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May 5, 2009

Plimer wants to talk science? OK, here goes...

Given that Ian Plimer has written today in The Australian that no "critic has argued the science" with him, I thought I'd have a go.

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“Critics, who have everything to gain by frightening us witless with politicised science, have now shown their true colours. No critic has argued science with me. I have just enjoyed a fortnight of being thrashed with a feather.” — Ian Plimer, today’s Australian

Bold claims that the science is “missing” from the extensive research conducted by the world’s premier research bodies (Hadley-Met, NASA, Potsdam-Oceanographic, CSIRO, Tindall, National academies of science) need to be backed by evidence. The argument that figures reported in thousands of peer-reviewed science journal papers and complied by International and government panels (IPCC, Stern, Garnaut) are wrong and amount to attempts at reinvention of the basic tenents of physics and chemistry of climate science needs to have solid science behind it.

These are the kinds of arguments in Plimer’s book “Heaven and Earth: Global Warming – The Missing Science”.[1] But he doesn’t back them up.

And given that he’s written today in The Australian that no “critic has argued the science” with him, I thought I’d have a go.

The book overlooks the effects of more than 305 billion ton of carbon (GtC) emitted since the 18th century, nearly 42% of the total atmospheric inventory of 750 GtC, which pushed CO2 levels to 387 ppm, 38% higher than the maximum of 280 ppm of the last 2.8 million years of glacial-interglacial Earth history. [3]

The consequent increase in the energy level of the atmosphere (1.6 Watt/m2 ~1.2 degrees C) (IPCC-2007), once the masking effects of emitted sulphur aerosols are taken into account, are manifest around the globe [2].

Further to numerous errors indicated earlier, Plimer’s book claims current global warming is a natural event consistent with climate variability through time and attributed primarily to the sun.

The book negates the well documented consistent relations between climate and carbon gases, which through the Earth’s history resulted in temperature changes in the range of several degrees C [4], including abrupt climate changes and related mass extinction of species [5].

The book exaggerates the effects of the sun. However, since the 18th century the overall rise of solar insolation accounts for no more than 0.12 Watt/m2 (about 0.1 degrees C), an order of magnitude less than the CO2 greenhouse effect [2].

A marked rise in insolation by about 0.3 Watt/m2 during the first half of the 20th century stabilized since the 1970s at +/-0.1 degrees according to the 11 years sunspot cycle, a period during which Earth warmed by about 0.6 degrees C due to the rise in CO2 [6].

Thus, Solanki et al. 2005 state:

“Although the rarity of the current episode of high average sunspot numbers may indicate that the Sun has contributed to the unusual climate change during the twentieth century, we point out that solar variability is unlikely to have been the dominant cause of the strong warming during the past three decades.” [6]

The book attempts to discredit national and international climate research reports, primarily the Intergovernmental Panel on Climate Change, to which the world’s leading climate scientists have contributed. By contrast, as shown by the tracking of CO2, temperature and sea level rises since 2001 at the top of IPCC projections [7], the IPCC reports appeared to err on the conservative end.

Lost in the current climate wars is an appreciation of the sensitive balance between the physical and chemical state of the atmosphere and the biosphere, which has controlled the emergence, survival and demise of species, including humans, and whose disruption resulted in abrupt climate shifts and mass extinction of species.

During human history even minor global mean temperature changes of +/-0.3 degrees C resulted in regional droughts and the collapse of agriculture, such as along the great river valleys the Nile, Euphrates, Indus and Yellow River.

The book underestimates the sensitivity of the atmosphere to external forcings, such as posed by massive injections of greenhouse gases with related carbon cycle and ice melt/water feedback effects. Leading US climate and paleoclimate scientists state:

“Large, abrupt, and widespread climate changes with major impacts have occurred repeatedly in the past, when the Earth system was forced across thresholds. Although abrupt climate changes can occur for many reasons, it is conceivable that human forcing of climate change is increasing the probability of large, abrupt event.” [8]

The book takes little account of the intimate relations between the greenhouse effect and the history of the atmosphere. By contrast to Venus, with its thick blanket of greenhouse gases, or Mars with its thin atmosphere, the modulation of the Earth’s atmosphere by trace Carbon gases, CO2 and methane, allows surface temperatures in the approximate range of -50 to +50 degrees C, presence of liquid water and thereby of life.

Significant increases in the level of carbon gases triggers powerful feedbacks. These include ice melt/warm water interaction feedback, further release of CO2 from the oceans and drying/burning vegetation, shifts of climate zones toward the poles, reduced capacity of the oceans to absorb CO2 and ocean acidification, documented by the IPCC [2].

