Published in Spanish in El español, Nov 1st 2016
(picture by blake.thornberry Flare Off & Pumpjack, Permian Basin Oil Field — Eddy County, NM)
Despite the scant attention paid to methane as a greenhouse gas, its contribution to global warming is enormous: its warming potential is 86 times greater than that of CO2 in the first 20 years.
New research reveals that methane emissions from the fossil fuel sector are between 20 and 60% greater than has been believed until now, which leads us to suspect that its climatic contribution has been systematically underestimated. The current political preference for natural gas, which is presented as a “clean” fuel, deliberately ignores this reality.
Fracking gas has a climatic impact almost three times greater than that of coal. Focusing political attention on methane emissions, and challenging the benevolent image of gas, will start to slow down warming earlier than will CO2 mitigation policies, which work over the longer term. The two must go hand in hand.
When we hear talk of global warming, what comes immediately to mind is a molecule: CO2. This is not surprising given that this gas is the number one cause of anthropogenic climate change, and therefore the focus of attention of mitigation policies. We all know, having heard it countless times, that CO2 is released from power stations, from industrial plants, from the exhaust pipes of our cars. However, in focusing almost solely on carbon dioxide, we barely pay attention to methane (CH4), which is relegated to a little-brother role. This, despite the fact that methane´s contribution to radiative forcing in the atmosphere is far from insignificant, as we can see from the reports of the International Panel on Climate Change (see Figure 1).
Figure 1: Estimations of radiative forcing in 2011 compared with 1750. (source: IPCC, 2013)
A common misconception: “Methane is 25 times more potent than CO2”
Methane is very dangerous in terms of its impact on the climate. Its global warming potential (GWP) is much greater than that of CO2. With the publication of successive reports from the IPCC, its GWP has been revised steadily upwards. The most recent report, in 2013, states that methane is 86 times more potent than CO2 over a time horizon of 20 years from its release into the atmosphere. This figure represents an increase compared to the estimates which appeared in the 2007 report (72) and the 2003 report (56).
However, what we normally hear in the news, and in discussions of climate change in various circles, is the statement that “methane is 25 times more potent than CO2”. Where does this oft-repeated assertion come from? 25 is the value quoted in the IPCC’s 4th report (in 2007) for the warming potential of methane over a time horizon of one hundred years. The value quoted in the most recent report for this period is 34, but many organisations and government agencies, such as the US Environmental Protection Agency (EPA), have still not recognised this change and continue to use the old value when calculating industrial emissions. Some even continue to use the value of 21, quoted in the IPCC’s 1996 report! Moreover, using a time horizon of 100 years makes the impact of this gas on global warming sound much less serious than it really is.
Table 1. GWP value of methane quoted in successive IPCC reports, for 20-year and 100-year time horizons (writer’s own tabulation).
There is no scientific reason to choose the 100-year horizon instead of any other time horizon
Why, in political circles, is the value for the 100-year time horizon chosen? This choice is arbitrary, and has the political advantage of casting the methane problem in a kinder light. In its latest report, the IPCC makes it as clear as day that there is no scientific reason to choose the 100-year horizon instead of any other time horizon. The choice of one horizon over another depends on the relative weight assigned to effects at different moments. The atmospheric half-life of methane is around 12 years, compared with 200 years for CO2. For this reason, the GWP potential as calculated for a 10- or 20-year horizon reflects much more accurately the potential of methane to affect the climate. This is especially true given that the present situation is urgent, leaving us little time to react, and given the measures we are committed to taking under the Paris Agreement. In addition to giving us a distorted vision of reality, choosing a time horizon of 100 years puts most of the responsibility for climate change mitigation on the shoulders of a future generation which has not caused the problem.
A “natural” methane bomb
The emission of greenhouse effect gases (GEG) of anthropogenic origin are the main cause of global warming. However, the increase in the earth’s average temperature caused by these anthropogenic GEGs also has an effect on the action of natural resources. For example, it leads to a loss of capacity to absorb these gases in sinks such as oceans and soils. Looking specifically at methane, the gas trapped in molecules of frozen water (hydrates and clathrates) in ocean floors and in permafrost – the permanently frozen ground found in periglacial zones – is released into the atmosphere when the ice melts. As Zimov et al (2006) describe, these frozen underground stores constitute a significant, ancient methane reserve, whose potential contribution to climate change is underestimated, and rarely included in GEG estimates.
We may be sitting on a timebomb, and we cannot know exactly when it will explode
The melting of methane clathrates is one of the thresholds which, once crossed, may give rise to uncontrolled climate change. Some weeks ago, scientists alerted us to the fact that the ice in Greenland is melting much faster than we thought. That is, the warming caused by our species is accelerating the release of GEGs by the Earth itself, blurring the border between natural and anthropogenic sources of warming. Scientific research suggests a threshold figure: if there is an increase of more than 1.8 ºC in the average global temperature, we will be at risk of reaching the critical point where there will be a massive melting of methane clathrates, releasing all the gas currently trapped in the ice. We are very close to exceeding this figure, if indeed we have not already done so. We may be sitting on a timebomb, and we cannot know exactly when it will explode. More warming means more methane released from the permafrost, which will in turn mean more warming. Incomprehensibly, this feedback loop does not receive the attention it deserves in the climate modelling carried out in the IPCC’s reports. This partly explains the conservative estimates made, which are then revised upwards every time fresh evidence is brought to light.
