Fresh out of meetings at the Heartland Institute (earlier involved in tobacco promotion) supported by the American Enterprise Institute, which received $1,625,000 from Exxon-Mobil between and 1998 and 2005, and an initial meeting with Penny Wong and our chief scientist, you’ve told the ABC, “So far I don’t think there’s been a real debate about the science” and “Let’s actually explore that.”
Unfortunately the climate is not waiting for your “exploration.”
So I’ve prepared some notes for you for your additional meeting with Penny and co.
According to a new paper titled “Is the climate warming or cooling by Easterling and Wehner (Geophysical Research Letters, 2009) global warming trend is tracking toward 3 or 4 degrees Celsius through the 21st century, likely including pauses, namely multi-year to a decade-long or two decades-long periods of cooling inherent in the ENSO (El-Nino La Nina) cycle to date.
Peaks in the trend represent El-Nino events (warming and droughts in some regions), whereas troughs represent La-Nina events (cooling and heavy rainfall in some regions). Such projected irregularities would continue trends observed during 1975-2009.
The paper states:
Numerous websites, blogs and articles in the media have claimed that the climate is no longer warming, and is now cooling. Here we show that periods of no trend or even cooling of the globally averaged surface air temperature are found in the last 34 years of the observed record, and in climate model simulations of the 20th and 21st century forced with increasing greenhouse gases. We show that the climate over the 21st century can and likely will produce periods of a decade or two where the globally averaged surface air temperature shows no trend or even slight cooling in the presence of longer-term warming.
Society may be lulled into a false sense of security by smooth projections of global change. Our synthesis of present knowledge suggests that a variety of tipping elements could reach their critical point within this century under anthropogenic climate change. The greatest threats are tipping the Arctic sea-ice and the Greenland ice sheet.
“Good news” for climate skeptics, who will be able to continue to confuse people no-end based on La-Nina pauses … Not so “good news” for future generations!
It is not clear from these projections whether, or at what point, tipping points which may overprint the oscillating warm/cool ENSO pattern. Tipping points refer to the critical threshold at which a minor perturbation of the climate system can qualitatively alter the state or development of a system. In principle, early warning systems could be established to detect the proximity of some tipping elements.
Major consequences of the trend include warming in the north Atlantic and sea level rise. Other potential tipping elements include:
- Melting of the West Antarctica ice sheet.
- Collapse of the Atlantic thermohaline circulation, regional cooling and southward.
- Shift of the inter-tropical convergence zone.
- Intensification and rise in frequency of the El-Nino Southern Oscillation, with consequent droughts in SE Asia and elsewhere.
- Retardation of the Indian summer monsoon and consequent droughts.
- Extension of the Sahara/Sahel and West African monsoon one positive outcome of global warming.
- Reduction of the Amazon rainforest and biodiversity loss.
- Reduction of the Boreal forest.
- Reduction of circum-Antarctic ocean vertical circulation (bottom water formation) associated with ocean warming, reducing ocean CO2 storage.
- Increase in Tundra tree cover.
- Reduction in permafrost and in marine methane hydrates, threatening methane and CO2 release.
- Oceanic anoxia and marine life extinction.
- Reduction in Arctic ozone and increase in UV radiation at the surface.
Should the Atlantic Thermohaline Circulation (Gulf Stream) fail, deeper cooling would occur in western Europe and northeast America, associated with advanced melt of Greenland glaciers, similar to events 11,700 years ago and 8200 years-ago. Similar cooling of unspecified length, followed by further warming, may occur in connection with the melting of Antarctic ice sheet.
Of critical importance is the ability to predict the time table of tipping elements in advance, to help mitigate or retard the process. Such potential advanced warning may be provided by activity lulls associated with an approach to critical tipping points.
According to a recent paper by Dakos and others (2008, Proceedings of the National Academy of Science) abrupt tipping points may be preceded by slowing down of the fluctuations starting well before the actual shift, as shown by analyses of eight ancient abrupt climate shifts, potentially allowing an early warning signal for upcoming catastrophic change. We should be so lucky…
And, according to Eby et al. 2008 (“Lifetime of Anthropogenic Climate Change: Millennial Time Scales of Potential CO2 and Surface Temperature Perturbations“, while it will take centuries for anthropogenic CO2 to be naturally sequestered from the atmosphere, the consequent warming “will persist for many millennia.”