The notion that global warming represents a threat of impending doom is commonly portrayed as indisputable fact, one entirely beyond discussion.
We are told, as in Al Gore’s film “An Inconvenient Truth,” that the warming trend may kill countless numbers of people living in coastal regions as melting glaciers raise the sea level.
Extreme weather events, like Hurricane Katrina, are touted as examples of the catastrophic results of global warming.
This view is spread by representatives of environmental organizations on our campus, such as Tim Webber, canvasser for the national environmentalist organization Greenpeace.
“The weather is getting more severe. I normally talk about Hurricane Katrina as a classic example of this,” Webber told me.
This sensationalism, often coupled with a call for drastic action, ends up hurting the debate on global warming. Many of the commonly reported claims of this type are highly disputed or contradicted by the same widely accepted reports that are said to support the notion of global warming.
The 2007 study being released this Friday by the United Nations Intergovernmental Panel on Climate Change – considered the authority on global warming – does not predict a catastrophic rise in the sea level over the next century, but rather a rise between 5 and 23 inches.
In an interview for Essential Science Indicators, the aptly named Christopher Landsea of the National Oceanic and Atmospheric Administration’s Hurricane Research Division, there is no evidence that storms are becoming more volatile as a result of global warming.
Both of these revelations, made by key global warming scientists, contradict the picture of disaster painted by environmentalists and sympathetic journalists.
The greenhouse effect, where atmospheric gases trap the sun’s energy, is itself largely uncontroversial, as is the recent trend of increased temperatures (a rise of 1 degree in the last century, according to the IPCC report).
The source of the controversy is the extent to which humans are responsible for this climate change.
According to the IPCC, there is only evidence that the earth is warmer than at any other time in the last six centuries, which it touts as proof that humans are responsible for recent climate change.
But proponents of the view that humans have caused this change must show that recent temperature changes result from an increase in emissions and are a departure from any natural trend.
Given that the time frame for natural climate variations is in the hundreds of thousands of years, this evidence is entirely unpersuasive.
Graphs from a National Academy of Sciences report that depict temperature change in the latter time frame suggest that the recent temperature change and increase in the concentration of carbon dioxide is part of a long-run natural cycle. The same report calls for action on impending climate change.
There are other inconsistencies. One of the two major periods of temperature increase in the 20th century occurred between 1910 and 1945. This warming cannot be explained by greenhouse gases, which increased only slightly during the period.
The IPCC report explains this by noting that solar radiation “may have contributed in an important manner to the warming in the 20th century, particularly in the period from 1900 to 1950.”
So the global warming advocates explain roughly half of the 20th century’s 1-degree rise by factors other than global warming when the data doesn’t match their predictions. And since the period from 1940 through the 1970s was a period of global cooling, proponents are left with only the last three decades as evidence for the theory that global warming is man-made.
One would think that, say, snow in Los Angeles would be an argument against a warming trend.
The IPCC reports that there is no evidence that weather events are becoming more extreme. To the contrary, the study finds that over the past few decades, there has been a “decrease in spatial and temporal variability of temperatures.”
But global-warming alarmists have managed to convince us, contrary to the evidence, that whatever happens – warming or cooling – is evidence of the phenomenon’s far-reaching effects.
If we’re going to be taking costly steps in the name of curbing humanity’s contribution to global warming, we better be sure that the temperature change is a man-made departure from any natural cycles. There ought to be conclusive evidence that global warming’s effects are disastrous, or at least greatly undesirable.
And I’m not convinced.
If you’re afraid of change, e-mail Lazar at dlazar@media.ucla.edu for some reassuring words. Send general comments to viewpoint@media.ucla.edu.