Scientists measure the effect of carbon emissions by their global warming potential (GWP), which is based on the amount of heat the gas can absorb in the atmosphere. In a sense, the higher the GWP, the higher the “R-value” of the atmosphere. In a building, a high R-value is good—it keeps the heat inside your house during the winter and outside your house during the summer, saving you money on your energy bills and increasing your comfort. In the atmosphere, a high R-value is not so good because it traps heat. It also increases the energy of the atmosphere so that storms and flooding are more frequent and severe and wildfires occur more often and for longer periods.
Thanks to the Department of Energy’s Tina Kaarsberg and Hashem Akbari of Lawrence Berkeley National Laboratory for pointing out to me years ago the dynamic at work in Global Climate Change and for explaining the influence of “Cool Roofs” on the Earth’s temperature. The sun’s rays penetrate the atmosphere and heat up the planet. Normally, most of the sun’s energy that is not absorbed by the Earth is reflected back and escapes through the earth’s atmosphere. The layer of greenhouse gases traps this heat inside the Earth’s atmosphere instead.
Carbon dioxide is the most commonly occuring greenhouse gas. However, methane gas—the natural gas we use in our buildings to heat and cook, in power plants to produce our electricity, and that comes out of both ends of cows—is a much worse offender. But there is good news buried in the detail. The long-term effect of greenhouse gases in the atmosphere is measured by GWP over 20 or 100 years. For example, the GWP of methane is about 34 times that of carbon dioxide over 100 years. But measured over 20 years, it is about 87 times as much.
Not really good news, but there is a very good silver lining in this dilemma. Methane gas stays in the atmosphere for about 12 years, while carbon dioxide can stay for hundreds of years. We are breathing in today the carbon dioxide that Napoleon exhaled at Waterloo, or that Abraham Lincoln expelled during his Gettysburg Address. Methane gas lasts about as long as the cow who made it. That means that after 12 years the methane has disintegrated and become harmless. So if we drastically decrease the amount of methane leaking from pipelines, produced in buildings and agriculture, and created in power plants, its effect on the climate occurs in a short 12 years. What we do to fight global climate change now matters to us, our parents, our kids and their kids.
Currently in the United States, agriculture produces about 10% of the greenhouse gases. Methane from cows and other cud-chewers produces half of that, 5%. But there is some good news on the cow front (and back?). According to research at U.C. Davis, adding 3 ounces of seaweed a day to a cow’s diet can decrease methane emissions from the cow by about 80%. Last summer, the researchers added seaweed to the diets of 21 beef cows and measured both the weight gained and the methane produced from the cows. After 5 months of 3 ounces of seaweed in their daily diet, the cows gained as much weight as cows eating a traditional diet of grass and hay. Their methane production decreased by a whopping 82%. An earlier study that lasted only two weeks showed a 50% reduction in methane. The longer, more recent study shows that the efficacy of seaweed in decreasing methane emissions from cows is robust and lasting.
And as you look at reducing your family's consumption of beef, remember you can commit to the Action "Eat Lower Down the Carbon Chain" as part of the Cleaner Contra Costa Challenge. You'll earn a whopping 1830 points for taking this action, and have access to a wealth of resources and recipes to make it easy and fun.
If we start phasing out methane now, as well as carbon dioxide, we can make a very big difference in curbing Global Climate Change in the next few decades and long after. And it’s easy to do. Ask a cow.
Photo by Christian Widell on Unsplash