Calvin Beisner, Cornwall Alliance: This is a review about carbon dioxide concentrations for people and nature with historical notes and photos. The change from 180 ppm to 410 ppm in the last two centuries is small compared to historical variations and easily tolerated by nearly all people. Some people may have trouble with higher levels of CO2, but some people have trouble with more cold, more heat, more humidity, more dryness, etc. It is treacherous for alarmists to claim they can control Earth's climate by raising taxes, carbon dioxide sequestration, stopping use of fossil fuels.