Posted on 08/12/2005 5:14:24 PM PDT by neverdem
Reconciling temperature trends that are all over the place
Anyone still holding onto the idea that there is no global warming ought to hang it up. All data sets--satellite, surface, and balloon--have been pointing to rising global temperatures. In fact, they all have had upward pointing arrows for nearly a decade, but now all of the data sets are in closer agreement due to some adjustments being published in three new articles in Science today.
People who have doubted predictions of catastrophic global warming (and that includes me) have long cited the satellite data series derived by climatologists John Christy and Roy Spencer at the University of Alabama Huntsville (UAH). That data set showed a positive trend of 0.088 degrees centigrade per decade until recently. On a straight line extrapolation that trend implied warming of less than 1.0 degree centigrade by 2100.
A new article in Science by researchers Carl Mears and Frank Wentz from Remote Sensing Systems (RSS) identified a problem with how the satellites drifted over time, so that a slight but spurious cooling trend was introduced into the data. When this drift is taken into account, the temperature trend increases by an additional 0.035 degrees per decade, raising the UAH per-decade increase to 0.123 degrees centigrade. Christy points out that this adjustment is still within his and Spencer's +/- 0.5 margin of error. What's the upshot? Although reluctant to make straight-line extrapolations, Christy notes in an e-mail, "The previous linear extrapolation indicated a temperature of +0.9 C +/- 0.5 C in 2100, the new data indicate a temperature of +1.2 +/- 0.5 C."
However, the Remote Sensing Systems team has made some additional adjustments, such that their global trend is 0.193 degrees per decade. Christy and Spencer disagree with those additional RSS adjustments, but acknowledge that it's an open scientific question which team is correct. If RSS is right, a straight-line extrapolation of future temperature trends implies that global average temperatures in 2100 will be about 2.0 degrees centigrade (3.6 degrees Fahrenheit) warmer than they are today—more than double the original Christy and Spencer trend. The RSS trend is more in accord with the higher projections of future temperature increases generated by climate computer models.
Is there a way to tell which data set is more accurate? Long term weather balloon data provide an independent measure of temperature trends; however, they also have some problems. Another of the Science articles looks at daytime biases in the radiosonde balloon data sets. A team led by Yale University climate researcher Steven Sherwood, suggests that researchers overcorrected for temperature increases caused by daytime solar heating of the instruments, and thus projected a spurious cooling trend. The researchers acknowledge that there are also nighttime biases, but do not correct for those in this article, coming to the not very robust conclusion that "the uncertainty in the late 20th century radiosonde trends is large enough to accommodate the reported surface warming."
The UAH temperature data set differs from a set of six different recent analyses of weather balloon radiosonde data by range from a low of 0.002 degrees centigrade to a high of 0.023 degrees centigrade. All are well within the +/-0.5 degree margin of error for the adjusted UAH data and lower than the adjusted RSS temperature trend. In other words, the balloon data suggest the global temperature trends are closer to the UAH number than they are to the RSS number. In its article, the RSS team agrees, "Trends from temporally homogenized radiosonde data sets show less warming than our results and are in better agreement with the Christy et al. results."
But what about the future? As the U.S. National Oceanic and Atmospheric Administration notes, "taking into account uncertainty in climate model performance, the IPCC [UN Intergovernmental Panel on Climate Change] projects a global temperature increase of anywhere from 1.4 - 5.8°C" by 2100.
So what's the bottom line? The UAH team finds warming of 0.123 degrees per decade. The balloon data tend to support the UAH team's findings. The RSS team finds warming of 0.193 degrees per decade. And the surface measurements show a warming trend of 0.15 degrees per decade.
Christy notes, "If you want to say model trends are bolstered, you must remember model trends are all over the map. Which trend is bolstered? Perhaps you want to say those model trends less than 0.2 C per decade are bolstered." Right now the available data sets appear to strengthen the case for arguing that the lower-end model projections for future temperature increases are more likely ones. Christy concludes, "The new warming trend is still well below ideas of dramatic or catastrophic warming."
Ronald Bailey is Reason's science correspondent.
Climate Change, not just global warming.
Bitt, would you please post this as a regular article, F.D.A. Imposes Tougher Rules for Acne Drug? Thank you in advance. The admin mods might go crazy on me with 2 articles, even though they both involve government decisions.
If you have joined my health and science ping list in the last few months or so, make sure you check the link in comment# 31, "Global Warming on Mars?" FReepmail me if you want on or off my health and science ping list.
Tonk, do you have a ping list for veterans?
Increasing Carbon Dioxide and Global Climate Change and Unilateral and Right
From the latter:
That's why a new study, funded in part by NASA and announced in a Harvard University press release on Monday, is so important. The study concludes that, contrary to popular belief, "Many records reveal that the 20th century is likely not the warmest nor a uniquely extreme climatic period of the last millennium" [emphasis in the study]....
...Soon is quoted as saying: "Many true research advances in reconstructing ancient climates have occurred over the past two decades, so we felt it was time to pull together a large sample of recent studies from the last five to ten years and look for patterns of variability and change...
"In fact, clear patterns did emerge showing that regions worldwide experienced the highs of the Medieval Warm Period and lows of the Little Ice Age, and that 20th century temperatures are generally cooler than during the medieval warmth." ...
And my favorite quote from this...Needless to say, there were no SUVs 1,000 years ago.
NO climate model has ever been validated.
I didn't say a climate model was validated. I did refer to real-world events, i.e. more folks are complaining about glaciers shrinking than growing, a martian phenomena explained by solar warming and temperature data that it's getting warmer.
IMHO, from stories that I've read about solar radiation observed by satellites and sunspot activty seen on earth, the sun is the main culprit. This story just dealt with the observed warming trend. It said nothing about the utility of the proposed remedy from the left, i.e. limiting emissions of "greenhouse gases", especially carbon dioxide.
Climate Change, not just global warming.
You are saying that cold winter temperatures are a sign of global warming ( as well as something else you are calling climate change ). Is that correct?
Perhaps think of it this way...both the mean and the standard deviation are predicted to increase.
During past eras of global warming, were the winters extremely cold?
It was a joke. Anyway, it's hubris to think that a) we're the agents of climate change and b) we can really do anything constructive about it.
Thanks... good to see a judge with a little sense.
(And I thought I was up late...)
I agree with you, on that.
When you get around to answering that question, answer this one too:
If our next winter is warmer than average, will that be a sign that the Kyoto treaty is less necessary or more necessary?
It is not the same as PROVING that it is caused by CO2 emissions that are the result of human activity.
You already see them blaming the greenhouse gasses on methane from Siberian tundra. Man will be reduced to the trigger of the trigger in the greeny whacko's eye.
I also love how all the data shows that it hasn't been this warm in XX years. Which, of course, means that natural cycles have made it this warm before.
""Anyone still holding onto the idea that there is no global warming ought to hang it up. All data sets--satellite, surface, and balloon--have been pointing to rising global temperatures. ""
yes, but is it man made..seems awfullly narcisistic to think global wamring can only occur with the hand of man
read later bump
Maybe what the hairy armpit tree huggers really fear is that we'll all start walking around half naked and in togas again and then everyone will see how ugly they are!
My fraternity was a lot like Animal House
There was no discussion about why it's getting warmer in the article.
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