[Illustrations, footnotes and references available in PDF version]
Nasa scientist warns the world must urgently make huge CO2 reductions
Ed Pilkington, The Guardian, Monday, 7 April, 2008. Commentary by Christopher Monckton
The scare: One of the world’s leading climate scientists warns today that the EU and its international partners must urgently rethink targets for cutting carbon dioxide in the atmosphere because of fears they have grossly underestimated the scale of the problem. In a startling reappraisal of the threat, James Hansen, head of the Nasa Goddard Institute for Space Studies in New York, calls for a sharp reduction in CO2 limits.
The truth: Hansen started the “global warming” scare during the hot Washington summer of 1988, when he presented the temperature projections in graphs A-C below to the US Senate, based on a computer model. The Senate duly panicked, and the IPCC was hastily established that year.
The graph that started the “global warming” scare: Hansen predicted that if CO2 concentration was reduced from 1988 and reached stabilization by 2000, temperatures would follow curve C (green); otherwise, curve B (blue) was his best estimate, curve A his high-end estimate. The IPCC, in its first assessment report, 1990, followed Hansen’s projections with the trend-line at F (orange). Outturn since 1988, according to the US National Climatic Data Center, is curve D (red), with a regression-line at curve G (purple) showing the trend. The slope of this trend is half that predicted by Hansen and the IPCC. However, McKitrick and Michaels (2006, 2007 in press) conclude in a meticulous and unchallenged paper that heat-island effects not sufficiently corrected in the data have caused the trend in the official record to be overstated by double. The corrected graph is at E (dark brown), with its regression line at H (pink).
Temperatures have risen since 1998 at a mean rate that is between one-half and one-quarter of that which Hansen had projected only 20 years ago. Ever since Hansen made this extreme projection, he has been attempting – with increasing desperation and diminishing success – to justify it. However, neither his own model nor the other models upon which the IPCC unduly relies predicted what has actually happened in the real climate –
The downtrend that The Guardian somehow failed to mention: Since late 2001, the trend of global surface temperatures has been firmly downward. “Global warming” stopped in 1998; and, though it may resume in future years, the rate of warming is self-evidently less than official forecasts had shown, and is very likely to be harmless.
There has been no “global warming” for a decade. In the past six or seven years global mean surface temperatures have actually fallen at a rate equivalent to 0.4 degrees C per decade (Hadley Centre for Forecasting / Climate Research Unit, University of East Anglia). It is only now, after a northern-hemisphere winter so cold that its consequences could not be ignored, that some of the news media are beginning to report that the IPCC must have got its sums wrong. Dr. Rajendra Pachauri, the IPCC’s current chairman, remarked in January that it would be necessary for the IPCC to rethink its calculations – a point I have been making for some years. Most news media did not report Dr. Pachauri’s remark.
Hansen says the EU target of 550 parts per million of CO2 – the most stringent in the world – should be slashed to 350ppm. He argues the cut is needed if "humanity wishes to preserve a planet similar to that on which civilisation developed". A final version of the paper Hansen co-authored with eight other climate scientists, is posted today on the Archive website. Instead of using theoretical models to estimate the sensitivity of the climate, his team turned to evidence from the Earth’s history, which they say gives a much more accurate picture.
One has only to reread the words in quotation marks to appreciate that poor Hansen is no longer speaking as a scientist: he is making partisan political points in a childishly Messianic tone. He is financially and politically very closely linked to Al Gore (whose film has been discredited as scientifically inaccurate and exaggerated by a UK High Court judge, who said “The Armageddon scenario that he depicts is not based on any scientific view”) and to John Kerry. Hansen has contributed several thousand dollars, on multiple occasions, to the re-election campaigns of both Gore and Kerry, whose wife recently awarded him $750,000 from a political charity she controls.
The team studied core samples taken from the bottom of the ocean, which allow C02 levels to be tracked millions of years ago. They show that when the world began to glaciate at the start of the Ice age about 35m years ago, the concentration of CO2 in the atmosphere stood at about 450ppm.
