Dear Editor:
I'd like to respond, if I could, to a passage in the article 'Evolution of Wishful Thinking' (Feb//March 2006) page 6. Therein, the author writes: "Legitimate scientists can't determine whether the Earth is experiencing global warming or going through the prelude to the next ice age. But the one thing the ego driven masses are sure of is that mankind is causing the change."
Helloooo! Yes, mankind IS causing the change! We know this, we have the long-term (e.g. ice core sample) evidence to substantiate it. This isn't a dream, and it's not a delusion, and it certainly isn't "wishful thinking". This is the sort of problem one observes when forthright commentators, with little or no background in the particular discipline, opinionate. To assert also that "legitimate scientists can't determine" whether the Earth is warming or going into another ice age is daft and disingenuous. Indeed, the organization embodying the greatest number of climate scientists in the world - The American Geophysical Union - issued the following cogent position statement, cf. Eos, Vol. 84, No. 51, December, 2003, p. 574:
"Human activities are increasingly altering the Earth's climate. These effects add to natural effects present over Earth's history. Scientific evidence strongly indicates that natural influences cannot explain the rapid increase in global near-surface temperatures observed during the second half of the 20th century.
"Human impacts on the climate system include increasing concentrations of greenhouse gases, air pollution, increasing concentrations of airborne particles, and land alteration.
"A particular concern is that atmospheric levels of carbon dioxide may be rising faster than at any time in Earth's history, except possibly following rare events like impacts from large extraterrestrial objects."
In terms of the last statement, this is a reminder that we're approaching catastrophic climate change. Since the 'rare events' referred to here were two asteroid strikes that altered the Earth's climate - the last 65 million years ago, wiping out all the dinosaurs in a literal cosmic 'heartbeat'.
The statement continues:
"Atmospheric carbon dioxide concentrations have increased since the mid-1700s through fossil fuel burning and changes in land use, with more than 80% of this increase occurring since 1900. Moreover, research indicates that increased levels of carbon dioxide will remain in the atmosphere for hundreds of thousands of years."
This last is cognizant of the fact that CO2 accumulates because earlier depositions remain in the atmosphere- wreaking their havoc- even as new burdens are added yearly! Thus, the CO2 warming we're now experiencing is not the result of just one year - but 100 years' accumulation. The process may be described something like a series with terms being added, viz: to describe the CO2 content now in the atmosphere, we must initiate the series with n= 1 (for 1906), viz.
CO2 (2006) = x_1 + x_2 + x_3 + x_4 +...+ x_100
where 'x_n' denotes the CO2 contribution for 1 year.
Thus, the CO2 effect for a given year (say 2005) is not just for that year, but rather inclusive of the cumulative additions for all the years - starting up to 100 years before! This means things can only get worse.
It is important to note here that the IPCC (International Panel on Climate Change) has a bona fide theory: nonlinear greenhouse warming as a forcing agent superimposed on a basal (natural) warming, from which a model (General climate model, GCM) has been arrived at. This is the theory referenced in the AGU statement.
It has also actually made specific numerical predictions, including the differential rise in Arctic sea and air temperatures, and the prediction of melting permafrost in Alaska. So long as that is the case, and the conveyor belt flippers have nothing comparable to offer, then we can't put them in the same category.
Let's even forget for the moment as James McCarthy, Alexander Agassiz Professor of Biological Oceanography at Harvard notes, that the IPCC provides the most conservative estimates of the warming change. As his colleague, Daniel Schrag, Professor of geochemistry and director of the Laboratory for Geochemical Oceanography observes, the IPCC is by nature a conservative organization. The breadth that gives its findings weight - 3,000 scientists, reviewers, and government officials involved in drafting its reports - means that consensus had to be reached across broad points of view, including those from countries whose economies are based on oil production.
Even good models proceed in increments, or successive approximations. A new IPCC model may yet incorporate higher resolution trends perhaps at 10 years or less, but not yet. Nevertheless, the IPCC model makes new predictions instead of merely claiming that earlier climatic events (like anomalous Greenland cooling) are already within its purview.
This is where Broeker's 'Conveyor Belt' -Climate flip hypothesis (the one suggesting warming can morph into ice age) doesn't seem to meet the challenge. The least he could do is provide a clear prediction, say for the increase in Arctic air temperatures ca. 2100, like the IPCC. But I've never seen any.
