It was a little disturbing
to read in last Sunday's St
Louis Post-Dispatch that "environmentalists" are proposing
to shoot pollutants up into the stratosphere to reduce the amount of sunlight
in the hopes of correcting the "average temperature of the planet" to some
arbitrary "optimal value" of almost 100 years ago--to reverse the effects
of the industrial revolution.
Al Gore has become a standard bearer for hyperbole on "global warming" that appears based on a belief that there is a "scientific concensus" with "90% certainty" that the earth is warming, that it is due to human meddling with the environment, primarily through evil industrialist generation of the "pollutant" carbon dioxide, and that this is a bad thing. Some of the "solutions" are horrifying, but mostly consist of blaming human prosperity, making it more difficult for humans to survive and providing more research funds for the people who came up with this idea in the first place.
The recent iteration of the Intergovernmental Panel on Climate Change (IPCC) has been trumpeted to "remove all doubt" that accelerated global warming is due to anthropogenic greenhouse gas (AGHG) emissions, primarily carbon dioxide, and that if severe measures are not taken to reverse the "pollution" of AGHG, then the Earth will warm, flood, and storm and it will soon be too late to fix the problem. Newspaper reports (e.g. New York Times) said all this is now established to be "90% certain."
The terminology, "90% certainty," is not something I'd encountered before in my 45-year scientific and statistical careers, and gives me some disquiet. Most scientists recognize that "90% confidence" means there is a 10% probability that the particular results reported occurred by chance, and inferences about the nature of the universe may easily be in error. "90% confidence" is not very convincing to the statistician. An inclination to overinterpretation is exacerbated because negative results are less likely to be published-- this is called the "publication bias." More publications supporting the importance of the work means more grant money and more prestige. Enthusiasm is good and leads to breakthroughs. The overinterpretation is not caused by some scientists being deliberately deceptive, but scientists, too, must beware of enthusiasm overwhelming objectivity.
I have put an annotated
copy of the UN Summary report at the website, politicallycorrecteconomics.com
Maybe I'm reading this wrong, but it seems even the highest level of those who may be prejudiced by their personal stake in the global warming industry are unable to come up with a high level of confidence in the anthropogenic GHG, global warming, extremes of weather or massive innundation of land areas story. It is remarkable that one could conclude with any level of confidence that sea level has risen by almost 7 inches in the last 100 years. Not being an expert in the field, I can only marvel at what technological capability makes such a minute measurement possible in the midst of all the variability and changes in measurement techniques. Likewise, the estimate that the "global average temperature" has risen by almost 1 degree C in that same time. It is believed that these parameters were relatively constant over many millennia in the past, resulting in the "Hockey Stick" appraisal that everything has suddenly been subjected to a major disruption that is in some way highly correlated with atmospheric carbon dioxide. The "Hockey Stick" dramatization depends on the assertion that all has been quiet for several millennia until the industrial revolution came along to disrupt the placidity of Nature. Yet, even the authors of the UN Report must admit "proxy data (e.g., tree ring width) may be influenced by both local temperature and other factors such as precipitation, and are often representative of particular seasons rather than full years....Uncertainties generally increase into the past due to increasingly limited spatial coverage."
Some of the data behind these charts are on the web, for example at http://data.giss.nasa.gov/gistemp/2004/ . Some of this is a little less disturbing if it's plotted on a larger scale than hundredths of degrees, or for different time periods. I guess that's why it's always shown as anomalies in hundredths of a degree. Some mightóand didówarn of "an approaching ice age" from the apparent declining trend from 1940 through 1980. As a matter of fact, it was pretty much the same folks.
Some important aspects of the Report are in the small print. We learn for example, that "high confidence" means 80% confidence, and that " more likely than not" means about 50-50, hardly "beyond a shadow of a doubt" that should be the criterion when we are considering drastic corrective measures that are likely to increase famines and other hardships in much of the world. The document is replete with appropriate admissions that there are a lot of uncertainties to be resolved, not the least of which is that carbon dioxide is a relatively minor component compared to water vapor, and "cloud feedbacks remain the largest source of uncertainty."
We will have Christmas every day!
Guess what YOU are getting for Christmas!
In summary, one could question whether we should be stampeded into drastic measures to "correct" atmospheric carbon dioxide concentrations to some arbitrary level based on possible publication bias and perverse optimism of a few people who may be overly enthusiastic in interpreting data of questionable significance, statistical or otherwise.
Very large problems may be caused by solutions, particularly, by political solutions to problems of uncertain etiology or significance.
Failure to provide adequate evidence doesn't mean that "Global Warming" theory is disproven--and catastrophic weather events will still happen even if there is no evident connection to "Global Warming." It would be nice if we could have more control over the weather.
I certainly don't feel comfortable about shooting pollution into the atmosphere to reduce the warmth of the sun, and one could also question the efficacy of buying trees for "carbon offsets" from Al Gore's company, General Investment Management.
Possibly the popular press assertion of "90% certainty" might be related to a footnote on page 2 that mentions the previous report (TAR) had used confidence intervals of 95% (2-sigma limits) around reported values, but confidence intervals were reduced to 90% for the current report--with the effect that estimates appear more precise.
R.J. Banis, PhD
St Louis Missouri
March 30, 2007
|Statistics in the news:
Interesting links on controversial statistics issues in the news:
Global warmingThis is a fascinating and hotly argued issue that provides some stimulating examples of poor statistical reasoning.
The base issue appears to be relationship between atmospheric CO2 concentrations and climate change. Correlation is not causality, and a look at the data allows strong questioning of the supposed "causal relationship" of CO2 to climate change.
The petition project and Environmental Effects of Increased Atmospheric Carbon Dioxide
Response to skeptics
by advocates of AGHG models--this site purports to refute the skeptics,
but much of the refutation appears to be name-calling and the discussions
reinforce skepticism if you look at the data--see, for example, the discussion
about correlation and causality for CO2 and temperature change:
is no proof that CO2 is causing global warming"
If you want to read more about this, just google united nations carbon