James Hansen and Pushker Kharecha of NASA’s Goddard Institute for Space Studies have published a study showing that the rise in carbon dioxide from burning fossil fuels can be kept below dangerous levels as long as emissions from coal are phased out globally within the next few decades.
Professor Hansen is head of the Goddard Institute and is well known for his research in climatology which raised awareness of the global warming issue in the 1980s.
Previously published research shows that a dangerous level of global warming will occur if carbon dioxide in the atmosphere exceeds a concentration of about 450 parts per million, beyond which point the disintegration of the Greenland and West Antarctic ice sheets and Arctic sea ice could set in motion feedbacks which lead to accelerated melting, further warming and extreme sea level rise.
In essence, the study found that, because of peak oil and relatively limited global reserves of gas, burning these two fuels without also burning coal would not result in atmospheric carbon dioxide levels above this point of no return. However, there are enormous global reserves of coal. Continuing to burn this in the current manner will take carbon dioxide levels above the critical 450 parts per million by about 2035.
To avoid this, developed countries need to begin reducing the amount of carbon they release from burning coal by 2013, with developing countries beginning to reduce their carbon emissions during the following decade. All emissions of carbon that reach the atmosphere from burning coal need to be phased out by 2050.