EarthTalk: What on Earth is “global dimming?” | Daily Loaf
Global dimming is a less well-known but real phenomenon resulting from atmospheric pollution. The burning of fossil fuels by industry and internal combustion engines, in addition to releasing the carbon dioxide that collects and traps the sun’s heat within our atmosphere, causes the emission of so-called particulate pollution—composed primarily of sulphur dioxide, soot and ash. When these particulates enter the atmosphere they absorb solar energy and reflect sunlight otherwise bound for the Earth’s surface back into space. Particulate pollution also changes the properties of clouds—so-called “brown clouds” are more reflective and produce less rainfall than their more pristine counterparts. The reduction in heat reaching the Earth’s surface as a result of both of these processes is what researchers have dubbed global dimming.
“At first, it sounds like an ironic savior to climate change problems,” reports Anup Shah of the website GlobalIssues.org. “However, it is believed that global dimming caused the droughts in Ethiopia in the 1970s and 80s where millions died, because the northern hemisphere oceans were not warm enough to allow rain formation.” He adds that global dimming is also hiding the true power of global warming: “By cleaning up global dimming-causing pollutants without tackling greenhouse gas emissions, rapid warming has been observed, and various human health and ecological disasters have resulted, as witnessed during the European heat wave in 2003, which saw thousands of people die.”
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