My position is that 1) CO2 levels are rising rapidly, largely as a result of human greenhouse emissions, 2) historic CO2 levels and historic ocean temperature levels correlate, 3) the causal relationship here is bidirectional, resulting in positive feedback, 4) since CO2 levels have increased dramatically and continue to increase, we should also expect ocean temperature levels to increase (though not in proportion to CO2 levels), and 5) that this could result in potentially disasterous environmental consequences including substantial rising of ocean levels, leaving a number of heavily populated areas under water.
Here are some of the problems one would encounter in maintaining the above positions: Let's take the frist claim first, that "CO2 levels are rising rapidly, largely as a result of human greenhouse emissions."
CO2 and Temperature: The Great Geophysical Waltz
Volume 2, Number 7: 1 April 1999
In a recent news release, NASA's Goddard Institute for Space Studies declared 1998 to be "a record temperature year," the warmest ever recorded during the period of instrumental temperature assessment. Likewise, in a new analysis of proxy temperature data, Mann et al. (1999) suggest that the past decade may well have been the warmest of the past millennium. And once again (see our Vol. 1, No. 1 editorial: Much Ado About Tiny Temperature Trends), we have the Goddard Institute for Space Studies' James Hansen being quoted as stating that "there should no longer be an issue about whether global warming is occurring, but what is the rate of warming, what is its practical significance, and what should be done about it."
In truth, there is no issue about whether the globe has warmed over the past century or so. Everyone accepts that it has warmed significantly, as the planet has recovered from the global chill of the Little Ice Age. There is also beginning to be a consensus about the practical significance of the warming. Growing seasons have lengthened and plant biomass formation has increased, as a result of both the warming and the concomitant increase in atmospheric CO2 concentration. So what should be done about it?
We suspect that very few people would want to turn back the climatic clock to the conditions that spelled the doom of the Viking colonists on Greenland and created extreme hardship in Northern Europe and elsewhere. Likewise, not many people have a problem with longer growing seasons and increased biomass production. So what's all the fuss about?
It's pretty much a tempest in a computerized teapot. For many years climate modelers have predicted that the ongoing rise in the air's CO2 content will intensify earth's natural greenhouse effect and boost surface air temperatures to levels that will create all sorts of planetary havoc, melting polar ice caps, raising sea levels, flooding some parts of the globe while turning others to deserts, reducing agricultural productivity, and on and on ad infinitum. And now the likes of James Hanson would have us believe that because atmospheric CO2 and global temperature have both been rising over the past century or so, the rise in atmospheric CO2 must be driving the warming that is asserted to be sure to bring on the worst of the apocalyptic predictions.
In assessing such claims, it is important to remember that correlation does not prove causation, and that causation, if it does exist, may well operate in reverse fashion from what one may have originally thought. Hence, it is important to have as much data as possible when attempting to evaluate claims of causal relationships between different parameters; and the last few weeks have given us a wealth of new data of just the type needed to determine if there is indeed any relationship between atmospheric CO2 concentration and surface air temperature.
Perhaps the most exciting new data come from Fischer et al. (1999), who examined records of atmospheric CO2 and air temperature derived from Antarctic ice cores that extended back in time across a quarter of a million years. Over this immense time span, the three most dramatic warming events experienced on earth were those associated with the terminations of the last three ice ages; and for each and every one of these tremendous global warmings, earth's air temperature rose well before there was any increase in atmospheric CO2. In fact, the air's CO2 content did not begin to rise until 400 to 1,000 years after the planet began to warm.
Clearly, increases in atmospheric CO2 did not trigger these massive climate changes. In addition, there was a 15,000-year period following the second of the glacial terminations when the air's CO2 content was essentially constant but air temperatures dropped all the way down to values characteristic of glacial times. Hence, just as increases in atmospheric CO2 did not trigger any of the major global warmings that lead to the demise of the last three ice ages, neither was the induction of the most recent ice age driven by a decrease in CO2. And when the air's CO2 content finally did begin to drop after the last ice age was fully established, air temperatures either remained fairly constant or actually rose, doing just the opposite of what the climate models suggest should have happened if changes in atmospheric CO2 drive climate change.
In much the same vein, Indermuhle et al. (1999) determined that after the termination of the last great ice age, the CO2 content of the air gradually rose by approximately 25 ppm in almost linear fashion between 8,200 and 1,200 years ago, over a period of time that saw a slow but steady decline in global air temperature, which is once again just the opposite of what would be expected if changes in atmospheric CO2 affect climate in the way affirmed by the popular CO2-greenhouse effect theory.
So who leads who? In the geophysical dance of carbon dioxide and temperature, which repeats itself every hundred thousand or so years, it is definitely not CO2. Sometimes the two parameters are totally out of sync with each other, as when one rises and the other falls. Sometimes one is in transit to a higher or lower level, while the other is in stasis. And even when they do move in harmony, temperature seems to take the lead.
