B. A rise of mean global temperature of more than 0.8 oC since 1850 and 0.6 oC since 1975-6. Mean temperature rise rates of 0.016C/year during 1970 - 2007 were about an order of magnitude faster than during 1850-1970 (0.0017C) and during the last glacial termination.
C. As indicated by paleo-temperature studies (δ18O and δD - deuterium) [stable isotope proxies for temperatures] studies of Greenland ice cores (Broecker, 2000; Braun et al., 2005) the atmosphere is amenable to abrupt climate changes and tipping points. Thus the last termination (14.7 – 11.7 kyr) [kyr = thousand years] displays extreme temperature changes on the scale of several degrees C in a few years (Steffensen et al., 2008) to decade scale (Alley, 2003; Kobashi et al., 2008), testifying to an extreme sensitivity of the atmosphere and the possibility of climate impasse tipping points.
D. The rise of mean Arctic and sub-Arctic temperatures in 2005-2008 by near +4oC relative to mean 1951 – 1980 values. Polar ice caps, commonly referred to as the “canary in the coal mine”, offer a sensitive parameter for global temperature changes, which they exceed by about a factor of X2.
E. Arctic Sea ice melt rates of ~5.4% per-decade since 1980, increasing to >10% per year during 2006-2007 (National Snow and Ice Data Centre [NSIDC], 2008) have surpassed the IPCC estimates.
F. West Antarctica warming and ice melt rates >10% per decade, culminating in mid-winter ice shelf breakdown (Wilkins ice shelf; June, 2008, NSIDC, 2008).
G. Advanced melt of the Greenland ice sheet of 0.6% per-year between 1979 and 2002 (Steffen and Huff, 2002; Frederick et al., 2006).
H. Slow-down of the North Atlantic thermohaline conveyor belt and down-welling water columns (NASA, 2004; Bryden et al., 2005), with attendant danger of its cessation analogous to conditions ~8.2 kyr ago (Alley et al., 1997, 2003).
I. Temperature projections for the North Atlantic Ocean (Keenlyside et al., 2008) may reflect the effect of Greenland ice melt waters, which may lead to transient cooling similar to events recorded in ice cores at ~12,900 – 11,700 (Steffensen et al., 2008) and ~8200 years-ago.
J. Increased frequency and intensification of categories 4 and 5 hurricanes (Webster et al., 2005). An overall increase in the intensity of extreme weather events, i.e. cyclones, floods and fires associated with high summer temperatures.
K. Mean sea level rise rate of ~0.32 cm/yr during 1988-2007 more than doubled relative to the mean ~0.14 cm/yr rate of 1973-1988 and three times those of 1850-1970 (Rahmstorf, 2006). In so far as doubling of sea level rise rates continues at this rate through the 21st century, they may approach rates similar to those of the last glacial termination (1.3 – 1.6 cm/yr) before mid-century, with sea level rise by several metres toward the end of the century as estimated by Hansen et al (2007).
L. Polar-ward migration of climate zones associated with the contraction of the Antarctic wind vortex, resulting in increase in temperature and decrease in rainfall in much of southern Australia, in particular the southwest and the southeast.
M. Increased frequency of the El-Nino events of the ENSO cycle, resulting in increased droughts in northeast Australia, India and parts of east Africa.
N. Methane (CH4), which after ~20 years has X23 times the greenhouse warming effect of CO2, rose by 10 ppb during 2007 (http://web.mit.edu/newsoffice /2008/techtalk53-7.pdf), exceeding the 1850-1970 rise rate (c. 5.4 ppb/yr) and orders of magnitude faster relative to the last glacial termination. Methane deposits vulnerable to small temperature rise reside in permafrost (~900 billion ton Carbon - GtC), high latitude peat lands (~400 GtC), tropical peat lands (~100 GtC), vegetation (~650 GtC) and methane hydrates in the ocean and ocean floor sediments (> 16,000 GtC).These concentrations exceed the atmospheric level of carbon (~750 GtC), carbon emissions to date (~305 GtC) and known economic carbon reserves (>>4000 GtC). Elevated methane release from Arctic Sea sediments and sub-Arctic permafrost were recently recorded (Walter et al., 2006; Rigby, 2008). Large scale release of methane is considered the trigger for the Paleocene-Eocene mass extinction at 55 Ma (Wing, 2003; Sluijs et al., 2007). Release of CO2 and methane associated with volcanic and impact events constituted a major factor associated with at least four of the five mass extinction of species, including the Permian-Triassic (~251 Ma), end-Triassic (~200 Ma), end-Jurassic (~145 Ma) and end-Cretaceous (~65 Ma) (Glikson, 2005, 2008).
B. The denial syndrome
For the last 20 years or so, through numerous public presentations, articles published in economic and social journals (but rarely in the peer-reviewed scientific literature), extensive media exposure and intense political lobbying, so-called climate change “skeptics,” many of whom affiliated with right-wing groups and fossil fuel corporations, have attempted, and continue to deny the reality of climate change, or interpret global warming in terms of natural processes, or claim it is beneficial.
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