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Inhofe and Crichton: Together at Last!

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Gavin Schmidt and Michael Mann

Today we witnessed a rather curious event in the US Senate. Possibly for the first time ever, a chair of a Senate committee, one Senator James Inhofe (R-Oklahoma), invited a science fiction writer to advise the committee (Environment and Public Works), on science facts–in this case, the facts behind climate change. The author in question? None other than our old friend, Michael Crichton whom we’ve had reason to mention before (see here and here). The committee’s ranking member, Senator James Jeffords (I) of Vermont, was clearly not impressed. Joining Crichton on climate change issues was William Gray of hurricane forecasting fame, Richard Benedick (a negotiator on the Montreal Protocol on ozone-depleting chemicals), and David Sandalow (Brookings Institution). As might be expected, we paid a fair bit of attention to the scientific (and not-so-scientific) points made. [Read more…] about Inhofe and Crichton: Together at Last!

What is a first-order climate forcing?

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Roger Pielke Sr. (Colorado State) has a blog (Climate Science) that gives his personal perspective on climate change issues. In it, he has made clear that he feels that apart from greenhouse gases, other climate forcings (the changes that affect the energy balance of the planet) are being neglected in the scientific discussion. Specifically, he feels that many of these other forcings have sufficient ‘first-order’ effects to prevent a clear attribution of recent climate change to greenhouse gases.

In general, I heartily agree – other forcings are important, even essential, for understanding observed climate variability and, as a community, we are only just starting to get to grips with some of the more complicated effects. Obviously, though, not all forcings are of the same magnitude (either globally or regionally) and so it is useful to separate the ‘first-order’ forcings from those that are relatively minor. But what exactly is ‘first-order’ and what is not? [Read more…] about What is a first-order climate forcing?

Hurricanes and Global Warming – Is There a Connection?

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Translations: (Français) (Español) (English)

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?

[Read more…] about Hurricanes and Global Warming – Is There a Connection?

Et Tu LT?

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In previous posts we have stressed that discrepancies between models and observations force scientists to re-examine the foundations of both the modelling and the interpretation of the data. So it has been for the apparent discrepancies between the Microwave Sounding Unit (MSU) lower tropospheric temperature records (MSU 2LT), radiosonde records and the climate models that try to simulate the climate of the last few decades. Three papers this week in Science Express, Mears et al, Santer et al (on which I’m a co-author) and Sherwood et al show that the discrepancy has been mostly resolved – in favour of the models.

[Read more…] about Et Tu LT?

The lure of solar forcing

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It’s obvious.

The sun provides 99.998% of the energy to the Earth’s climate (the rest coming from geothermal heat sources). The circulation patterns of the tropical Hadley Cell, the mid latitude storm tracks the polar high and the resulting climate zones are all driven by the gradients of solar heating as a function of latitude. So of course any significant change to solar output is bound to affect the climate, it stands to reason! Since we can see that there are changes in solar activity, it’s therefore just a question of finding the link. Researchers for over a century have therefore taken any climate records they can find and searched for correlations to the sunspots, the solar-cycle length, geomagnetic indices, cosmogenic isotopes or smoothed versions thereof (and there are many ways to do the smoothing, and you don’t even need to confine yourself to one single method per record). At the same time, estimates of solar output in the past are extremely uncertain, and so there is a great deal of scope in blaming any unexplained phenomena on solar changes without fear of contradiction.

[Read more…] about The lure of solar forcing

Planetary energy imbalance?

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The recent paper in Science Express by Hansen et al (on which I am a co-author) has garnered quite a lot of press attention and has been described as the ‘smoking gun’ for anthropogenic climate change. We have discussed many of the relevant issues here before, but it may be useful to go over the arguments again here.

The key points of the paper are that: i) model simulations with 20th century forcings are able to match the surface air temperature record, ii) they also match the measured changes of ocean heat content over the last decade, iii) the implied planetary imbalance (the amount of excess energy the Earth is currently absorbing) which is roughly equal to the ocean heat uptake, is significant and growing, and iv) this implies both that there is significant heating “in the pipeline”, and that there is an important lag in the climate’s full response to changes in the forcing.

[Read more…] about Planetary energy imbalance?

Pollution-Climate Connections

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Translations: (Français) (English)

Guest commentary by Loretta Mickley, Harvard University

Every summer over much of the United States, we brace ourselves for heat waves. During these periods, the air turns muggy and usually smoggy. After a few days, a cold front moves in, sweeping away the pollution and ending the heat. Given that we are on a path towards global warming, atmospheric chemists are asking how climate change could affect air quality. Will warmer temperatures mean more pollution during these episodes? Will episodes last longer? Most importantly, what effect will changes in air quality have on human health?

[Read more…] about Pollution-Climate Connections

Doubts about the Advent of Spring

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A “consensus view” amongst climate scientists holds that the Northern Hemisphere will be warming this month, as spring is coming. This is thought to be due to the Earth’s orbit around the sun and the inclination of the Earth’s axis, tilting the Northern Hemisphere progressively towards the sun throughout March and April and increasing the amount of solar radiation received at northern latitudes.

In a new novel, State of Euphoria, bestselling author Michael Crikey uncovers major flaws in this theory and warns against false hopes for the arrival of spring.
[Read more…] about Doubts about the Advent of Spring

IPCC in action: Part II

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The primary purpose of the Intergovernmental Panel for Climate Change (IPCC) is to assess the available scientific knowledge about climate change, not to initiate new research. The next IPCC report (Assessment Report 4, or AR4) is due in 2007, and in order to update of the state of knowledge it will only consider papers published in peer-review scientific journals between 2000 and papers submitted by May 1st 2005 (must be accepted before December 2005). It is essential that the papers be published in scientific quality journals in order to ensure the credibility of the results. Nevertheless the IPCC reports undergo several additional reviews and revisions involving a large number of independent referees. Thus, the IPCC reports undergo a more stringent review process than common papers in the scientific literature.

[Read more…] about IPCC in action: Part II