Climate change due to rising levels of carbon dioxide (CO2) and other greenhouse gases is the first global problem that humanity has ever faced. I don’t mean to downplay other big problems, like major wars, ozone holes, and declines in biodiversity. These things have been, and continue to be huge, complex and more than a little troubling, but they only involve parts of the world. Climate change is truly global because it has to do with our air, which is literally everywhere. It is also expected to have pervasive and far-reaching implications for other big systems, including the oceans and our globalized economy.
Climate change is on my mind because of two recent studies that look at different parts of the global carbon budget, from different perspectives. One is a study of shale gas production, which has become a major industry in parts of Saskatchewan. Based on research published in the latest Proceedings of the National Academy of Sciences (click here for a summary), the amount of gas (and therefore carbon) that might come from a shale gas well can’t be estimated using models for conventional oil and gas, because shale gas wells are drilled horizontally and conventional wells are drilled vertically.
The study also shows that “eventually, gas diffusion causes the pressure in the well to drop, and gas production decreases exponentially.” This conclusion is sobering, partly because of the word “exponentially.” That’s a good way to change – by leaps and bounds – when it refers to positive things, but not when it describes a decrease in our energy supply.
The second study looks at changes in CO2 levels over the last 800,000 years. By studying ancient polar ice and bubbles of air that are trapped in it, scientists have shown that changes in global temperature and CO2 move in parallel. The odd thing is: past increases in temperature seemed to happen first, followed by a rise in CO2.
People who are skeptical about climate change have used this point to cast doubt on these studies, but that should be harder to do now, thanks to a recent paper in Science. By applying a new method to identify the age of ancient bubbles and global temperatures, Parrenin et al. have shown that global temperatures did not rise first, during periods of abrupt change. In fact, they found “no significant asynchrony” between changes in global temperature and atmospheric CO2.
It will be interesting to see what the skeptics have to say about that.