Sheriff Arpaio Meets Al Gore

Not since the Reese's Peanut Butter Cups have there been two great populist tastes that go so great together.  In an amazing bit of fact-free scare mongering gauged to panic everyone across the political spectrum, Michael Oppenheimer (embarrassingly a professor at my alma mater) manages to combine demagoguing against Mexican immigration with climate alarmism

Climbing temperatures are expected to raise sea levels and increase droughts, floods, heat waves and wildfires.

Now, scientists are predicting another consequence of climate change: mass migration to the United States.

Between 1.4 million and 6.7 million Mexicans could migrate to the U.S. by 2080 as climate change reduces crop yields and agricultural production in Mexico, according to a study published online this week in the Proceedings of the National Academy of Sciences. The number could amount to 10% of the current population of Mexicans ages 15 to 65.

The proceedings of the NAS has become a joke of late.  Roger Pielke Jr responded:

To be blunt, the paper is guesswork piled on top of "what ifs" built on a foundation of tenuous assumptions. The authors seem to want to have things both ways -- they readily acknowledge the many and important limitations of their study, but then go on to assert that "it is nevertheless instructive to predict future migrant flows for Mexico using the estimates at hand to assess the possible magnitude of climate change"“related emigration." It can't be both -- if the paper has many important limitations, then this means that that it is not particularly instructive. With respect to predicting immigration in 2080 (!), admitting limitations is no serious flaw.

To use this paper as a prediction of anything would be a mistake. It is a tentative sensitivity study of the effects of one variable on another, where the relationship between the two is itself questionable but more importantly, dependent upon many other far more important factors. The authors admit this when they write, "It is important to note that our projections should be interpreted in a ceteris paribus manner, as many other factors besides climate could potentially influence migration from Mexico to the United States." but then right after they assert, "Our projections are informative,nevertheless, in quantifying the potential magnitude of impacts of climate change on out-migration." It is almost as if the paper is written to be misinterpreted

I thought this response was instructive

Philip Martin, an expert in agricultural economics at UC Davis, said that he hadn't read the study but that making estimates based solely on climate change was virtually impossible.

"It is just awfully hard to separate climate change from the many, many other factors that affect people's decisions whether to stay in agriculture or move," he said.

The same exact statement, by the way, could be made as to the relationship of climate change to the single variable manmade CO2 without reference to the myriad of other factors that affect the complex climate system.


  1. Sean:

    "It is a tentative sensitivity study of the effects of one variable on another, where the relationship between the two is itself questionable but more importantly, dependent upon many other far more important factors."

    This is actually precisely the problem with almost every single socioeconomic study done in the name of Climate Change. I'm actually a believer in the ~3deg sensitivity of the climate to CO2, yet am persistently annoyed by anyone bringing up the effects of climate change on anything besides climate. I have now proclaimed myself "Pro-Global Warming" among my friends to avoid the moniker of "denier" (which I am not), and because I see first hand the benefits of increased CO2 (living in developing Asia).

    A few of the examples which have been most egregious: Malaria studies showing increased range of mosquitoes due to climate change when the effects are literally swamped by humans maintaining water infrastructure. One study that I was given was basically a computer model that based increased malaria on the increased human usage of exposed water tanks. There's another large WHO study which breaks down mortality according to many factors -- nutrition, violence, disease, etc. It claims that the increased number of people dying from climate change in 2005 was almost 20 million!! How did they determine this? It turns out this number was the error term between the 1960-1990 average using the calculated regression terms and the actual mortality in 2005. Absolutely no direct contribution, and no admission that an error in their model could drastically affect that number.

  2. Sean:

    Hm, wanted to update the above. The WHO "World Health Report 2002" reported that:

    Climate change was estimated to be responsible in 2000 for approximately 2.4% of worldwide diarrhoea, 6% of malaria in some middle income countries and 7% of dengue fever in some industrialized countries. In total, the attributable mortality was 154 000 (0.3%) deaths and the attributable burden was 5.5 million (0.4%) DALYs.

    So not at all the 20m that I noted above, rather only 154k. And the year analyzed was 2000, not 2005. The subsequent WHO health reports avoid such claims, and only mention climate change in passing.

  3. rxc:

    Math and statistics are very important tools for scientists. Unfortunately, when put into the hands of people who do not understand what they are doing, you end up with results like this. I consider all of the soft "sciences" to suffer from this disease. Maybe it should be listed in the upcoming DSM revision - something like "Abuse of Math/Statistics Syndrome" - they are including everything else they can think up.

  4. Buddy Y.:

    Who cares about 1.4 million to 6.7 million Mexicans migrating to the U.S. by 2080 due to climate change anyway? A lot more than that have already migrated. If we don't get control of the border, there will be more than that in the next 10 years!

  5. Stan:

    We all have an embarrassing professor at our alma mater. Mine is an intelligent design guy that always seems to be quoted as proof of the theory.

  6. Buz:

    "Between 1.4 million and 6.7 million Mexicans could migrate to the U.S. by 2080"

    I didn't realize that there were any more Mexicans in Mexico left to migrate!

  7. Dr. T:

    The National Academy of Sciences is comprised of people with degrees in science but no ability to think or act like true scientists. I once received an invitation to join the Academy, and I was insulted. None of the medical scientists I worked with would have joined that organization of political pseudoscientists. Naturally, governments and "green" organizations love the NAS (almost as much as they love the WHO and the IPCC).

  8. me:

    Between 1.4 million and 6.7 million Mexicans could migrate to the U.S. by 2080

    didn't they do that much last year?

  9. ADiff:

    Oh come on, Warren! It's the TV generation! Everything has to be simplified and dramatized in a script that can satisfy the preferences of the audience within a 90 minute period. Real facts and accuracy take too long, are too much work and are just way too unsatisfying! Science increasingly matches the general public in not wanting to think about what is, but to think what it wants is.