Global warming is primarily a problem of too much carbon dioxide in the atmosphere. The gas acts as a blanket, trapping heat and warming the planet. When fossil fuels like coal, oil and natural gas are burnt for energy or forests are cut down and burnt to create pastures and plantations, carbon accumulates and overloads our atmosphere. Certain waste management and agricultural practices aggravate the problem by releasing other potent global warming gases, such as methane and nitrous oxide. A breakdown of heat means trapping global warming emissions by economic sector. Substantial scientific evidence indicates that an increase in the global average temperature of more than 2 degrees F above where we are today poses severe risks to natural systems and 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, the US needs to reduce heat-trapping emissions by at least 80% below 2000 levels by 2050. Delayed action is likely to make it more difficult and costly to not only make these reductions, but also address the climate consequences. CO2 gas lasts in the atmosphere for a long period 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. The carbon we put in the atmosphere today will literally determine our climate future but that of future generations as well. Over the last century, global average temperature has increased by more than 1 degree F. The 2001-2010 decade is the warmest since 1880 the earliest year for which comprehensive global temperature records were available. In fact, nine of the warmest years on record have occurred in just the last 10 years. This warming has been accompanied by a decrease in cold days and nights and an increase in extremely hot days and warm nights. While record shows that some parts of the world are warming faster than others, the long-term global upward trend is unambiguous. Any action to reduce or eliminate the release of heat-trapping gases to the atmosphere helps slow the rate of warming and, likely, the pace and severity of change at any hot spot.