We can scarcely pick up a newspaper without reading about “global warming” or “climate change” and how it affects us. Often the dire warnings are followed by a list of “solutions to the climate problem”—things we must do to minimize climate change. These solutions would require immense costs and dramatic changes to areas that affect our everyday lives, including transportation, energy, and agriculture.
Since it is widely known that climate varies naturally and has done so over thousands of years, the current controversy focuses on the effects of recent human activities. We call this “anthropogenic global warming” (AGW). While this is primarily a scientific issue, the addition of politics and economics has created an explosive mixture.
First, a Glance at the Science
Climate science is extremely complex because climate change involves every aspect of the “geophysical system” on or around the earth, as well as the sun, moon, and other outside agents. To understand climate change, we must recognize four basic earth systems:
- Atmosphere—especially the troposphere, where weather happens
- Hydrosphere—oceans, lakes, rivers, and so on
- Biosphere—plants and animals
- Cryosphere—frozen ground, especially in high elevations and high latitudes.
Changes in Any of These Can Influence Climate
Much of the controversy involves the atmosphere’s “greenhouse effect,” which traps heat on the earth. As explained in “Global Warming’s Solar Connection,” pp. 53–55, the greenhouse effect is a good thing, and the most important greenhouse gas is water vapor, which is almost entirely of natural origin. The next most important gases are carbon dioxide and methane. Both are largely natural, but certain human activities can increase their concentrations. For example, driving vehicles releases carbon dioxide, and manure on farms can release methane.
And this is where “anthropogenic global warming” comes in. All else being equal, if the amount of greenhouse gases changes, climate will change. The questions we need to ask are “by how much?” and “how do we measure this?” We can look to careful scientific observations to give us clues, as well as climate simulation models.
Observations of Climate Changes over the Past 1,000 Years—Reliable climate observations go back several hundred years. Earlier estimates of temperature, precipitation, and other parameters are made using “proxy” data—geophysical and biological indicators that “imply” climate. Examples of these include tree rings, lake sediments, and ice cores. The assumptions appear reasonable and indicate an interesting pattern over the last thousand years (see figure in “Global Warming’s Solar Connection”).
From about A.D. 1000 to 1400 temperatures were comparable to what they are today, but they dipped during a period known as the “Little Ice Age,” marked by crop failures and significant storms. After rising slowly, temperatures dropped again from about 1940 until the mid-1970s. In the last 10 years, temperatures have gone down slightly.
If carbon dioxide were primarily responsible for temperature change, as some people suggest, we would expect a steady rise in temperatures over the last 70 years. Instead, we see two periods of declining temperatures bracketing a brief period of rise.
Unreliability of Existing Climate Models—Climate models are simulations of the atmosphere, mathematical constructs intended to simulate the fundamental processes and estimate the effects of changes. These are similar to the models used to predict short-term weather changes. But models are good only if they can be validated by observations.
In its first and most significant global warming report, the U.S. Climate Change Science Program (CCSP) looked at the most current models and claimed that there is “clear evidence” for AGW (anthropogenic global warming).
Yet the Science and Environmental Policy Project (www.sepp.org), a watchdog group founded by atmospheric physicist S. Fred Singer, took a closer look at the details and reached a far different conclusion:
“The report shows a clear disagreement between models and observations in the tropical region, which is the most sensitive for model validation. . . . A more careful and more detailed examination of this [AGW] issue reveals that the disparity between observations and models is real and significant; it suggests that a major part of current warming is due to natural causes and that the human component due to greenhouse gases is only minor. It also suggests that the computer models cannot be considered as having been validated by observations.”
How can climate scientists look at the same data and reach opposite conclusions? Clearly more is involved than “pure science.” Scientists on both sides recognize that the ramifications will affect every one of us.
The key controversy seems to be “Do human activities significantly affect climate?”
The key controversy seems to be “do human activities significantly affect climate?” If so, changing those activities (for example, reducing our output of greenhouse gases) would have a measurable effect on climate. On the other hand, if human impacts are insignificant, controlling human emissions will have a negligible effect.
