Climate change: State of the science
In 1960 Charles Keeling fi rst showed with measurements that the amount of carbon dioxide (CO 2 ) in our atmosphere is increasing. 1 More than 60 years earlier, in 1896, the Swedish Nobel laureate Svante Arrhenius had fi rst calculated how a doubling of CO 2 in the atmosphere would warm the planet, 2 after the British physicist John Tyndall had proven in 1859 in laboratory measurements that CO 2 is a greenhouse gas (GHG). By 1960 the physics of the greenhouse effect was well understood, and in 1965 the fi rst expert report to the United States (US) president thus warned of a coming global warming. 3
Since then, important core fi ndings of climate research have been so well confi rmed in recent decades that they are now generally accepted as fact by climate researchers. These core fi ndings include the following:
1 The atmospheric CO 2 concentration has risen strongly since about 1850, from 280 parts per million (ppm) (a value typical for warm periods during at least the past 800,000 years) to over 380 ppm.