Declines in cooling sulfates combined with increases in greenhouse gas concentrations have increased the intensity and frequency of African
Excerpt from this story from Inside Climate News:
When Southern Europe was hit by aĀ catastrophic heat waveĀ last month, it dominated global news cycles. Spain experiencedĀ its longest heat wave on record: lasting 16 days with temperatures reaching 109 degrees. By August 19, wildfires stoked by the heat hadĀ torchedĀ more than 40,000 acres in France. At the peak of the heat wave,Ā 60 percent of Italian citiesĀ were placed under the highest alerts for deadly temperatures. The death toll from the heat in Europe is still being tallied, but includesĀ a four-year-old boy who died of heat stroke in Italy.
When higher-latitude, and thus cooler, regions that havenāt prepared for health-threatening high temperatures endure waves of unusual heat, they become obvious examples of heat stress brought on by a warming climate. But places that we assume are always hot have also been burdened by more extreme heat, Joyce Kimutai, principal meteorologist and climate scientist at the Kenya Meteorological Department, said.
āThere was the misconception that, because Africa is warm anyway, people are tolerant to the heat,ā she said. āI think that tolerance level is now superseded.ā
Recent researchĀ published in NatureĀ has found that the frequency and intensity of heat waves throughout Africa have increased significantly since the end of the 20th century. But the steep upward trend in temperatures on the continent is due not only to increases in the emissions that warm the climate. A decline in emissions that cool the Earthās surface is also increasing the heat.
As greenhouse gas emissions, like carbon dioxide, have been increasing, efforts to clean up energy supplies have led to a decrease in coal burning in many areas, including Africa. While reductions in coal burning substantially reduce how much carbon dioxide is emitted to warm the climate in the long term, they also reduce the emissions of sulfates that reflect some heat away from the Earth in the short term. The combination of long-term climate warming and short-term reductions in planet-cooling sulfates has increased the frequency and intensity of heat waves throughout the continent over the past 30 years.
As sunlight warms the Earthās surface, the planet sends some of this energy back to space. Carbon dioxide, methane and even water vapor in the atmosphere hold some of that heat in like a blanketāthe more of those greenhouse gases in the atmosphere, the warmer the blanket. But certain aerosolsālike sulfate particles, which are emitted along with carbon dioxide when coal is burnedāact like mirrors that reflect some solar radiation away from the planet, thus cooling it.Ā
In Africa, sulfate emissions fromĀ coal-producing and consuming countriesĀ such as Zimbabwe, Democratic Republic of the Congo and Namibia increased until the late 1980sĀ along with greenhouse gas emissions.
