Cutting Back on Soot Could Save Millions of Lives While Cooling Off the Arctic

A new report from the World Bank and the International Cryosphere Climate Initiative sums up the very significant health and climate benefits that we can bring about by cutting back on short-lived climate pollutants such as soot. Reducing black carbon emissions can also have a remarkable impact on increasing crop yields, the report notes.

"On Thin Ice" finds that the greatest way to reduce black carbon pollution is by replacing older open-air cookstoves with more modern versions using smaller amounts of or cleaner-burning fuels. Doing so could save a full million lives every year.

The negative health and climate effects of traditional indoor cookstoves, used today primarily throughout South Asia and Africa, have been well-documented. In total, roughly 3.5 million people die annually from indoor air pollution, with the pollution from these indoor open-air stoves, burning dung, charcoal, or another form of biomass, shouldering a lot of the blame.

More deaths can be averted by targeting other sorts of particulate pollution. Reducing open-field and forest burning can save 190,000 lives each year, the report finds. Europe and Central Asia will see the greatest benefit from this. Furthermore, cutting back on sooty emissions from diesel transportation and diesel-powered equipment can save 340,000 lives annually.

Reducing diesel emissions also will boost food production, with Southeast Asia seeing the greatest benefit. We could see a 16-million-ton per-year boost in crop yields of rice, soy, and wheat, the report estimates, if older, dirty, diesel engines are replaced with less-polluting alternatives. Reducing methane emissions, such as from leaky natural gas pipelines and other industrial sources, could more than double the increase in crop yields, bringing in in total  nearly an additional 34 million tons per year. Considering the negative impact on crop yields caused by warming temperatures, this is a pretty significant counterweight.

As for the climate benefits of undertaking these efforts, the report focuses on the planet’s cryosphere—those areas of the planet covered in ice and snow, which are experiencing a disproportionate and quite dramatic amount of warming and changes.

“Warming in the cryosphere,” the report warns, “poses serious threats to disaster preparedness, to water resources in some heavily populated regions, and to adaptation and ecosystem preservation.”

Ecosystem preservation in this case extends far beyond the parts of the globe covered in ice and snow. The report reminds us that warming in the Arctic resulting in the release of the massive amounts of carbon stored in permafrost, “could contribute as much as 5-30 percent more carbon to the atmosphere by the end of this century, if current cryosphere warming is now slowed.”

This additional carbon will make it even more difficult to keep global temperature rise below the critical threshold of 2° C above pre-Industrial levels, above which the risk of genuine, long-lasting, and potentially civilization-ending climate catastrophe becomes more likely.

Though not a substitute for radically reducing CO2 emissions, the report says the climate-benefits for the cryosphere from reducing black carbon pollution can be “very large” and “carry less uncertainty that they would in other parts of the globe,” due to the fact that black carbon “almost always leads to warming over reflective ice and snow.”

When black carbon soot falls on ice and snow it changes the reflectivity of that frozen surface, increasing melting beyond what would happen if it was just warming the atmosphere. In the short term this can be quite dramatic. Previous research has shown that a good deal of the observed glacier melting in the Himalaya can be traced back to soot, rather than the amount of warming that has happened so far.

In the Arctic, if short-lived climate pollutants are reduced, it could slow warming by a full degree Celsius by 2050, in turn reducing sea ice loss in summer by 40 percent, as well as reducing the amount of snow cover lost each spring by one quarter. A similar reduction in the amount of warming could be seen in the Himalayas.

None of this is a substitute for making carbon emission reductions throughout the globe, but it could keep open the window for making the crucial transition to a low-carbon, less resource-intensive economy.