Not just hot air
When it comes to global warming, CO2 gets all the coverage. But carbon dioxide isn’t the only greenhouse gas. It is not even the most potent. It’s just that we, human society, release literally billions of tons of it every year as we burn our way through the planets reserves of fossil fuels laid down millions of years ago.
By comparison, 570 million tons of methane released into the atmosphere each year doesn’t sound so bad. However, methane is 86 times more potent as an insulating greenhouse gas, reflecting back heat to the Earth, than CO2 per unit mass. It’s this fact – and our rapidly increasing emissions – that make methane the second-largest driver of global warming. It is also the primary source of ground-level ozone, which causes up to one million premature deaths every year.
Scientists also suspect that methane was the cause of previous rapid warming events in our planet’s geological history. Under high pressure, like those in the ocean depths, the gas we know at the surface solidifies into a slush-like material called methane hydrate. Vast amounts of methane are ‘frozen’ in place at the bottom of the sea in this state. These hydrates are generally stable unless disturbed by energy input, such as warmer water.
Around something like 55 million years ago, the Earth experienced a warming event that some scientists believe was initiated by destabilized hydrates. Large amounts of methane leached up from the ocean floor to the atmosphere, creating a drastic and rapid rise in temperature as the gas trapped heat in the atmosphere. You can see this effect in action today with methane bubbles frozen in forest lakes in the far north.
In the atmosphere of more recent times, methane concentrations have risen dramatically. More than 150% today compared to that in the year 1750. It’s unclear if this will continue, however the UN’s Intergovernmental Panel on Climate Change (IPCC) warns that keeping methane emissions in check is essential to prevent further global warming.
Cutting methane emissions will be essential to achieving net-zero. The good news is, it’s easier than cutting CO2. The bad news is, we’re not moving fast enough.
What is methane and where does it come from?
Methane is the simplest organic hydrocarbon molecule; a gas (at Earth temperature and pressure), abundant across the universe, made from a single carbon atom and four hydrogen atoms: CH4.
The three biggest sources of human-generated (anthropogenic) methane are:
- Agriculture (42%): Cattle, or more specifically, the microbes in their guts, produce methane as a byproduct of digestion. So do the bacteria that thrive in flooded rice paddies. And they produce a lot. There are 1.4 billion cattle in the world, and that number is growing as demand for beef and dairy increases: together with other grazing animals. Livestock emissions alone account for more than 32% of anthropogenic methane emissions. Forest fires and burning biomass also add to the total.
- Fossil fuels (36%): Methane is the primary constituent of natural gas, which escapes from coal mines and leaky oil and gas pipelines, and the exhausts of cars, lorries, and buses. Recent studies suggest that wells in the US alone produce around 60% more methane than previously estimated by the US Environmental Protection Agency.
- Human waste (18%): Landfills, open dumps, and sewage provide a veritable feast for methane-releasing microbes.
How much should we be worried about methane?
There are two key characteristics that determine the impact of different greenhouse gases on the climate: the length of time they remain in the atmosphere and their ability to absorb energy. Methane has a much shorter atmospheric lifespan than CO2 (around 12 years compared with centuries for CO2), but its higher potency as an insulator and energy absorber makes it far more worrying.
In calculating its effect on global warming, the IPCC has indicated a global warming potential (GWP) for methane of between 84-87 over a 20-year timeframe, and between 28-36 when considering its impact over a 100-year timeframe. This means that just one ton of methane is equivalent to 28 to 36 tons of CO2 if looking at its impact over 100 years, or 84-87 tons over 20 years. Or in other words, methane traps more than 80 times the heat that the same amount of carbon dioxide does in its first two decades in the atmosphere.
It is not only the potency of methane that is the problem. Methane emissions are also rising at their fastest rate since records began in the 1980s. There is now 2.5 times more methane in the air than in pre-industrial times, and it increased sharply during 2020, when even CO2 slowed down, due largely to the impact of the COVID-19 pandemic. In the first eight ‘lockdown’ months of 2020, large methane leaks rose some 32%, according to Paris-based data firm Karryos.
