If you’re an avid reader or a film aficionado, you’ve probably seen what a nuclear winter would look like according to filmmakers and novelists. But what do scientists have to say on the matter? Now you can find out.
In a new study, a team of four U.S. atmospheric and environmental scientists modeled what would happen after a “limited, regional nuclear war.” At first—the consequences seem relatively subtle. A drop of two to three degrees in temperature, a nine percent reduction in rainfall…deceptively small numbers that could result in crop failures and famines.
“I’m drawn to extreme scenarios,” Luke Oman, a scientist at the Goddard Space Flight Center, says. Using a computer simulation, he and his colleagues modeled the climate’s response to the smoke from fires brought about by regional nuclear war. Specifically, the work modeled how sulfur dioxide gas ejected from volcanoes is converted into solid sulfate particles and then circulated into the upper atmosphere, impacting climate.
For the purpose of the study, the team of researchers imagined 100 nuclear warheads, each the size of the atomic bomb dropped on Hiroshima, detonate over the Indian subcontinent in an India-Pakistan nuclear war. Those two countries have relatively small nuclear stockpiles compared to the international giants—so you can only imagine the damage we could cause. Or Russia. Or China.
“With the emergence of smaller nuclear states, we wanted to make estimates of regional-scale conflicts,” Oman notes. “What kind of climate anomalies would we see? How would growing seasons change?”
Here’s how the Indian-Pakistani nuclear exchange would unfold, as reported by Popular Science:
• Five megatons of black carbon enter the atmosphere immediately. Black carbon comes from burned stuff and it absorbs heat from the sun before it can reach the Earth. Some black carbon does eventually fall back to Earth in rain.
• After one year, the average surface temperature of the Earth falls by 1.1 kelvin or about two degrees Fahrenheit. After five years, the Earth is, on average, three degrees colder than it used to be. Twenty years on, our home planet warms again to about one degree cooler than the average before the nuclear war.
• Earth’s falling temperatures reduces the amount of rain the planet receives. Year five after the war, Earth will have 9 percent less rain than usual. Year 26 after the war, Earth gets 4.5 percent less rain than before the war.
• In years 2-6 after the war, the frost-free growing season for crops is shortened by 10 to 40 days, depending on the region.
• Chemical reactions in the atmosphere eat away Earth’s ozone layer, which protects Earth’s inhabitants from ultraviolet radiation. In the five years after the war, the ozone is 20 to 25 percent thinner, on average. Ten years on, the ozone layer has recovered so that it’s now 8 percent thinner.
• The decreased UV protection may lead to more sunburns and skin cancers in people, as well as reduced plant growth and destabilized DNA in crops such as corn.
“A primary goal of this work was to get the information revealed by our study into the hands of decision-makers as well as to get other groups interested in this problem and to be aware of the potential impacts. Before we did this study, we didn’t know what the climate anomalies would be or how long they would last. This is critical information that needs to be known in advance with knowledge that the consequences of such a scenario would be global,” Oman told NSA.
Sources: Popsci.com, NASA.gov