Global Warming Is a Crisis

March 9, 2007 — -- When confronted with the power of a hurricane, a blizzard or theintensity of a heat wave, the idea that humans could control or eveninfluence the elements seems ridiculous, even arrogant. However, thanksto the development of industrial societies and the accompanying use of fossil fuels, that farfetched idea is becoming a reality.

Concentrations of carbon dioxide (CO2), methane (CH4) and other gases(all of which add to the greenhouse effect that creates a warmingblanket over the Earth) have increased sharply over the last century --by 35 percent for CO2, and by more than 100 percent for CH4. This is overwhelmingly due to humanindustrial and agricultural activity.

The conclusions from theoreticalstudies, direct observations and models are all quite clear and showthat these rising concentrations have led to a warming of theplanet over the last century. This warming can be seen in the weather station records, ocean temperatures, disappearing mountainglaciers, melting permafrost and retreating Arctic ice, and isbeginning to be felt in the statistics of extreme events.

There are other factors in climate change -- such as increases inparticulate pollution, changes in the sun or volcanic eruptions.However, even when you take all these into account the temperaturerise of the last few decades can only be understood if the warminginfluence of rising greenhouse gases is factored in. It is thisunfortunate fact that is at the heart of the global warming crisis.

It is true that the changes we have seen so far (thankfully) have notbeen globally disastrous. But three factors mean that our expectationfor the future is worse. First, CO2 put into the atmospherenow will continue to have a greenhouse effect for decades andcenturies to come. Second, emissions of CO2, which are soclosely linked to energy production, continue to rise at a rapidrate (around 2 percent a year). Finally, at concentrations which we are verylikely to attain in the coming decades, it will become increasinglydifficult to avoid temperature rises of 5 or more degrees Fahrenheitin the century to come.

Gavin Schmidt is a climate scientist at the NASA Goddard Institute for Space Studies. Scientific American magazine cited him as one of the 50 Research Leaders of 2004. For more information about the debate series, go to www.iq2us.org