We’re swamped with information about anticipated levels of carbon dioxide in the atmosphere. But the indicators vary wildly. A new study compared the historic numbers of 22 trendsetting organizations to actual findings and found out where data fouls up.
The researchers compared the composite output of 22 leading global climate models with actual data. Many of these models are also incorporated in research by the UN Intergovernmental Panel of Climate Change (IPCC), the recent Nobel laureate.
Turns out that the historic predictions of these models do not match current climate change by far. The problem lies in the measurement of key portions of the atmosphere, the researchers say. They devised a better method which they claim will be more reliable for future predictions because datasets that have been faulty have been pinpointed at long last.
The research published in the Royal Meteorological Society’s International Journal of Climatology, arrives amid already adverse circumstances and raised new concerns about the reliability of models used to forecast global warming.
So how bad is it? After all, if we know how ‘off’ historic forecasts have been compared to this present moment, we might get an impression of how serious to take the plethora of studies predicting the scenario for the next 100 years.
The answer is "rather bad’. But the irony of the story is that this refers to the studies’ reliability, not to the climate. The good news from the climate front is; there possibly reason for less pessimism, but we really have no guarantees.
The Royal Society says it has devised a better scientific method for studying global warming. “The usual discussion is whether the climate model forecasts of Earth’s climate 100 years or so into the future are realistic,” said the lead author, Dr. David H. Douglass from the University of Rochester. “Here we have something more fundamental: Can the models accurately explain the climate from the recent past?
“It seems that the answer is no.”
The scientists compared the climate change “forecasts” from the 22 most widely-cited global circulation models with tropical temperature data collected by surface, satellite and balloon sensors. The models predicted that the lower atmosphere was going to warm significantly more than it actually did.
Models are very consistent in forecasting a significant difference between climate trends at the surface and in the troposphere, the layer of atmosphere between the surface and the stratosphere, according to Dr. John Christy, director of UAH’s Earth System Science Center.
“[But] when we look at actual climate data, we do not see accelerated warming in the [particularly tropics-based] troposphere. Instead, the lower and middle atmosphere are warming the same or less than the surface. The warming trend we see in the tropics is typically less than half of [the forecasts],” he points out.
The scientists relied on data collected by sensors aboard NOAA satellites since late 1979, plus data from the tropics by thermometers carried into the atmosphere by helium balloons.
They claim that there was a high degree of ‘agreement between the various atmospheric data sets’ stretching out over long time frames.
“The last 25 years constitute a period of more complete and accurate observations, and more realistic modeling efforts,” said Dr. Fred Singer from the University of Virginia. He points out that the models of the 22 institutions deviate from the findings. "We suggest, therefore, that projections of future climate based on these models should be viewed with much caution,” he said.
However, the findings of the study itself contrast very strongly with those of a recent study that used 19 of the same climate models’ datasets. The scientists take this in their stride and arguably so, because the scientists involved in devising the explanations for the differences between reality on the ground (eh, atmosphere) and the predictions resorted to blaming it on errors in the data too.
It is imperative that scientists find what the aggegate models forecast for the upper air climate change over the past 25 years has been, and how the numbers have compared to reality. It is quite amazing that this is being studied only now, but hey ho, let’s be happy it is actually taking place. The fact that people are beginning to duplicate is also a very healthy sign. Peer reviews in meta environmental research are a luxury still.
The Royal Society scientists focused on those climate model results that matched the actual surface temperature changes during that same time to find out if there was reason to believe that models inaccuracies were due to a specific area. "If the models got the surface trend right but the tropospheric trend wrong, then we could pinpoint a potential problem in the models."
Turns out that the models were right on surface temperatures in the tropics. "That meant we could do a very robust [ie reliable] test of their reproduction of the lower atmosphere", says Christy.
The other study is way less reliable, because it did not get to do this precise verfication. “Instead of averaging the model forecasts to get a result whose surface trends match reality, the [other] study looked at the widely scattered range of results from all of the model runs combined. Many of the models had surface trends that were quite different from the actual trend,” Christy said.
Christy believes his experiment is more robust and provides more meaningful results. He failed to say just how bad the damage really is. But guess what, I will go with his predictions in future, whatever they turn out to be.
Curious what the alternative study’s conclusions were? Its authors simply said that since both the surface and upper atmosphere trends were somewhere in a (very) broad range of model results, any disagreement between the climate data and the models was likely been ‘due to faulty data’.
The weaknesses in scientific data are worrying for different reasons too. Politicians can take advantage of it. This became very obvious in the US in the past week, where a draft report by a congressional committee showed that the Bush administration had been ‘editing’ scientific researchers’ findings. The changes were made so that scientists were made to sound as if there’s no link between global warming and natural disasters and other adverse changes in the climate that are strongly believed to be connected.
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