For many years, carbon dioxide has been considered the biggest problem regarding climate change. If you’ve been in the science community for years, or probably just in the world in general, you’ve probably heard of the problems with carbon dioxide. It’s a greenhouse gas that can lead to planet warming. There’s also the somewhat lesser-known consequence – that it can acidify the ocean. So given all this information, it makes sense that world leaders at COP26 have pledged to reduce methane.
Don’t You Mean Carbon Dioxide?
No, I mean methane. You see, methane is like the Luke Hemsworth of greenhouse gasses (no offense to him). Everyone knows about Chris Hemsworth (and maybe Liam as well but for the context of this metaphor let’s leave him out), but few people know Luke. However, Luke is still an actor that has a strong filmography. Methane is kind of like that.
When we talk about greenhouse gasses, people tend to only focus on carbon dioxide. However, methane is another greenhouse gas whose importance, until recently, has stayed out of the limelight.
Why is Methane Important?
Methane’s warming effect is 25x greater than carbon dioxide.
Methane’s warming effect is 25 times greater than carbon dioxide over a 100-year period. You read that right – 25 times greater. Additionally, it stays in the atmosphere for approximately 12 years. In comparison, carbon dioxide stays in the atmosphere for 300-1,000 years. So, a little bit longer. These metrics mean that, while methane accounts for significantly fewer greenhouse gas emissions from human activities in the United States (about 10%) than carbon dioxide, reducing the amount of methane emissions could lead to a more rapid reduction in global warming. In fact, a U.N. report called methane reductions “the strongest lever we have to slow climate change over the next 25 years.”
Where Does Methane Come From?
Methane can reach the atmosphere from many human sources including agriculture (think cattle), industry (natural gas drilling), and landfills. It is also produced naturally from certain ecosystems, such as wetlands. However, 50-65% of global methane emissions come from humans. That means that there is a lot of opportunity to reduce our output.
How Can We Reduce Methane Emissions?
If someone tells you that cow toots are causing global warming, your initial reaction may be to laugh (mine was). It’s true, though. Methane is expelled from both end of the cow’s digestive tract. Cows, which are ruminants, can digest cellulose. During that digestion process, methane is produced. And it has to go somewhere. The methane eventually leaves the cow from one end or the other and ends up in the atmosphere. Combine that with the methane gas that is released from manure, and the agricultural sector becomes the largest US source of methane emissions.
There are two ways to reduce methane emissions from agriculture. The first solution is to simply breed less cattle. According to the USDA, there are 93.6 million cows in the US. That’s a lot of opportunity to reduce methane. Moreover, cows don’t just produce methane. They also produce other greenhouse gasses like carbon dioxide and nitrous oxide. All these greenhouse gasses would be decreased if there were less cattle. But let’s say we don’t want to do that. Is there another option?
Turns out, there is. A relatively new technology, a dairy digester, can turn manure into natural gas. This natural gas is renewable, unlike most natural gas, and can power cars, electricity, and more. This can reduce dairy’s impact on the climate, but it’s not a silver bullet.
Now, cows aren’t the only things adding methane to the atmosphere. We’re doing it too. How? We’re drilling for it. We want oil and gas, and we drill and frack to get it. This process releases methane, because, well, methane is natural gas.
How is this natural gas different than the natural gas I mentioned that is produced with the dairy digester? Excellent question. The gas from the dairy digester is renewable energy. Diagram Cows eat cellulose, digest it, and excrete manure. The methane is extracted from the manure, powers a car, and returns to the atmosphere where it breaks down into carbon dioxide. This carbon dioxide is then used to by plants to grow via photosynthesis. It’s removed from the atmosphere and stored in the plant. The plant is eaten by the cow, and the process starts all over again. It’s a cycle that, when nothing else is taken into consideration, stays at net zero methane emissions.
However, the natural gas produced by fracking is adding new methane into the equation. It’s not inside the cycle. Thus, this natural gas is not a renewable energy. In fact, one study published in 2019 suggested that shale-gas production (aka fracking) in North America could account for >50% of global fossil fuel emissions over 10 years (Howarth et al.). Basically, it’s a problem.
How do we reduce industry emissions? Like with the cattle suggestion, the easiest method would be to stop using it and speeding the transition to renewable energy. In the absence of that option, the next best bet is to streamline the process to reduce methane “leaks.” To do that, equipment needs to be upgraded, and methane venting (aka the direct release of methane into the atmosphere) needs to stop. These are the methods proposed by the EPA this week.
Shale gas could account for >50% of emissions
Is This How We Solve Climate Change?
Not quite, but it’s a start.