Most people are under the impression global warming has risen by about 0.8 degrees C since the dawn of the industrial age. Unfortunately, mean temperatures have risen much further when account is taken of the short-term masking effect of aerosols emitted from coal and oil, mainly sulphur dioxide and its oxidized products. Moreover, since 2005 (the last year on which the IPCC-2007 report is based) Arctic Sea ice melt has resulted in lowering of the Earth reflectance of solar radiation back to space. As sea ice melts, exposure of open water to solar radiation results in the absorption of thermal infrared radiation and thereby further warming of the oceans.
Thus, according to the IPCC AR4-2007 report (figure SPM.2), the total anthropogenic greenhouse effect since 1750 AD, which is equivalent to about +2.3 degrees C, is masked by a compensating aerosol albedo effect equivalent to about -1.1 degrees C. However, given the short-lived residence time of sulphur aerosols in the atmosphere, this masking effect dissipates within periods up to a few years.
Currently continuing emission of SO2 maintains the aerosol albedo effect, preventing further sharp temperature rises. But in a situation akin to methadone addiction, proposed reduction of sulphur emissions would lift this barrier, enhancing global warming.
A dissipation of aerosols and the melting of polar ice would raise polar temperature anomalies to levels exceeding even the current 4 to 5 degrees C warming in parts of the Arctic circle, Siberia and west Antarctica. Such high degrees of warming result from ice melt/water interaction feedback processes.
The climate change trend is highly irregular, representing an increase in climate variability with global warming, reflected by variations in the El Nino — La Nina Southern Oscillation cycle (ENSO). Sharp ENSO anomalies include the 1998 El-Nino peak (near +0.55C) and the 2007 La Nina trough (near -0.7C). Mean global temperature continued to rise during 1999-2005 by about 0.2 to 0.3C.
The irregular nature of climate change is underpinned by variations in the extent of winter and summer sea ice cover. These include:
- Reduction in the Arctic Sea multi-year ice cover from about 4.2 to 2.5 million square km during 2000-2009;
- Increase in Greenland September ice melt area from 350,000 to 550,000 square km during 1997-2007;
- Warming of the entire Antarctic continent by 0.6C and of west Antarctic by 0.85C during 1957-2006, reflected by collapse of west Antarctic ice shelves.
Variations in temperature and sea ice cover around Antarctica are effected by several factors, including (1) the shrinking polar wind vortex, which results in higher wind speed chill factors, (2) decrease in tropospheric ozone concentrations, ozone being a greenhouse gas this results in cooling, and (3) decreased in stratospheric ozone levels, which results in increased UV radiation.
By contrast, the solar sun-spot cycle effect is responsible to small variations at about +/-0.1 degrees C, an order of magnitude less than the global warming effects of greenhouse gases.
Ongoing global warming may lead to the release of methane from frozen polar and subpolar soils (permafrost), collapse of the Gulf Stream (the North Atlantic salty warm current), high-energy weather events and yet little-specified shifts in atmospheric states (tipping points).
The progress of climate change may include periods of cooling, as may be indicated by the current slow-down of Greenland glaciers. In a recent paper by Dakos et al. (2008), abrupt climate changes in the past are shown to have been preceded by quiet periods.
The implications of climate change for ecosystems are illustrated in the new book Heatstroke: Nature in an Age of Global Warming by Anthony Barnosky, of Yale University, who states:
I think probably the biggest cause for worry is we really are seeing the disappearance of whole ecological niches, which means extinctions. By the year 2100, earth will be hotter than it’s been in 3 million years. Three million years ago, probably not one species that you’re familiar with on earth today was alive. So, yes, there were species, there will be species in the future, but the problem is that the earth that people have adapted to and are familiar with will be very different in the future. We will be outside the bounds of anything humanity has ever experienced.
Given that warnings by climate scientists have proven correct, as contrasted with watered-down reports percolating upward through bureaucracies, there is little evidence the Rudd government is listening to the recent dire warnings by climate scientists, including several petitions and requests for meetings between climate scientists and ministers.
