It is now well known that the phenomenon of global warming—also called climate change—is caused significantly by the emissions of the so-called greenhouse gases. The principal culprit here is carbon dioxide which is emitted into the atmosphere from the combustion of fossil fuels. Given the salient contribution of carbon dioxide to global warming, policymakers throughout the world have focused their attention on the steps that we humans can take to reduce our dependence on fossil fuels.
Even tough carbon dioxide is a key contributor to global warming, methane, another greenhouse gas, is a much more potent contributor to climate change than carbon dioxide. Studies by Kevin Trenberth and others have shown that in terms of its contribution to global warming, over a 100-year period, methane is about 28 times more powerful than carbon dioxide. This and similar figures have caused some policymakers to focus on steps we might take to attenuate methane emissions into the atmosphere.
A rather unusual step has been taken by tiny New Zealand where the National Geographic points out that 5 million humans reside peacefully with 26 million sheep and 10 million cows. Specifically, because cows release methane when they burp (and also via flatulence), the Kiwi government has introduced legislation to tax cow burps! Although this action has clearly angered farmers, it is unclear whether this “burp tax” will have any noticeable impact on helping this nation reach its laudable goal of net-zero emissions by 2050.
To see this, it is important to comprehend that although some carbon dioxide can stay in the atmosphere for hundreds of years, methane stays in the atmosphere for only about ten years before being oxidized to form carbon dioxide. Practically speaking, this means that a rise in methane emissions has no real impact on global warming after about 30 years. This also means that when we view global warming and its ill effects from the standpoint of hundreds of years, the negative impact of methane over centuries has been greatly exaggerated and its impact in the first three decades has been understated.
This explains why climate scientists are increasingly suggesting that when we formulate policy to attenuate the ill effects of global warming on the world, we separate the contributions of ephemeral climate pollutants such as methane from the contributions of enduring pollutants such as carbon dioxide.
Biogenic methane or methane produced by living organisms comes not only from cows but also from sheep, goats, deer, and buffalos. Therefore, singling out cows and taxing their burps is more like a Band-Aid that does not address the root cause of the global warming problem. The key policy point to grasp here is that although lowering methane in the atmosphere may buy us ten years of lower temperatures, lowering fossil carbon will buy us hundreds of years of lower temperatures.
Batabyal is the Arthur J. Gosnell professor of economics and the Interim Head of the Sustainability Department, both at RIT, but these views are his own.d