Putting a price on superpollutants

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In contrast to carbon dioxide, governments have been reluctant to enact policies to curb the release of methane into the atmosphere. Only 13% of global methane emissions are covered by any government policy, and even where they are, their impact is often limited.

In part this may reflect an unwillingness to penalise the main emitters. Agriculture for example, accounts for more than one-third of global anthropogenic methane emissions, but governments are typically very sensitive to concerns about food security and the risk of pushing up prices (see Gas pains: A super-pollutant gets the cold shoulder).

The knock-on impact of limited government policy involvement to date is that climate finance targeted at methane abatement is negligible, accounting for less than 2% of total climate finance flows.

Methane is one of the so-called "superpollutants" thought to be responsible for between 35% and 50% of net global warming to date. Other examples include nitrous oxide (NOx), F-gases (synthetic chemicals including HFCs and PFCs), ozone-depleting substances (ODS), and black carbon.

In contrast to CO2, which persists in the atmosphere for centuries, most superpollutants have a much shorter lifespan: from just a few days for black carbon, a decade or so for CH4, and up to 120 years for NOx. It's why they are also sometimes referred to as short-lived-climate-pollutants (SCLPs).

They may have a short lifespan in the atmosphere, but their impact on the climate, the environment, and human health is anything but sweet.

NOx for example has almost 300 times the global warming potential (GWP) as CO2, while hydrofluorocarbons (HFC) are almost 15,000 times as powerful. They also harm ecosystems (NOx for example increases the concentration of nitrogen), while also aggravating heart and respiratory diseases (tropospheric ozone and black carbon are the biggest villains in this story) (see Blue sky thinking: As climate policy splutters, governments should sell the benefits of clean air).

In the absence of government policy tackling superpollutants, there is a clear case for the verified carbon market (VCM) to help fill the gap and start putting a price on CH4, NOx and other superpollutants. As this article will show, significant near-term impacts on the climate can be achieved, and at relatively low cost.