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Some have been trying to whitewash history by claiming that fears of global cooling didn’t really exist back in the 1970s. Well, guest author Kenneth Richard shows that that was hardly the case at all. Fears of cooling were very real.

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Scientists devised schemes to warm the climate in the 1960s-70s

By Kenneth Richard

During the 1960s and 1970s, there was widespread concern about a dramatically cooling climate, especially in the Northern Hemisphere. For example, Starr and Oort (1973)1 determined there was -0.6°C of Northern Hemisphere cooling during the late 1950s to early 1960s alone. A throng of scientific papers were written about the observed global-scale cooling, a potentially imminent ice age, and how anthropogenic pollution may be contributing to the climate changes. The effects of CO2 were, at the time, thought to be less concerning. The paper below by Cimorelli and House (1974) was prototypical of the period.

Cimorelli and House, 1974:

Aside from such long-term changes, there is also evidence which indicates climate changes occurring in contemporary history. Mitchell (1971) among others, claims that during the last century a systematic fluctuation of global climate is revealed by meteorological data. He states that between 1880 and 1940 a net warming of about 0.6°C occurred, and from 1940 to the present our globe experienced a net cooling of 0.3°C. The effect of increasing global concentrations of CO2 is to increase the average global surface temperature. … As for increasing global concentrations of particulate matter, the opposite is true. Due to the backscattering characteristics of the particles an increase in the albedo occurs which produces a decrease in average global surface temperature. … Since it had been thought that the two effects canceled one another, their use as criteria for developing standards has not been considered. However, it has since been found that the rate of temperature increase decreases with increasing CO2 and increases with increasing particulates. Therefore, global particulate loading is of foremost concern. … Sellers (1973) has developed a climate model which quantitatively relates particulate loading to surface temperature. He has shown that an increase in man-made global particulates by a factor of 4.0 will initiate an ice-age. In order that we safeguard ourselves and future generations from a self-imposed ice-age it is necessary that we effectively monitor global concentrations of particulate matter. … Their results showed that an increase by a factor of eight of global CO2 concentrations will produce an increase in surface temperature of less than 2°C, whereas increasing particulate concentration by a factor of four could decrease the mean surface temperature as much as 3.5°C. Therefore, as the global concentrations of both CO2 and particulates are increased, it is the radiative shielding effect of the particulates which plays the dominate role. … Ludwig and Morgan, 1970, predict that man’s potential to pollute will increase six-to-eight fold in the next fifty years. All of these studies point to the possibility, in the not so distant future, of man polluting himself into an ice age.

It was during this same cooling period — which has since been curiously erased in modern-day temperature graphs — that scientists and engineers were devising “schemes” to warm the planet by, for example, intentionally melting Arctic sea ice, or by using dams to redirect warmer waters into cooler regions. The paper below (Fletcher, 1969) summarized some of these “schemes” to warm the planet and prevent cooling.

Fletcher, 1969:

The post-glacial warming culminated in the “climatic optimum” of 4000-2000 BC, during which world temperatures were 2-3°C warmer than they are now …Since the “little ice age” of 1650-1840, which climaxed the cooling trend from about 1300, a new warming trend predominated which seems to have reached a climax in this century, followed by cooling since about 1940, at first irregularly but more sharply since about 1960. SPECIFIC SCHEMES FOR CLIMATE MODIFICATION Ice Free Arctic Ocean The largest scale enterprise that has been discussed is that of transforming the Arctic into an ice free ocean. As was noted earlier this has been most carefully studied by the staff of the Main Geophysical Observatory in Leningrad. … It is possible that the capacity of present technology may be sufficient to accomplish this task. but this has not been established. Three basic approaches have been proposed (Fletcher 1965): (1) influencing the surface reflectivity of the ice to cause more absorption of solar heat; (2) large scale modification of cloud conditions by seeding; (3) increasing the inflow of warm water from the Atlantic. Bering Strait Dam Soviet engineer Borisov (1959, 1967) has been the most active proponent of the much publicized Bering Strait Dam. The basic idea is to increase the inflow of warm Atlantic water by stopping or oven reversing the present northward flow of colder water through Bering Strait. The dam would be 50 miles long and 150 feet high. Deflecting the Kuroshio Current The Pacific Ocean counterpart of the Gulf Stream is the Kuroshio Current, a small branch of which enters the Sea of Japan and exits to the Pacific between the Japanese islands. It has been proposed that the narrow mouth of Tatarsk Strait be blocked by a giant “water valve” to increase the warm inflow to the Sea of Okhotsk and reduce the winter ice there.

