The use of nuclear weapons in an urban area, particularly by a terrorist group, remains a palpable threat for many in a post-9/11 world. As populations congregate in ever-larger cities around the globe, scientists are seeking to measure all the likely physical impacts of such an attack on these dense clusters.

A 2006 paper by researchers at the University of Colorado-Boulder, Rutgers and UCLA, “Atmospheric Effects and Societal Consequences of Regional Scale Nuclear Conflicts and Acts of Individual Nuclear Terrorism,” analyzed the likely effects of both a regional nuclear exchange and an individual act of nuclear terrorism on a megacity.

The study’s findings include:

• If the densest city in the United States were targeted, the U.S. could expect immediate fatalities of more than 400,000 from a single 15-kiloton detonation. The densest cities in India, Pakistan, China and Egypt could expect more than one million immediate causalities.
• A single conflict between any two nuclear-capable countries involving one hundred 15-kiloton weapons has the potential to create fatalities rivaling those of World War II.
• Smoke from an explosion would reach its peak height (6 kilometers) in minutes, but the intense firestorms generated by a nuclear blast may take more than 30 minutes to reach peak strength. Due to the high level of combustible material in urban cities, these fires would likely cause smoke to rise even higher, to the upper troposphere.
• Smoke and soot reaching these heights would cause strong local heating of the stratosphere. Additionally, observation of nuclear tests has recorded a reduction of total ozone by 50% at some Northern Hemisphere locations, while increasing it by 50% in the Southern Hemisphere, all within 20 days of the detonations.
• In such an event, a city could see atmospheric fallout of long-lived radionuclides, forcing the area to be abandoned. Global disruptions to the climate and ozone layer could also be expected.

Worldwide, people are congregating in large urban centers, creating megacities with populations of 10 million and more. This study indicates that the conditions within urban centers may exacerbate the environmental fallout from such an attack, causing even longer-term damage to the atmosphere.

Tags: China, nuclear weapons, terrorism