The Earth’s poles serve as critical “thermostats” for the rest of the planet, with major effects on global temperatures due to their high albedo, polar wind vortexes and cold ocean currents.
Since the 1980s mean temperatures at the Earth’s poles have risen faster, by a large factor, than rises in mid and low latitudes, due to the feedback effects which combine decreased albedo of melting ice sheets, and absorption of infrared and warming of exposed water, which in turn further re-melt ice.
In 2008, surface temperature anomalies in the Arctic and northern Siberia, the Antarctic Peninsula and parts of west Antarctica have risen by near-3.5 degrees C higher than the base period of 1951-1980, while global mean in 2008 was 0.44 degrees higher than the base period.
In Antarctica new satellite and surface-based analysis indicates surface temperatures rose by 0.12 degrees C per decade between 1957-2006, namely 0.5 degrees C in the last half century, with maximum rise in west Antarctica of 0.17 degrees C per decade.
Recent studies which correlate atmospheric CO2 levels with the appearance and disappearance of the polar ice sheets, define thresholds at levels no higher than about 500 parts per million CO2 — within the range of the Garnaut report’s alternative targets of 450-550 ppm.
This suggests that, depending on ice melt lag effects, at the current CO2 growth rate exceeding 2 ppm/year (for 2005-2009) (at Mouna Loa), by mid-century CO2 levels and temperatures will rise to levels at which not much ice will be left in he northern hemisphere, and much less ice left in Antarctica.
At a current CO2 rise rates of ~2.2 ppm/year, CO2 levels by mid-century would reach 470-480 ppm (current 387 ppm, plus ~90 ppm to 2050), even without considering CO2-rise due to feedback effects. This corresponds broadly to ~0.5 degrees C rise.
Such a rise, combined with carbon cycle and ice melt/water feedback effects, which are hardly specified by the IPCC AR4 2007 report, will exceed upper CO2 and temperature thresholds defined for the Greenland and Antarctica ice sheet melt conditions.
With consequent tens of metres-scale sea level rise, in contrast to IPCC projections of 0.59 metres by year 2100. The IPCC report specifically excludes “future rapid dynamical changes in ice flow” [Table SPM-1]. It thus takes little account of the evidence that temperature rises in the range of about 2 to 4 degrees C (the median levels of 21st century scenarios (Fig. SPM-5) take the Earth to a greenhouse climate state before the ice sheets formed some 34 million years ago (the end of the Eocene).
Which precedes the flourishing of large mammals, including humans, on Earth.
There is little evidence the IPCC reports, and thereby reviews such as the Stern and Garnaut reports which are partly or largely based on the IPCC, have taken the full implications of 450-550 ppm targets for the terrestrial environment and survival of civilisation into account.
Interesting problem.
I guess if Mr Glikson had simply written that the 450-550ppm targets were a recipe for the end of the world as we know it, people would’ve written in and demanded to know what the science is behind his ridiculous claims.
Instead he has written a detailed piece with references and links and it’s rather harshly described as bilge and muck. Why? So when the next writer dispenses with all the scientific detail, in an effort to connect with people like John, it can be attacked as unscientific hyperbole?
But even if Mr Glikson had managed to somehow write a piece that was both concise and clear for laypeople to understand, while still communicating the necessary scientific evidence, he would still be taken to task by people like Michelle for not sugar-coating the grim reality we face, or for not providing an easy solution that we all implement painlessly at home.
The fact is that the science of AGW is hugely complex and difficult, and that there are various interests who are only too willing to use this inherent difficulty to try and derail serious efforts to save civilisation. Mr Glikson’s article, while impenetrable to some and difficult for others (myself included), is part of an ongoing effort to bring scientific thinking into our discussions about the climate and the huge difficulties we face today.
Too much time has been wasted on differences in philosophy mimicking scientific discussion and articles like this one, with it’s prediction of massive sea-level rises, helps put nonsense like percentage point changes in our GDP into stark relief.
John Lewis, can you stop using the second person please? Its not Glikson’s fault that you’re science-illiterate. The fact that you don’t understand it doesn’t mean the rest of us don’t either.
Frankly, I think its nice that, from time to time, the media doesn’t dumb down science.
Sorry CG but until you ‘dumb down’ the science of climate change people will continue to not understand the real implications. It is only when people begin to understand the real impact of climate change with they be compelled to change their behaviour. Glikson’s article made no sense to me or probably the general ‘joe punter’ that is going to need to change to prevent the predicted climate change outcome.
We need to make climate change real and accessible – 40,000 years of temperature graphs and end of the world scenarios only make people think that they can’t do anything to change it – that’s it all too big and too scary and too past the point of no return so I’ll turn my lights on, drive my big car and enjoy it while I can.
Sorry Michelle, It is because there are those who misrepresent climate science, spreading misconceptions, that climate scientists need to present the evidence in accurate quantitative form. For those who care about the future, it should not be too hard to follow the nature of the evidence and, in so far as they still find it difficult, ask those who have been studying the Earth and its atmosphere for much of their lives to explain their observation further. Alternatively they just fall pray to snake oil merchants …
I had to listen to the painful Barnaby Joyce waffle on ABC this morning about how he ‘welcomes the debate’ about climate change. That one is straight from the playbook of the tobacco industry circa 1960, and look how well that debate turned out.