The decline by CSIRO to report directly to the recent Senate climate inquiry, reminiscent of Howard era practices, has only been saved by the courage of individual scientists, one of whom compared Labor’s targets to ‘Russian roulette with the climate system with most of the chambers loaded’.
You could be right Andrew .
In fact a man who can extrapolate and interpret figures to predict variable open ended futures can’t really be proved wrong.
I’m guessing that’s why you claim vaguely ‘Given that warnings by climate scientists have proven correct’ etc.
However the important thing at the moment is the Swine Flu.
Could you possibly use your science to help the over 350 australians who have been struck down in this global warming pandemic. These people are suffering from sore eyes, runny noses and yes … increased temperatures.
Do you think these people ( who are probably exhaling slightly warmer CO2 ) are adding to the Global Warming problem and deserve vilification or are victims like those poor polar bears ( and the people with expensive beach front houses).
These people need your help now Andrew , they don’t have time to wait for that Russian roulette solution although i do think that might work.
I’m glad to learn that you are a palaeoclimate scientist Andrew because the continued failure of those waring of AGW’s dangers to meet the simple test of retroprediction – often enough put to them – leaves me with my biggest doubts about the supposed scientific consensus. What, please, is the best answer you can give – with a plethora of links only used as subsidiary to the argument you put – to the need for any convincing model of climate change to explain 1. the collapse of the first Indus civilisation; 2. the collapse of the Egyptian Old Kingdom under the effects of drought drying up the Nile and turning the Sahara finally and forever (until now anyway) into desert; 3. the drying up of the Great Lakes of North America – all of these well after the end of the last Ice Age? If, as seems reasonable to presume in the absence of convincing contrary evidence, the global atmostpheric temperature was much higher leading in to these catastrophic climatic outcomes, why was there not a runaway feedback effect such as is now at the heart of the most doom laden predictions for the 21st century?
One or two good links you might provide however: anything showing reliably the levels of CO2 in the atmosphere by, say 100 year averages, for the last 10 million years or so. Any correlated measurements of global temperatures and ice coverage would be welcome too.
Anyone who is intereested in the nature of past and present climate changes, whether during the last few hundreds of millions of years, or during the glacial/interglacial eras, or the Holocene – including the rise and fall of civilizations due to changes in rivr flow regimes (Nile, Indus, Euphrates), only has to consult the vast scientific literature which exists in this regard. Below I list some up-to-date literature.
Some essential references:
Framework Convention on Climate Change, United Nations 1992;
http://www.unfccc.int/
Intergovernmental Panel on Climate Change (IPCC), Climate
Change 2007, Solomon S, Dahe Q, Manning M, et al. (eds), Cambridge
Univ Press: New York 2007; pp. 996.
Mastrandrea MD, Schneider SH. Probabilistic integrated assessment
of “dangerous” climate change. Science 2004; 304: 571-5.
European Council, Climate change strategies 2005; http://register.
consilium.europa.eu/pdf/en/05/st07/st07242.en05.pdf
Hansen J, Sato M, Ruedy, et al. Dangerous human-made interference
with climate: a GISS modelE study. Atmos Chem Phys 2007;
7: 2287-312.
Hansen J, Sato M. Greenhouse gas growth rates. Proc Natl Acad
Sci 2004; 101: 16109-14.
Hansen J, Sato M, Kharecha P, Russell G, Lea DW, Siddall M.
Climate change and trace gases. Phil Trans R Soc A 2007; 365:
1925-54.
Hansen J, Nazarenko L, Ruedy R, et al. Earth’s energy imbalance:
Confirmation and implications. Science 2005; 308: 1431-35.
Harvey LDD. Dangerous anthropogenic interference, dangerous
climatic change, and harmful climatic change: non-trivial distinctions
with significant policy implications. Clim Change 2007; 82:
1-25.
Matthews HD, Caldeira K. Stabilizing climate requires near-zero
emissions. Geophys Res Lett 2008; 35: L04705.
Archer D. Fate of fossil fuel CO2 in geologic time. J Geophys Res
2005; 110: C09S05.