Image 1. Lakes of melted permafrost near Greenland in 2008 (CC Licence. Photographer: Steve Jurvetson)
A Methane from fossil fuel industries: an underestimated sector
Since 1750, the concentration of methane in the atmosphere has doubled. When we talk about climate change and methane, everyone thinks of flatulent cows. Anthropogenic methane emissions do come from sources such as the agricultural sector and from cattle. But they also come from rotting rubbish dumps and from the fossil fuel industry. The extraction of natural gas, oil and goal causes methane leaks at several points in the process. The fossil fuel sector is responsible for between 15 and 22% of global methane emissions – or so we have believed until now. However, a revelatory report in Nature at the beginning of this month, produced by researchers from the NOAA and the University of Colorado, indicates that methane emissions from this sector are 20-60% greater than has previously been estimated by organisations such as the IPCC. The authors arrived at this conclusion based on an analysis, the most exhaustive conducted to date, of recorded emissions of methane carbon isotopes and methane gas over the long term.
It has been known for some time that methane escapes from gas industry installations such as compression tanks, methane tankers, pipelines, boreholes and underground storage. Who can forget the spectacular images, obtained using infrared cameras, of a leak from a gas well belonging to SoCalGas in Aliso Canyon (California) at the end of 2015? The leak, which took 4 months to bring under control, released into the atmosphere nearly one hundred thousand tonnes of methane, leaving a carbon footprint greater than that of the oil spill caused by the gas explosion on the Deepwater Horizon drilling platform. However, the intensity and the frequency with which such leaks occurred has been the subject of some debate, and the information available has been both scarce and opaque.
Image 2. Methane leak from a gas well belonging to SoCalGas in Aliso Canyon, California, recorded with a thermal imaging camera. The leak began in October 2015 and was not brought under control until February 2016 (source: Earthworks)
Recent observations by satellite of methane emissions, however, have now revealed that the energy sector is in fact haemorrhaging gas. In February this year, researchers from Harvard University published data showing that between 2002 and 2014, methane emissions in the USA grew by more than 30%. Official data from the EPA suggested, on the other hand, that there had been a reduction of 10%. This implies that when it comes to methane emissions, we are flying blind. This is very worrying given that we are talking about the second most important source of emissions. The Harvard University study argues that the significant increase in global methane emissions over the last decade is in large measure due to an increase in emissions in the USA. The EPA’s underestimation has been shown to be partly due to a rather imprecise method of calculation, using the wrong instruments.
In February this year, researchers from Harvard University published data showing that between 2002 and 2014, methane emissions in the USA grew by more than 30%. Official data from the EPA suggested, on the other hand, that there had been a reduction of 10%. This implies that when it comes to methane emissions, we are flying blind.
The study indicates that there is no conclusive proof of the origin of these emissions, and warns that more research is required to investigate anthropogenic sources of methane in the US. However, the possibility of a link with the oil and gas industry, in the context of the fracking boom of the last decade, is obvious to all. Over the decade, US production of gas and oil has increased by 20%, and the production of shale gas (extracted using the fracking technique) has multiplied by nine, reaching 40% of total US gas production in 2013. Satellite observations, published in 2014, were able to identify the sources more precisely. When methane emissions from before the US fracking boom are compared to those produced in the first years of this boom (2009-2011), the geographical correspondence between emissions and fracking locations is clear: atmospheric concentrations of methane increased dramatically in many regions where shale gas was produced (Eagle Ford, Bukken, Marcellus).
A Climate policy taking methane into account
The blatant, systematic underestimation of US methane emissions drew a timid response from the EPA earlier this year. The absence of controls and the poor quality of the information offered in relation to this pollutant by the authorities was so obvious that the agency proposed a series of measures, including the cancellation of exceptions, an improvement in standards and an increase in controls. However, these measures will probably have an insufficient impact given the scale of the problem.
The myth that gas is a “clean” fossil fuel must be challenged. While it is true that burning gas produces fewer emissions than the burning of coal or oil, calculations of its carbon foorprint do not take methane leaks into account. The evidence is mounting that when leaks occurring throughout the life cycle are included in the calculations, the climatic advantages of gas are more than cancelled out. In particular, emissions from fracking gas are almost three times greater than the emissions from coal, according to the most recent research. How can it be that between 2009 and 2013, GEG emissions in the USA increased, if CO2 emissions decreased? One possible answer, tweaking the famous phrase of the Clinton campaign: “It’s the methane, stupid!”.
Figure 2. GEG emissions in the USA, expressed as CO2 equivalents. The grey line shows only CO2 emissions. The green line represents CO2 and methane emissions together, but accepting as valid the erroneous assumptions of the EPA, which underestimate the contribution of methane. The red line shows the emissions of CO2 and methane emissions together, using more realistic methane emission factors. (source: adapted from Howarth, 2015)
How can it be that between 2009 and 2013, GEG emissions in the USA increased, if CO2 emissions decreased?
“It’s the methane, stupid!”.
This evidence makes it clear that there is an urgent need for a radical reformulation of the current narrative on gas. Almost one year after the Paris Agreement, the mitigation activities of signatory countries cannot be based on an attempt to transition from coal to gas. Gas is not only a fossil fuel; it is a fossil fuel whose climatic impact we are ignoring. Many countries are turning eagerly to the use of gas and justifying it as action on climate change. For the reasons set out here, this approach is utterly mistaken. The European Union, to take an example close to home, is embarking on an orgy of investment, worth millions of euros, in gas pipelines, regasification capacity, liquefied natural gas (LNG) imports, et cetera. This does not respond to our actual energy requirements, and in fact is leading us to climate suicide. Given the long period during which CO2 remains present in the atmosphere, even the required drastic reduction in CO2 emissions, undertaken today, will take decades to have an effect. On the other hand, reducing methane emissions right now will mean a much more rapid reduction in the temperature increase.
Abandoning all fossil fuels, including gas, is the only sensible solution available to us.