A key aspect of Broeker's hypothesis is that water vapor exceeds or rivals CO2 as a greenhouse agent. This is simply not so. Even a tiny, minuscule amount of CO2 is vastly more efficient at blocking the re-radiation of energy than any equal mass amount of water vapor- at those bands. Part of the misconception arose because early researchers, lacking the current technology of infrared spectroscopy, assumed that water vapor bands already blocked out most of what would (ordinarily) be taken by CO2. (Cf. 'The Discovery of the Risk of Global Warming', by Spencer Weart, in Physics Today, Jan. 1997, p. 34).
As other researchers have noted, however (e.g. D. Lubin in Science, Vol. 265, July, 1994, p. 224) the effects of water vapor will kick in once the super-greenhouse gets under way. Thus, the water vapor will provide a non-linear driver and forcing mechanism to ramp up global warming as the oceans evaporate worldwide.
A more recent article in Eos (Vol. 83, No. 34), from August 20, 2002, 'Progress Made in Study of Ocean's Calcium Carbonate Budget', notes that sedimentary carbonates represent the largest reservoir of carbon on Earth. The author also notes that "a third of the anthropogenic CO2 that has been added to the atmosphere since the middle of the 18th century has been absorbed by the oceans. This means that the oceans, acting as CO2 reservoirs, have actually masked the worst effects of global warming. And that when their saturation point is reached, the spillover effect will be rapid and calamitous indeed.
Increases of atmospheric CO2 also increase concentrations of inorganic carbon, mainly in the forms pCO2 and HCO3. A side effect is to also diminish the pH of sea water. The author notes p. 374: "Future decreases in sea water pH (and CO3(-2)) concentration will decrease the saturation state of the waters with respect to Ca CO3". This means that spillover becomes much more likely, as the saturation threshhold is lowered, with masses of CO2 released additionally into the atmosphere. Melting ice from glaciers, etc. - far from being an assisting agent to a new ice age, will surely reduce further the sea water pH and accelerate the release of CO2 from the oceans. Leading to much much warmer conditions.
Of course, another set of current skeptics, mainly on the political right - who cite shills for the fossil fuel industry, more recently Sallie Baliunas and Willie Soon, and parrot their palaver that the Sun as the ultimate culprit. However, no evidence indicates the Sun's total power output rivals that of the anthropogenic variety. (Note: In one of their most egregious papers, Baliunas and Soon used 50-year data periods, increments when the IPCC scientists already disclosed anthropogenic warming appears at 30 -year levels. In effect, Baliunas and Soon employed what we call a 'selective effects filter' to remove the data they preferred not to deal with.)
The maximal magnitude of solar -induced climate variability was probably first highlighted by Sabatino Sofia et al in their paper Solar Constant: Constraints on Possible Variations Derived from Solar Diameter Measurements, in Science, 204, p. 1306, 1979. Their estimate was a solar change in irradiance of roughly 0.1 % - averaged over each solar cycle. (Irradiance is a measure of the energy per square meter received from the Sun).
More recent space-based observations appear to show a variation in solar irradiance of at least 0.15% over the standard 11-year solar cycle. (E.g. Parker, E.N., Nature, Vol. 399, p. 416). However, even with this higher percentage ascribed to solar changes, the heating effect is nowhere near comparable to that induced from man-made global warming. (See, e.g. Martin I. Hoffert et al, in Nature, Vol. 401, p. 764).
While it is understandable that conservative-libertarian ideologues would have a problem with the current scientific data - since it clearly shows the need for human responsibility in climate change and hence economic change - calling the messengers 'Chicken Littles' or exponents of "wishful thinking" serves no rational purpose. It merely continues to fuel the ideological far-right agenda that NO genuine human contributions exist. Meanwhile, the Earth - our sole habitable home in the cosmos - is subjected to a slow (and more recently, not so slow) burn.
Contrary to Kort E. Patterson's assertion of what defines the "ego driven masses" - allow me to put it in truer perspective: the ego-driven masses are the ones that fall for PR, and spin from think-tank sources, corporate media whores and others with an agenda- rather than examining the actual scientific data in an objective and exhaustive fashion.
P.A. Stahl
Member: American Geophysical Union