Clearly, there is no way that these real-world observations can be construed to even hint at the possibility that a significant increase in atmospheric CO2 will necessarily lead to any global warming, much less the catastrophic type that is predicted to produce the apocalyptic consequences that are driving fear-ridden governments to abandon all sense of rationality in the current hysteria over "what should be done about" the ongoing rise in the air's CO2 content.
We need to get real about this issue. We need to look at real phenomena that have actually occurred in the real world. And in spite of all the computer simulations to the contrary, we have got to realize what these real data are really telling us. When this is done, the answer comes very simply, as simply as mastering the old-time waltz that the planet has been playing for a quarter million years or more. The key is in the interaction of the participants; when you know who leads, you can avoid a lot of missteps.
Dr. Craig D. Idso
President Dr. Keith E. Idso
Vice President
References
Fischer, H., Wahlen, M., Smith, J., Mastroianni, D. and Deck, B. 1999. Ice core records of atmospheric CO2 around the last three glacial terminations. Science 283: 1712-1714.
Indermuhle, A., Stocker, T.F., Joos, F., Fischer, H., Smith, H.J., Wahlen, M., Deck, B., Mastroianni, D., Tschumi, J., Blunier, T., Meyer, R. and Stauffer, B. 1999. Holocene carbon-cycle dynamics based on CO2 trapped in ice at Taylor Dome, Antarctica. Nature 398: 121-126.
Mann, M. 1999. Northern hemisphere temperatures during the past millennium: Inferences, uncertainties, and limitations. Geophysical Research Letters 26: 1759-1762.
Persistent Millennial-Scale Climate Oscillations of the Past Million-Plus Years Reference
Raymo, M.E., Ganley, K., Carter, S., Oppo, D.W. and McManus, J. 1998. Millennial-scale climate instability during the early Pleistocene epoch. Nature 392: 699-702.
What was done
The authors studied various physical and chemical characteristics of an ocean sediment core obtained from a water depth of nearly 2,000 meters at a site south of Iceland.
What was learned
It was found that millennial-scale oscillations in climate were occurring well over one million years ago in a region of the North Atlantic that has been shown to strongly influence circum-Atlantic, and possibly global, climate. These oscillations appeared to be similar in character and timing to the Dansgaard-Oeschger cycles of the most recent glacial epoch.
What it means
Because the climate of the early Pleistocene was too warm to support the growth and development of large 100,000-year ice sheets characteristic of the late Pleistocene, and because similar millennial-scale climate oscillations are evident in both time periods, the authors conclude that millennial-scale climate oscillations "may be a pervasive and long-term characteristic of Earth's climate, rather than just a feature of the strong glacial-interglacial cycles of the past 800,000 years." Consequently, since neither the glacial nor the independent millennial-scale climate oscillations of the past million-plus years have been attributed to variations in atmospheric CO2 concentration, and since the air's CO2 content has varied significantly over this time period, there would appear to be little reason to attribute the observed warming of the past century or so to the concurrent increase in the atmosphere's CO2 concentration or to expect that any further rise in the air's CO2 content would trigger any significant warming in the future.
Warmer Temperatures at Lower CO2 Concentrations Reference
Cheddadi, R., Lamb, H.F., Guiot, J. and van der Kaars, S. 1998. Holocene climatic change in Morocco: a quantitative reconstruction from pollen data. Climate Dynamics 14: 883-890.
What was done
The authors of this paper provide quantitative estimates of Holocene climate change using proxy data from a lake-sediment core in the Middle Atlas of Morocco. Specifically, they reconstructed January and July temperature and annual precipitation values over the past 10,000 years.
What was learned
Three main climate intervals were apparent in the data: (1) a warm and dry phase from 6.5 to 10 thousand years ago, where January and July temperatures were found to be about 4°C higher than present, (2) an intermediate phase characterized by relatively high mean January temperatures, and (3) a cooler and moist most recent phase. In addition, the authors note that "superimposed on the longer-term trends are short-term variations in all three climatic parameters," lasting in some cases a century or more.
What it means
This paper adds to a growing body of research that clearly shows that over a period in earth's climatic history when atmospheric carbon dioxide concentration varied but little and was approximately 100 ppm less than today's value, mean annual temperatures in some locations were as much as "4°C warmer than the present." Therefore, even major future warming would not be proof of the claim that it is CO2-induced. History often repeats itself; and climatic history is no exception.
For relevant studies on ocean temperature vis a vis CO2 content, go to
www.co2science.org/scripts/CO2ScienceB2 ... N50/C2.jsp
As to sea level rise, sea level has been rising for centuries, and has continued right to the end of the 20the century. A confluence of ideology and nature? Precisely.