A small nuclear war would cause global cooling

NASA research physical scientist Luke Oman gave a presentation of research into the impact of a regional nuclear war on global temperatures and precipitation at the American Association for the Advancement of Science on February 18, 2011. Such a nuclear conflict, while less severe than a major nuclear conflict resulting in nuclear winter, would cause unprecedented climate change cooling the planet for up to ten years, and cause major famines and starvation from agricultural disruption.

Research from Japan has found that Atmospheric nuclear testing stagnated mid 20th century global warming.


Using climate models the impact of a small nuclar war can be estimated resulting in a decrease in global average temperatures by about 1.5 degrees Celsius and a 10 per cent reduction in rainfall.

"We studied the scenario of using 100 Hiroshima-size bombs, the fires from which would inject upward of 5 teragrams (megatons) of black carbon particles into Earth's upper troposphere. Observations of forest fires have shown this to occur on much smaller scales." said Luke Oman in an interview published on the NASA website.

"On the ground, global temperatures would fall by a little over 1 degree Celsius (C) (1.8 Fahrenheit (F)) over first three years. In contrast, aerosols from the 1991 eruption of Mount Pinatubo contributed to about 3/10 of a degree C (~ 0.5 F) of cooling over one year. Black carbon particles are smaller than sulfate particles and can be lofted much higher by solar heating, where their influence on climate can last up to a decade."

"We also saw that two to four years after the event, rainfall would decrease globally by an average of about 10 percent." Luke Oman said in the NASA feature article.

Such a nuclear war would also drive global stratospheric ozone loss leading to higher levels of ultra-violet radiation.

Even communities far distant from the conflict would be deeply affected. Agriculture would be disrupted from the combination of cooler temperatures, less precipitation and decreases in solar radiation reaching the surface. There would be widespread interruptions to growing seasons by producing more frequent frosts.

The disasterous effects of nuclear winter caused by a major nuclear war between superpowers strongly influenced Mikhail Gorbachev to end the nuclear arms race. But even a small nuclear war could have catastrophic global climate effects.

Figure Caption:
Time variation of global average net surface shortwave radiation, surface air temperature, and precipitation changes for the 5 Tg standard case. The global average precipitation in the control case is 3.0 mm/day, so the changes in years 2-4 represent a 9% global average reduction in precipitation. The precipitation recovers faster than the temperature, but both lag the forcing. For comparison the global average net surface shortwave forcing from a model simulation of the 1991 Mt. Pinatubo eruption is shown. By contrast, volcanic particle last for a much shorter time in the atmosphere, as they are not lofted by solar absorption. Figure drawn by Luke Oman.

Read more at this index page by Alan Robock on the Climatic Consequences of Nuclear Conflict

Dr Brian Toon at Colorado University on the climate impacts of nuclear war (April 17, 2008) - What would happen if India and Pakistan got into a nuclear war?