Global warming revisited

Here's what you had to say about global warming, and some more detail on the subject.

Several readers wrote in questioning the idea that humans are causing global warming. My thanks to everyone who shared their views. Global warming is one of the biggest challenges facing humanity, so it is absolutely vital for us to discuss the subject.

Here is what you said, and how I responded.

Many scientists reject global warming. It is wrong to stifle this debate. We should not accept global warming on blind faith.

The idea that global warming is under debate is simply incorrect. No scientific body of national or international standing rejects this idea—not one! (See Wikipedia and the update below.) I welcome scientific debate on climate change, but we should not pretend that there is a debate when none exists.

I recognize that individual scientists question global warming, but scientific debate requires more than an opposing opinion. For in idea to have scientific value, it must be backed by data and methodologies that can pass a peer review. To date, not one criticism of global warming has passed this test. For example, a study of 928 peer-reviewed papers found exactly zero papers disagreeing with the consensus on global warming. (See the Oreskes study.) Thus, I find it very difficult to see how one could characterize the global warming as "under debate."

In short, I do not think engineers should accept global warming blindly. However, we should acknowledge that scientists have reached a consensus on this issue.

Scientific consensus does not equal proof. Scientific ideas have been proven wrong in the past.

This argument is completely pointless. Any scientific idea might be disproven in the future. Even the law of gravity might be proven wrong.* Without a time machine, we cannot tell which ideas will be rejected. It is absurd to selectively ignore one idea on the basis that it might be disproven in the future.

*This was a test to see if you were paying attention! Newton's law of gravity was already proven wrong. However, it is still in use because it is accurate enough in most cases. This demonstrates both (1) that any scientific idea can be proven wrong and (2) that scientific models do no need to be perfect in order to be useful.

Climate science models are untrustworthy. They are unable to explain past climate events.

Not true! Climate models have been used to reconstruct the climate of the last 100 years with a high degree of accuracy. The ability to reconstruct the past demonstrates that the models are trustworthy.

Current models have known shortcomings, but the models do not need to be perfect in order to be useful. Short-term weather forecasts are also imperfect, yet we rely on them on a regular basis. Nobody expects clear skies when the forecast calls for rain, for example. Why anyone takes a different attitude towards global warming is beyond me.

Several readers claimed that climate science cannot explain the Little Ice Age or the following warming. This is not true—both events are well understood. The Little Ice Age and the following warming were caused by variations in solar and volcanic activity. Solar and volcanic activity will vary in the future, but such short-term variations will not change the long-term warming trends caused by greenhouse gasses.

Efforts to curb global warming might have unintended consequences. We should wait to act until we know more about the mechanisms of global warming.

I appreciate the desire not to leap into ill-advised action. However, most actions we could take to curtail global warming carry economic and health benefits. As one example, replacing incandescent bulbs with compact florescent bulbs saves money over the lifetime of the bulbs. As another example, cutting automobile emissions reduces incidences of asthma, cancer, etc. Thus, there is very little downside to acting now.

In contrast, there is a huge downside to waiting for perfect information. Scientists warn that we are nearing a tipping point where a lack of action will lead to devastating and irreversible consequences. With so much at stake, it does not make sense to wait.

Global warming is a money-making scam. Critics of global warming cannot get funding.

This is a bizarre claim. The science of global warming is open for all to see. It is published at the IPCC site as well as in any number of science journals, university web sites, etc. How could anyone pull off a con job when all of the data is out in the open?

This idea is even more preposterous when you consider the size of the industries involved. The industries that could benefit from global warming (such as solar panel manufacturers) tend to be small. The industries that might be hurt (such as oil companies and car manufacturers) are huge. If scientist were selling out to the highest bidder, one would expect them to oppose global warming, not support it.

Finally, the idea that warming deniers cannot get funding is laughable. Until recently, for example, Exxon funded warming skeptics.

Global warming is a leftist conspiracy. Critics of global warming are being silenced by political pressure.

This idea is ridiculous. Republicans controlled the US presidency, Congress, and Senate, for most of the last eight years. Despite this, the US government's acceptance of global warming has increased. How then is it possible that global warming is a left-wing conspiracy?

Furthermore, global warming is a concern to people across the political spectrum. I can easily name major Republicans who accept global warming. This list includes President Bush, Senator John McCain, and Governor Arnold Schwarzenegger. Even evangelical pastors are working to halt warming.

Update:
Several readers pointed me to articles claiming that the American Physical Society (APS) no longer accepts global warming. These articles are wrong. The APS home page makes the following statement:

The American Physical Society reaffirms the following position on climate change, adopted by its governing body, the APS Council, on November 18, 2007:

"Emissions of greenhouse gases from human activities are changing the atmosphere in ways that affect the Earth's climate."

An article at odds with this statement recently appeared in an online newsletter of the APS Forum on Physics and Society, one of 39 units of APS. The header of this newsletter carries the statement that "Opinions expressed are those of the authors alone and do not necessarily reflect the views of the APS or of the Forum." This newsletter is not a journal of the APS and it is not peer reviewed.