Most people associate climate change with carbon dioxide, a long-lived greenhouse gas (GHG). But scientists estimate that carbon dioxide (CO2) is only responsible for about half of the world's current warming. The other half comes from lesser known but highly potent short-lived climate pollutants (SLCPs), such as methane, black carbon, hydrofluorocarbons (HFCs) and tropospheric ozone. SLCPs have a powerful impact on global temperature and the climate system, particularly over short time horizons. For example, methane has a warming impact that is 86 times that of carbon dioxide over a twenty-year time horizon.
In the near term, taking fast, ambitious action to reduce SLCPs is vital to reducing the rate of global warming and keeping temperature rise below 1.5 degrees Celsius (2.7 degrees Fahrenheit)—an ambition that all countries signed on to as part of the Paris Agreement and an essential goal for ensuring poor and vulnerable communities are spared from climate catastrophes. Reducing SLCPs also can save lives and deliver multiple benefits for sustainable development and human well-being.
Yet despite their significance, SLCPs are not well represented in countries' national climate plans, known as nationally determined contributions (NDCs). A new WRI/Oxfam working paper published today explains why reducing SLCPs should be a big part of every country's climate and development agendas, and how countries' NDCs can produce effective and equitable actions.
1) Short-Lived Climate Pollutants Impact Health and Agriculture
Despite their esoteric name, short-lived climate pollutants matter to all of us. They're a consequence of how we produce energy, grow food, drive and cool ourselves.
Methane is perhaps the best-known SLCP, emitted as a result of oil and gas production, as well as by rice production, livestock and during the decay of organic waste in landfills and water treatment facilities. Tropospheric ozone forms as a byproduct of other air pollutants, including methane. Burning biomass for cookstoves or burning coal for electricity and household heating can produce black carbon. HFCs are a product of air conditioning and refrigeration systems, both of which are on the rise as temperatures and incomes around the world go up.
While SLCPs are often emitted from food production and everyday household practices, they can also be harmful. For example, tropospheric ozone is a health hazard and reduces crop yields, while black carbon increases the risk of heart and lung disease. At a global level, experts estimate that reducing SLCPs can prevent as much as 52 million metric tons of crop losses per year, and avoid an estimated 2.4 million premature deaths from outdoor air pollution annually by 2030.
Reducing SLCPs can therefore provide many sustainable development benefits, including poverty reduction, food security, improved health, clean energy, gender equality and more sustainable cities. However, governments should be careful to implement policies that respect and respond to community needs. For example, to reduce black carbon emissions from cooking and heating, cleaner fuels must first be readily available and affordable. However, solutions must factor in the cultural sensitivities and nuances associated with cooking in particular places and cultures in order to deliver equitable benefits to people—particularly opportunities for women and girls.
2) We Need to Reduce Short-Lived Climate Pollutants Now to Limit Global Warming to 1.5°C
Reducing SLCPs is also central to fighting climate change. SLCPs have a powerful impact on global temperature and the climate system, particularly over shorter time horizons. Despite being short-lived, they are highly potent and currently produced continuously from many sources. Significant reductions in SLCPs can avoid 0.6 degrees Celsius (1.1 degrees F) of warming by mid-century—an essential down payment on limiting temperature rise to 1.5-2 degrees Celsius (2.7-3.6 degrees Fahrenheit), the level scientists say is necessary for preventing the worst impacts. Indeed, without a focus on SLCPs, we increase the risk of overshooting 1.5 degrees Celsius of warming and triggering potential tipping points – dangerous feedback loops in the climate system that are irreversible, impossible to recover from, and which would likely disproportionately affect the world's poorest and most vulnerable communities.
How would taking early action on short-lived climate pollutants (SLCPs) and long-lived greenhouse gases (GHGs) affect global temperature increase in this century?
By 2020: We will have baked in almost 1°C of warming above pre-industrial levels
By 2040: Early action on reducing SLCPs has a noticeable impact on limiting global temperature rise in the near-term
By 2060: Without significant reductions in SLCPs, along with reductions in long-lived GHGs, global temperature increases are likely to exceed 2°C by mid-century
By 2080: Action on both SLCPs and long-lived GHGs is essential to meet the Paris Agreement’s temperature goal
By 2100: It is clear that, when taking both near- and long-term temperature trajectories into account, action on SLCPs will be critically important alongside reductions in long-lived GHGs emissions
Note: Global temperature increase relative to pre-industrial levels
Sources: Shindell et al. (2017); Shindell (2018); CCAC (2017).
3) Countries Need to Address Short-Lived Climate Pollutants in Their National Climate Action Plans
Despite the importance of reducing SLCPs, actions to mitigate these pollutants were not well represented in the first round of NDCs submitted as part of the Paris Agreement on climate change. Many countries have set broad greenhouse gas and pollution targets that do cover some SLCPs, but few have identified specific SLCP targets, actions or policies.
As Parties to the Paris Agreement look toward submitting new or updated NDCs by 2020, countries now have an opportunity to incorporate and strengthen actions to reduce SLCPs in their NDCs. Doing so will bring countries' policies in line with the Paris Agreement's ultimate purpose and temperature targets. Inclusion in new NDCs could also mobilize funding toward SLCP-reduction initiatives.
By acting on SLCPs, countries also have an opportunity to address Sustainable Development Goals (SDGs) related to air pollution, health, food security and poverty reduction. Connecting plans for reducing SLCPs to development goals can help ensure solutions that benefit the poor. The connection to development also makes climate and pollution issues more local, resonant and real for communities. Communities that view action on SLCPs as a benefit to them could provide political support for leaders who want to demonstrate more ambition on climate and development action.
How Countries Can Address Short-Lived Climate Pollutants
The new WRI/Oxfam working paper published today presents options for how countries can incorporate targets, policies and actions on SLCPs into new or updated NDCs, including:
- Expanding their NDCs' scope and coverage to cover all GHGs
- Incorporating emissions-reduction targets on individual SLCPs
- Including specific SLCP-related policies and actions
Ambitious action to reduce SLCPs offers a tremendous opportunity to reap immediate climate and development benefits, lift people out of poverty, and ensure that those least responsible for our changing climate aren't left to deal with its increasingly severe impacts.
Carni Klirs and Beth Elliott also contributed to this blog post.