The simple fact is, if methane emissions keep rising, it won’t matter how much CO2 we cut, we won’t keep global warming below the Paris Agreement target of 1.5°C. However, the fact that, despite its potency as a greenhouse gas, methane degrades so rapidly, means that action taken now can have an almost-immediate cooling effect on the Earth’s temperature, buying us more valuable time to ease the transition from fossil fuels and keep the net zero target in sight.
What can we do about methane emissions?
Why are methane emissions so high? Our increasing appetite for animal protein is one of the biggest culprits. With the world’s population approaching 10 billion—and more than ever able to afford meat—this demand is expected to increase by up to 70% by 2050.
So, what can done? Quite a lot, actually. According to the UN Environment Programme (UNEP), it’s possible to cut almost half the 380 million metric tons of methane released each year with currently available and (mostly) cost-effective methods. Doing that would reduce global temperatures by 0.18°C by 2050.
If that doesn’t sound like much, consider that it would take us between 20% and 45% of the way towards keeping temperatures within the Paris Agreement targets. Not to mention the immediate health benefits. According to the UNEP, the subsequent reduction in ground-level ozone would prevent 260,000 premature deaths, 775,000 asthma-related hospital visits, 73 billion hours of lost labor from extreme heat, and 25 million tons of crop losses every year.
Luckily, we have a host of options available to us. And we’re going to need them. Methane emissions are intermittent and widely dispersed, making it tricky to capture data, coordinate action, and pay for everything.
Agriculture is particularly challenging because it includes innumerable producers and smallholdings scattered around the world. Many methane abatement solutions also come with trade-offs. For example, detecting and repairing leaks in the oil and gas industry is usually more cost-effective than doing the same in coal mining. Similarly, changing animal feed may reduce methane emissions, but it can also lead to lower yields. Not ideal when global demand for animal protein is rising. In short, reducing methane emissions requires technical solutions and changing consumption patterns. However, because changing consumption is notoriously difficult to achieve, especially on a global scale, the pressure is on the tech.
UNEP Food Systems and Agriculture Advisor James Lomax says the world needs to begin by “rethinking our approaches to agricultural cultivation and livestock production.” ‘Methane footprints’ on food products could help. Shifting to plant-rich diets and alternative sources of protein may be appealing to health-conscious people in wealthy countries. However, it’s not realistic to expect people in middle-income countries to forgo the relatively little meat they eat now—particularly when increased protein is key to improving their health.
According to McKinsey & Co., the agriculture, fossil fuel, and waste management industries could reduce global annual methane emissions by 20% by 2030 and 46% by 2050. Here’s how:
A significant proportion of agricultural methane emissions could be reduced with existing and readily available technologies. Improving cattle feed and using additives can reduce the amount of methane they emit. Feeding cows seaweed, for example, can slash emissions by up to 80%. Land management is another critical area. Intermittently draining rice paddies, rather than keeping them wet all the time, could halve emissions while saving money and water. By employing these and other available solutions, the agricultural sector could reduce its emissions by 30% in 2050, states McKinsey in its report.
The UN is actively supporting food producers to address some of these issues. The Koronivia Joint Work on Agriculture, for example, established by the UN’s Food and Agriculture Organization in 2017, is helping producers to become more efficient in a changing climate, while a Food Systems Summit held in New York in September 2021, called on nations to do more to support the transition to more sustainable food production systems. Agricultural emissions were also on the agenda for the UN Framework Convention on Climate Change and a key topic of discussion at the COP 26 Climate Change Conference, held in the UK in October and November 2021.
The oil and gas sector has numerous proven technologies to address methane emissions, including Leak Detection and Repair programs (LDAR), electrification, instrument air systems, and vapor recovery units. Together, they could reduce emissions by 70% by 2050.
Coal mining emissions are harder to measure and capture but could be reduced by 13% in 2050. China accounts for 70% of global coal mining emissions, so it makes economic and environmental sense for them to pioneer and lead investment in abatement.
