . However, the most convincing arguments for scientists (based on isotopes and oxygen decreases in the atmosphere) may be hard to understand for the general public because they require a high level of scientific knowledge. I present simpler evidence of the same statement based on ocean observations, and I explain how we know that not only part of the atmospheric CO2 increase is due to human activities, but all of it.

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Global Dimming may have a brighter future

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Translations: (Français)

A while ago, we wrote about Global Dimming – a reduction in downward solar radiation of about 4% or about 7W/m2 from 1961 to 1990 was found at stations worldwide. We said at the time that there were hints of a recovery underway post-1990; now research has been published showing this. From Dimming to Brightening: Decadal Changes in Solar Radiation at Earth’s Surface by Martin Wild et al. (Science 6 May 2005; 308: 847-850; subscription required for link) uses surface measurements; Do Satellites Detect Trends in Surface Solar Radiation? by Pinker et al., Science 2005 308: 850-854 uses satellites; both find a recovery of surface downward radiation since about 1990.

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2005 Record Arctic Ozone Loss

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You read it here first!


Update (09/05/05): Markus Rex was kind enough to send us the full figure from which Nature made their thumbnail, and which is a little clearer. He also cautions that the 2005 numbers are still preliminary, however there is a clear trend towards increasing potential for Arctic ozone loss, which is realised or not depending on the vagaries of each individual winter.