Of course, today’s version of anthropogenic climate change alarmism insists that dangerous climate warming is predominantly caused by changes in atmospheric CO2 concentrations. Therefore, in contrast to the tendentious climate modification schemes proposed in the 1960s and 1970s, we are told we must make every policy attempt to cool the climate – or at least prevent more warming – by replacing fossil fuel energies and infrastructure with renewable energy sources like wind and solar.

And yet recent detailed analyses indicate that a calculated policy effort to significantly reduce CO2 emissions may be particularly inefficient and ultimately ineffective in preventing the projected dangerous warming. That’s because even if all the CO2 emissions reduction measures by agreeable nations were put into effect and adhered to through to the year 2100, the amount of reduced warming achieved would be less than -0.2°C over the next 85 years2, 3. Since the claims are that we may get 3.0°C and more of dangerous warming by 2100 even with these severe emissions reduction policies, a savings of just -0.2°C would not appear to be significant.

So what would be significant?

Consider the conclusions of Zhang and co-authors from a recently published (2016) paper (“The updated effective radiative forcing of major anthropogenic aerosols and their effects on global climate at present and in the future“). These scientists found that human aerosol emissions (“sulphate (SF), black carbon (BC), and organic carbon (OC)”) cooled planetary surface temperatures by a massive -2.53 K between 1850 and 2010. In addition, the authors conclude that if we continue to reduce aerosol emissions (air pollution) at the rate we have been in recent decades, this will consequently lead to a warming of 2.06 K by 2100 – a warming not significantly different than projections due to business-as-usual increases in CO2 emissions.

Below are excerpts from the Zhang et al. (2016) abstract:

The effective radiative forcing (ERF), as newly defined in the Intergovernmental Panel on Climate Change’s Fifth Assessment Report (IPCC AR5), of three anthropogenic aerosols [sulphate (SF), black carbon (BC), and organic carbon (OC)] and their comprehensive climatic effects were simulated and discussed, using the updated aerosol-climate online model of BCC_AGCM2.0.1_CUACE/Aero. From 1850 to 2010, the total ERF of these anthropogenic aerosols was −2.49 W m−2 From 1850 to 2010, anthropogenic aerosols brought about a decrease of ∼2.53 K and ∼0.20 mm day−1 in global annual mean surface temperature and precipitation, respectively. Surface cooling was most obvious over mid- and high latitudes in the northern hemisphere (NH). … Experiments based on the Representative Concentration Pathway (RCP) 4.5 given in IPCC AR5 shows the dramatic decrease in three anthropogenic aerosols in 2100 will lead to an increase of ∼2.06 K and 0.16 mm day−1 in global annual mean surface temperature and precipitation, respectively, compared with those in 2010.

So if (a) anthropogenic aerosol pollution can reduce global temperatures by -2.53 K in 160 years with -2.49 W m-2 of forcing; (b) severe CO2 emissions cuts may only reduce surface temperatures by a modest -0.2° C in the next 85 years; and (c) 2.06 K of warming may occur if further cuts in aerosol pollution continue to accrue at the same pace of recent decades, this begs the question: Why are climate policies centered around reducing CO2 emissions instead of on the strategic management of aerosol emissions? Considering its alleged forcing strength or potential to induce warming and/or cooling, increasing or decreasing aerosol pollution would ostensibly be far more effective and efficient at modifying the climate than attempting to geoengineer our way to an optimum temperature with CO2 emissions policies.

Even more problematic for the dangerous CO2-induced global warming paradigm constructed in the last few decades is that an anthropogenic aerosol-forced -2.49 W m-2 cooling of -2.53 K between 1850 and 2010 would necessarily eliminate the capacity for anthropogenic CO2 forcing to have been the cause of the overall warming trend of about 0.8°C between 1850 and 2010. After all, “basic physics” tells us – and even the IPCC and blogs like Skeptical Science agree – that even if we were to double the pre-industrial levels of CO2 concentration from 280 ppm to 560 ppm (without feedbacks), the associated radiative forcing would amount to about 4 W m-2 , and this forcing would lead to a modest 1.2°C of warming 4, 5, 6, 7, 8, 9.

