Vertaisarvioitua jääkausikauhua 1970-luvulta

Olen tässä jo listannut 70-luvun jääkausikauhusta kertovia uutisia, joissa mm. ilmastotieteen asiantuntijat kertovat uskovansa uuden jääkauden olevan tuloillaan. Vertaisarvioituja tutkimuksia asiasta ei ole tullut vastaani – ennen kuin nyt.

Nimimerkki catweazle666 toi täällä tietooni paperin nimeltä:

Schneider S. & Rasool S., “Atmospheric Carbon Dioxide and Aerosols – Effects of Large Increases on Global Climate”, Science, vol.173, 9 July 1971, p.138-141

Tämä onkin hyvin mielenkiintoinen paperi. Abstrakti kertoo seuraavaa:

Eflects on the global temperature of large increases in carbon dioxide and aerosol densities in the atmosphere of Earth have been computed: lt is found that, although the addition of carbon dioxide in the atmosphere does increase the surface temperature, the rate of temperature increase diminishes with increasing carbon dioxide in the atmosphere. For aerosols, however, the net effect of increase in density is to reduce the surface temperature of Earth. Because of the exponential dependence of the backscattering, the rate of temperature decrease is augmented with increasing aerosol content. An Increase by only a factor of 4 in global aerosol background concentration may be sufficient to reduce the surface temperature by as much as 3.5°K. If sustained over a period of several years, such a temperature decrease over the whole globe is believed to be sufficient to trigger an ice age.

Muualta tekstistä:

We will report here on the first results of a calculation in which separate estimates were made of the effects on global temperature of large increases in the amount of CO2, and dust in the atmosphere. It is found that even an increase by a factor of 8 in the amount of CO2, which is highly unlikely in the next several thousand years, will produce an increase in the surface temperature of less than 2°K. However, the effect on surface temperature of an increase in the aerosol content of the atmosphere is found to be quite significant. An increase by a factor of 4 in the equilibrium dust concentration in the global atmosphere, which cannot be ruled out as a possibility within the next century, could decrease the mean surface temperature by as much as 3.5°K. If sustained over a period of several years, such a temperature decrease could be sufficient to trigger an ice age! – – 

From our calculation, a doubling of CO2 produces a tropospheric temperature change of 0.8°K. However, as more CO2 is added to the atmosphere, the rate of temperature increase is proportionally less and less, and the increase eventually levels off. Even for an increase in CO2 by a factor of 10, the temperature increase does not exceed 2.5°K. Therefore, the runaway greenhouse effect does not occur because the 15-µm CO2 band, which is the main source of absorption, “saturates,” and the addition of more CO2 does not substantially increase the infrared opacity of the atmosphere. – –

The main conclusion of this part of the study is that even an order of magnitude increase of CO2 in the atmosphere by human activities, which at the present rate of input is not expected within the next several thousand years, may not be suficient to produce a runaway greenhouse effect on Earth. On the short time scale, if CO2 is augmented by another 10 percent in the next 30 years, the increase in the global temperature may be as small as 0.1 °K.  – –

Even if we assume that the rate of scavenging and of other removal processes for atmospheric dust particles remains constant, it is still difficult to predict the rate at which global background opacity of the atmosphere will increase with increasing particulate injection by human activities. However. it is projected that man’s potential to pollute will increase six- to eightfold in the next 50 years (24). If this increased rate of injection of particulate matter in the atmosphere should raise the present global background opacity by a factor of 4, our calculations suggest a decrease in global temperature by as much as 3.5°K. Such a large decrease in the average surface temperature of Earth, sustained over a period of few years, is believed to be sufficient (25) to trigger an ice age. However, by that time, nuclear power may have largely replaced fossil fuels as a means of energy production.

Tiivistettynä suomeksi

Paperin mukaan hiilidioksidipäästöt eivät voi lämmittää ilmastoa kuin asteen kymmenyksiä. Hiilidioksidipitoisuuden kaksinkertaistuminen lämmittää ainoastaan 0,8C, ja kahdeksankertaistuminenkin vain 2C. Sen sijaan ihmisten toiminnan aiheuttama pienhiukkasten määrän lisääntyminen ilmakehässä uhkaa jäähdyttää ilmastoamme merkittävästi.

Sen viilentävällä vaikutuksella ei ole ylärajaa, vaan voimme odottaa jopa useiden asteiden viilenemistä. Tästä syystä ilmasto voi tutkijoiden laskelmien mukaan olla vuonna 2021 jopa 3,5C kylmempi kuin nykyään. Tämä voi riittää käynnistämään uuden jääkauden!

Eli kun seuraavaksi joku toteaa jääkausikauhun olleen pelkkää median keksintöä ilman vastinetta vertaisarvioidussa tieteessä, voitte viitata tuohon paperiin.

PS.

Kyseisen paperin kirjoittaja, edesmennyt Stephen Schneider on ollut mielellään esillä myös mediassa ennustelemassa omia kauhujaan. Hän vaihtoi vuosikymmenten saatossa kuitenkin kauhukuvaansa trendikkäämmäksi, kuten tästä voi havaita: