HOW A CARBON-EMITTING ATOM-SPLITTING SPECIES THREATENS TO TURN A LIVING PLANET INTO A RADIOACTIVE, +3 to 6 DEGREES CELSIUS, HIGH SEA LEVEL WORLD
Earth and paleo-climate scientist
Australian National University
The sensitivity of the Earth’s atmosphere to anthropogenic carbon gases has been underestimated. As the orgy of burning carbon products of 400 million, biological evolution continues unabated, a Faustian bargain pushed by business, advertisers and consumption-promoting governments, global warming proceeds at a pace faster than projected by the IPCC (Houghton et al., 2001; Rahmstorf, 2007), tracking toward likely climate tipping points. The science fiction-like specter of global warming precludes many from discriminating between the climate and the weather. A well financed denial syndrome frustrates 11th hour attempts at mitigation. Governments, caught between the climate and fossil fuel interests, debate woefully inadequate carbon emission targets (Garnaut, 2008) unlikely to stabilize the rise of temperature, migration of climate zones, sea level and storm intensities (Anderson and Bowes, 2008). Only a global strategy aimed at immediate deep cuts of carbon gas emissions, innovation of technology for CO2-sequestration and down-draw to levels below 350 ppm (Hansen et al., 2008), albedo enhancement over polar regions and fast tracked reforestation campaigns may be capable of mitigating the worst consequences of runaway global warming. As time goes on, in an increasingly stressed world, the possibility of a nuclear conflagration of hair-trigger missile fleets, by accident or design, becomes a probability. Hapless populations are faced with the non-choice between a greenhouse summer and/or a nuclear winter. Over most of the world, leaders are involved in power games instead of the truth and right and wrong issues. Will the powers to be, always willing to use $trillions to bomb peasants in remote corners of the globe (in the name of freedom and democracy), or rescue corrupt bankers, be able to protect the young, future generations and nature?
‘The sleep of reason produces monsters’ (Francisco Goya)
The climate crisisBy contrast to the frozen surface of Mars (0.006 bar; -140oC to +20oC) and the greenhouse atmosphere of Venus (92 bars; 467oC), the Earth’s atmosphere (1 bar)) buffers a surface temperature range of -89oC to +57.7oC through the absorption/ emission effect of infrared radiation by greenhouse gas (GHG) molecules (H2O, CO2, CH4 [methane], N2O), allowing liquid water at the surface and thereby life. Had GHG been absent the Earth surface would have been several tens of degrees colder. Primary energy sources of the atmosphere and oceans are derived from solar radiation, terrestrial heat flow, volcanism and hydrothermal activity, reinforced or mitigated by feedback effects from the hydrosphere, cryosphere and biosphere. These processes include changes in CO2 solubility in the oceans, drying or flourishing vegetation, and the activity of animals. Ocean currents and winds controlled by temperature gradients, salinity and continent-ocean-mountain patterns redistribute the primary and feedback energy forcing effects. During glacial eras the polar continental ice sheets and sea ice provide powerful feedback effects through an increase or decrease in albedo and the exposure or closure of heat absorbing ocean surface areas. Clouds increase the albedo as well as act as a greenhouse warming medium. Short term rises in aerosols (volcanic eruptions, dust storms) affect the Earth’s albedo.Since 1750 carbon emission from human industry and land clearing resulted in the rise of CO2 levels by ~38%, triggering atmospheric energy rise of +1.6 W/m2 [Watts per square metre], methane levels by 150% (+0.45 W/m2), and N2O +0.15 W/m2 (IPCC, 2007), a rate of increase unrecorded in the recent history of Earth. The total energy rise of the climate system during 1961-2003 represents a near-3 fold acceleration of global warming. Increased evaporation due to surface warming results in higher atmospheric water vapor content and precipitation, often associated with cyclones, over tropical and subtropical zones. By contrast mid-latitude zones are drying up due to polar-ward migration of climate zones by near-400 km (Hansen et al. 2007, 2008), the Murray-Darling being an example. Increased atmospheric CO2 levels result in ocean acidification due to an increase in the role of carbonic acid, decreasing the pH by 0.1, with effects on marine fauna and coral reefs such as the Great Barrier Reef. Changes associated with the 20th century GHG rise include rise in solar insolation (+0.06 – 0.30 W/m2) during the first half of the 20th century (Solanki, 2002, 2004), albedo rise due to sulphur aerosols released by carbon burning (-0.5 W/m2), cloud formation (-0.7 W/m2) due to rising temperatures and land clearing (-0.2 W/m2). The relation between GHG and temperature is calibrated by the parameter of Climate Sensitivity, estimated with a mean value of 3oC per doubling of CO2 levels. The rise of CO2 from 280 to 387 ppm [parts per million] since the 19th century corresponds to temperature rise of ~1.1oC, above the measured mean global temperature rise of ~0.8 oC, though carbon cycle feedbacks and ice melt-water interaction push this value further upward.
The critical role of CO2 and CH4 in governing past climates is demonstrated by correlations of palaeobotanical evidence (plant stomata pore density), glacial sediments and carbon mass balance calculations (Berner, 2004; Beerling and Berner, 2005; Royer, 2006; Royer et al., 2004, 2007; Ruddiman, 2003). Ice core records of the last 740,000 years leave little doubt regarding the role of CO2 and CH4 during the glacial-interglacial Milankovic cycles and Dansgaard-Oeschger (D-O) ~1470 years-long cycles (Ganopolski and Rahmstorf, 2001) during the last ice age. The emission of over 305 Gigatons of Carbon since the industrial revolution resulted in conditions not known since the last interglacial termination 124,000 years-ago and are tracking toward conditions analogous to the mid-Pliocene (~3.0 Ma) when CO2 levels reached ~400 ppm, temperatures rose by 2-3oC relative to the 20th century and sea level rose by 25+/-12 metres (Dowsett et al., 2005; Haywood et al., 2005; Zachos et al., 2001; Gingerich, 2006). Climate impasse developments through the late 20th century and the early 21st century include:
A. Atmospheric CO2 rates, rising to 2.2 ppm/yr in 2007, exceed 1850-1970 rates by factors of ~4 to 5, two orders of magnitude higher than mean CO2 rise rates of the last glacial termination (~0.014 ppm/yr).
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).