According to a scientists at Hawaii's Mauna Loa Observatory, where researchers have been recording CO2 levels since 1958, the daily average has risen above 400 parts per million for the first time in about four and a half million years.
The finding, first reported in the Financial Times, is not a surprise, given recent increases and the unabating quantities of CO2 still being emitted through the combustion of fossil fuels, but it is a significant symbolic landmark for scientists and brings the world uncomfortably close to the 450 ppm mark widely predicted as the tipping point for runaway warmlng.
"The last time in the earth's history when we saw similar levels of CO2 in the atmosphere was probably about 4.5m years ago when the world was warmer on average by three or four degrees Celsius than it is today," commented professor Sir Brian Hoskins, director of the Grantham Institute for Climate Change at Imperial College London."Th ere was no permanent ice sheet on Greenland, sea levels were much higher, and the world was a very different place."
The rate of increase in CO2 concentrations has accelerated from about 0.7 ppm per year in the late 1950s to 2.1 ppm per year during the past 10 years. The average global temperature has already risen about 0.8°C since pre-industrial times as carbon dioxide levels have increased. Many scientists fear that warming of 2°C or more will cause a far less predictable climate, with many more incidents of extreme weather such as the disastrous floods and droughts many countries have experienced in recent years.
Linkedin
