Melting could be one of the most important phenomena of the 21st century. Thanks to man-made climate change, Arctic ice levels have hit a record low this year. Among the many profound changes that could stem from ice melting across the world, according to a new study from an international group of scientists, is the release of deeply buried radiation.
The international team studied 17 icy locations across the globe, including the Arctic, the Antarctic, Iceland, the Alps, the Caucasus mountains, and British Columbia. While radiation exists naturally, the scientists were looking for an example of human-made radiation. It was common to find concentrations at least 10 times higher than levels elsewhere.
“They are some of the highest levels you see in the environment outside nuclear exclusion zones,” says Caroline Clason, a lecturer in Physical Geography at the University of Plymouth, speaking in a press statement.
When human-made radiation is released into the environment, be it in small amounts like the Three Mile Island accident of 1979 or larger quantities like the Chernobyl disaster of 1986and the Fukushima Daichii accident of 2011, it goes into the atmosphere. That includes elements like radioactive cesium, which have been known to make people sick to the point of death across the globe.
After Chernobyl, clouds of cesium travelled across Europe. Radiation spread without regard for borders, reaching as far as England through rains. But when rain freezes, it takes the form of ice. And within ice, it can lay trapped.
“Radioactive particles are very light so when they are taken up into the atmosphere they can be transported a very long way,” Clason tells the AFP. “When it falls as rain, like after Chernobyl, it washes away and it’s sort of a one-off event. But as snow, it stays in the ice for decades and as it melts in response to the climate it’s then washed downstream.”
What does that response look like? Humanity is starting to find out, Clason says. She points to wild boar in Sweden, who in 2017 were found to have 10 times the levels of normal radiation.
Traces of human-made radiation last a famously long time. Ice around the globe contains nuclear material not just from accidents involving nuclear power plants, but also man’s use of nuclear weapons.
“We’re talking about weapons testing from the 1950s and 1960s onwards, going right back in the development of the bomb,” Clason says. “If we take a sediment core you can see a clear spike where Chernobyl was, but you can also see quite a defined spike in around 1963 when there was a period of quite heavy weapons testing.”
Elements within radiation have different life spans. Perhaps the most notorious of these, Plutonium-241 has a 14-year half-life. But Americium-241, a synthetic chemical element, has a half-life of 432 years. It can stay in ice a long time, and when that ice melts will spread. There isn’t much data yet on its ability to spread into the human food chain, but Clason called the threat of Americum “particularly dangerous”.
A term popular in science these days is the Anthropocene, which refers to the idea that humans have permanently altered the very core of how the Earth functions as a living ecosystem. Looking for radiation buried within icy soil and sediment could offer stronger proof of those changes.
“These materials are a product of what we have put into the atmosphere. This is just showing that our nuclear legacy hasn’t disappeared yet, it’s still there,” she says.
“And it’s important to study that because ultimately it’s a mark of what we have left in the environment.”
Originally published on Popular Mechanics