Influence of Atmospheric Nuclear Explosions on Climate Change

Yoshiaki Fujii

Rock Mechanics Laboratory, Hokkaido University, N13W8, Sapporo, 060-8628, Japan, fujii6299 at eng.hokudai.ac.jp,

The stagnation in the average air temperature between 1945 and 1964 can be explained by the atmospheric nuclear explosions including Nagasaki, Hiroshima and the succeeding atmospheric nuclear weapons testing.

The average air temperature has been basically rising in this one hundred and several ten years (Fig. 1). The temperature rise looks stagnated between 1945 and 1964. The difference before (Line A in Fig.1) and after (Line B in Fig. 1) the stagnation is approx. 0.5K. It is apparent that this stagnation could not be simulated well in IPCC AR4 (2008). This stagnation also cannot be explained by only solar activity since it showed a maximum around 1950. There were no giant eruptions in this period.

It can be noted that the stagnation began with the atomic bomb attacks against Nagasaki and Hiroshima in 1945 and lasted for the period in which the succeedingatmospheric nuclear weapons testing were carried out. It began to rise again at the almost the same rate soon after PTBT (Partial Test Ban Treaty) prohibited atmospheric nuclear weapons testing in 1963 (Fig. 1).

It is well known that nuclear wars can induce nuclear winter (Ehrlich et al., 1985). The smoke from nuclear war reaches the upper troposphere and rapidly spreads with the jet streams and reaches the stratosphere to stay there for several months to years reflecting insolation. The climate model used in Ehrich et al. (1985) was a simple one. However, recently, Roback et al. (2007) obtained similar results by using a modern climate model.

According to Ehrｌich et al. (1985) temperature drop is 10K for 3000 Mt or 32 K for 100 Mt (this is not a mistype) nuclear war without or with smoke from urban cities. The historically known atmospheric nuclear explosions were 80 Mt including Nagasaki, Hiroshima and succeeding nuclear weapons testing. Temperature fall by 80 Mt nuclear explosions can be roughly estimated as 10K x 80 Mt / 3000 Mt = 0.27K. Considering the fact that Nagasaki and Hiroshima were completely burned and much smoke was induced, and there should be much more nuclear weapons tested other than historically known ones, it can be said that there is a possibility that the 0.5K stagnation was due to the atmospheric nuclear explosions.

Let's compare Tsar Bomba, the largest nuclear weapon ever tested in atmosphere and Pinatubo eruption in 1991, the largest eruption in 20th century since it is also well known that average temperature was lowered by giant eruptions. Energy of Tsar Bomba was 5 orders smaller than Pinatubo eruption (Table 1). However, the maximum height of ejecta is twice that of Pinatubo. It is very important for smoke to cool down the earth that the smoke reaches stratosphere and Tsar Bomba easily cleared this requirement. Ejacta mass of Tsar Bomba is one tenth that of Pinatubo. However, the mass for Pinatubo is of magma. Smoke mass for Tsar Bomba can be more than Pinatubo.

Ehriich et al. (1985) also pointed out nuclear summer which is gradual global warming by CO2 concentration increase after the temporary nuclear winter. There is a possibility that we are suffering petti nuclear summer if the stagnation was petti nuclear winter. It can also be pointed out that there is a possibility that human beings can control and lower air temperature by, for example, sprinkling detoxified fly ash by transport planes in the upper troposphere and the stratosphere. Deliberate considerations are required before the execution of course.

It can be said that quantitative validation for the stagnation would be useful. However, it can also be said that the stagnation was a result of the in-situ experiments and proved the validity of the simulations on nuclear winter.

Table 1Comparison between Tsar Bomba explosion and Pinatubo eruption in 1991

Tsar Bomba / Pinatubo eruption
Energy (J)* / 2.1 x 1017 / 1.1 x 1022
Max. height of ejecta (km)* / 60 / 34
Ejecta mass (kg) / 4 x 1011** / 5 x 1012***

*Based on reference 3, **Calculated by the author based on reference 3, ***Mass of magma6

Fig. 1Temperature anomaly by NASA1 between 1880 and 2008 with the biggest eruptions2 whose VEI (volcanic explosivity index) is 6 and TNT equivalent mass3 of historic nuclear explosions (red bars). Green bars are underground testing for references.

References

  1. Wikipedia, "VEI"
  2. Wikipedia Ja, "Nuclear Weapons Testing"
  3. P. R. Ehrlich, C. Sagan, D. Kennedy and W. O. Roberts (1985), The Cold and the Dark, W. W. Norton & Company.
  4. Alan Robock, Luke Oman and Georgiy L. Stenchikov (2007), Nuclear winter revisited with a modern climate model and currentnuclear arsenals: Still catastrophic consequences, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 112, D13107,
  5. National Astronomical Observatory (ed., 1997), Chronological Scientific Tables, Maruzen Co. Ltd.

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