Some reflections on these issues by Dr Andrew Glikson, an Earth and paleo climate scientist. the comments are the start of a short essay entitled “At A Climate Tipping Point” that was published Saturday in John Menadue’s Pearls and Irritations weekly. Glikson, who graduated from UWA in 1968, is now a Visiting Fellow at ANU.
Glikson:
”According to Hans Joachim Schellnhuber, chief climate advisor to the European Union, “We’re simply talking about the very life support system of this planet”. As fascism and the horror of murderous hate crimes are spreading around the world, governments are presiding over runaway climate change which is leading toward a mass extinction of species, costing the lives of billions and the demise of much of nature, while children are protesting the betrayal of their future.
”More than 30 years since Professor James Hansen, then NASA’s chief climate scientist, presented a stern warning to the US Senate regarding the existential risk posed by global warming, the consequences of the ignorance, criminal denial and pro-carbon ideology promoted by vested interests and their accomplices among the political classes and in the media are upon us, as the climate system is shifting into a dangerous uncharted territory.
While the Earth as a whole continues to heat, transient temperature polarities between warming land masses and Arctic-derived cold air masses lead to extreme weather events.
“Evidence based on early climates and on current global warming requires revision of the mostly-linear International Panel of Climate Change (IPCC) climate change trajectories proposed for the 21st to 23rd centuries.
“The polar ice sheets, acting as the thermostats of the climate controlling the current mean Earth surface temperature of 15oCelsius, are melting at an accelerated rate. Polar temperatures have been rising at twice the rate of lower latitude zones, weakening the jet stream and the Arctic boundary, which is becoming increasingly undulated. This allows cold air masses to breach the boundary as they move southward, as happened recently in North America and Europe, while warm air masses migrate northward.
“As the large ice sheets are melting, large pools of cold ice melt water are forming in the North Atlantic Ocean south and east of Greenland (Rahmstorf et al. 2015). The AMOC (Atlantic Meridional Ocean Circulation) is slowing down and the probability of future transient freeze event/s (stadials) lasting a few decades or longer (Hansen et al. 2016) is increasing.
“The juxtaposition of polar-derived freezing fronts and tropics-derived warm air masses leads to a rise in extreme weather events.Arctic air temperatures for 2014-2018 have exceeded all previous records since 1900. According to NOAA, Arctic warming has led to a loss of 95 percent of its oldest sea ice over the past three decades.
“Reports of the IPCC, based on thousands of peer reviewed science papers and reports, offer a confident documentation of past and present processes in the atmosphere. On the other hand, when it comes to estimates of future ice melt and sea level rise rates the IPCC models are subject to a number of uncertainties. This includes the difficulty in quantifying amplifying feedbacks from land and water, ice melt rates, linear versus irregular temperature trajectories, sea level rise rates, methane release rates, the role of fires and the observed onset of transient freeze events...”
