On July 16, 1945, at 5:29 am (local time), the United States detonated in the Jornada del Muerto desert, 35 miles from the city of Alamogordo in New Mexico, the first nuclear bomb, calledTrinity, which was part of the Manhattan project. With this test the atomic age began. Twenty days later, the next two bombs were dropped on the Japanese civilian population in Hiroshima and Nagasaki, ending World War II.
Since then, the United States has detonated 1,129 more bombs through 1992 as part of its nuclear tests. They are joined by the former Soviet Union with 981, France (217), United Kingdom (88), China (48), India (6), Pakistan (6) and North Korea (6), whose last nuclear test took place in September 2017.
In total, nearly 2,500 nuclear bombs have been tested over the past decades, for a total energy of more than 540 megatons on Earth. The bombs dropped into the atmosphere alone accounted for 428 megatons, the equivalent of more than 29,000 bombs the size of the Hiroshima one, which had caused 166,000 deaths by the end of 1945.
Considered necessary to measure the safety, effectiveness and power of nuclear weapons, the tests were conducted in various types of environments, in remote parts of the world and far from civilization. The objective was to avoid harming people, since they could suffer from skin lesions, poisoning or various types of cancers in the long term, due to the effect of radiation.
In the atmosphere, underground and under water were mainly the chosen locations and different methods were used to launch them: aboard barges, on top of towers, from airplanes, suspended from balloons, with rockets, on the surface of the Earth. , more than 600 meters under water and more than 200 meters underground.
However, although there were no concerns in the early years of the trials, several events began to show that these tests did affect the environment and people. Due to the growing environmental threats such as radioactive fallout –deposition of a mixture of particles from the atmosphere from an explosion– or pollution, the United Nations Organization celebrates every August 29, since 2010, the International Day against Nuclear Tests.
"The severe environmental damage caused by these nuclear tests, the most powerful ever conducted in the atmosphere, as well as the general context of global nuclear weapons tests, laid the groundwork for the first large-scale international cooperation to eliminate them," notes the researcher at the University of Bucharest in Romania, Remus Prăvălie, in an article published in the journalAmbio.
In fact, the UN had already shown in previous years –as this 2000 General Assembly resolution shows– its concern about the damaging effects on “present and future generations of the radiation levels at which humanity and the environment were facing. exposed with these tests ”.
Towards a ban on trials
One of the first consequences of the tests was observed in 1954 with the pumpCastle bravo, detonated in Bikini Atoll, in the Marshall Islands in the Pacific Ocean. The explosion accidentally tripled the estimated performance in its design, reaching 15 megatons, the highest power ever recorded by the US. It was a thousand times greater than each of the two bombs dropped in Japan, but less than the power of the biggest bomb in history: theTsar Bomb(from the Soviet Union), about 50 megatons.
The detonation occurred seven meters above the ground surface and caused a crater two kilometers in diameter and 70 meters deep and an atomic mushroom that reached 14 kilometers in altitude and seven kilometers in diameter in one minute. At 10 minutes, the cloud exceeded 40 km in altitude and 100 km in diameter, expanding at more than 100 meters per second.
The catastrophe, the largest in the United States, generated a radioactive fallout with pulverized coral that spread to the rest of the islands of the archipelago and fell, heavier in the form of white ash, on residents and the military. A more particulate and gaseous rain reached the rest of the world as far as Australia, India and Japan, even the USA and part of Europe. In total, the contamination directly affected an area of about 18,000 km2 of the Pacific Ocean.
In the aftermath of the explosion, it did not take long for international reactions to be heard against atmospheric thermonuclear tests, of which 500 have been launched so far, according to the Centers for Disease Control and Prevention (CDC, for its acronym in English). All this culminated in 1963 in the ratification of the Treaty for the partial prohibition of nuclear tests, in which North Korea would never participate - France and China joined years later.
According to an investigation by the US center, even today radioactive fallout is present in small amounts throughout the world, and in fact, anyone born after 1951 in the US has received some type of radiation exposure from this phenomenon related to nuclear weapons tests.
How the clouds changed
The radioactive period after the tests has caused other alterations in the atmosphere, such as changes in precipitation patterns. A work, recently published in the magazinePhysical Review Letters, suggests that tests carried out mainly between the 50s and 60s of the last century by the United States and the Soviet Union have been able to produce effects in the clouds even thousands of kilometers from the detonation sites.
British physicists, led by Gilles Harrison, from the Department of Meteorology at the University of Reading, in the United Kingdom, used historical records between the years 1962 and 1964 from a research station located in Scotland to compare the days with low and high radioactive load . The results show that the clouds were visibly denser and thicker, and there was 24% more rain on average on the days with the most radioactivity.
"Scientists at the time learned about atmospheric circulation patterns by studying the radioactivity released from the Cold War nuclear tests. Now, we have reused that data to examine the effect on precipitation, ”says Harrison, professor of Atmospheric Physics at the British university.
The nuclear race in the years after the Second World War has thus allowed researchers to study how electrical charge - released by ionization of the air due to radioactivity - affects rain. Until now, the former was thought to modify the way water droplets in clouds collided and merged, altering their size and influencing rain.
Ancient meteorological records have allowed to solve part of this hypothesis, especially considering that the data come from stations located near London and in the Shetland Islands, in the North Atlantic, about 480 km northwest of Scotland, little affected by anthropogenic pollution. "This made it a much better place to observe the effects of rain," the authors note.
Although the explosions of the tests loaded the atmosphere of the entire world with radioactivity, since the mid-1990s the international community has joined forces to reach a total ban with a new treaty, currently signed by 184 countries and ratified by 168 Now, waiting for nuclear powers such as India, North Korea and Pakistan to approve it, it only remains for the agreement to enter into force.
By Adeline Marcos