There are a few options for dealing with methane emissions from human waste. Where possible, organic waste could be diverted and turned into composts, and the food industry could switch to anaerobic digestion. After that, it’s a matter of minimizing the emissions that escape from what’s left.
For solid waste, it comes down to collecting, capturing, and using landfill gas. Similarly, for wastewater management, covered lagoons and microalgae could recover or prevent gas formation. Many of these options would require expensive upgrades, with limited opportunity to offset the cost, which might put them out of reach of some countries. Nevertheless, the possibility remains to reduce solid waste by 91% and wastewater by 77% by 2050.
So, how much is all this going to cost?
The cost of implementing such methane abatement measures could be up to US$ 5.1 trillion over 30 years.
Fortunately, methane is a valuable commodity, unlike CO2, making it easier to offset abatement efforts. The additional methane captured can often be monetized directly, and this is typically easier in the oil and gas sectors than elsewhere in the energy sector. This means that emissions reductions could result in economic savings or be carried out at low cost. For example, the International Energy Agency (IEA) estimates that 40% of oil and gas sector emissions could be eliminated at no net cost. It’s not cheap, but it could be much higher.
Measurement and reporting
As William Thomson, Lord Kelvin, said as far back as in 1883, (paraphrased) “What gets measured; gets done!”. Currently, too much methane data is based on estimates and best guesses. Governments, NGOs, and industries need to increase investment and collaboration to improve measurement. For instance, oil and gas companies are pretty good at collecting data, but they usually keep it to themselves. This needs to change. Reporting methane emissions separately from CO2 would also provide much-needed clarity while increasing scrutiny on the biggest emitters and supporting markets for lower emissions products.
The OGMP will soon feed its data into the International Methane Emissions Observatory, a joint initiative by UNEP and the European Commission to get a handle on both private and public sector emissions.
How will all this data be collected? This is where technology can play a vital role.
At any time, there are about 100 major methane leaks and countless smaller ones around the world. The trouble is they’re sporadic and easy to miss. Ground-based sensors have limited coverage. Airplane and drone surveys are expensive, time-consuming, and barred from flying in some places. That’s where satellites come in.
There has been a number of launches in the last five years, with even more on the way. Perhaps the most impressive of these is Carbon Mapper, a joint initiative including NASA, the California Air Resources Board, satellite company Planet, universities, and nonprofits, and funding from private donors like Bloomberg Philanthropies.
The project will launch two satellites in 2023, with plans to have up to 20 providing virtually 24/7 methane monitoring around the world. Meanwhile, another venture, MethaneSAT, is due to launch in 2022. The eponymous satellite will orbit much lower and provide 1 Km2 resolution, helping to pinpoint more minor methane releases, particularly from the oil and gas sector.
This is only the beginning
Although regulations and international agreements are patchy, there are some promising signs that the world is waking up to methane. The EU previously wanted to cut the 2030 emissions to 29% below 2005 emissions. It’s now increased the target to 35%–37%. In September 2021, the United States and EU announced a Global Methane Pledge to reduce methane emissions by 30% in 2030, which could limit global warming to 0.2℃ by 2050. The pledge was officially launched at COP26 and has already been signed by more than 100 countries, representing over two-thirds of global GDP. In November 2021, the US also published proposals for a Methane Emissions Reduction Action Plan that includes a raft of measures to target methane leaking from oil and gas rigs across the US.
In the NGO space, in September 2021, 20 philanthropic organizations pledged US$ 223 million to support methane emissions reductions, the largest contribution of its kind so far.
Methane may not command the headlines in the way that CO2 has done for decades, but the world is increasingly taking action to curb the threat of this ubiquitous and increasingly dangerous greenhouse gas.
There is a lot to be done but lowering methane emissions is tantalizingly within our grasp.
There are a host of readily available options available to us, and, in most cases, they’re more straightforward than cutting CO2. But there is no time to lose. Action must begin now.