[Editor’s note: This is the second article in a series by Walter Cunningham, pilot of the Apollo 7 space mission and holder of a master’s degree in physics. Cunningham has served on the Advisory Board for the National Renewable Energy Laboratory.]
Claims of a scientific consensus regarding the causes, extent, or consequences of climate change are simply false. While climate scientists may agree that the Earth’s temperature is always changing, there is tremendous disagreement and debate over whether humans are responsible for those changes. Climatology is a new science, and there is great uncertainty about fundamental scientific questions, preventing scientists from knowing for certain what is causing current climate trends and accurately predicting future climate conditions.
A U.S. Senate Environment and Public Works Committee report identifies 700 prominent scientists who have publicly repudiated the alarmist position on global warming expressed by Al Gore and James Hansen. Their ranks include experts in climatology, geology, oceanography, biology, glaciology, biogeography, meteorology, economics, chemistry, mathematics, environmental sciences, engineering, physics, and paleo-climatology.
The scientists have signed a letter pointing out climate change is a well-known natural phenomenon and when changes are gradual, man has an almost infinite ability to adapt and evolve.
More than 31,000 scientists in the United States have signed a petition saying “there is no convincing scientific evidence that human release of carbon dioxide, methane, or other greenhouse gases is causing or will, in the foreseeable future, cause catastrophic heating of the Earth’s atmosphere and disruption of the Earth’s climate.”
Debating Carbon Dioxide
The advocates of an anthropogenic global warming (AGW) crisis say the United States must impose a devastating tax scheme to force industry to emit less carbon dioxide, which will then reverse the warming trend, they say. This policy prescription is based on two assumptions: (1) that CO2 is the cause of changes in the Earth’s temperature, and (2) that a warmer Earth would be bad for the planet’s flora and fauna, including humans.
In reality, atmospheric CO2 has a minimal impact on greenhouse gases and world temperature. Water vapor is responsible for 95 percent of the greenhouse effect, while CO2 contributes just 3.6 percent. Since human activity is responsible for only 3.2 percent of the total CO2, we can influence only 0.12 percent of the total greenhouse gases. Some studies have found CO2 levels are largely irrelevant to global warming.
The true believers in AGW base their case on a broad and weak correlation between CO2 and global temperature in the last half of the twentieth century. However, they cannot be sure which is cause and which is effect. Looking at a longer period of history, it becomes clear that temperature increases have preceded high CO2 levels by anywhere from 100 to 800 years, suggesting higher temperatures cause CO2 levels to rise, rather than vice versa.
High CO2, Low Temps
There have been periods when atmospheric CO2 levels were as much as 16 times higher than they are now—periods characterized not by warming but by glaciations.
You might have to go back half a million years to match the earth’s current level of atmospheric CO2, but you have to go back only to the Medieval Warming Period, from the 10th to the 14th centuries, to find an intense global warming episode, which was followed immediately by the drastic cooling of the Little Ice Age. Neither of those events can be attributed to variations in CO2 levels.
With CO2 being a relatively minor constituent of “greenhouse gases,” and human activity contributing only a tiny portion of atmospheric CO2, why have alarmists made it the whipping boy for global warming? They know CO2 is a tiny player in the complex system we call “climate,” but they also know how fruitless it would be to propose controlling the real drivers of global temperature: greenhouse gases, water, methane, and nitrous oxide. So they wage war on CO2, no matter how ridiculous it makes them appear.
Walter Cunningham ([email protected]) maintains the waltercunningham.com Web site.