Even if humanity is long gone in tens of millions of years, there will still be a clear sign of us and the way we lived left preserved in our planet’s geological record.
There is now overwhelming evidence that our impact on Earth constitutes its own distinct geological epoch, dating from the middle of the 20th century. Here are the seven signs that will clearly identify the Anthropocene epoch for future geologists.
1.Nuclear weapons
Our war efforts have left their mark on geology. When the first nuclear weapon was detonated on 16 July 1945 in New Mexico, it deposited radionuclides – atoms with excess nuclear energy – across a wide area. Since 1952, more explosive thermonuclear weapons have been tested, leaving a global signature of isotopes such as carbon-14 and plutonium-239.
2. Fossil fuels
The products of burning fossil fuels will also be an obvious giveaway of the Anthropocene. Current rates of carbon emission are thought to be higher than at any time in the last 65 million years. The concentration of carbon dioxide in the atmosphere has risen sharply since 1850 and now exceeds 400 parts per million, which will be recorded in any Antarctic ice cores that manage to survive global warming. Burning fossil fuels has also increased the ratio of carbon-12 to carbon-13 isotopes, which will be detectable in tree rings, limestone, and fossilised bones and shells. Our fuel consumption also spreads small, unburned particles of carbon in the air, which can become captured in sediments and glacial ice.
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