What is the cost of a ton of greenhouse gases? When a climate-warming gas such as carbon dioxide or methane is emitted into the atmosphere, its impacts can be felt years or even decades into the future – in the form of sea level rise. , changes in agricultural productivity or more extreme weather events. , such as droughts, floods and heat waves. These impacts are quantified in a metric called the “social cost of carbon”, considered a vital tool for developing healthy and effective climate policies.
A new study by a team including researchers from the Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley reports that the social cost of methane – a greenhouse gas 30 times more powerful than carbon dioxide in its ability to trap heat – varies by an order of magnitude between industrialized and developing regions of the world.
Recently published in the journal Nature, the study finds that by taking into account the economic inequalities between countries and regions, the social cost of methane decreases by almost a factor of 10 in sub-Saharan Africa and goes almost by a factor of 10 for industrialized countries, such as United States. The study calculated a global average estimate of the social cost of methane to be $ 922 per metric tonne (disregarding inequity), falling to $ 130 per metric tonne for sub-Saharan Africa and rising to $ 8,040 per metric tonne. for the United States.
“The document broadly supports previous U.S. government estimates on the social cost of methane, but if you use the number as it’s typically used – as a global estimate, as if all countries are equal – then it ignores the numbers. inequalities, ”said William Collins, Berkeley Lab scientist, one of the study’s co-authors.
The lead authors of the study were David Anthoff, a professor in the Energy and Resources Group at UC Berkeley, and Frank Errickson, a graduate student of the group at the time of the study. “The Biden administration’s climate policy agenda calls for prioritizing environmental justice and fairness. We provide a way for them to directly integrate equity concerns into methane emissions regulations, ”said Errickson, now a postdoctoral fellow at Princeton University. “Our results show that the same climate impact, measured in dollars, results in a greater loss of well-being for low-income regions compared to rich regions.”
Like the social cost of carbon, the social cost of methane is a metric that is not widely used by the public, but is increasingly used by government agencies and businesses to make decisions about policies and capital investments. By properly accounting for future damage that could be caused by greenhouse gas emissions, policymakers can weigh current costs against future avoided damage. In fact, the recent White House decree on the climate crisis established a task force to provide accurate accounting of the social costs of carbon, methane, and nitrous oxide within a year.
“President Biden’s action represents a much needed return to science policy in the United States,” Anthoff said. “Devastating weather events and forest fires have become more common, and the costs of climate impacts are increasing.”
“The social costs of methane and carbon dioxide are used directly in cost-benefit analyzes all the time,” Collins said. “You have to figure out how to maximize the benefits of a dollar spent to mitigate methane emissions, as opposed to any other way you might choose to spend that dollar. You want to make sure you’re not using gold – band aid plate. “
Given the current estimate of global methane emissions of 300 million metric tonnes per year, that puts the annual social cost of methane at nearly $ 300 billion, said Collins, head of the climate science division and of Ecosystems at Berkeley Lab and also a professor at UC Berkeley’s Earth. and Department of Planetary Sciences. “Wetlands will become wetter and drier, so there is an increase in the severity of storms and droughts,” he said. “The cost would include everything that arises from it, such as damaged infrastructure, increased expenses to keep the premises cool, the health risks associated with the heat, etc.”
While some of the methane comes from natural sources – mainly wetlands – around 60% of methane emissions come from human activity, including agriculture, fossil fuel production, landfills and animal production. It is considered a short-lived climate pollutant, only remaining in the atmosphere for about ten years, compared to more than 100 years for carbon dioxide.
“Given its potency as a greenhouse gas, regulating methane emissions has long been recognized as an essential element in designing an economically efficient climate policy,” said Anthoff. “Our study updates the social cost of methane estimates and fills a critical gap in determining social costs.”
Under the Obama administration, the price was estimated at around $ 1,400 per tonne. Berkeley researchers made a technical correction for compensating influences on the climate system, arriving at a global average estimate of $ 922 per metric tonne. “We suggest they slightly overestimated him,” Collins said.
But more importantly, the uncertainty around the social cost of methane comes more from the social side than the physical. “As a climatologist, we have strived to improve our estimates of the warming caused by methane,” Collins said. “But it turns out that the physical side is no longer the main source of uncertainty about the social cost of methane. It is now shifted to the socio-economic sector, which explains the damage and inequalities.”
How societies choose to develop in the future – such as expanding cities along coastlines or areas prone to flooding or forest fires, or moving away from those areas – is a big unknown. “If we choose to mitigate climate change more aggressively, the social cost of methane drops dramatically,” Collins said.
“Continuing our work to further explore the relationship between climate change and socio-economic uncertainties – not to mention the complex but important issues that arise when we consider equity – is a promising area for future research and development. policy exploration, ”Anthoff said.
The other co-authors of the study were Klaus Keller and Vivek Srikrishnan from Pennsylvania State University. The research was supported by the National Science Foundation, the Sloan Foundation, and the Penn State Center for Climate Risk Management.