The war in Ukraine is intensifying. A few days ago, US President Joe Biden warned that involving NATO in the war would entail World War III and recently Putin warned that he had nuclear warheads ready. What can we expect from now on if the conflict seems to be entrenched and nuclear war is back on the table? Science is very clear about the consequences of an escalation of war on the climate and on food shortages.
Climate models allow us to simulate the impact of war on agricultural, livestock and fish production. Below we review some of the different possible scenarios that a war confrontation can leave us: from a nuclear winter to a scenario of growing rivalry between countries.
Conflicto nuclear regional
Decades after the end of the Cold War, the nuclear weapons debate is back on the table. Actually, it's a debate that never went away. The arms race between India and Pakistan, for example, can have global consequences even if it is a local war.
Under a scenario of nuclear war between these two countries, where only 1% of the world's nuclear arsenal would be used, 5 million tons of soot would be emitted into the stratosphere. That is, the plumes of the bombs would inject into the upper layers of the atmosphere a huge amount of aerosols that would block solar radiation.
Solar radiation would hit these aerosols and be reflected. As a result, the global temperature would decrease by 1.8 ℃. The resulting darkening and cooling would affect world production of maize and wheat, which would decrease by 13 per cent globally.
This decline would not affect everyone equally, but the temperate zone of the northern hemisphere, which includes Europe, the United States and China, would be the most affected. Agricultural production would decrease by 20 to 50 per cent in these countries. A famine would therefore be triggered with global impacts that would last about 15 years. After this time, we would return to the current climate change scenario.
Nuclear World War
A large-scale nuclear conflict between the United States and Russia using 4,400 100-kt bombs (kilotons, equivalent to thousands of tons of TNT) would inject 150 million tons of aerosols into the stratosphere. This would decrease solar radiation and the sea temperature would drop 6.4 ℃. We are talking about a scenario in which only about half of the current atomic arsenal would be used.
Globally, two years after the war, food production would decline by 80%. Such reductions would also be more pronounced in the temperate zone of the northern hemisphere, where they would reach 99%.
Directly, 770 million people would die after the bombs (many of them would be vaporized). The survivors would face a nuclear winter. In the temperate zone, we would have less than 1% of the food currently produced. It should be noted that, probably, the human species would survive such a nuclear scenario. This is not a cataclysm comparable, for example, to that caused by the Chicxulub meteorite, which killed dinosaurs in the late Cretaceous. In that case, more than 1.5 billion tons of soot were emitted.
Regional rivalry and exacerbated nationalism
The nuclear war scenario is undoubtedly an extreme scenario and should be avoided at all costs. What is already happening today is that the Western world is trying to isolate Russia economically, and we do not yet know how the other world powers will react. It was to be hoped that international cooperation would decline and that there would be an increase in inter-regional rivalry.
Not only Putin's policies, but many of the current or recent regional or national leaders fall within the scenario that the IPCC qualifies as SSP3. It is a scenario where, in the words of its creators, a “resurgent nationalism” takes place.
In this scenario, the major powers focus mainly on their domestic short-term food security needs and national security. The current climate pacts are abandoned, along with technological and educational improvements. Environmental degradation is of little importance in a divided world.
We don't know if we will encounter this climate scenario after the war, but it is an expected consequence of a schism between the West and the East. Under these circumstances, we would encounter an intensification of climate change. Today, with the agreements that are approved, the global temperature at the average level would rise by 2.7 ℃ by the end of the century. Under the scenario of resurgent nationalism, the temperature would rise to 4 ℃.
We are talking about the global average temperature. This means that in some areas the heating could reach 7 ℃.
Climate simulations teach us that the price of a nuclear escalation or that of a nationalist resurgence is food security (although to different degrees, obviously). An escalation of war would not only not save our neighbors in Ukraine, but would also compromise the availability of food in other parts of the world. We must therefore decrease, not increase, the number of countries participating in this war.
* The author is Professor of Forest Fires and Global Change at PVCF-Agrotecnio, University of Lleida
(C) The Conversation.-
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