Hansen J, Sato M, Ruedy R, et al. Efficacy of climate forcings. J
Geophys Res 2005; 110: D18104.
Charney J. Carbon Dioxide and Climate: A Scientific Assessment.
National Academy of Sciences Press: Washington DC 1979; pp.
33.
Hansen J, Lacis A, Rind D, et al. J Climate sensitivity: Analysis of
feedback mechanisms. In Climate Processes and Climate Sensitivity,
Geophys Monogr Ser 29. Hansen JE, Takahashi T, Eds. American
Geophysical Union: Washington, DC 1984; pp. 130-63.
Braconnot P, Otto-Bliesner BL, Harrison S, et al. Results of PMIP2
coupled simulations of the Mid-Holocene and Last Glacial Maximum
– Part 1: experiments and large-scale features. Clim Past
2007; 3: 261-77.
Farrera I, Harrison SP, Prentice IC, et al. Tropical climates at the
last glacial maximum: a new synthesis of terrestrial paeleoclimate
data. I. Vegetation, lake-levels and geochemistry. Clim Dyn 1999;
15: 823-56
Petit JR, Jouzel J, Raynaud D, et al. 420,000 years of climate and
atmospheric history revealed by the Vostok deep Antarctic ice core.
Nature 1999; 399: 429-36.
Vimeux F, Cuffey KM, Jouzel J. New insights into Southern Hemisphere
temperature changes from Vostok ice cores using deuterium
excess correction. Earth Planet Sci Lett 2002; 203: 829-43.
Siddall M, Rohling EJ, Almogi-Labin A, et al. Sea-level fluctuations
during the last glacial cycle. Nature 2003; 423: 853-58.
Hansen J, Sato M, Ruedy R, Lacis A, Oinas V. Global warming in
the twenty-first century: An alternative scenario. Proc Natl Acad
Sci 2000; 97: 9875-80.
Masson-Delmotte V, Kageyama M, Braconnot P. Past and future
polar amplification of climate change: climate model intercomparisons
and ice-core constraints. Clim Dyn 2006; 26: 513-29.
EPICA community members. One-to-one coupling of glacial climate
variability in Greenland and Antarctica. Nature 2006; 444:
195-8.
Caillon N, Severinghaus JP, Jouzel J, Barnola JM, Kang J, Lipenkov
VY. Timing of atmospheric CO2 and Antarctic temperature
changes across Termination III. Science 2003; 299: 1728-31.
Mudelsee M. The phase relations among atmospheric CO2 content,
temperature and global ice volume over the past 420 ka. Quat Sci
Rev 2001; 20: 583-9.
Hays JD, Imbrie J, Shackleton NJ. Variations in the Earth’s orbit:
pacemaker of the ice ages. Science 1976; 194: 1121-32.
Zachos J, Pagani M, Sloan L, Thomas E, Billups K. Trends,
rhythms, and aberrations in global climate 65 Ma to present. Science
2001; 292: 686-93.
Kohler P, Fischer H. Simulating low frequency changes in atmospheric
CO2 during the last 740 000 years. Clim Past 2006; 2: 57-78.
Siegenthaler U, Stocker TF, Monnin E, et al. Stable carbon cycle –
climate relationship during the late Pleistocene. Science 2005; 310:
1313-7.
Archer D. Methane hydrate stability and anthropogenic climate
change. Biogeoscience 2007; 4: 521-44.
Berner RA. The Phanerozoic Carbon Cycle: CO2 and O2; Oxford
Univ Press: New York 2004; p. 150.
Hansen J, Russell G, Lacis A, et al. Climate response times: Dependence
on climate sensitivity and ocean mixing. Science 1985;
229: 857-9.
Thompson WG, Goldstein SL. Open-system coral ages reveal
persistent suborbital sea-level cycles. Science 2005; 308: 401-4.
Hearty PJ, Hollin JT, Neumann AC, O’Leary MJ, McCulloch M.
Global sea-level fluctuations during the last interglaciation (MIS
5e). Quat Sci Rev 2007; 26: 2090-112.
