15M YEARS AGO C02 WAS THIS HIGH
New research, reported in ScienceDaily shows that the last time carbon-dioxide was at its present 387 parts per million was 15 million years ago. The research uses a new method of calculating carbon-dioxide levels that enables data to be extracted back to about 20 million years. It checks against data extracted from ice-cores going back 800,000 years, which was the previous limit.
15 million years ago the planet was radically different, which suggests that we have put it on an inelectable path to an environment inimical to our civilisation.