According to the IPCC (2013, Summary for Policy Makers), the accumulated anthropogenic CO2 radiative forcing (RF) was only about +1.8 W m-2 in total for the entire 1750-2011 period10 — a value considerably lower than the alleged -2.49 W m-2 of negative anthropogenic forcing (cooling) indicated by Zhang et al. (2016) for 1850-2010 due to aerosol emissions. In other words, the presumed heat forcing from CO2 would not have been strong enough to overcome the radiative heat losses associated with anthropogenic aerosol forcing. The alleged anthropogenic influence on climate would necessarily have been one of net cooling, not warming, for the past few hundred years, and therefore the ~0.8°C of net warming since 1850 would have to have been forced by factors other than anthropogenic CO2. This would obviously be incompatible with the dangerous CO2-induced global warming paradigm that exists today.

A few years ago, a paper published in Environmental Research Letters (McClellan et al. [2012], http://iopscience.iop.org/1748-9326/7/3/034019/pdf/1748-9326_7_3_034019.pdf) summarized the costs of geoengineering a cooler climate via stratospheric albedo modification. Specifically discussed was a proposal to pump millions of tons of sulfuric acid into the high atmosphere with a 20-kilometer pipe (which would presumably block sunlight and lead to surface cooling). About 45 years ago, an albedo modification scheme designed to warm the planet by melting Arctic sea ice was likewise assessed for feasibility. Considering the presumably much higher radiative forcing impact of artificially blocking more or less of the sun’s energy from reaching the surface (albedo modification), these “schemes” may actually not be quite as strange or outlandish as they might first appear. Especially if we compare the effectiveness and efficiency of “schemes” like this to that of CO2 emissions reduction policies, which have been shown to have even less of an effect on climate.

References

1. http://www.nature.com/nature.html:

“Between May 1958 and April 1963 the mean temperature of the atmosphere in the northern hemisphere fell by about 0.60° C.”

2. http://globalchange.mit.edu/files/Outlook.pdf

“Assuming the proposed cuts are extended through 2100 but not deepened further, they result in about 0.2°C less warming by the end of the century compared with our estimates, under similar assumptions, for Copenhagen–Cancun.”

3. http://onlinelibrary.wiley.com/full

“All climate policies by the US, China, the EU and the rest of the world, implemented from the early 2000s to 2030 and sustained through the century will likely reduce global temperature rise about 0.17°C in 2100. These impact estimates are robust to different calibrations of climate sensitivity, carbon cycling and different climate scenarios. Current climate policy promises will do little to stabilize the climate and their impact will be undetectable for many decades.”

4. http://www.ipcc.ch/ipccreports/.htm

“If the amount of carbon dioxide were doubled instantaneously, with everything else remaining the same, the outgoing infrared radiation would be reduced by about 4 Wm-2. In other words, the radiative forcing corresponding to a doubling of the CO2 concentration would be 4 Wm-2. To counteract this imbalance, the temperature of the surface-troposphere system would have to increase by 1.2°C (with an accuracy of ±10%), in the absence of other changes.”

5. www.atmos.washington.edu/Hansen81_CO2.pdf

“The increase of equilibrium surface temperature for doubled atmospheric CO2 is ∼1.2°C. This case is of special interest because it is the purely radiative-convective result, with no feedback effects.”

6. www.atmos.washington.edu/ice-core.pdf

“The radiative forcing resulting from doubled atmospheric CO2 would increase the surface and tropospheric temperature by 1.2°C if there were no feedbacks in the climate system.”

7. www.skepticalscience.com/print=967

“If there were no feedbacks in the Earth’s climate system, physics tells us climate sensitivity would be 1.2°C for a doubling of CO2.”

8. http://onlinelibrary.wiley.com/pdf

“An increase in atmospheric CO2 concentration from 275 to 550 ppm is expected to increase radiative forcing by about 4 W m2, which would lead to a direct warming of 1.2°C in the absence of feedbacks or other responses of the climate system”

9. www.yaleclimateconnections-global-temperatures/

“By itself, doubling atmospheric CO2 would increase global temperatures by about 1.2 degrees C. Even most of the scientists skeptical of the severity of climate change agree on this basic point.”

10. www.ipcc.ch/pdf/WGIAR5_SPM_en.pdf

“Emissions of CO2 alone have caused an RF of 1.68 [1.33 to 2.03] W m–2. Including emissions of other carbon-containing gases, which also contributed to the increase in CO2 concentrations, the RF of CO2 is 1.82 [1.46 to 2.18] W m–2.”