Fears over the alleged catastrophic effects due to man-made greenhouse gases continues to terrorize Californians.
Assembly Bill 1058, authored by Assemblywoman Fran Pavley (D-Woodland Hills), and signed by Gov. Gray Davis "instructs" the California Air Resources Board to come up with regulations that allow "maximum and cost-effective" cuts in greenhouse gas emissions from new cars and light trucks by the years 2006-2009.
But why the rush to action called for in AB 1058?
According to Assemblywoman Pavley, "Unless we act, California will experience heat waves, droughts, floods and forest fires that could devastate the economy of the state, including agriculture, fishing, timber, real estate, insurance, construction and tourism. ... Climate change is already beginning to impact California, the world's fifth largest economy."
Assemblywoman Pavley's extreme claims are deeply rooted in the "story-lines" fueled by computer climate models that purport to show a connection between human-induced greenhouse gas emissions - such as CO2 emitted from automobiles -- and rising temperatures on Earth. But as a scientist, I have been searching for evidence of global warming that can be attributed to rising man-made greenhouse gases like carbon dioxide for some ten years now. Thus far, I have found none.
Computer climate models say that the largest greenhouse gas heating is supposed to occur in air layers a few miles above the surface. But intensive monitoring by both satellites and weather balloons over the last 22 years have demonstrated no warming in this part of the atmosphere. Thus, the idea of using computer models to confirm the impact of man-made greenhouse gases on California is most likely a futile, if not confusing, effort.
Why is this so?
For starters, the Earth's climate is an enormously complex, dynamic phenomenon, and many climatic processes are still mysterious. For example, our knowledge of the way sunlight at different colors or wavelengths interacts with clouds is limited.
Right now somewhere on the order of 5 million different parameters have to be followed in a computer mock-up of the climate system. All their important interactions and impacts must be known. But they are not known.
Moreover, how long would it take to conduct a full climate mock-up, covering all the spatial scales and generating a 40-year forecast of climate change? It would take more than 10 to the power of 34 years of supercomputing! This is a septillion (10 to the power of 24) times longer than the current age of the universe (about 10 billion years). In other words, an incredibly long wait and a near-impossible task.
Yet, the main goal of serious climate research is to find out if any observed regional or global warming can be properly attributed to rising greenhouse gases. Has California been warming at an alarming rate as suggested by the rapid increase of man-made greenhouse gases? I propose a simple test to answer this question.
Temperature is among the most direct climatic variables from which one would expect to discern the effects of added greenhouse gases. So let us look at the state-wide averaged temperature record for California from 1900 to 2001. Consider these two important points: First, the year-to-year temperature fluctuations are very large -- about 2 to 4 degrees Fahrenheit. So claiming a 100-year warming trend in the California record will not be possible unless those larger year-to-year changes are properly understood. Second, over the full 100-year temperature record, no systematic warming trend is attributable to the increase in atmospheric carbon dioxide. And if one considers that 80% of the gradually accumulated carbon dioxide of the 20th century in air came only after 1950s, then one should expect a large warming in the post-1950 period. But nothing unusual can be seen in the record. Thus, it is clear that one cannot link temperature change in California to the increased emissions of greenhouse gases. Reason for concern over disastrous climatic impacts from greenhouse gases simply cannot be found in the real climate system.
Despite these facts, Assemblywoman Pavley continues to mislead California voters by saying that with AB 1058, "we can help avert a devastating worldwide calamity." This promise is simply untrue. No one really knows if reducing or adding carbon dioxide will actually impact the climate. Moreover, carbon dioxide reduction from California will be extremely small on a global scale. But efforts to reduce CO2 - in the form of taxes or smaller and thus less safe autos -- will prove extremely costly to the Golden State's drivers. That is a fact we know for sure.