Rep. Michele Bachmann (R-MN) announced last week that she will not run for reelection in 2014.  Her departure is good news for anyone who believes policymakers should embrace science.  Consider the comments Bachmann made about climate change on the House floor in 2009:

“We’re told the crux of this problem is human activity. It’s human actions that are creating more carbon dioxide. Is that true or false? Well, carbon dioxide is a natural part of the Earth’s atmosphere. But carbon dioxide is perhaps 3 percent of the total atmosphere that’s in the Earth. So if you take a pie chart and all of Earth’s atmosphere, carbon dioxide is perhaps 3 percent of that total.

“What part of human activity creates carbon dioxide? If carbon dioxide is a negligible gas and it’s only 3 percent of Earth’s atmosphere, what part is human activity? Human activity contributes perhaps 3 percent of the 3 percent. In other words, human activity is maybe 3 percent contributing to the 3 percent of carbon dioxide that’s in Earth’s atmosphere. It’s so negligible; it’s a fraction of a fraction of a percent. It can hardly be quantified.”

(See the April 21, 2009 Congressional Record – House, p. H4561 for Rep. Bachmann’s full remarks.)

Bachmann, founder of the House of Representative’s Tea Party Caucus, has drawn plenty of ridicule for these and similar comments.  But instead of making fun of her further here, let’s consider why it is evident that Bachmann either made little effort to understand climate science or was being deliberately misleading when she spoke on the House floor.

With her jumbled syntax, Bachmann wrapped together three bogus arguments in her attempt to deny the fact that human activity is causing climate change.  First, she suggests that because carbon dioxide already exists in the atmosphere, the addition of more carbon dioxide must not be problematic.  No one disputes that carbon dioxide exists in nature without human interference.  In fact, without carbon dioxide and other naturally occurring greenhouse gases in our atmosphere, our planet’s average surface temperature would be about 0°C (32°F) instead of about 15°C (59°F) according to climate models.  (Cronin, Thomas M.; Paleoclimates, 2010)  That’s because short wave radiation arriving from the sun is emitted back toward space as long wave radiation.  Greenhouse gases absorb this radiation and warm our atmosphere.  But the argument that because a substance exists in nature adding more of it does not cause harm is without merit.  Water is often harmless but a flood can do severe damage.  Radon is a naturally occurring substance but overexposure causes lung cancer.

Second, Bachmann implies that because carbon dioxide makes up only a small portion of the atmosphere, it cannot have a large impact.  Ironically, while making this argument Bachmann vastly overstates the amount of carbon dioxide in the atmosphere.  Hopefully she now knows that is far less than 3%.  Early in May, measurements showed that carbon dioxide levels have hit 400 parts per million by volume (ppm), an unwelcome milestone to those who are concerned about our planet.  400 ppm equates to 0.04% of our air.  Earth’s climate is a complex system and no one knows exactly what amount of carbon dioxide in the atmosphere can be tolerated without throwing our climate out of whack but many promote 350 ppm as the right target.  (Carbon dioxide levels of 3% (that’s 30,000 ppm), where Bachmann put them, may have existed during the Precambrian Era. (Cronin))

In any case, a good cook knows that too much salt – though still a tiny percentage of the overall ingredients – can ruin an otherwise great dish. Bachmann, however, appears oblivious to the idea that seemingly small amounts of something can have a significant impact.  She might give ozone some attention.  Tiny amounts of ozone can do serious harm to humans when near ground level.  The EPA’s National Ambient Air Quality Standards include ozone as one of the six criteria pollutants and sets the threshold at 0.075 ppm.  That’s 0.0000075%, Rep. Bachman.  The Centers for Disease Control and Prevention’s guidelines provide that air consisting of just 5 ppm (0.0005%) of ozone is immediately dangerous to life or health.

While a tiny amount of ozone in the air we breathe can cause health problems, a tiny amount of the same substance in the upper atmosphere plays a critical role in protecting us from harmful solar radiation.  In the ozone layer in the stratosphere, where it is most abundant, ozone constitutes only about 1 to 10 ppm of the atmosphere.  (University Corporation for Atmospheric Research)  But that “fraction of a fraction of a percent” makes a big difference, protecting people (and other living creatures) from harmful ultraviolet light.

Even Ronald Reagan caught on.  Signing the Montreal Protocol on Ozone Depleting Substances that phased out chemicals that destroy ozone in the ozone layer, Reagan called it “the result of an extraordinary process of scientific study” and “a monumental achievement.”  (See his statement.)  Perhaps after she leaves office Rep. Bachmann will find some time to read up on Ronald Reagan.

Finally, Bachmann states that human activity has only increased the amount of carbon dioxide in the air by 3%.  In fact, pre-industrial levels of carbon dioxide were about 280 ppm.  The additional 120 ppm caused by human activity represents about 30% of the carbon dioxide in the atmosphere today.  (Carbon dioxide levels are rising about 2 ppm per year due to continuing fossil fuel emissions.)

Politicians on both sides of the aisle sometimes play fast and loose with the facts.  In some cases the errors are honest mistakes or tolerable attempts to simplify a complicated message.  But Bachmann combines a blatant disregard for the facts with baseless assertions about scientific theory.  She is either confused about climate change (in which case making a speech on the House floor is reckless) or, worse, she is deliberately distorting science in order to mislead the public.  Her departure from the House of Representatives is a win for science.