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Ozone

Carbon Dioxide Levels Reach Unprecedented Highs: But Catastrophic Climate Change Can Still be Avoided

Alan Miller's picture

 Courtesy of World Meteorological Organization
Graph shows concentrations of atmospheric Co2 for the last 800,000 years, with measurements, starting from 1958, made at Mauna Loa in Hawaii. - Image courtesy of World Meteorological Organization

Scientists monitoring atmospheric concentrations of CO2 from a mountaintop in Hawaii recently reported that the presence of this greenhouse gas exceeded 400 parts per million (ppm) for the first time in at least three million years – a period when temperatures were much warmer than today. The significance of this seemingly dry statistical trend is stunning as reported in the New York Times:

From studying air bubbles trapped in Antarctic ice, scientists know that going back 800,000 years, the carbon dioxide level oscillated in a tight band, from about 180 parts per million in the depths of ice ages to about 280 during the warm periods between. The evidence shows that global temperatures and CO2 levels are tightly linked.

In addition to the location in Hawaii, several other Global Atmosphere Watch stations from the Arctic to the Equator reported CO2 concentrations exceeding 400ppm.

Experts believe that in order to limit warming to 2°C – a goal based on expected impacts – concentrations should rise to no more than 450 ppm, a level we may reach in only about 25 years based on current trends.

Celebrating 25 Years of the Montreal Protocol - and Looking Ahead

Rachel Kyte's picture

The world’s leaders set a high bar when they adopted the Montreal Protocol, which has helped protect the Earth’s protective ozone layer for the last 25 years. Even with its ambitious goals, the treaty won universally ratification – 197 parties have agreed to legally binding reduction targets to phase out ozone-depleting gases, and they have stuck to them.

The result: we, as a global community, have almost completely phased out the use of 97 substances that were depleting the ozone layer.

It’s a success worth celebrating, but we can’t rest on our laurels. We phased out CFCs, once used for cooling most refrigerators on the planet, but some of their replacement gases have become a climate change problem we still have to contend with.

The CFCs story showed that the world can move at speed and scale to reduce environmental threats. Scientists realized that CFCs were depleting the ozone layer in 1974. The ozone hole over Antarctica became common knowledge in the 1980s and helped drive global action which led to the Montreal Protocol being adopted in 1987.

Celebrating 25 Years of the Montreal Protocol - and Looking Ahead

Rachel Kyte's picture

Ozone depletion reached its highest level in 2006, NASA monitoring found.
The world’s leaders set a high bar when they adopted the Montreal Protocol, which has helped protect the Earth’s protective ozone layer for the last 25 years. Even with its ambitious goals, the treaty won universal ratification – 197 parties have agreed to legally binding reduction targets to phase out ozone-depleting gases, and they have stuck to them.

 

The result: we, as a global community, have almost completely phased out the use of 97 substances that were depleting the ozone layer.

 

It’s a success worth celebrating, but we can’t rest on our laurels. We phased out CFCs, once used for cooling most refrigerators on the planet, but some of their replacement gases have become a climate change problem we still have to contend with.