For the first time in 2.5 million years carbon dioxide (CO2) in the atmosphere is over 400 parts per million. Before the industrial revolution CO2 was less than 300 ppm. The last time CO2 was at 400ppm there were forests in the Canadian Arctic and sea levels were around 5m higher.
The atmosphere is an incredibly thin skin that keeps us warm and protects us. But 99% of it actually plays very little role in maintaining the physical conditions for life on earth. The gases that control the physical conditions, such as temperature, ultra violet light, etc. comprise less than 1% of the atmosphere.
If the entire ozone layer was brought to ground level and spread all over the world it would be only 3mm thick. Yet, without this 3mm layer, life as we know it would not exist. CO2 has an importance that is many orders of magnitude greater than its percentage in the atmosphere.
Internationally, electricity generation reached a record high in 2010. CO2 emissions from electricity also increased and electricity remains the single-largest source of international CO2 emissions from energy (compared to transport and industrial heat energy emissions), with 11.7 billion tonnes of CO2 released in 2010, according to a report from the International Energy Agency in 2013.
Earlier this year, the International Monetary Fund released a report calculating that the damages incurred by climate change will cost $25 per ton of CO2 emissions. Other researchers put that number as high as $85.