As surely as the rains fall and flowers blossom, the Northern Hemisphere awakens every June to another, less inspiring rite of spring — a new peak level for global atmospheric carbon dioxide. This year, that number is 419 carbon dioxide molecules for every million molecules of air, a.k.a. parts per million.
Based on geological evidence collected over the six decades scientists have been tracking atmospheric CO2, this year’s peak appears to be the highest in as long as 4.5 million years. This continued accumulation of greenhouse gas is driving dangerous global heating around the world.
In 1958, when modern measurements began, atmospheric CO2 was at 316 ppm. Three centuries ago, before the beginning of the industrial age, geological records show that number was 280 ppm. In other words, by burning fossil fuels in generators and cars, humanity has increased concentrations of the most important greenhouse gas by 50%.