But their message could be dangerous, since in his paper, "Target Atmospheric CO2: Where Should Society Aim," NASA Climate scientist Jim Hansen said recently, "The evidence indicates that the safe upper limit for atmospheric CO2 is no more than 350ppm."
If burning fossil fuels like coal and oil during industrialization has created the mess we're in with climate change, it seems only logical that we should aim for pre-industrial levels of atmospheric CO2 of 280 ppm. We should be aiming for a number that is sure to reverse climate change, especially now that feedback effects like methane, a greenhouse gas 25 times more powerful than CO2, is bubbling out of melting permafrost in the arctic and could rapidly accelerate climate change. If we're organizing around a goal that is too little, too late, with the survival of humanity hanging in the balance, we're not just wasting time, we're toying with our own annihilation.
We've come a long way from President Bush's plan to lower average U.S. temperatures by switching from Fahrenheit to Celsius. However, we are currently at 390 ppm CO2 and rising 2 ppm annually. Rising CO2 and other greenhouse gas levels are directly linked to increasing average global temperatures, which are now expected to rise as high as 7.2 degrees Fahrenheit, the very worst case scenario just a few years ago.