Every year we will be in the field; In these summer campaigns often delt with by J.R. Petit, we will follow the slow and demanding progress of the core drillings carried out by the Russians often stuck and lost in the depths. It is a question of strengthening the results obtained on the last climate cycle and, to do so, go back farther in time.
They will never give up and their tenacity will be finally rewarded : In 1998 the drilling will reach the depth of 3623 meters, where the ice is 420,000 years old. The results are a sensational confirmation of the relationship between climate and greenhouse gas and give a consistent explanation of our Quaternary large natural climate variations at the million years scale. The average temperature difference on the globe between glacial periods and warm ones is of 5°C, leading in the past to sea level variations of 120m, caused by the growth or the decrease of the continental ices.
This testimony of former times ices helps understand the working of the climate machine and explain the present global warming with a look towards the one in the future. An evidence resulting from campaigns and measurements then carried out for around thirty years and of which we had no idea at the beginning.
But we had not reached the end of our way.