Scientists make predictions in the event of a nuclear war. Most people will survive the explosions of nuclear bombs, but the worst will begin later: giant fires, nuclear winter, hunger and cold, and then drought, blindness and skin cancer. "Spectrum" writes about the terrible consequences for the climate and the person.
The two studies on the climatic effects of nuclear war have come to very different conclusions. How is it that climate change forecasting is becoming more advanced? Although does it really matter how?..
A global nuclear war, which will use 20% or more of all nuclear weapons in the world, will devastate the Earth to a large extent. The nuclear powers together currently have approximately 13,900 nuclear warheads. Therefore, we can talk about at least 2.8 thousand explosions of atomic bombs, many times exceeding the power of the bomb dropped on Hiroshima. These explosions will not necessarily lead to the immediate death of all mankind - almost all of us will experience the first moments of the catastrophe. But what will come next?
According to climatologist Alan Robock, the suffering of the survivors will be exacerbated by a nuclear winter that will last at least three years. After nuclear explosions, huge fires will start, and they will release into the atmosphere such masses of smoke and soot that the sun's rays reaching the Earth's surface will become weak and pale. At the same time, the protective ozone layer will suffer enormously. The survivors will find themselves in a cold, destroyed world. Pale, low-warming sunlight will contain many harmful UV rays, which can cause clouding of the cornea and skin swelling. Sunlight won't be pleasant anymore. In Germany, one of the coldest winters will freeze Lake Bodensee and never melt: winter will be followed by cold summers. Cereals will not be able to ripen, flowers on fruit trees and shrubs will freeze,the cattle will have to be slaughtered. People will shiver from the cold and starve.
Ten years will pass, and the greatly reduced humanity will gradually leave the destruction, and the nuclear powers will still have enough weapons to repeat the catastrophe. But climate fluctuations will continue. The huge amount of greenhouse gases generated by fires will lead to a strong rise in temperature on Earth. If in the first years it will be cold, like during the ice age, then the Earth will warm up by several degrees. In such conditions, it will not be possible to harvest sufficient crops for food. The food distribution system is unlikely to be able to function properly. And even if we assume that humanity will not die out as a result of all this, in any case it will sink to a lower level of cultural development.
Small Disaster: Regional Nuclear War
No one doubts the catastrophic consequences of a major nuclear war, but different expert groups assess the danger to the world of regional nuclear conflicts in completely different ways.
In 2007, a group of climatologists led by renowned scientist Alan Robock published an article on the consequences of a possible nuclear war between the two states in the subtropics. The article assumed that in this war, one hundred atomic bombs would be detonated, comparable in power to the Hiroshima one (about 15 kilotons of TNT). They meant the nuclear powers India and Pakistan. The researchers assumed that huge fires would throw 5 million tons of soot into the troposphere.
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The term "troposphere" denotes the lower level of the atmosphere - the so-called "weather layer". Above it is the stratosphere, which also contains the ozone layer. Having penetrated into the upper layers of the troposphere, the soot will rise higher and enter the stratosphere. It will stay there for years, shade the sun and weaken the ozone layer. In the publication, the authors use the term black carbon to refer to black carbon. This is not entirely accurate. But in any case, we are talking about black particles arising from incomplete combustion, consisting mainly of carbon.
Robock and his team concluded that 5 million tons of such particles in the stratosphere would lower temperatures around the world by one to two degrees for many years. This phenomenon will be expressed in different places with different intensities. For example, Northern Europe, Eastern Siberia and parts of Canada will be particularly hard hit in the first year. Europe will need to prepare for extremely cold winters. The snow reflects the sun's rays, which will further cool the Earth.
And if it is cold, then the evaporation of water will decrease, and the world will become drier. This will definitely lead to crop failures. As these climate changes last for several years, the world's grain and rice supplies will decline. Two global crop failures at 85% of the usual amount of grain harvested will completely empty the warehouses. This study is widely accepted, and subsequent publications such as the work of a team of scientists led by Andrea Stenke of the Swiss Higher Technical School of Zurich in 2013 have confirmed its results.
Expert dispute
However, in 2018, a research team led by Jon Reisner of Los Alamos National Laboratory published a slightly different estimate. Scientists have come to the conclusion that a regional nuclear war in the Indian subcontinent will not lead to a change in the global climate. In doing so, they proceeded from the same number and the same power of nuclear explosions.
