A response to climate change denialism.
This is actually an assignment for a class UC San Diego offers entitled “Life and Climate on Earth.” It is one of many taught at the university by professors from the Scripps Institute of Oceanography. I enjoyed the class (and assignment) despite some misgivings but wanted to share this information with the planet.
Climate change is something I am quite interested in and the class afforded the opportunity to really dig in and further understand some of the science behind what we know and how we know it. Indeed, many of the business ventures I am formulating in my head revolve around how to harness the power of free markets to solve the problem presented by the great carbon menace. But alas, many things must be done in the short-term and for that we require governmental action and governmental action requires public support. While I think the interesting questions around climate change involve the cost of it (frankly, the only useful argument against it), in order for there to be public support, we require people to understand the issue and for denialists to be brought home.
Make no mistake - if you deny climate change, you are arguably putting the lives of future generations in danger. When approximately 80% of the world’s population lives within 60 miles of an ocean, not solving this problem requires very real effort and very real agreement. Let’s talk about some of the statements made below.
I also made some of my own graphs which look pretty damn spiffy.
Danielle Pletka (conservative commentator) – “We need to…recognize we just had two of the coldest years, biggest drop in global temperatures that we have had since the 1980’s, the biggest in the last 100 years.” – on NBC’s Meet the Press
This required some digging to see just what on earth she was referencing. Turns out, it was an article from the site Real Clear Markets. How Ms. Pletka described it is categorically false and then misleading (but not necessarily untrue) in that order. The first point, two of the coldest years (she is speaking of 2016 and 2017), is categorically false. Here is the temperature data from 1980 (downloadable from NASA’s climate website). The blue line represents the mean, the orange is smoothing the trend. Vertical axis is difference from pre-industrial levels in degrees Celsius.
Ms. Pletka’s second claim, probably what she was really meaning to call out, is an example of data distortion – taking a short-term trend and using it as definitive example of long-term data. She is (correctly) referring to difference in temperature from February 2016 to February 2018, when global temperatures dropped by .56o C. (according to the RCM article – the data I downloaded from NASA GISS says .51o C). This is an interesting use of data as it cherry-picks a two-year period. Useful if you want to nab a statistically loud year like 2016 (due to an el nino event) and use it to make a trend argument.
Here is what that data might look like when taking temperatures in February. The axes are the same as the previous graph with the vertical being difference from pre-industrial levels. The critical difference is trend data are February-to-February and the actual temps are means calculated in February of that year. She is referring to the double-black-diamond ski slope we see in blue lines:
Of course, this is entirely out of context from actual temperature measurements that show the long-term warming trend since 1882:
Hence, Ms. Pletka’s claim is an example of misrepresenting data out of context.
Donald Trump (President) – “As to whether or not it’s man-made and whether or not the effects that you’re talking about are there, I don’t see it.” – interview with Washington Post
In this case, there’s no way to prove whether he understands and therefore “sees” the evidence. Luckily, however, we do not require the president’s eyes to test whether or not it is a) (hu)man-made and b) the effects are there. The first line of evidence being that it most certainly has changed drastically during human use of fossil fuels (and not as dramatically before):
The other piece is quite possibly too technical for Mr. Trump, but it has to do with how our climate models struggle to recreate the observational data – unless we account for the additional CO2 used since the industrial revolution. Then it works a treat!
Hence, we know that it is both human-caused (from measurements of atmosphere carbon dioxide), and that warming requires the input of both human and natural forces to correctly model our present climate.
Joni Ernst (Republican Senator) – “Our climate always changes and we see those ebb and flows through time.” – on CNN
Yes, Joni. Yes, we do. But we understand those. This is a non-sequitur fallacy (the conclusion doesn’t necessarily follow the premises). In this case, just because it can change naturally does not mean that it must change naturally. Besides – we know how it has changed naturally.
The ebbs and flows through time involve forcing from many factors including the sun, earth’s orbital dynamics (Milankovitch cycles), volcanic activity, carbon dioxide, reflectivity (albedo), and particulates in the air, among other things. However, according to a paper published in Nature in 2012, the various forcing factors above tend to cause local warming that in turn causes a rise in CO2, with temperature lagging behind. Which supports “the conclusion that an antiphased hemispheric temperature response to ocean circulation changes superimposed on globally in-phase warming driven by increasing CO2 concentrations is an explanation for much of the temperature change at the end of the most recent ice age.” (Shakun, et al., 5 April 2012)
Further, when we look at data from a paper published in 2005, we have the following:
(Source: Hansen, et al., 3 June 2005)
What we are seeing is negative climate forcings from volcanic eruptions and overwhelming positive forcings by greenhouse gases. To answer the senator’s claim – we do see ebbs and they are related to carbon dioxide in the air far more than other forcings – which themselves actually only affect how much carbon dioxide is in the air.
This is obviously not a robust enough response to the entirety of climate change denialist positions, but it’s certainly a primer for some of the more popular arguments made in recent times. For more information on fascinating studies of things like Milankovitch cycles, volcanic emissions, and how much heat the ocean has been storing for us, visit this badass website: