Portents of climate tipping points in the atmosphere-ocean system

Linear global temperature projections portrayed by the IPCC for 2100 to 2300 are examined in perspective of the history of the atmosphere-ocean system during the last 800,000 years. Previous interglacial periods display sharp transient cooling (stadials) events in the wake of peak temperatures, consequent on the flow of cold ice melt water from the major ice sheets into the oceans. 

Such cooling is evident from weakening of the Atlantic Meridional Ocean Current (AMOC) and large pool of cold ice melt water south and east of Greenland, with major consequences for future climate trajectories. While sharp cooling occurs in the north Atlantic and Antarctic fringe oceans, advanced warming continues in intermediate land masses and in the tropics, leading to temperature polarities and consequent storminess. 

Concomitantly, a weakened jet stream separating the warming Arctic is becoming undulated, allowing penetration of cold fronts southward and warm air masses northward. Global adaptation measures need to take these projections into account. At the present stage the most important strategy to avert such consequences would be investment in CO2 down-draw measures and the channeling water from flooded to desiccated regions, such as from northern Australia to the Murray-Darling basins.

Dr Andrew Glikson, an Earth and paleo-climate scientist, graduated at the University of Western Australia. He has conducted geological surveys of the oldest geological formations in Australia, South Africa, India and Canada, studied large asteroid impacts, including effects on the atmosphere and the oceans, the effects of fire on human evolution and the mass extinction of species.