On May 2nd 2013 the daily average atmospheric CO2 level reached 400ppm at the Moana Loa observatory. The last time atmospheric CO2 reached this level was 800,000 years ago. I know that I am only one of many to comment on this topic, yet I think it is worth a post.
Atmospheric CO2 levels have fluctuated between around 170 and 350 ppm over the past 800,000 years and have been rising gradually for the past few thousand years. It is only in the past 100 or so years that they have risen rapidly and have exceeded levels unseen for hundreds of thousands of years.
As anyone who reads this blog will be aware, our human population has risen rapidly in the past 100 years. Global CO2 emissions and atmospheric CO2 levels have risen lock-step with this increase in human population. The vast majority of climate scientists agree that humans are the cause of climate change. If this is the case, then reducing human population growth is a key component in addressing climate change. Unfortunately very few scientists, politicians or anyone else acknowledge this fact.