Los Alamos National Laboratory has an excellent reputation. During World War II, scientists at the Manhattan Project created the first atomic bomb there. Until now, this laboratory is considered one of the largest research centers in the world studying thermonuclear processes. According to official information, more than 10 thousand people work there, and the laboratory's budget is $ 2.55 billion. A publication from such a scientific institution simply cannot be ignored.
Unlike the authors of previous publications, these researchers modeled both explosions and fires caused by them using their own computer programs. In doing so, they came to the conclusion that although a large amount of "black carbon" will arise, only a small amount will enter the stratosphere. Most of them will reach the lower layers of the atmosphere and, with rains, will be back on the ground before they can do any significant harm.
This sounds quite convincing. Large-scale wildfires that have raged in Russia, Alaska and Brazil this year have thrown relatively little soot into the stratosphere, although the area burned out was presumably larger than all of Germany's forests. For soot to rise to a height of ten kilometers or more, a large fire is not enough. This requires a fiery tornado. With this phenomenon, the chimney effect arises, when the incandescent gases arising during combustion rush upwards, and cold air masses enter the place of heated air from below, fanning the fire even more.
But a fire tornado can occur only when the area of the fire is at least 1.3 square kilometers, it contains more than 40 kilograms of combustible material per square meter, and more than half of this material burns at once. True, these figures are very approximate: they are based on the experience of the Second World War, when the carpet bombing of Germany by the Allies constantly led to the emergence of firestorms in German cities. A nuclear explosion over Hiroshima 20 minutes later resulted in a devastating firestorm. During the second bombing in Nagasaki, although there were numerous fires, they did not merge together and did not form a tornado.
Fire Tornado: Yes or No?
John Reisner's working group concluded that the structure of modern cities in India and Pakistan is such that firestorms are unlikely to arise there. And therefore there is no danger of a global nuclear winter. But Alan Robock's working group did not rest on this. Four of the six authors of the 2007 article, along with other scientists, published the following article on October 2, 2019, in which they once again confirmed their findings.
This time they proceeded from the fact that the battle between the two countries would be even more fierce. Instead of calculating the impact of 100 atomic bombs with a yield of 15 kilotons each, they worked out three complex scenarios. They say that Pakistan will detonate 150 atomic bombs over the enemy's settlements, and India - 100 atomic bombs, and the power of the bombs will be 15, 50 or 100 kilotons, respectively. These will be supplemented by less powerful explosions over military bases.
The direct death toll from these explosions will range from 50 to 125 million. And since the authors continue to assume that most of the generated carbon will quickly enter the stratosphere, the temperature in the world will drop by two to five degrees. The amount of precipitation will decrease by 15-30%, the restoration of the climate will take more than ten years. That is why the danger of crop failures and world hunger is great.
True, the authors of the article, as in the 2007 paper, failed to convincingly prove the assumptions about the harmful effects of soot on the stratosphere. Although they provide relatively detailed arguments, they do not support them with the results of their own fire simulations. On the central point of the dispute, they can not present anything.
The nuclear danger is real
To summarize, it is still not clear whether a regional nuclear war will indeed have disastrous consequences for the global climate. Perhaps the teams of scientists should just sit down and exchange views on the reliability of their simulations. The topic is too serious to waste time advocating different points of view.
It is noteworthy that neither the one nor the other group did not calculate the aspect of the radioactive fallout. The simulations do not take into account the amount, nature, or distribution of this precipitation. In a recent article published on Science Advances, a group of scientists led by Owen B. Toon refers to their own earlier article, but after lengthy discussion comes to the following conclusion:
“Calculation of the radiation level … is complicated, among other things, by such variable quantities as wind speed or the presence of rain at the time of the explosion. But the most controversial issue is where the bomb exploded (for example, on the ground or not). The number of deaths due to radioactive fallout depends on how good the protection of the population was and how quickly the region was evacuated."
It is clear that this conclusion is not very informative. In the heat of the climate debate, we sometimes forget that the world is also threatened by other man-made dangers. Atomic bombs and the growing number of nuclear powers are certainly not the least of them. While the United States and Russia have markedly reduced their nuclear weapons in recent decades, India, Pakistan, China and North Korea are increasing them.
Regional nuclear wars are possible, including in Europe, and their possibility cannot be ruled out in the long term. In any case, the humanitarian and economic consequences of such wars for the entire world would be catastrophic, whether the climate is affected or not.
Thomas Grüter