Cutting carbon dioxide emissions alone cannot prevent catastrophic global warming. But a new study concludes that a strategy that simultaneously reduces emissions of other widely neglected climate pollutants would halve the rate of global warming and give the world a chance to keep the climate safe for humanity.

Published this week by the Proceedings of the National Academy of Sciences, the study is the first to examine the importance of reducing non-carbon dioxide climate pollutants in relation to the mere reduction of fossil fuel emissions, both in the short and medium term.

It confirms growing fears that the current almost exclusive focus on carbon dioxide cannot in itself prevent global temperatures from exceeding 1.5 degrees Celsius above pre-industrial levels, the internationally accepted barrier beyond which the world climate is expected to surpass irreversible inflection points.

In fact, this decarbonization alone would hardly prevent temperatures from exceeding even the much more dangerous limit of 2 degrees Celsius.

The study – conducted by scientists at Georgetown University, Texas A&M University, Scripps Institution of Oceanography at UC San Diego and others – concludes that the adoption of a dual strategy that simultaneously reduces emissions of carbon dioxide and other climate pollutants would reduce the rate of warming. by 2050, making it much more likely to stay within these limits.

Non-carbon dioxide pollutants include methane, hydrofluorocarbon refrigerants, black carbon soot, tropospheric ozone air pollution, as well as nitrous oxide. The study calculates that together these pollutants currently contribute almost as much to global warming as carbon dioxide. As most of them last little time in the atmosphere, cutting them slows down warming faster than any other mitigation strategy.

So far, however, the importance of these non-carbon dioxide pollutants has been underestimated by scientists and policymakers and largely overlooked in efforts to combat climate change.

Recent reports from the Intergovernmental Panel on Climate Change conclude that cutting fossil fuel emissions – the main source of carbon dioxide – decarbonises the energy system and switching to clean energy, in isolation, it actually worsens global warming in the short term. This is because the burning of fossil fuels also emits sulfate aerosols, which act to cool the climate, and these are reduced along with carbon dioxide when switches to clean energy. These cooling sulfates fall from the atmosphere rapidly, in days or weeks, while much of the carbon dioxide lasts hundreds of years, leading to general warming in the first decade or two.

The new study explains this effect and concludes that focusing exclusively on reducing fossil fuel emissions can result in "weak, short-term warming," which could cause temperatures to exceed the 1.5 degrees Celsius level by 2035 and the 2 degrees Celsius level by 2050.

In contrast, the dual strategy that simultaneously reduces non-carbon dioxide pollutants, especially short-lived pollutants, would allow the world to stay well below the 2 degree Celsius limit and significantly improve the chance of remaining below the 1.5 degree Celsius target.

In fact, an important insight from the study is the need for climate policies to address all pollutants emitted from fossil fuel sources, such as coal plants and diesel engines, rather than considering just carbon dioxide or methane individually, as is common.

Continuing to reduce carbon dioxide emissions from fossil fuels remains vital, the study emphasizes, as this will determine the long-term climate's fate beyond 2050. The phasing out of fossil fuels is also essential because they produce air pollution that kills more than eight million people each year and causes billions of dollars in damage to crops.

Combating carbon dioxide and short-lived pollutants at the same time offers the best and only hope of humanity reaching 2050 without triggering irreversible and potentially catastrophic climate change.

Source: EcoDebate