Why healthy-climate advocates don't speak with one voice

Environmentalists are united in their belief that fossil fuels must be quickly replaced with clean sources of power. But they are not united in how to achieve this aim. The divisions in the advocacy community arise from an underappreciated conflict that will not be easy to resolve.

The problem is well illustrated by natural gas, the abundant fossil fuel consisting primarily of methane, which is used for heating, cooking, generating electricity and powering manufacturing processes. We can get to the core of the environmentalists' disagreement by looking at the meaning of three numbers relevant to methane: 86, 220 and 9.

86 is the most common number used to emphasize the potency of methane as a greenhouse gas.¹ One ton of emitted methane creates 86 times more global warming than an equivalent ton of carbon dioxide. This is by far the most common piece of data that healthy-climate advocates use to highlight how dangerous methane emissions are, and it is clearly effective in mobilizing political support against the natural gas industry. But the often exclusive focus on the number 86 by some groups also serves a climate policy agenda that many other environmentalists disagree with.

If methane is 86 times more potent, why have climate scientists been emphasizing the supreme importance of carbon dioxide for so long? One answer is that the present atmospheric concentration of carbon dioxide (425 parts per million) exceeds that of methane by a factor of about 220. Here is our second important number. Together, increased emissions of the rare (but potent) methane and the abundant (but weak) carbon dioxide are responsible for most anthropogenic global warming.

There is another reason, however, for climate scientists' traditional emphasis on carbon dioxide: its longevity in the atmosphere. Presently, a little over half the carbon dioxide emitted from fossil fuel burning is absorbed by the oceans and land within one year, with about 45% remaining in the atmosphere. Unfortunately, natural processes can only remove the remaining carbon dioxide over timeframes of hundreds and thousands of years. The last few percent will still be present in the atmosphere a quarter million years from now. This is the legacy that our fossil fuel profligacy has wrought.

In sharp contrast, the half-life of emitted methane is just 9 years. Here is our third number, and the key to understanding the conflict that explains the inability of the environmental movement to speak with one voice. Half the methane emitted now will be removed from the atmosphere by natural processes in nine years, another half will have dissipated nine years after that, and so on. Within two generations, just 1/64th of the emitted methane will remain. Unlike carbon dioxide, methane is not a legacy greenhouse gas. Its effects are felt only in the relatively short term.

The division in the climate advocacy community is, at root, a conflict of values. For many advocates, myself included, the motivation to dedicate ourselves to the political work is rooted in our love of Nature and our desire to keep it as intact as possible. We want to preserve the Earth's bounty for our grandchildren's grandchildren, and their descendants in turn. We are dedicated to intergenerational equity. This value system naturally leads us to support policy that will mitigate, as much as possible, the legacy effects of carbon dioxide emissions.

Many other healthy-climate advocates are instead primarily motivated by concerns about social equity. They respond to the call of environmental justice, a field rooted in the knowledge that low-income communities, communities of color and nations of the Global South contributed little to climate change yet are bearing the brunt of the damages. They are concerned, first and foremost, with the most immediate effects of climate policy decisions on the well-being of these communities. This value system naturally leads to an emphasis on mitigating methane's power to create intense global heating in the next few decades.

Of course, this division between intergenerational and social equity advocates is far from absolute. Intergenerational equity advocates see the potential of short-term, intense heating to disrupt sensitive ecologies and perhaps lead to tipping points that would damage the biosphere in the long term. And social equity advocates certainly do not ignore the importance of legacy heating to future generations. The two groups are aligned on many aspects of climate policy and recognize the need for solidarity against the agenda of climate change deniers and their allies. But the distinctions in some key policy areas are enough to create significant breaks in the climate advocacy movement. And the emerging landscape of climate and energy technologies, unfortunately, has significant potential to worsen the policy divide.

In upcoming posts, I will explore the divisions between these two camps in detail. For now, I will simply mention that there are many aspects of the emerging low-carbon energy economy where the distinct values of advocates for intergenerational versus social equity lead to diverging policy agendas. The moral dilemmas inherent in carbon capture and sequestration, the enormous required expansion of renewable electricity sources and the national transmission grid, and the necessary future role of chemical fuels like hydrogen can all be viewed through the distinct lenses of social and intergenerational equity. How we negotiate these decisions is likely to have considerable impact on the shape of our common climate future.

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¹Because the half-life of methane is so short, the relative potency of methane versus carbon dioxide depends on the assumed timeframe. The numerical value of 86 is the relative potency computed for a 20 year period. Longer assumed timeframes would yield lower values.