Monday, August 19, 2013

Climate change, not a carbon tax, is a war on the poor

Gas prices in BC, home to N America's only carbon tax (CP)
An op-ed by Elizabeth Nickson in Friday's Vancouver Sun relied on confused and un-factual "facts" to claim that a carbon tax, like we have here in British Columbia, is an attack on the poor. As I tweeted Friday, every single paragraph of the column was ridiculous.

I'll leave the correction of all Nickson's mistakes to colleagues, one of whom now has a response in the Sun (also see Andy Skuce), and focus on the backwards premise.

The fundamental objective of carbon controls is to reduce the emission of gases that contribute to climate change. A primary reason to combat climate change is to protect those most vulnerable to its effects. Pretty much every analysis, not to mention every extreme weather event, shows that the most vulnerable are and will continue to be the poor and disenfranchised. Politics certainly influence the design of the carbon policy,more than many people would like. Nevertheless, at the most base level, carbon taxes are being proposed and enacted to help the poor, not to hurt the poor.

There is evidence that the BC carbon tax is influencing the consumption of carbon-based fuels. At the same time, the system is not perfect, nor should anyone expect it to be. As we develop policies and programs to deal with climate change, there will inevitably be missteps, like the loopholes in the UN's Clean Development Mechanism, the number of carbon credits distributed in a cap-and-trade system, or the level of low income carbon tax credit (in BC). That happens with any policy, from climate to education to health care. The design is never perfect at first.

A sensible solution is to learn from and correct the missteps - close the loopholes, buy credits from the system, increase the tax credit, compensate those hurt - rather to throw the whole concept out the window.

Monday, August 12, 2013

Does temperature really cause depression? Correlation vs. Causation in "big data"

Image by Olimpia Zagnoli, New York Times
Back in Mr. Wardle's high school economics class, we were once asked to look for a correlation between any two datasets. I searched through the small school library and stumbled across historical data on marijuana use in Canada.

So, for fun, I compared it to unemployment data and found a strong negative correlation. More marijuana use, less unemployment.

Mr. Wardle liked my assignment. Granted, his sense of humour was famous; on the weekly ten point quizzes, we got a bonus mark for adding a caption to a Far Side cartoon, and he announced the funniest caption the following class.

When he handed back the assignment, he reminded me of one key rule of research:

Correlation does not imply causation.

Which brings us to an op-ed in yesterday's New York Times. Seth Stephens-Davidowitz, an economist interning at Google, presented evidence from Google searches for possible causes of depression in the United States. After unemployment, what was the best predictor of searches for depression?

I tested dozens of variables in many different categories. The strongest predictor by far: an area’s average temperature in January. Colder places have higher rates of depression, with the correlation concentrated in the colder months. The relationship between weather and mental health has been debated, but those debates have generally relied on “small” data. Google searches, the biggest data source we currently have, are unambiguous: when it comes to our happiness, climate matters a great deal. 

Paging Mr. Wardle, wherever you are.

What else happens in January in cold places?

It is dark. You don't need to be a mental health expert to know about 'seasonal affectiveed disorder', a common condition in places where the winter days are short. Yet Stephens-Davidowitz misses this critically relevant correlate to temperature and goes on to provide temperature-based advice:
 
The striking correlation between temperature and depression suggests they should consider moving to a more temperate location. Of course, people at risk for depression should hesitate to abandon a job in a cold-winter location for no job in a warm-winter clime, and they should think twice about moving away from family and friends.

The advice may be good, even though the op-ed is probably mistakenly attributing many cases of northern depression to lower temperatures rather than less sunlight. If colder places are also darker in winter, does it matter which variable you use? 
Yes, it matters, because we are talking about a correlation, not a perfect relationship. There are cold, northern cities with glorious sunny winters as well as mild, northern cities with depressing grey winter. 

For example, if you suffer from winter depression, should you move from Montreal, with its notoriously frigid winters, to more temperate Vancouver? Probably not, because in Vancouver you're likely to experience weeks on end without seeing the sun. I counted 22 days of non-stop rain a few Novembers back.
 
The availability of internet search data allows researchers to probe questions previously answered only with high effort, limited sample-size opinion polls. There can be real value to analyses with Google Trends or other storehouses or search data. The Centers for Disease Control, for example, works with Google because the number of people in an area searching for information on the flu turned out to be the best available indicator of a flu outbreak. On a simpler note, want to know whether people are more likely to use the term "climate change" or the term "global warming"? Try Google Trends, and you'll see the answer is clearly "global warming".

So by all means, examine data with Google Trends. Just remember Mr. Wardle's lesson; correlation does not imply causation. Even Stephens-Davidowitz seemed to understand this, at least in the case of one variable:

More Hispanic-Americans meant fewer searches (though this might have been a result of language factors).

Might have. You think?

Monday, August 05, 2013

Ask Google to stop supporting Senator Inhofe and others who deny and obstruct science

Last week, a group of us Google Science Communication fellows sent a letter to the Chairman and CEO of the Google, pasted below, expressing our disappointment that the company held a fundraiser in support of Oklahoma Senator James Inhofe.
 
Our reaction to news of the fundraiser was a mix of confusion and shock. We were brought to Mountain View in 2011 to learn how new technologies could improve science communication, with a focus on climate science. Raising funds for someone who has openly threatened climate scientists, mocked scientific practice and tried to impede scientific progress was completely incongruous with the conduct of the company we visited two years ago.

I urge people not to succumb to cynicism - "that's business" - about Google's actions. This is an opportunity. Google has made a mistake. Let's bring attention to that mistake, and ensure Google, and other companies, don't repeat it. As four of my colleagues wrote at Dot Earth:

Responsibility, however, also rests with scientists, civil society leaders, and the public.  Indeed, this may be the enduring lesson of Google’s mistake.  By speaking out when our admired companies and political leaders let us down, we are the only ones who can create the conditions where the morally right thing to do is also good for politics and business.

How do you speak out?

If you work for Google, sign the virtual petition at coworker.org asking your employer to stop raising money for Senator Inhofe and others who obstruct and deny science. If you know people who work for Google, bring the petition to their attention.
 
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