Climate change, 55 million years ago

About 55million years ago, Earth's temperature suddenly shot up owing to a massive release of carbon dioxide into the atmosphere, new research have revealed. Scientists are warning that we should take note and cut carbon emissions to avoid a repeat.

Historically, Earth was much warmer. About 55 million years ago, temperatures were, on average, 8 degrees Celsius higher than they are now. There were crocodiles living off Greenland, and palm forests in Wyoming.

Suddenly, the levels of carbon-dioxide doubled and global temperatures increased by 5 degrees.

Previously, scientists had thought this warming had taken tens of thousands of years.

But now researchers Morgan Schaller and James Wright have been studying offshore clays dating from this period from Maryland and Delaware. They discovered a repeating pattern in the clay, resembling tree-rings, corresponding to a yearly cycle of rivers dropping more and less sediment into the ocean.

By looking at different isotopes of carbon present in each of the clay layers, including carbon-12, which is more easily taken up by living things, and carbon-13, which is more common in inorganic carbon sources, they found evidence for a huge injection of about 3000 billion tonnes of carbon into the atmosphere over a period of a few months.

Over the next 13 years, this dissolved into the shallower parts of the sea causing it to become acidic, killing off more deep sea species than at the end of the cretaceous which killed off the dinosaurs. It then took 150 000 years for things to return to normal.

This, they say, should help us to understand not only an interesting piece of Earth's early history, but also serves as the best model we have of the experiment we are doing to our climate by adding CO₂ to the atmosphere by burning fossil fuels.