Environmental Effects of Increased Atmospheric Carbon Dioxide

{This article supports the observation that Anthropogenic sources of carbon dioxide are not causing global warming or climate change. As can clearly be seen in the Figures, the Medieval warming period shows much greater temperatures than those of post modern industrialization. Additionally, sea levels have been rising well before the onset of the oil and gas age.

This is an abridged version of the original piece by Arthur Robinson, Noah Robinson and Willie Soon, a bit lengthy but well worth the read. It is reprinted by permission of the authors. The complete article is available here. - Ed. }

by Arthur Robinson, Noah E. Robinson, and Willie Soon


Figure 1 (Main photo): Average length of 169 glaciers from 1700 to 2000 (4). The principal source of melt energy is solar radiation. Variations in glacier mass and length are primarily due to temperature and precipitation (5,6). This melting trend lags the temperature increase by about 20 years, so it predates the 6-fold increase in hydrocarbon use (7) even more than shown in the figure. Hydrocarbon use could not have caused this shortening trend.

Political leaders gathered in Kyoto, Japan, in December 1997 to consider a world treaty restricting human production of "greenhouse gases," chiefly carbon dioxide (CO2). They feared that CO2 would result in "human-caused global warming" – hypothetical severe increases in Earth's temperatures, with disastrous environmental consequences. During the past 10 years, many political efforts have been made to force worldwide agreement to the Kyoto treaty.

When we reviewed this subject in 1998 (1,2), existing satellite records were short and were centered on a period of changing intermediate temperature trends. Additional experimental data have now been obtained, so better answers to the questions raised by the hypothesis of "human-caused global warming" are now available.

Figure 2: Surface temperatures in the Sargasso Sea, a two million square mile region of the Atlantic Ocean, with time resolution of 50 to 100 years and ending in 1975, as determined by isotope ratios of marine organism remains in sediment at the bottom of the sea (3). The horizontal line is the average temperature for this 3,000-year period. The Little Ice Age and Medieval Climate Optimum were naturally occurring, extended intervals of climate departures from the mean. A value of 0.25 °C, which is the change in Sargasso Sea temperature between 1975 and 2006, has been added to the 1975 data in order to provide a 2006 temperature value.

The average temperature of the Earth has varied within a range of about 3°C during the past 3,000 years. It is currently increasing as the Earth recovers from a period that is known as the Little Ice Age, as shown in Figure 2. George Washington and his army were at Valley Forge during the coldest era in 1,500 years, but even then the temperature was only about 1° Centigrade below the 3,000-year average.

During the Medieval Climate Optimum, temperatures were warm enough to allow the colonization of Greenland. These colonies were abandoned after the onset of colder temperatures. For the past 200 to 300 years, Earth temperatures have been gradually recovering (26). Sargasso Sea temperatures are now approximately equal to the average for the previous 3,000 years.

The historical record does not contain any report of "global warming" catastrophes, even though temperatures have been higher than they are now during much of the last three millennia.

Figure 3: Arctic surface air temperature compared with total solar irradiance as measured by sunspot cycle amplitude, sunspot cycle length, solar equatorial rotation rate, fraction of penumbral spots, and decay rate of the 11-year sunspot cycle (8,9). Solar irradiance correlates well with Arctic temperature, while hydrocarbon use (7) does not correlate.

The most recent part of this warming period is reflected by shortening of world glaciers, as shown in Figure 4. Glaciers regularly lengthen and shorten in delayed correlation with cooling and warming trends. Shortening lags temperature by about 20 years, so the current warming trend began in about 1800.

Figure 4: Average length of 169 glaciers from 1700 to 2000 (4). The principal source of melt energy is solar radiation. Variations in glacier mass and length are primarily due to temperature and precipitation (5,6). This melting trend lags the temperature increase by about 20 years, so it predates the 6-fold increase in hydrocarbon use (7) even more than shown in the figure. Hydrocarbon use could not have caused this shortening trend.

Surface temperatures in the United States during the past century reflect this natural warming trend and its correlation with solar activity, as shown in Figure 3. Compiled U.S. surface temperatures have increased about 0.5 °C per century, which is consistent with other historical values of 0.4 to 0.5 °C per century during the recovery from the Little Ice Age (13-17). This temperature change is slight as compared with other natural variations. Three intermediate trends are evident, including the decreasing trend used to justify fears of "global cooling" in the 1970s.

