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April 29th 2010 print

Andrew Glikson

Credibility lies with experienced authorities

Andrew Glikson: "As in other fields of science and technology, credibility lies with the respective experienced authorities and is protected, as much as humanly possible, by the peer review system."

Response to Joanne Nova

I respond to criticisms by Joanne Nova (JN) as in her article “No, Dr Glikson” (Quadrant Online, 21.4.2010) of my article “The origin and consequences of climate change” (Quadrant Online, 21.4.2010), basing my comments on recent climate change reports, including among other the Copenhagen Synthesis Report, 2009; Four Degrees and Beyond conference, 2009; Steffen, 2010 and CSIRO-BOM[1]. I point to statements inconsistent with instrumental measurements and direct observations and to misunderstanding of atmosphere/ocean climate processes.

1. The troposphere hot spot (whose presence and intensity is related to global temperatures).

JN states:The models are wrong. The “Hot Spot” is missing. The net effect of the warming due to man-made CO2 has been exaggerated”. 

Response by AG: The consequences of global warming, whether from natural or anthropogenic factors, do not in themselves identify the origin of climate change, it is the identification of the external forcings which does, i.e. solar, volcanic or anthropogenic. JN’s information regarding the troposphere hot spot (2006) is outdated. More recent studies (Sherwood et al., 2008) have identified the troposphere hot spot (see Figure 1), stating “stronger warming is shown in the Northern Hemisphere where sampling is best[2].

 Sea level rise.

JN states:If anything, instead of an up-curve, the graph has slightly flattened off. The trend is utterly predictable, except that it might be rising less fast than the predictions.”

Response by AG: JN’s figure portrays only the last stage of sea level rise, from 1993 to the present (mean SL rise rate: c. 3.2 mm/year). As is shown in Figure 2[3] sea level rise rates have increased through the 20th century from below 1 mm/year early in the 20th century to near 3.5 mm/year.

3. Melting of the cryosphere.

JN states:Then there’s the problem that global sea ice is looking fairly robust.  The Arctic has shrunk some, but the Antarctic has grown”.

Response by AG: Freezing and melting of thin sea ice constitute seasonal to perennial-scale variations.[4]  It is the decade-scale behaviour of the several kilometres-thick continental ice sheets which represents climate trends.  Arctic sea ice has declined while Antarctic sea ice fluctuates strongly with the seasons, with only about 3 to 4 million square kilometre remaining at summer’s end and with trends varying around the Antarctic continent[5].

Melting of the thick continental ice sheets includes increase in the melt extent in Greenland by about 16% from 1979 to 2002. According to Ian Allison[6] (Division and Antarctic Climate and Ecosystems CRC): “These new estimates suggest that the total annual loss from Antarctica since 1993 is around 100 billion tonnes of ice per year, equivalent to ~0.25 mm/yr global sea level rise, but the error range is large. In Antarctica, mass loss has been greatest along coastal sectors of the Antarctic Peninsula and West Antarctica, but with thickening further inland and over most of East Antarctica partially offsetting this.”

4. Ocean acidification.

JN states:It’s worth noting that fears of ocean acidification are largely theoretical and calculated, rather than based on empirical evidence” and “Atmospheric CO2 levels may have risen 30% recently, but at least in that marker, there’s no clear relationship between ocean acidity and atmospheric CO2.

Response by AG: The relations between atmospheric CO2 and oceanic CO2 are governed by partitioning coefficients dependent mainly on temperature. The transition from the carbonate ion (CO3[-2]) which calcifying organisms use to bicarbonate and carbonic acid which organisms can not use, which occurs about 8.2-8.1, is critical for marine life, as indicated by the summary statement by the symposium on “The Ocean in High-CO2 World” 6-9 October, 2008[7]

“When CO2 dissolves in seawater, carbonic acid is formed. This phenomenon, called ocean acidification, is causing seawater to become corrosive to the shells and skeletons of numerous marine organisms. It also affects the reproduction and physiology of some marine organisms. These impacts have now been detected in living organisms in several regions around the world. Within decades, the chemistry of the tropical oceans will not sustain coral reef growth while large parts of the polar oceans will become corrosive to calcareous marine organisms. These far-reaching changes will impact food webs, biodiversity and fisheries.”

5. Excess CO2 – beneficial or harmful for plants?

JN states:Overall, hundreds of studies show that plants typically grow 20-50% more biomass with higher CO2 levels.[iv]” 

Response by AG:  According to Morgan (2002)[8]:

Global climate change is expected to have ecological consequences. Field studies attempting to simulate these effects often do not investigate multiple environmental factors and may therefore miss some important feedbacks. In his Perspective, Morgan highlights the multiple-factor, 3-year field study reported by Shaw et al., who find that increasing CO2 may inhibit plant growth. Morgan discusses possible explanations for this counterintuitive result, but cautions that short-term, transient responses may not reflect the long-term ecological response.”


Writing in the journal Science, researchers concluded that elevated atmospheric carbon dioxide actually reduces plant growth when combined with other likely consequences of climate change — namely, higher temperatures, increased precipitation or increased nitrogen deposits in the soil”. "To understand complex ecological systems, the traditional approach of isolating one factor and looking at that response, then extrapolating to the whole system, is often not correct," Mooney said. "On an ecosystem scale, many interacting factors may be involved."[9]

Although JN questions an apparent absence of a troposphere Hot Spot (which would imply as if no global warming occurs) (see my Point 1 above), in other part of the article JN accepts that warming is real, as represented by ice melt and sea level rise. Elsewhere JN appears to accept humans are in part responsible, stating “we need to know how much of the recent warming has been directly due to our carbon emissions and how much has been natural”. JN further questions: “what exactly is the evidence for the theory of man-made global warming?”

