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Focus on Methane for quick climate action
Read more on - Polity | Economy | Schemes | S&T | Environment
- Why just CO2: The debate in climate change is often focussed on only carbon dioxide emissions reduction. But the rich world may not truly volunteer for a cut in living standards. And the developing world may have its reservations too, now that they have a shot at getting richer. (economic growth = getting richer = more CO2 emissions)
- Focus on the other gas: That being the case, it makes sense to concentrate on doing other things. Technological change that shifts economies away from using fossil fuels as their principal energy sources may be able to achieve this in the long term. But some sort of effective action is also needed now. One such course of action is available, for carbon dioxide is not the only cause of global warming. About a quarter of the effect is a consequence of methane. And it is far more manageable that CO2 is.
- CO2 v CH4: Going after methane, a compound of one carbon atom with four hydrogens, makes sense, for it is a potent greenhouse agent.
- Over the 20 years subsequent to its emission a tonne of methane causes 86 times more warming than does a tonne of CO2.
- It does not hang around. It has a half-life in the atmosphere of about a decade, so what is released soon vanishes.
- By contrast, CO2 lingers for hundreds, or even thousands, of years.
- The number: The Climate and Clean Air Coalition, a collaboration of governments and environmental lobby groups, therefore reckons that halving anthropogenic methane emissions over the next 30 years could shave 0.18°C off the average global temperature in 2050. That may not sound much, but it is between 20% and 45% of the gap between current temperatures and the goal, agreed on in Paris in 2015 by most of the world’s countries, of stabilising temperatures between 1.5°C and 2°C above pre-industrial averages.
- Useful methane: Moreover, in many cases the cost of stopping emissions of methane can be offset against the fact that, unlike carbon dioxide, it is a valuable commodity. The International Energy Agency (IEA, an intergovernmental organisation based in Paris) estimates that 75% of emissions from the oil and gas sector—some 16.5% of total human emissions—could be avoided with technologies available today, and that 40% (9% of total human emissions) could be eliminated at no net cost.
- How trends happen: After a plateau which began in 1999, concentrations of methane in the atmosphere started rising again in 2007, a trend that continues to this day. Today, more than 300 m tonnes are emitted every year as a consequence of human activity, and that rate is growing. As a result, methane concentrations are now more than two-and-a-half times what they were before the Industrial Revolution, and are rising faster than allowed for in all but the most pessimistic climate projections for the 21st century. The rise after 2007 prompted a rush to understand methane’s sources and how it degrades in the atmosphere. That rise was originally seen as an anomaly, but now that it has been going on for 13 or 14 years, we see the plateau as the anomaly.
- Leaky pipes: Studies show that leaky natural-gas pipes are one culprit. In 2018, instruments mounted on planes flying downwind of Washington, Baltimore, Philadelphia, New York and Boston found that 8,50,000 tonnes of methane a year was wafting from these cities. That is roughly ten times the official estimate of the American government’s Environment Protection Agency (EPA). A bigger source of emissions, though, is further up the fossil-fuel supply chain— at the points where natural gas, oil and coal are extracted from Earth’s crust, processed and moved around the globe. Some 13m tonnes of methane escaped from these facilities each year, approximately 60% more than the EPA’s official figures.
- Coal mines, the liberator: The IEA, meanwhile, estimates that each year the world’s coal mines liberate roughly 40m tonnes of methane that was once trapped in the coal being extracted. As coal is on its way out, there is hope, but it maintains a stronghold in Asia, and in China in particular, where it could stymie efforts to stabilise the climate. Planned new mines will emit a further 13.5 m tonnes a year.
- The methane cycle: Researchers are trying to understand this cycle, by tracing how much CH4 makes its way into and out of the atmosphere every year and developing a model that describes this. Besides leaky wells and pipelines, and gassy coal mines, methane is also emitted by belching cattle, rice paddies, forest fires, slash-and-burn agriculture, rubbish dumps, wastewater-treatment plants, cars and lorries, and natural ecosystems such as swamps, rivers and lakes. A perfect inventory would require knowledge of the size, nature and locations of all such sources around the globe, currently impossible.
- The bottom-up approach: Then the best thing to do is to scrape national and international sets of data for information on all possible sources of the gas (numbers and sizes of cattle herds, sizes and locations of paddies, inventories of fossil-fuel operations and so on), and then combine this with estimates of how much methane each type of source emits. The top-down approach employs direct satellite and ground-based measurements of methane concentrations. The two are reconciled by plugging the list of sources into a computer model. It was found that between 550m and 880m tonnes of methane per year were emitted between 2008 and 2017—roughly 9% more than the average between 2000 and 2006. Between 50% and 60% of this came from human activities. Fossil fuels and agriculture each account for a third, and the remainder is from a combination of emissions from things like cars, fires, landfills and waste-water processing. The post-2007 uptick in methane levels was caused by extra human emissions, though there may also be some diminution in the atmosphere’s ability to destroy the gas. Thankfully, there was little sign of increased release of methane from Arctic tundra, which some fear may happen as the tundra warms.
- Agri methane: The lion’s share of agricultural methane, though, comes from ruminant livestock—cows and sheep, mainly. Such husbandry generates 79% of the sector’s contribution. That amounts to 30% of all anthropogenic emissions. Asking people to eat less meat and drink less milk, while fashionable at the moment in rich countries, probably goes against the fact that middle-income world is seeing higher discretionary spending and diets improving. Some studies suggest a diet rich in certain seaweeds can decrease an animal’s methane emissions by as much as 80%. A compound called bromoform, abundant in these algae, inhibits the chemical reactions that produce methane inside the animals’ rumens. Unfortunately, cattle fed enough seaweed to experience the 80% cut produce less meat or milk than they otherwise would. That methane emissions are a prime target for reduction is an idea which has caught on with politicians, at least in rich countries. In October, the European Commission adopted a “European methane strategy”, the implementation of which will be thrashed out this year. The previous plan had been to cut the EU’s emissions in 2030 to a level 29% below those of 2005. That target has now been increased to 35-37%.
- IPCC and methane satellites: The Oil and Gas Methane Partnership (OGMP), a UN-led project, standardises methods for measuring and reporting methane emissions in the fossil-fuel industry. Data collected through the OGMP will be fed into a new International Methane Emissions Observatory being cooked up by the UN Environment Programme and the European Commission. This will combine them with other measurements, including from the growing number of satellites that measure methane sources from above. The best one is the MethaneSAT, scheduled for launch in 2022. The Intergovernmental Panel on Climate Change envisages a 35% drop in methane emissions below 2010 levels by 2050. The IEA’s numbers suggest that 14% of this is possible in the oil and gas sector alone, at no net cost.
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