The Antarctic ice sheet formed some 34 million years ago when temperatures plunged associated with the decline of CO2 levels below 500 ppm [9]. Combined with methane, current CO2-equivalent levels are tracking toward 440 ppm. Large land-based mammals, whose breathing mechanism is adapted to glacial-interglacial climates, did not exist on a greenhouse Earth warmer by several degrees C relative to the present.

About 3 Ma-ago, CO2 rise to about 400 ppm and temperature rise by about 2 to 3 degrees C resulted in a sea level rise of 25+/- 12 meters. About 124 thousand years ago, during the Emian interglacial, mean global temperatures rose by about 1 degrees C and sea levels by 6 to 8 meters [10].

These relations indicate a ratio of sea level rise to temperature rise of at least 5 metres/1 degree C. With mean temperatures tracking at the top of the IPCC projections toward 2 – 4 degrees C later in the century, low fertile delta regions and urban coastal population world-wide will be flooded. So much for the “beneficial” global warming promulgated in the book.

Continuing emissions of CO2 reaching levels as high as 400 ppm, as at 3 million years ago, or 500 ppm as at 34 million years ago, embodies a similar logic as hypothetical open-ended influx of acid into the oceans, “rationalized” by the fact seas were acid during past periods of Earth history. That East Antarctic is still holding its ice does not justify further emission of hundreds of billion tons of carbon before this last part of the cryosphere is lost.

Carbon emission reductions aimed at an upper temperature level of 2 degrees C [11] may overlook carbon cycle feedbacks, methane release, ice melt feedback effects, and possible climate tipping points.

I’ve included all of my footnotes. See below.

[1] “Heaven and Earth: Global Warming – The Missing Science” by Ian Plimer. Connor Court Publishing, 2009)

[2] http://www.ipcc.ch/; http://ipcc-wg1.ucar.edu/wg1/wg1-report.html; http://www.garnautreview.org.au/CA25734E0016A131/pages/home; http://www.hm-treasury.gov.uk/sternreview_index.htm; http://americasclimatechoices.org/; http://books.nap.edu/collections/global_warming/index.html

[3] http://www.sciencemag.org/cgi/content/abstract/311/5768/1747; http://www.agu.org/pubs/crossref/2006/2006GL027817.shtml; http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V62-414P195-5&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=2f2cfd319d56a702ab8adb95773bd442;

[4] http://www.pnas.org/content/105/2/407.full?ck=nck; http://www.soest.hawaii.edu/GG/FACULTY/POPP/Royer%20et%20al.%202004%20GSA%20Today.pdf; http://www.sciencemag.org/cgi/content/abstract/292/5517/686?siteid=sci&ijkey=NBnP2T9W00vlw&keytype=ref; http://www.google.com.au/search?sourceid=navclient&aq=t&ie=UTF-8&rlz=1T4PCTA_enAU204AU206&q=hansen+2007+trace+gases; http://arxiv.org/abs/0804.1126

[5] http://www.amazon.com/Under-Green-Sky-Warming-Extinctions/dp/006113791X; Keller, 2005 (AJES v. 52 No 4 and 5); http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V61-4GCX1MR-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=8aae6e7978f2eeaaaaaf7212b44f140c; http://www.amazon.com/Speed-Violence-Scientists-Tipping-Climate/dp/0807085774/ref=pd_bxgy_b_img_b#reader; http://www.amazon.com/Six-Degrees-Future-Hotter-Planet/dp/142620213X/ref=pd_bxgy_b_img_b;

[6]http://scholar.google.com.au/scholar?q=Solanki+2002+solar+variability&hl=en&safe=off&rlz=1T4PCTA_enAU204AU206&um=1&ie=UTF-8&oi=scholart; http://www.nature.com/nature/journal/v431/n7012/abs/nature02995.html
[7] http://www.sciencemag.org/cgi/content/abstract/sci;316/5825/709
[8] http://www.sciencemag.org/cgi/content/abstract/299/5615/2005; http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V62-414P195-5&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=2f2cfd319d56a702ab8adb95773bd442;

[9] http://www.nature.com/nature/journal/v451/n7176/full/nature06588.html

[10] http://www.agu.org/pubs/crossref/2008/2008EO490001.shtml; http://geology.geoscienceworld.org/cgi/content/abstract/28/12/1063

[11] (http://www.nature.com/nature/journal/v458/n7242/full/nature08017.html)

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