Global Warming Is Urgent and Can Be Addressed
CO2 survives in the atmosphere for a long time—up to many centuries—so its heat-trapping effects are compounded over time. Of the many heat-trapping gases, CO2 puts us at the greatest risk of irreversible changes if it continues to accumulate unabated in the atmosphere—as it is likely to do if the global economy remains dependent on fossil fuels for its energy needs. To put this in perspective, the carbon we put in the atmosphere today will literally determine not only our climate future but that of future generations as well.
Substantial scientific evidence indicates that an increase in the global average temperature of more than 3.6 degrees Fahrenheit (°F) (or 2 degrees Celsius [°C]) above pre-industrial levels poses severe risks to natural systems and to human health and well-being. The good news is that, because we as humans caused global warming, we can also do something about it. To avoid this level of warming, large emitters such as the United States need to greatly reduce heat-trapping gas emissions by mid century. Delay in taking such action means the prospect of much steeper cuts later if there is any hope of staying below the 3.6°F (2°C) temperature goal. Delayed action is also likely to make it more difficult and costly to not only make these reductions, but also address the climate consequences that occur in the meantime.