"If you leave us at 450ppm for long enough it will probably melt all the ice – that’s a sea rise of 75 metres. What we have found is that the target we have all been aiming for is a disaster – a guaranteed disaster," Hansen told the Guardian.
Bloodcurdling, but characteristically exaggerated. Hansen’s error is not to go back far enough in time. Here is a comparison of reconstructed CO2 concentrations and global mean surface temperatures going back 600 million years. Note that in the Cambrian era, 550 million years ago, CO2 concentration was 7000 parts per million, or close to 20 times today’s 380 parts per million. Yet global mean surface temperatures were no higher than 22 degrees Celsius. That temperature, some 7 degrees C higher than today, appears to have been the normal temperature of the planet.
Lack of correlation necessarily implies lack of causation: Global mean surface temperatures (blue curve) show no correlation with mean atmospheric carbon dioxide concentrations (black curve). Note that both temperatures and CO2 concentrations are currently at or very close to record low levels.
At levels as high as 550ppm, the world would warm by 6C, the paper finds. Previous estimates had suggested warming would be just 3C at that point.
Assuming that all non-CO2 climate forcings sum to zero (as they broadly do), and that equilibrium ocean heat-uptake efficiency is zero, the increase in global mean surface temperature for a given concentration of CO2 may be evaluated using the following formula:
ΔT = 5.35κ ln(C/C0) / (1 – bκ) °K, (1)
where the first bracketed term is the proportionate increase in CO2 concentration, κ ≈ 0.3 °K W–1 m2 is the no-feedbacks climate sensitivity parameter, and b ≈ 2.16 W m–2 °K–1 is the sum of all unamplified climate-relevant temperature feedbacks. Thus,
ΔT ≈ 5.35 x 0.3 ln(550/278) / (1 – 2.16 x 0.3) ≈ 3.1 °K. (1a)
The IPCC has strong confidence that its CO2 forcing formula ΔF = 5.35 ln(C/C0) is correct. However, Douglass et al. (2007) have pointed out that the IPCC’s models fundamentally misunderstand the behaviour of outgoing longwave radiation in the tropical mid-troposphere, and Lindzen (2008) says this error in all the models causes all terrestrial forcings to be overstated by at least a factor of three.
If anything, the IPCC’s value κ ≈ 0.3 for the no-feedbacks parameter is an overstatement: and even a small overstatement of this parameter causes a substantial overstatement of climate sensitivity. Indeed, if McIntyre & Michaels are right, the implication is that the correct value is κ ≈ 0.2, which, even if all other variables were left unaltered, would reduce ΔT in the above equation from 3.1 °K to 1.3 °K.
The feedback factor f = 1 / (1 – bκ) has also been overstated by the IPCC, which – without explanation or justification – has increased f by 70% since its 1995 report.
There is, therefore, a very high probability that the IPCC has overstated the effect of a doubling of atmospheric CO2 concentration on temperature by a factor of 3 to 6. Hansen’s new estimate ΔT ≈ 6 °K, which is characteristically extreme, would of course double the problem already evident in the IPCC’s calculations.
It is no surprise, then, that all of the IPCC’s models altogether failed to predict that there would be no temperature increase for a decade after 1998, and that the temperature trend would actually fall during the past six or seven years.
Hansen has long been a prominent figure in climate change science. He was one of the first to bring the crisis to the world’s attention in testimony to Congress in the 1980s.
What he actually brought to the world’s attention was a series of exaggerated and now-discredited projections that have been proven flagrantly unreliable.
But his relationship with the Bush administration has been frosty. In 2005 he accused the White House and Nasa of trying to censor him. He has steadily revised his analysis of the scale of the global warming and was himself one of the architects of a 450ppm target. But he told the Guardian: "I realise that was too high."
Given the vast amount of public exposure that Hansen has had, his statement that he has somehow been “censored” must be as exaggerated as everything he says about the climate.
The fundamental reason for his reassessment was what he calls "slow feedback" mechanisms which are only now becoming fully understood. They amplify the rise in temperature caused by increasing the concentration of greenhouse gases. Ice and snow reflect sunlight but when they melt, they leave exposed ground which absorbs more heat.
