On July 16, 1945, at 5:29 a.m. (local time), EE.UU. detonated in the desert of Jornada del Muerto, 35 miles from the city of Alamogordo in New Mexico, the first nuclear bomb, named Trinity, which was part of the Manhattan project. With this test began the atomic age. Twenty days later, the next two bombs were dropped on the Japanese civilian population in Hiroshima and Nagasaki., ending World War II.
Since then, EE.UU. ha detonado 1,129 bombas more until 1992 as part of their 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.
Total, almost 2,500 nuclear bombs have been tested over the past decades, giving a total energy of more than 540 megatones 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 one in Hiroshima, 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 the radiation.
In the atmosphere, underground Y underwater 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 below Earth.
However, although there were no concerns in the early years of the trials, several events began to show that these tests they did affect the environment and people. Due to increasing environmental threats such as radioactive fallout –Deposition of a mixture of particles from the atmosphere from an explosion– or the 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 premises for the first large-scale international cooperation to eliminate them ”, says the researcher from the University of Bucharest in Romania, Remus Prăvălie, in an article published in the magazine Ambio.
In fact, the UN already showed from previous years – as this demonstrates General Assembly resolution from 2000 – his concern about harmful effects for “present and future generations of radiation levels to which humanity and the environment were exposed with these tests.”
Towards a ban on trials
One of the first consequences of the tests was observed in 1954 with the pump Castle Bravo, detonated in the 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. a thousand times higher to each of the two bombs dropped in Japan, but less than the power of the largest bomb in history: the Tsar 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 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 the residents and the military. A more particulate and gaseous rain reached the rest of the world, until Australia, India and Japan, even the US 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, they did not take long to make themselves heard international reactions against the tests atmospheric thermonuclear cells, of which 500 have been released so far, according to the Centers for Disease Control and Prevention (CDC). All of it culminated in 1963 in the ratification of Partial nuclear test ban treaty, in which North Korea would never participate – France and China joined years later.
According to a research from the American center, even today radioactive fallout is present in small amounts around the world, and in fact, anyone born after 1951 in the US has received some form of radiation exposure from this phenomenon related to nuclear weapons testing.
How the clouds changed
The radioactive period after the tests has caused other alterations in the atmosphere, such as changes in the patterns of the precipitation. A work, recently published in the magazine Physical Review Letters, suggests that tests carried out mainly between the 50s and 60s of the last century by the US and the Soviet Union have been able to produce effects on clouds even thousands of kilometers from 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 clouds were visibly more dense and thick, 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 radioactivity released from 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 during the years after World War II has thus enabled researchers to study how the electric charge –Released by the ionization air due to radioactivity – affects rain. Until now, the former was thought to modify the way Raindrops in the clouds collided and merged, altering its size and influencing the 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 the anthropogenic pollution. “This made it a much better place to observe the effects of rain,” the authors note.
Although the test explosions charged the world’s atmosphere 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 like India, North Korea and Pakistan they approve it, the only thing missing is for the agreement to come into force.