ATMOSPHERIC CARBON DIOXIDE

During the past 50 years, atmospheric CO2 has increased by 22%. The magnitude of this atmospheric increase is currently about 4 gigatons (Gt C) of carbon per year. Total human industrial CO2 production, primarily from use of coal, oil, and natural gas and the production of cement, is currently about 8 Gt C per year (7,56,57). Humans also exhale about 0.6 Gt C per year, which has been sequestered by plants from atmospheric CO2. Office air concentrations often exceed 1,000 ppm CO2.

Much of that CO2 increase is attributable to the 6-fold increase in human use of hydrocarbon energy. However, figures 2, 3, &4 show that human use of hydrocarbons has not caused the observed increases in temperature.

Between 1900 and 2000, on absolute scales of solar irradiance and degrees Kelvin, solar activity increased 0.19%, while a 0.5 °C temperature change is 0.21%. This is in good agreement with estimates that Earth's temperature would be reduced by 0.6 °C through particulate blocking of the sun by 0.2%(18).

Figure 5: U.S. surface temperature from Figure 3 as compared with total solar irradiance (19).


Between 1900 and 2006, Antarctic CO2 increased 30% per 0.1 °C temperature change (72), and world CO2 increased 30% per 0.5 °C. In addition to ocean out-gassing, CO2 from human use of hydrocarbons is a new source. Neither this new source nor the older natural CO2 sources are causing atmospheric temperature to change.

Carbon dioxide has a very short residence time in the atmosphere. Beginning with the 7 to 10-year half-time of CO2 in the atmosphere estimated by Revelle and Seuss (69), there were 36 estimates of the atmospheric CO2 half-time based upon experimental measurements published between 1957 and 1992 (59). These range between 2 and 25 years, with a mean of 7.5, a median of 7.6, and an upper range average of about 10. Of the 36 values, 33 are 10 years or less.

There is no experimental evidence to support computer model estimates (73) of a CO2 atmospheric "lifetime" of 300 years or more.


FERTILIZATION OF PLANTS BY CO2


How high will the CO2 concentration of the atmosphere ultimately rise if mankind continues to increase the use of coal, oil, and natural gas? At ultimate equilibrium with the ocean and other reservoirs there will probably be very little increase. The current rise is a non-equilibrium result of the rate of approach to equilibrium. One reservoir that would moderate the increase is especially important.

Plant life provides a large sink for CO2. Using current knowledge about the increased growth rates of plants and assuming increased CO2 release as compared to current emissions, it has been estimated that atmospheric CO2 levels may rise to about 600 ppm before leveling off. At that level, CO2 absorption by increased Earth biomass is able to absorb about 10 Gt C per year (100).

Does a catastrophic amplification of these trends with damaging climatological consequences lie ahead? There are no experimental data that suggest this. There is also no experimentally validated theoretical evidence of such an amplification.

GLOBAL WARMING HYPOTHESIS

Predictions of catastrophic global warming are based on computer climate modeling, a branch of science still in its infancy. The empirical evidence – actual measurements of Earth's temperature and climate – shows no man-made warming trend. Indeed, during four of the seven decades since 1940 when average CO2 levels steadily increased, U.S. average temperatures were actually decreasing. While CO2 levels have increased substantially and are expected to continue doing so and humans have been responsible for part of this increase, the effect on the environment has been benign.

Not only has the global warming hypothesis failed experimental tests, it is theoretically flawed as well. It can reasonably be argued that cooling from negative physical and biological feedbacks to greenhouse gases nullifies the slight initial temperature rise (84,86).

Figure 6: Qualitative illustration of greenhouse warming. "Present GHE" is the current greenhouse effect from all atmospheric phenomena. "Radiative effect of CO2" is the added greenhouse radiative effect from doubling CO2 without consideration of other atmospheric components. "Hypothesis 1 IPCC" is the hypothetical amplification effect assumed by IPCC. "Hypothesis 2" is the hypothetical moderation effect.


When an increase in CO2 increases the radiative input to the atmosphere, how and in which direction does the atmosphere respond? Hypotheses about this response differ and are schematically shown in Figure 6. Without the water-vapor greenhouse effect, the Earth would be about 14 ºC cooler (81). The radiative contribution of doubling atmospheric CO2 is minor, but this radiative greenhouse effect is treated quite differently by different climate hypotheses.

