The tricky task of tallying carbon
To slow or stop global warming, the world agrees it must cut carbon dioxide emissions. But monitoring each nation’s output of greenhouse gases is not always straightforward.
More than 60 years ago, atmospheric scientist Charles David Keeling began regular measurements of carbon dioxide concentrations in the atmosphere. In the heart of the Pacific and far from the largest human sources of the gas, Hawaii’s Mauna Loa Observatory was an ideal location for these measurements. Within just two years, Keeling had detected two patterns in the data. The first was an annual rise and fall as the seasons came and went. But the second — a year-by-year increase — suggested something alarming: a rise in carbon dioxide produced by the widespread burning of fossil fuels. In 1965, Keeling’s measurements were incorporated into a report for US President Lyndon B. Johnson that described carbon dioxide from fossil fuels as “the invisible pollutant” and warned of its dangers.
Since then, global emissions of carbon dioxide and other greenhouse gases have continued to rise, as have the concerns over the changes that such an atmospheric shift brings. Both of these trends took center stage this week in Madrid, where the United Nations is holding its annual climate change summit, the 25th Conference of the Parties (COP25).
Observations are still taken at Mauna Loa today, and the resulting “Keeling Curve” reveals that atmospheric carbon dioxide levels have increased by almost a third since the first measurements were taken. The world’s average temperature has already warmed by around 1 degree Celsius (1.8 degrees Fahrenheit) since preindustrial times, driving increases in everything from sea levels to the frequency of extreme weather events.
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