A climate change timebomb may be just 10 years away from detonating, according to the latest global warming evidence.
New data from a deep ice core drilled out of the Antarctic permafrost reveal a shocking rate of change in carbon dioxide concentrations.
The core, stretching through layers dating back 800,000 years, contains tiny bubbles of ancient air that can be analysed.
Scientists who studied the samples found they left no doubt as to the extent of the build-up of greenhouse gases.
For most of the past 800,000 years, carbon dioxide levels had remained at between 180 and 300 parts per million (ppm) of air. Now they are at 380ppm.
In the past, it had taken 1,000 years for carbon dioxide to rise by 30ppm during natural warming periods. According to the new measurements, the same level of increase has occurred in just the last 17 years.
Isotopic tests confirmed that the recent carbon dioxide had come from fossil fuel sources and must be due to human activity.
Dr Eric Wolff, from the British Antarctic Survey, who presented the findings at the BA Festival of Science in Norwich, said: "The rate of change is the most scary thing.
"We really are in a situation where something's happening that we don't have any analogue for in our records.
"It's an experiment we don't know the result of."
