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Hockey sticks: Round 27

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Two more teams in the seemingly endless jousting over the ‘hockey-stick’ have just made their entry onto the field. In the first two (of four) comments on the original McIntyre and McKitrick (2005) (MM05) paper in GRL, von Storch and Zorita, and Huybers have presented two distinct critiques of the work of M&M.

The two comments focus on the ‘PC normalisation’ issue raised in MM05 which we discussed previously. Specifically, von Storch and Zorita show that in a GCM model emulation of the Mann, Bradley and Hughes (MBH) method, changing the PC normalisation technique makes no difference to the eventual reconstruction (i.e. it is not the normalisation that creates the ‘hockeystick’), consistent with earlier conclusions. Huybers comments that neither of the two suggested normalisations are actually optimal, and proposes a third method which looks like it gives results halfway between MBH and MM05. However, given the von Storch result, this too is unlikely to matter in the final reconstruction. [Read more…] about Hockey sticks: Round 27

Q & A: Global Warming

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There was an interesting piece that appeared in the October 12 edition of the Seattle Times, “Q&A: Global warming — a world of evidence”. This follows up on a previous article by journalist Sandi Doughton in the October 9 issue of the Times, “The Truth About Global Warming”.

In the Q&A, a group of University of Washington scientists, including atmospheric scientist and climate researcher J. Mike Wallace, weigh in with answers to questions fielded from the paper’s readers. Many of the questions, such as “Isn’t it true that scientists in the 1970s said the earth was cooling?” are quite similar to those we’ve addressed here at RealClimate (see “The Global Cooling Myth”). [Read more…] about Q & A: Global Warming

Global warming on Earth

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Translations: (Français) (English)

The Washington Post picked up on the latest update to the 2005 temperature anomaly analysis from NASA GISS. The 2005 Jan-Sep land data (which is adjusted for urban biases) is higher than the previously warmest year (0.76°C compared to the 1998 anomaly of 0.75°C for the same months, and a 0.71°C anomaly for the whole year) , while the land-ocean temperature index (which includes sea surface temperature data) is trailing slightly behind (0.58°C compared to 0.60°C Jan-Sep, 0.56°C for the whole of 1998). The GISS team (of which I am not a part) had predicted that it was likely the 2005 would exceed the 1998 record (when there was a very large El Niño at the beginning of that year) based on the long term trends in surface temperature and the estimated continuing large imbalance in the Earth’s radiation budget.

In 1998 the last three months of the year were relatively cool as the El Niño pattern had faded. For the 2005 global land-ocean index to exceed the annual 1998 record, the mean anomaly needs to stay above 0.51°C for the next three months. Since there was no El Niño this year, and the mean so far is significantly above that, this seems likely. [Read more…] about Global warming on Earth

Global warming on Mars?

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Translations: (Français) (English)

Guest contribution by Steinn Sigurdsson.

Recently, there have been some suggestions that “global warming” has been observed on Mars (e.g. here). These are based on observations of regional change around the South Polar Cap, but seem to have been extended into a “global” change, and used by some to infer an external common mechanism for global warming on Earth and Mars (e.g. here and here). But this is incorrect reasoning and based on faulty understanding of the data.

[Read more…] about Global warming on Mars?

Happy Birthday to Us

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Just recently, RealClimate topped 500,000 visits (and well over a million page views) since starting in December 2004. And by happy coincidence, a present arrives in the form of RealClimate being selected for the “Science & Technology Web Awards 2005” by Scientific American, with the citation:

A refreshing antidote to the political and economic slants that commonly color and distort news coverage of topics like the greenhouse effect, air quality, natural disasters and global warming, Real Climate is a focused, objective blog written by scientists for a brainy community that likes its climate commentary served hot. Always precise and timely, the site’s resident meteorologists, geoscientists and oceanographers sound off on all news climatalogical, from tropical glacial retreat to “doubts about the advent of spring.”

Saltier or not?

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Translations: (Français) (English)

In a recent (of Sept. 16, 2005) publication in Science, Hatun et al. find that record-high salinities have been observed over the past decade in the region where water from the Atlantic flows into the northern oceans. They combine an analysis of observations with simulations using an ocean model, concluding that the salinity of the inflow to the northern oceans is controlled by ocean dynamics and the circulation in the sub-polar gyre. The observations by Hatun et al. may suggest that at the moment the warm and salty waters from the south are especially warm and salty.

In another publication paper in Science from June 17th 2005, on the other hand, Curry & Mauritzen conclude that as a whole the northern North Atlantic has become significantly fresher (less salty) in recent decades. The latter study was based entirely on observations (hydrographic data between Labrador and Europe in the past 50 years). The recent evidence for salinification provided by Hatun et al. has been interpreted by some as being inconsistent with the evidence for high-latitude North Atlantic freshening found in previous reports. So what is really happening? Is the salinity increasing or decreasing? And can the two recent Science studies be consistent with each other?

[Read more…] about Saltier or not?

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?

Huracanes y calentamiento global ¿Hay conexión?

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Translations: (Français) (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 Huracanes y calentamiento global ¿Hay conexión?