The hypotheses that the IPCC (82,83) has chosen to adopt predict that the effect of CO2 is amplified by the atmosphere, especially by water vapor, to produce a large temperature increase. Other hypotheses, shown as hypothesis 2, predict the opposite – that the atmospheric response will counteract the CO2 increase and result in insignificant changes in global temperature (81,84,85,91,92). The experimental evidence, as described above, favors hypothesis 2.

The computer climate models upon which "human-caused global warming" is based have substantial uncertainties and are markedly unreliable. This is not surprising, since the climate is a coupled, non-linear dynamical system. It is very complex. Figure 7 illustrates the difficulties by comparing the radiative CO2 greenhouse effect with correction factors and uncertainties in some of the parameters in the computer climate calculations. Other factors, too, such as the chemical and climatic influence of volcanoes, cannot now be reliably computer modeled.

Figure 7: The radiative greenhouse effect of doubling the concentration of atmospheric CO2 (right bar) as compared with four of the uncertainties in the computer climate models.

The greenhouse effect amplifies solar warming of the earth. Greenhouse gases such as H2O, CO2, and CH4 in the Earth's atmosphere, through combined convective readjustments and the radiative blanketing effect, essentially decrease the net escape of terrestrial thermal infrared radiation. Increasing CO2, therefore, effectively increases radiative energy input to the Earth's atmosphere. The path of this radiative input is complex. It is redistributed, both vertically and horizontally, by various physical processes, including advection, convection, and diffusion in the atmosphere and ocean.

The reasons for the failure of the computer climate models are subjects of scientific debate (87). For example, water vapor is the largest contributor to the overall greenhouse effect (88). It has been suggested that the climate models treat feedbacks from clouds, water vapor, and related hydrology incorrectly (85,89-92).

The 3,000-year temperature record illustrated in Figure 1 also provides a test of the computer models. The historical temperature record shows that the Earth has previously warmed far more than could be caused by CO2 itself. Since these past warming cycles have not initiated water-vapor-mediated atmospheric warming catastrophes, it is evident that weaker effects from CO2 cannot do so.

There is no indication whatever in the experimental data that an abrupt or remarkable change in any of the ordinary natural climate variables is beginning or will begin to take place.

CONCLUSIONS

There are no experimental data to support the hypothesis that increases in human hydrocarbon use or in atmospheric carbon dioxide and other greenhouse gases are causing or can be expected to cause unfavorable changes in global temperatures, weather, or landscape. There is no reason to limit human production of CO2, CH4, and other minor greenhouse gases as has been proposed (82,83,97,123).

We also need not worry about environmental calamities even if the current natural warming trend continues. The Earth has been much warmer during the past 3,000 years without catastrophic effects. Warmer weather extends growing seasons and generally improves the habitability of colder regions.

As coal, oil, and natural gas are used to feed and lift from poverty vast numbers of people across the globe, more CO2 will be released into the atmosphere. This will help to maintain and improve the health, longevity, prosperity, and productivity of all people.


References:

1. Robinson, A. B., Baliunas, S. L., Soon, W., and Robinson, Z. W. (1998) Journal of American Physicians and Surgeons 3, 171-178.

2. Soon, W., Baliunas, S. L., Robinson, A. B., and Robinson, Z. W. (1999) Climate Res. 13, 149-164.

3. Keigwin, L. D. (1996) Science 274, 1504-1508. ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/keigwin1996/

4. Oerlemanns, J. (2005) Science 308, 675-677.

5. Oerlemanns, J., Björnsson, H., Kuhn, M., Obleitner, F., Palsson, F., Smeets, C. J. P. P., Vugts, H. F., and De Wolde, J. (1999) Boundary-Layer Meteorology 92, 3-26.

6. Greuell, W. and Smeets, P. (2001) J. Geophysical Res. 106, 31717-31727.

7. Marland, G., Boden, T. A., and Andres, R. J. (2007) Global, Regional, and National CO2 Emissions. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center,Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, TN, USA, http://cdiac.ornl.gov/trends/emis/tre_glob.htm

8. Soon, W. (2005) Geophysical Research Letters 32, 2005GL023429.

9. Hoyt, D. V. and Schatten, K. H. (1993) J. Geophysical Res. 98, 18895-18906.

10. - 132. are available in the original publication.