Since the beginning of the industrial revolution, atmospheric concentrations of carbon dioxide have increased nearly 30 percent, methane concentrations have more than doubled, and nitrous oxide concentrations have risen by about 15 percent. The previous 2000 years show a high degree of stability of concentrations. The combined effect of these increases is to place more energy into the atmosphere due to the greenhouse effect. Additionally the rate of increase is accelerating. The ramifications of these changes are still beyond quantification for the most part, hence the many arguments. There are also many major and minor cyclic changes within the oceanic and atmospheric circulatory systems that continue in the background. The impact of additional energy pumped into these systems is as yet not clear. However there are fears that when certain trigger points are met events cascade to a new equilibrium and many of these could make life extremely untidy for humanity. Potential scenarios are the cessation of the Atlantic conveyor, melting methane hydrates, methane release from melting tundra, cessation or change of direction of monsoons, rapid destabilisation of the greenland ice cap etc. These things may not come to pass but gas guzzling, centrally heated obese westerners should perhaps question the sustainability of their present lifestyles in the light of what could happen. Some scientists also believe that changes that were once thought to require several lifetimes to occur could actually occur in the space of several years.