Andrew Glikson: Trends and tipping point in the climate system: portents for the 21st century

Trends and tipping point in the climate system: portents for the 21st century 


Andrew Glikson (Earth and Palaeo climate science , Australian National University )

Mass extinctions in the history of Earth occurred when the  atmosphere-ocean-land carbon and oxygen cycles, on which the  biosphere depends, have been perturbed at rates to which species could not adapt. Rising atmospheric greenhouse gas levels above  330 ppm CO2 at rates of ~2 ppm/year and mean temperature rise of ~0.02 oC/year since 1975 and 1976 are driving the fastest climate change trend recorded since about 34 million years ago,  representing a critical climate threshold leading into uncharted  territory and threatening the biosphere and human civilization. It is suggested the arrest of carbon emissions may not be sufficient to  halt the current trend, except if accompanied with global efforts at drawdown of atmospheric CO2 using a range of bio and sequestration,  organic and chemical methods.