Those in the former camp (significant human impacts) suggest sweeping changes in energy use, transportation, and other activities. Most of these would entail huge costs. Those of the “insignificant human impact” persuasion suggest that such changes would entail “all pain and no gain”—huge expense with little measurable effect.
The human role in global warming has gotten deeply immersed in politics. Since politics involves making decisions that govern other people’s lives, it’s critical to base these decisions on solid information.
One major problem exists: while climate science is filled with approximations and uncertainties due to the complexity of the climate system, politics typically requires simple “yes/no” answers. On the climate issue, many scientists are very polarized. Some believe that the human impact is significant and requires rapid and significant action to “control” it; others believe that the human impact is minor, and that humans can no more “control” climate than they can volcanoes.
While there is a moderate middle ground on this issue, the extreme positions have tended to dominate the conversations. Instead of acknowledging the uncertainties, politicians are tempted to claim certainty about climate change. Even if we understood the causes fully (and we don’t), scientists aren’t equipped to answer the next two important questions: (1) will changes in human activity change climate, and (2) what actions should governments take?
Science can help explain what is but not what should be. That is a moral question about right and wrong, good and bad, which is based on moral convictions. Such questions lie outside the scope of science.
One well-known politician leads the pack of those who make human-caused global warming their rallying cry: former U.S. Vice President Al Gore. He has spent the last 15 years sounding the alarm. His documentary film An Inconvenient Truth (2006) won an Academy Award, and in 2007 he was awarded the Nobel Peace Prize for his efforts.
Gore believes his cause is so important that “over-representation” of the facts is justified: “Nobody is interested in solutions if they don’t think there’s a problem. Given that starting point, I believe it is appropriate to have an over-representation of factual presentations on how dangerous it is, as a predicate for opening up the audience to listen to what the solutions are” (Grist interview, May 9, 2006).
Despite such rhetoric and call to action, the public appears to be growing less concerned about the seriousness of global warming (in part because temperatures have declined over the last decade and because the dissenting scientific view has achieved more widespread awareness). According to a Gallup poll of Americans in March 2010, for example, “48% of Americans now believe that the seriousness of global warming is generally exaggerated, up from 41% in 2009 and 31% in 1997, when Gallup first asked the question.”
New revelations about shoddy—and even deceptive—reports from leading scientists have thrown cold water on the debate.
When Politics and Science Mix—Climategate
In November 2009 thousands of private emails and other documents were made public that put climate-science politics in a bad light. The “Climategate” incident continues to reverberate, revealing what appear to be willful acts to suppress dissenting views, restrict publication of dissenting material, and otherwise control the discussion of AGW.
The documents embarrassed the Climatic Research Unit (CRU) of the University of East Anglia, which had been instrumental in analyzing global temperature changes and sounding the alarm about mankind’s role in global warming. An initial investigation by a committee of the House of Commons cited “a culture of withholding information—from those perceived by CRU to be hostile to global warming,” when the unit was asked to disclose information under the Freedom of Information Act.1
Climategate has called into question the activities of many scientists and organizations, including the Intergovernmental Panel on Climate Change (IPCC), the UN-based group that oversees international climate activities. In 2007 this group received the Nobel Peace Prize “for their efforts to build up and disseminate greater knowledge about manmade climate change, and to lay the foundations for the measures that are needed to counteract such change.” Perhaps that prize was undeserved.
But I haven’t told you my opinion. I have been involved in weather and climate for nearly forty years. I have studied climate change and have arrived at several conclusions:
a. Human activities affect climate in various ways. Greenhouse gases are just one parameter.
b. Natural variations affect climate. I believe that these variations have been more significant influences on climate because they do a much better job of explaining observed variations in climate.
c. Effects of future changes in carbon dioxide are likely to be modest.
d. Many aspects of climate remain poorly understood. We learn new things about climate all the time.
If the “facts” change, I reserve the right to change my mind. But talk of overhauling society is unwarranted. Such major decisions should not be left to scientists or politicians anyway. If this is a moral issue—and stewardship of the earth’s resources is a moral issue—then the appropriate response is to turn to the Creator and His Word for wisdom, including the careful fulfilling of our human responsibilities to God’s glory.