Long description

A graph of temperature and atmospheric CO₂ concentration changes from the EPICA ice core over the last 22 000 years BP. The horizontal axis is time, measured in years before present (BP), and the minimum is 22 000 years BP with ticks every 2 000 years. The maximum on this axis is 0 which is the present day. The left-hand vertical axis is temperature change relative to the present day (mean of the past 1000 years) and the minimum is −12 °C and the maximum 4 °C, with ticks every 2 °C. There is a dashed line parallel to the horizontal axis at a temperature change of 0 °C (which refers to temperatures similar to today). The right-hand vertical axis is atmospheric CO₂ concentration with a minimum of 165 ppm, a maximum of 305 ppm and ticks every 20 ppm. The temperature data shows a lot of variability compared with the atmospheric CO₂ data. At 22 000 years BP the temperature change is around −9 °C whilst atmospheric CO₂ is about 190 ppm. From about 18 000 years BP both the temperature and atmospheric CO₂ rise until about 14 000 years BP when for a very short period of time the temperature change is −1 °C and atmospheric CO₂ is as high as ~240 ppm. By 12 800 years BP the temperature rapidly falls to −5 °C below present whilst atmospheric CO₂ remains approximately constant at around 240 ppm. This time period is labelled ‘Younger Dryas’. From about 11 600 years BP to 11 000 years BP the temperature and atmospheric CO₂ again rise with the temperature change at around 0 °C and atmospheric CO₂ about 265 ppm. There is another feature where the temperature and atmospheric CO2 fall at 8 200 years BP to −2 °C and 260 ppm, respectively. This is labelled as the ‘8.2 ka event’. From this time period onwards both temperature and atmospheric CO₂ concentration increase. The CO₂ data finish slightly before 0 years BP with a value of around 280 ppm and after this the temperature data show a rapid increase to around 3 °C above the mean of the past 1000 years.