Hansen’s original calculations of 1984, essentially reproduced and updated in his 1988 paper, were to the effect that f = 3 to 4. The IPCC, in its 1995 paper, inferentially chose f = 1.8, but has since increased this to its current estimate f ≈ 3.1. Given that this value is producing temperature projections which, like Hansen’s original projections, have been thoroughly disproven by events, it is difficult to find any credible scientific basis for his attempt at further feedback inflation.
However, let us test Hansen’s proposition that the IPCC’s current central estimate f ≈ 3.1 is too small. First, we rearrange the fundamental climate sensitivity equation (1) to express it in terms of f:
f = 1 / (1 – bκ) = ΔT / [5.35κ ln(C/C0)] ≈ 3.1 (IPCC, 2007) (2)
Now, the most reliable period of figures we have is the satellite era, which began in 1980. That year, CO2 concentration was 338.67 parts per million by volume (Mauna Loa: Keeling & Whorf, 2004). The NCDC global mean surface temperature anomaly, expressed as the five-year running mean, was 0.144 °K. In 2005, the most recent year for which a five-year running mean temperature can be calculated, the CO2 concentration was 378.77 ppmv, and global mean surface temperature was 0.557 °K. This is all the information we need to evaluate f over the 27-year period:
f = (0.557 – 0.144) / [5.35 x 0.3 ln(378.77/338.67)] ≈ 2.3. (2a)
The value of f, therefore, is demonstrated to be a great deal less than the IPCC’s current value f = 3.1. Of course, we are here assuming that the IPCC’s (probably-overstated) value for κ is correct, and that McIntyre & McKitrick are wrong. If κ is reduced somewhat to reflect the papers actually cited by the IPCC in support of its chosen value, and if McIntyre & McKitrick are right that ΔT over the chosen period is half what the official records show, then of course the value of f must be reduced still further:
f = (0.207) / [5.35 x 0.27 ln(378.77/338.67)] ≈ 1.3. (2b)
We may legitimately conclude that a reasonable interval on which f must fall is f = [1.3, 3.1], with a central estimate f = 2.3. Yet Hansen, by implying that climate sensitivity is double the IPCC’s central estimate, is implying that f ≈ 6.2, or double the IPCC’s central estimate (which we have shown to be better understood as the high-end estimate).
As ice sheets recede, the warming effect is compounded. Satellite technology available over the past three years has shown that the ice sheets are melting much faster than expected, with Greenland and west Antarctica both losing mass.
The truth is a great deal less alarming than Hansen says. First, compared with the Ice Ages, there is very little ice remaining: therefore, even if it were all to melt (and no one is suggesting this), the ice albedo feedback would be very small, particularly because so little of the total outgoing radiation departs from the Poles, for the obvious reason that the azimuth angle of the Sun is so small there.
Next, the NASA GRACE gravitation-anomaly measurements of ice-mass are not yet calibrated, and are considerably at odds both with terrestrial measurements such as side-looking radar and with satellite-based laser interferometry – techniques which were used to demonstrate that the vast majority of the Antarctic ice-sheet has thickened throughout the past 50 years, as the continent has cooled (Doran et al., 2002), and that the mean thickness of the Greenland ice sheet increased by 5 cm (2 inches) per year throughout the decade 1993-2003 (Johannesen et al., 2005).
The “warming island” which an explorer thought he had discovered off northern Greenland in 2005 is now known to have been visibly an island as recently as the mid-1950s, when a previous explorer had clearly drawn it as an island on a map of the region.
The West Antarctic Ice Sheet has indeed been losing mass, chiefly in the Antarctic Peninsula, which, however, is only some 2% of the continent; and studies following the disappearance of ice shelves such as Larsen B have revealed that the shelves were also absent during the Mediaeval Warm Period, suggesting that the coming and going of ice shelves in the region is a natural process, possibly exacerbated at present by undersea volcanic activity.
Hansen said that he now regards as "implausible" the view of many climate scientists that the shrinking of the ice sheets would take thousands of years. "If we follow business as usual I can’t see how west Antarctica could survive a century. We are talking about a sea-level rise of at least a couple of metres this century."
