350ppm is Possible by 2100

Dr Hansen's 6% Solution

Dr. James Hansen and a team of leading climate scientists have a prescription for bringing the Earth back into balance.  There is no shortcut.  Reducing CO2 emissions (ie:  our fossil fuel use) is the only way. 

Dr Hansen, in a paper entitled “The Case for Young People and Nature:  A Path to a Healthy, Natural Prosperous Future”, Hansen and his team of climate scientists predict that If atmospheric CO2 levels can be brought back from today’s 392 parts per million to 350 ppm (the 1990 level), the Earth’s energy balance will be approximately restored.  This assumes major reforestation and sustainable agriculture efforts would also take place. 

The Earth is giving us clear signals that the present day global warming of 0.8ºC over pre-industrial levels is too much.  However we have so far taken no action to reduce our burning of fossil fuels.  International meetings and protocols to address climate change have led to no real reduction at all.  We just continue to burn more every year. 

Hansen’s team uses detailed models of the carbon cycle to predict warming based on various scenarios.  They recommend we act immediately by burning 6% less fossil fuels per year globally, updating our agricultural practices, and restoring forests that have already been destroyed.  In this case, our planet’s atmosphere will return to 350 ppm CO2 (the 1990 level, considered by Hansen to be the threshold to restore approximate planet-wide energy balance) by 2100, and warming will exceed 1ºC for three decades.  However, If we wait until 2030 before taking this action, warming will exceed 1ºC until 2500.  Roughly every 20 days we wait adds an extra year of unsafe climate.

What does “unsafe climate” mean?  A longer period of hotter climate makes it more likely that planet-wide feedback mechanisms (such as the melting of reflective continental and ocean ice sheets, and the release of frozen methane) with the potential to suddenly push the climate over a “tipping point.”  A longer period of hotter climate will also cause more droughts, heat waves, crop failures, and other threats to human life. 

It is difficult to predict exactly how further warming will affect ecological and human systems such as the food and water supplies in the coming decades.  But it is certain that future warming depends on what we do, or fail to do.  Waiting another decade to take action and hoping to “get lucky” would be like playing Russian roulette with the Earth.