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The United States currently has ~1400
Housatonic (10 Mt)
Housatonic (10 Mt) A thermonuclear warheads deployed on land-
Housatonic (10 Mt)
150
atmospheric bomb-test yield (Mt/y) 100 Mike (10.4 Mt) Mike (10.4 Mt) Mike (10.4 Mt) Yankee (13.5 Mt) Yankee (13.5 Mt) Yankee (13.5 Mt) (~50 Mt USA (>8Mt) another ~400 at U.S. Air Force bases
T Ts
Tsarsarar
and submarine-based ballistic missiles and
bomba
bomba
bomba
(~50 Mt))
(~50 Mt)
(Kristensen and Korda, 2021). A recent
USSR (>8Mt)
estimate of Russian nuclear-weapon deploy-
ment is similar (Kristensen and Korda,
50
2022). Both nations have several thousand
0
available for deployment, with a total of
1950 1960 1970 1980 1990 additional nuclear warheads in storage and
~8300 warheads and bombs available for
2.0 23 Pu + 240 200 use in a major nuclear war. NATO members
Pu falloutalloutPu fallout B
239 Pu + 240 Pu (PBq) 1.5 1377 Cs f 150 137 Cs (PBq) weapons. The nuclear-weapon arsenal of
Pu f
239+240
239+2409
France and UK have another ~500 nuclear
Cs f
Cs falloutalloutallout
137
13
the United States is intended to defend the
30 member nations of NATO, with a popu-
1.0
100
Cs f
Cs fallout remainingallout remainingallout remaining
Cs f
1377
lation of ~950 million, plus an additional
13
137
in 2012
in 2012
in 2012
200 million people in Japan, South Korea,
50
0.5
and Australia. The Russian arsenal is
intended to defend the ~146 million people
0.0 0
1950 1960 1970 1980 1990 in Russia plus the additional 47 million
people in allied countries of the Collective
1000 Security Treaty Organization.
>45°
>45°
Jan. 1, 196
Jan. 1, 1963 >45° NNN C
Jan. 1, 19633
800 The primary targets of Russian and
>10° S
>10° SS
>10° American nuclear weapons are the nuclear
∆ 14 C (‰) 400 1987). Stationary land-based missile sites
weapons of the opposing countries (Hafner,
600
would be targeted with the intent of destroy-
200 ing the missiles before launch. Other mili-
tary facilities, including those in and near
0 cities, would be targeted, with higher-eleva-
1950 1960 1970 1980 1990 tion detonation for more dispersed targets.
year The number and types of non-military tar-
gets, including infrastructure, industry, and
Figure 1. (A) Histogram of annual yield, in megatons of TNT equivalent, for
atmospheric nuclear-bomb tests (UNSCEAR, 2000; USDOE, 2015). Atomic cities, is not public knowledge, but enor-
bomb-test yields before the first thermonuclear bomb test in 1952 are too mous destruction and loss of life could
small to plot at the scale shown. Names of some major tests are also result from attack on these targets with a
shown. Atmospheric testing by the United States (USA) and Union of
Soviet Socialist Republics (USSR) ended with the 1963 Partial Test Ban small fraction of either nation’s nuclear
Treaty. Later atmospheric tests were conducted by China and France. forces (Glasstone, 2020).
(B) Combined 239 Pu and 240 Pu fallout as calculated from more readily mea-
sured 137 Cs and Sr fallout, with higher ( 239 Pu+ 240 Pu)/ 137 Cs in earlier U.S.
90
(neutron-rich) tests versus later Soviet tests (Koide et al., 1985; UNSCEAR, NUCLEAR WINTER
2000; Hancock et al., 2014). (C) Graph of C as measured in tree rings and
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in the atmosphere showing the high values measured at sites >45° N and Nuclear winter is the concept that, during
low values measured at sites >10° S before global atmospheric mixing a major nuclear war, firestorms caused by
(modified from fig. 4 of Hua et al., 2021).
nuclear explosions will engulf cities and
inject smoke into the stratosphere where it
will spread around the globe and reduce
atmosphere contain C rather than stable NUCLEAR WAR sunlight at ground level to the point where
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12 C or C (e.g., Dutta, 2016). Neutrons pro- Radioisotope fallout in the mid-twentieth winter-like conditions persist for months or
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duced by nuclear explosions also cause century occurred during the development years (e.g., Crutzen and Birks, 1982; Turco
transformation of N to C. Thermonuclear- and deployment of thousands of nuclear et al., 1983, 1990). The severity of a nuclear
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bomb tests during 1952–1962 produced so weapons by North Atlantic Treaty Org- winter would depend on the fuel load and
much C that concentrations of C in atmo- anization (NATO) nations and the USSR. flammability of targeted areas as well as
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spheric CO almost doubled (Fig. 1C; Hua et The military posture represented by these atmospheric conditions and other environ-
2
al., 2021). Elevated C concentrations are nuclear weapons, known as “mutual assured mental factors. While the primary targets of
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measurable in tree rings and ice cores (e.g., destruction,” ensures a catastrophic nuclear U.S. and Russian nuclear weapons are the
Levchenko et al., 1996) and have been pro- response to a major nuclear attack, thus opposing nation’s nuclear weapons and
posed as the most precise geologic marker restraining adversaries as long as those in command and control infrastructure, most
for the beginning of the Anthropocene charge behave rationally and command and of which are not particularly large or flam-
(Turney et al., 2018). control infrastructure performs as intended. mable, potential secondary targets include
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