Global warming constitutes the direct consequence of the emission of 370 billion tons (GtC) of carbon, namely more than 60% of the original carbon concentration of the atmosphere pre-1750 (590 GtC), as well as extensive deforestation and clearing, methane release from animals and nitric oxide release from fertilisers. Some 46% of the CO2 stays in the atmosphere (a dynamic balance which changes as the oceans warm), imparting radiative forcing of about 1.66 Watt/m2, consistent with basic physics of greenhouse gas resonance and infrared absorption/emission effects. The rise of  atmospheric CO2 concentrations from the top interglacial level of 280 ppm to the current 389 ppm, the highest level recorded since 2.8 million years ago, is proceeding at a rate of c.2 ppm/year, unprecedented in the geological record (bar major volcanic periods, asteroid impacts and eruption of methane).

As indicated by the vast peer-reviewed literature, every alternative mechanism potentially underlying climate change has been examined, including solar cycles, cosmic rays, ocean current patterns, the ENSO cycle and other factors.  Following a small rise in insolation during the first part of the 20th century (c. 0.2 Watt/m2), solar radiation follows the 11 years sunspot cycle of about c. +/-0.1 Watt/m2 since the mid-20th century, accompanied by corresponding oscillations of cosmic rays. The total rise in insolation since 1750 is estimated as c. 0.12 Watt/m2[10].

Advances in the study of the atmosphere-ocean-cryosphere system in the during the last 800,000 years using the ice cores, and during the last 34 million years using multiple proxies (fractionation of oxygen, carbon and boron isotopes between plankton, water and the atmosphere, fossil plant pores [stomata]), indicate high climate sensitivities (i.e. response of global temperatures to CO2 variations), above 5 degrees C per doubling of atmospheric CO2[11]. During the mid-Pliocene (2.8 – 3.0 million years ago) and mid-Miocene (14-16 million years ago) CO2 levels were about 400+/-50 ppm and mean global temperatures about 3 to 4 degrees Celsius higher than 18th century levels, suggesting that, at 389 ppm CO2, climate change is tracking toward similar conditions.

JN writes:
Committee reports count as “evidence” in a court of law, but in science, certificates, declarations, contracts, commission hearings, or 3000 page reports don’t mean anything. Clouds don’t give a toss about what committees predict.”

Response by AG: Courts of law don’t deal with scientific questions. Clouds follow the laws of atmospheric physics and chemistry, which climate science investigates. As in other fields of science and technology, credibility lies with the respective experienced authorities and is protected, as much as humanly possible, by the peer review system, which attempts to ensure publications are consistent with the data base, direct field observations, correct calculations and the basic laws of physics and chemistry.

The CRU E-mails. Play the ball not the man. That individual scientists used terms in personal E-mails, or objected to publication of what in their view are unfounded claims, as part of the peer review process, hardly reflect on the scientific discipline as a whole and in no way detract from the overwhelming reality of ice melting, sea level rise, the polar-ward shift in climate zones, the increasing frequency of droughts and extreme weather events around the globe.

It will be interesting to know what amount of direct observations and physical and chemical evidence for the past and present behaviour of the atmosphere-ocean-cryosphere system would convince societies to pause before continuing to use the atmosphere as an open channel for the emission of some 8 billion tons of carbon per year.

Dr Andrew Glikson, Earth and paleo-climate scientist, Australian National University


Figure 1.

Radiosond (weather balloon) measurements and models of the equatorial troposphere hot spot trend, seen to intensify from 1959-2005 to 1979-2005. Sherwood et al. 2008



Figure 2. 


A. Rate of sea-level rise obtained from tide gauge.

B. Sea level relative to 1990 obtained from observations.

Rahmstorf et al. 2007. Science 315.

[1] Richardson K. et al., Copenhagen Synthesis Report:Climate Change, Global Risks, Challenges and Decisions (http://www.anu.edu.au/climatechange/wp-content/uploads/2009/07/synthesis_report_-_01072009.pdf); Four Degrees and Beyond, 2009 (http://www.eci.ox.ac.uk/4degrees/); Steffen, W., 2009. Climate Change 2009, Faster change & More Serious Risks (http://www.anu.edu.au/climatechange/wp-content/uploads/2009/07/climate-change-faster-change-and-more-serious-risks-final.pdf); CSIRO and BOM, 2010. State of the Climate. http://www.csiro.au/files/files/pvfo.pdf

[2] Sherwood et al., 2008: Robust Tropospheric Warming Revealed by Iteratively Homogenized Radiosonde Data. American Meteorological Society, v. 21.

[3] Rahmstorf, S. et al., 2007. Science, 315. (http://www.sciencemag.org/cgi/content/abstract/1135456)

[8] Science, vol 298, pp. 1903-1904.

[10] IPCC 2007 (http://www.ipcc.ch/)

[11] Pagani et al., 2010 (http://www.nature.com/ngeo/journal/v3/n1/abs/ngeo724.html);

Schneider & Schneider, 2010 (http://www.nature.com/ngeo/journal/v3/n1/abs/ngeo736.html).