Rohling EJ, Grant K, Hemleben Ch, et al . High rates of sea-level
rise during the last interglacial period. Nat Geosci 2008; 1: 38-42.
Tedesco M. Snowmelt detection over the Greenland ice sheet from
SSM/I brightness temperature daily variations. Geophys Res Lett
2007; 34: L02504, 1-6.
Rignot E, Jacobs SS. Rapid bottom melting widespread near Antarctic
ice sheet grounding lines. Science 2002; 296: 2020-3.
Zwally HJ, Abdalati W, Herring T, Larson K, Saba J, Steffen K.
Surface melt-induced acceleration of Greenland ice-sheet flow.
Science 2002; 297: 218-22.
Chen JL, Wilson CR, Tapley BD. Satellite gravity measurements
confirm accelerated melting of Greenland Ice Sheet. Science 2006;
313: 1958-60.
Hansen J. A slippery slope: how much global warming constitutes
“dangerous anthropogenic interference”? Clim Change 2005; 68:
269-79.
DeConto RM, Pollard D. Rapid Cenozoic glaciation of Antarctica
induced by declining atmospheric CO2. Nature 2003; 421: 245-9.
Zanazzi A, Kohn MJ, MacFadden BJ, Terry DO. Large temperature
drop across the Eocene-Oligocene transition in central North
America. Nature 2007; 445: 639-42.
Dupont-Nivet G, Krijgsman W, Langereis CG, Abeld HA, Dai S,
Fang X. Tibetan plateau aridification linked to global cooling at the
Eocene–Oligocene transition. Nature 2007; 445: 635-8.
Sackmann IJ, Boothroyd AI, Kraemer KE. Our sun III Present and
future. Astrophys J 1993; 418: 457-68.
Pagani M, Zachos J, Freeman KH, Bohaty S, Tipple B. Marked
change in atmospheric carbon dioxide concentrations during the
Oligocene. Science 2005; 309: 600-3.
Bartdorff O, Wallmann K, Latif M, Semenov V. Phanerozoic evolution
of atmospheric methane. Global Biogeochem Cycles 2008;
22: GB1008.
Beerling D, Berner RA, Mackenzie FT, Harfoot MB, Pyle JA.
Methane and the CH4 greenhouse during the past 400 million years.
Am J Sci 2008; (in press).
Edmond JM, Huh Y. Non-steady state carbonate recycling and
implications for the evolution of atmospheric PCO2. Earth Planet Sci
Lett 2003; 216: 125-39.
Staudigel H, Hart SR, Schmincke H-U, Smith BM. Cretaceous
ocean crust at DSDP Sites 417 and 418: Carbon uptake from
weathering versus loss by magmatic outgassing. Geochim Cosmochim
Acta 1989; 53: 3091-4.
Berner R, Caldeira K. The need for mass balance and feedback in
the geochemical carbon cycle. Geology 1997; 25: 955-6.
Zeebe RE, Caldeira K. Close mass balance of long-term carbon
fluxes from ice-core CO2 and ocean chemistry records. Nat Geosci
2008; 1: 312-5.
“Three million years ago, probably not one species that you’re familiar with on earth today was alive.”
Last time I checked, I believe crocodiles have existed in their current form for 200 million years, sharks for around 60 million years and there are likely numerous other examples.
Why twist facts and words if you are undeniably correct?
Andrew your response, which gives me a long list of links (though actually far less accessible than electronic links), reminds me of litigation in which a party would attempt to hide the truth in a mountain of unsorted discovered documents. You have given a response which is exactly what I pointed to as not useful to answering my questions. You are a palaeoclimate scientist. Surely you can say which of those article prove what and, better still, give the nub of the argument and the gist of the proof in relation to each of the Indus, the Nile/Sahara and the Great Lakes. If you don’t regard those particular cases as relevant and important to the AGW case then you are off the planet and if you are concealing knowledge of the best attempts at explaining those phenomena then I must suspect you of bad faith. If you are going to rely on the list of unclassified articles it would be a help if you were to provide access to them via URL to scanned copies if you can’t give direct electronic access, though, better by far, to give the best answer you can in the terms I requested.