The November 17th issue of Science has an interesting exchange of letters between Christy and Spencer; Mears and Wentz; and Sherwood and Lanzante (ref here; subs required for substance). The context of this discussion is the tropospheric temperature record; see Et tu LT and The tropical lapse rate quandary for two RC posts that discuss the issue, and in particular three papers in the August 11th issue of Science.
By James Annan and William Connolley
In this post, we will try to explain a little about chaos theory, and its relevance to our attempts to understand and forecast the climate system. The chaotic nature of atmospheric solutions of the Navier-Stokes equations for fluid flow has great impact on weather forecasting (which we discuss first), but the evidence suggests that it has much less importance for climate prediction.
Vote for RealClimate!
No, we’re not going to abandon our policy of steering clear of political commentary, but yes, you can nonetheless vote for us!
Some of you may have noticed the new logos up in the upper right hand corner of the RC webpage. As a followup to our selection last month for the “Science & Technology Web Awards 2005” by Scientific American, we are pleased to have now made it to the final round of Deutsche Welle’s 2005 Weblog Awards (for those of you not familiar with them, Deutsche Welle is sort of the German equivalent of Britain’s BBC World Service). [Read more…] about Shameless Self Promotion
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
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.
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.”
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?
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!
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?
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.
[Read more…] about Did the Sun hit record highs over the last few decades?