Rising Levels of Methane Feed Menace of Climate Change

Posted June 8, 2016

MP3 Interview with Robert Howarth, professor of ecology and evolutionary biology at Cornell University, conducted by Melinda Tuhus


In addition to carbon dioxide, methane is a critical global warming gas. In the short term, methane is many times more powerful than carbon dioxide in warming the planet’s atmosphere. Even so, the impact of methane is often given short shrift in discussions about climate change. The global climate change activist organization, 350.org, for example, takes its name from the concept that carbon dioxide in the atmosphere must be reduced to 350 ppm from the current 400 ppm in order to stabilize the climate.

The Intergovernmental Panel on Climate Change, IPCC, states that methane is more than 100 times more powerful than carbon dioxide for the first decade after emission, 86 times over a 20-year period, and 34 times over 100 years. This is why many climate activists and scientists are critical of the assertion that natural gas is a bridge fuel to future renewable energy sources.

Cornell University researcher Robert Howarth co-authored a groundbreaking report in 2011 showing that hydraulic fracking for natural gas can be worse for the climate than the burning of coal. He observes that global methane emissions have recently spiked due to the significant increase in fracking across the U.S. Between The Lines' Melinda Tuhus spoke with Howarth, who explains that methane comes from various sources and is released in a variety of ways, including the major leak from the Aliso Canyon storage facility in Southern California that continued uninterrupted for four months last fall and winter before being brought under control.

ROBERT HOWARTH: There are a variety of sources of methane, some of them natural and more under human control. Humans have basically increased the amount of methane going into the atmosphere by about 1.6-fold over what it used to be. The natural sources are largely from wetlands, some geological seeps, but the human-controlled sources, the biggest one is the oil and gas industry in the U.S. Coal mining produces some, landfills, sewage treatment plants, and animal agriculture is also a big source – probably right up there globally with the oil and gas industry. Within the U.S., the oil and gas industry is pretty clearly the largest source of methane emissions; animal agriculture would be a distant second, like other fossil fuels and landfills and sewage treatment plants. If we look globally at the total amount of carbon dioxide emissions and methane emissions at the moment, and compare them in terms of their immediate influence on global warming, the two gases are about equal – methane is actually a little more important in current global warming, when you do it that way. An incredibly important gas.

BETWEEN THE LINES: Natural gas is almost all methane. So what are the different ways that the methane gets into the atmosphere?

ROBERT HOWARTH: When you burn the natural gas, you're burning methane and it's converted to carbon dioxide, so burning it reduces the issue. The methane emissions are coming partly from leaks, but also from purposeful venting – it's part of the normal operations of the oil and gas industry. For instance, after you get gas out of the ground and you compress it into a pipeline, the compressors that are typically used will purposefully vent some of that gas as part of normal operation. And when you go to do maintenance on a storage tank or maintenance on a gas pipeline, the normal procedure is to vent all of the gas that's in the storage tank or the pipeline into the atmosphere, so it's both accidental leaks and purposeful venting of the gas.

BETWEEN THE LINES: Climate scientists say that methane is 86 times more powerful as a greenhouse gas than carbon dioxide in the first 20 years after release. That seems pretty significant.

ROBERT HOWARTH: We look at the period of a decade, say, after emission, current human emissions of methane equal or exceed the emissions of carbon dioxide in terms of their influence on the heat budget of the planet. But carbon dioxide and methane are very different in how they act; carbon dioxide, once it's admitted into the atmosphere, it's equilibrating some with the oceans, it's being taken up by forests, and it's equilibrating with the land surfaces of the earth. What that means is that the carbon dioxide we're putting into the air today will be with us for hundreds of years, perhaps a thousand years, into the future. Methane, on the other hand, if we reduce methane emissions now, it reduces global warming now. So, when the nations of the world came together at the U.N. COP 21 in Paris last December, they recognized we want to keep the planet well below 1.5 degree Celsius above the pre-industrial baseline temperature, and they agreed we really must keep it well below 2 degrees Celsius. And it turns out you cannot reach that target by reducing carbon dioxide emissions, because we're on a trajectory to reach 1.5 degrees in about 12 years or so from now, and to reach 2 degrees in 35 years. The only way to reach that target set by the governments in Paris is to reduce methane emissions. We need to reduce both.

BETWEEN THE LINES: But do you really think there's any possible way to keep global warming increases even below 2 degrees Celsius, much less 1.5 degrees C?

ROBERT HOWARTH: I think we need to reduce methane emissions. If you look over the last decade, there's been a fairly large rate of global increase in methane. Turns out that's been almost entirely attributable to increases from the U.S., and at least a major part of that, maybe most of it, is attributable to the shale gas revolution. We see that in the satellite data. I think we need to reverse that trend, and either stop developing shale gas or certainly get the emissions from it under much better control. That would be a huge help. If we just reverse and go back to where we were with the oil and gas industry ten years ago it would be a big help. But we can also do things to reduce emissions from animal agriculture and we should.

BETWEEN THE LINES: I don't know if you delve into politics, but I'd love to ask you about the Democratic presidential race. We won't bother with the Republicans. Sen. Bernie Sanders has called for a ban on fracking and for ending all new fossil fuel leases on public lands. And even though Hillary has moved toward a lot of Bernie's positions, she hasn't called for either of these moves yet.

ROBERT HOWARTH: I think Sanders' position on fracking and on fossil fuels is exactly right. He's quite strongly opposed fracking. He has for quite some time; it's not a new position of his. He's always been a critic of fracking and he's definitely been a mover among politicians in the "Keep it in the ground movement" in terms of public lands. As you say, Hillary Clinton has expressed some worries about fracking, but her positions have been more ambivalent, and actually, as secretary of state, she and the State Department worked quite hard to promote fracking abroad, so her background on that is rather colored in my view.

For more information, visit Robert Howarth's website at howarthlab.org.

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