Once again, Hansen is taking a characteristically extreme position, and in a field beyond his competence. It is he who excoriates so-called “skeptics” for allegedly questioning the scientific “consensus” about “global warming”. The consensus among Antarctic research specialists, of whom Hansen is not one, is that there is no appreciable threat other than to the margins of the West Antarctic Ice Sheet. Whalers’ logs going back several centuries show that icebergs hundreds of miles in length have calved from West Antarctica, even when temperatures were considerably colder than they are now. Niklas Moerner, the world’s foremost expert on sea level, says that even the IPCC’s estimate (a maximum sea-level rise of 2 m over the coming century) is a baseless exaggeration. He sees no reason to expect a sea-level rise to 2100 of more than the 20 cm (8 inches) observed in the 20th century.
The mean rate sea-level rise since the end of the last Ice Age 10,000 years ago has been 1.2 metres (4 feet) per century. The 20th-century rate of increase was accordingly one-sixth of the mean centennial rate. Hansen’s estimate of sea-level rise – again, outwith his own area of expertise – is accordingly very much at variance both with the IPCC’s projection (he takes their maximum as his minimum), and with the projections of the world’s foremost expert on the subject.
The revised target is likely to prompt criticism that he is setting the bar unrealistically high. With the US administration still acting as a drag on international efforts, climate campaigners are struggling even to get a 450ppm target to stick.
Here is another explicitly partisan remark from this lifelong Democrat and intimate financial associate of Gore and Kerry. India and China have both declared that they will not reduce their greenhouse-gas emissions. Even if the entire West were to shut down, and were to revert to the Stone Age, without even the ability to light fires, the growth in emissions from China and India alone would replace the West’s entire output in little more than a decade. Accordingly, and rightly, the US Senate voted 95-0 under the chairmanship of Al Gore in 1997 not to ratify the Kyoto Treaty: and the overwhelming majority in the Senate continue to assert that there is no point in agreeing to any treaty that does not bind the world’s greatest emitters.
It would be the acme of futility for the West to shut down up to 80% of its economic activity in the name of “saving the planet”: for we should merely be exporting our jobs and our carbon emissions to China and India, whose record of pollution control is far less satisfactory than our own. It is difficult to conceive of any environmental benefit whatsoever that might flow from such a policy.
Hansen said his findings were not a recipe for despair. The good news, he said, is that reserves of fossil fuels have been exaggerated, so an alternative source of energy will have to be rapidly put in place in any case. Other measure could include a moratorium on coal power stations which would bring the CO2 levels to below 400ppm.
Once again, Hansen speaks outside his area of expertise. For instance, a new oilfield potentially containing half a trillion barrels of oil has just been discovered in Kurdistan. However, increasing demand for fuels, metals and other natural resources as China and India grow will greatly increase the cost of commodities worldwide in the coming years, rationing them by price. It is competition for finite natural resources, not “global warming”, that is the true strategic problem now facing the West.
Hansen’s revised position will pile yet further pressure on Britain over plans to build a new generation of coal power stations. Last year he wrote to Gordon Brown urging him to block the first such power station; the Royal Society has made similar suggestions to the government.
Hansen, a paid official of a foreign power, has no business intervening in United Kingdom politics. As for the Royal Society, the world’s oldest taxpayer-funded quango, under its present Left-leaning leadership it more reliably reflects a purely political, atheistic-humanist, bureaucratic-centralist stance than any sound scientific case. Policy-makers in the UK have long learned to ignore it, just as policy-makers in the US have long ignored Hansen and his discredited exaggerations.
It is now evident both from the observed record and from the proven exaggerations in the IPCC’s calculations that the still more extreme estimates peddled by Hansen have no scientific basis. Though greenhouse-gas enrichment of the atmosphere will cause some warming, very few serious and impartial scientists now believe the IPCC’s exaggerations, still less those of Hansen and his financial associate Al Gore. “Global warming” will be small, and will prove to be not merely harmless but beneficial. End of scare.