2 May, 2017
Chalk up another climate milestone
Atmospheric carbon dioxide concentrations hit 410 parts-per-million last week, the highest they've been in more than 15 million years. The last time there was this much carbon dioxide in the atmosphere, global temperatures were 3deg to 6deg warmer and New Zealand was a very different place; inland Otago was dominated by a lake full of crocodiles and covered in Eucaplytus and other Australian forests.
The 410ppm record was taken at the Mauna Loa Observatory in Hawaii on Tuesday last week. The Southern Hemisphere isn't far behind. A reading at Baring Head in Wellington last Thursday was 401ppm, and National Institute of Water and Atmospheric Research scientists expect it to climb over winter. Bearing Head is the longest-running record in the Southern Hemisphere. When scientists started taking records there in 1972, carbon dioxide concentrations were around 325ppm.
It's now a year since New Zealand and other countries signed the Paris Agreement on climate change, promising to hold global warming to no more than 2deg, and hopefully to 1.5deg. At the current rate of global greenhouse gas emissions, the carbon budget to achieve the 1.5deg goal will be burned up in five years, with the 2deg milestone about 10 years behind.
Source: Friday Offcuts