This is not a climate science blog, nor is it a political or media critique blog. But it does cover physics, so I'd like to get some physics facts straight.
On the August 6 edition of Fox and Friends Saturday, the hosts interviewed Joe Bastardi—whom they introduced as “chief meteorologist at WeatherBell”—on global warming.
Before introducing Bastardi the hosts said that the global warming debate was heating up “after a new NASA study seems to debunk whether it’s actually manmade.” No further details were provided. Instead, as evidence the hosts provided the results of a poll. But presumably the Fox presenters were referring to a study that has created a lot of controversy and media hype.
The most jarring part however came later, when Bastardi commented that he didn’t believe CO2 emissions could ever affect the climate. Unfortunately, Bastardi’s argument was based on what seemed to be poor understanding of basic physics, including thermodynamics and atmospheric physics.
“If you look at carbon dioxide, it increases by 1.5 parts per million a year,” Bastardi said. “We contribute 3 percent of that.”
According to the International Energy Agency, global CO2 emissions have reached a record of 30.6 billion tons during the year 2010.
Many natural sinks and sources also contribute to the global carbon cycle. The oceans absorb more CO2 than they release, and so do vegetation and the soil, while natural sources such as volcanoes contribute smaller amounts. In other words, natural sources and sinks, if anything, would reduce the amount of CO2 in the atmosphere. Therefore, if there is any increase in CO2 concentrations, it is entirely due to emissions caused by humans.
To make matters worse, Bastardi claimed that the idea of manmade global warming is incompatible with the laws of physics.
“[Saying that CO2 could affect the climate] contradicts what we call the first law of thermodynamics: energy can never be created nor destroyed,” Bastardi said. “So, to look for an input of energy into the atmosphere you have to come from a foreign source.” His prepared remarks were accompanied by screens that seemed to display an intent from the TV show to be pedagogical.
The first law of thermodynamics does indeed guarantee conservation of energy. And the CO2 injected into the atmosphere does not carry energy with it—or rather, it does, because matter always carries energy, but not in a way that would raise temperatures significantly, if at all. But no one has ever claimed that CO2 would raise temperature by itself. Putting it this way is a grotesque distortion of what climatologists say.
What climate science says is not that CO2 carries energy into the atmosphere or somehow magically generates it out of nowhere. Instead, it says that CO2 and other gases acts as a blanket, keeping heat from escaping into space. This, as Bastardi should know, is called the greenhouse effect.
The Earth radiates into space roughly the same amount of energy that it receives from the sun. But much of what it radiates is in the infrared spectrum, whereas most of the sun’s energy reaches us in the visible spectrum.
The greenhouse effect results from the fact that CO2 (and other greenhouse gases, chiefly water vapor) is more opaque to infrared radiation than it is to visible light. So it lets the sun's rays in, but it won't allow the Earth to cool down too much.
Bastardi proceeded to say that what global warming there is "is already out there, carbon dioxide being a part of it," a statement that seems devoid of any meaning, and that "you can trace it to the sunspot cycles and you can trace it to the movement of the oceans."
But if global warming was caused by sunspots, why would it be happening now, when the sun
is has been in an unusually long period of low activity?
According to Washington Post blog Capital Weather Gang, WeatherBell, the company that employs Bastardi, is "funded entirely by angel investors."
[Note added August 12: I recommend reading John Rennie's "Seven Answers to Climate Contrarian Nonsense"; I will not respond to comments that are already addressed therein.]
David Biello contributed some reporting for this story; many thanks to Robin Lloyd for pointing me to the Media Matters story.