Is Global Warming the Same as Climate Change?

Is Global Warming the same as Climate Change?

Readers of the Climate Science weblog know that the answer to this question is a definitive NO.

However, the media frequently use the two terms interchangeably. A search on google provides ready examples of the intermixing of the two terms. For example, see http://www.cln.org/themes/global_warming.html where a “global warming/climate change theme page” is presented for educational purposes.

At http://www.ec.gc.ca/climate/home-e.html, the Kyoto Protocol has been promoted as a priority with respect to climate change, where it is clear that global warming and climate change are being interpreted as interchangeable. From this Environment Canada website,

“Climate change is one of the most significant environmental challenges the world has ever faced. We are already seeing the effects of climate change in Canada. The potential impacts on our health, economy and environment require us to take action.
With the ratification of the Kyoto Protocol, the Government of Canada has made climate change a national priority, and is working closely with Canadians and the global community to meet this challenge.”

The focus of this effort to “control” global warming is with respect to the reduction of well-mixed greenhouse gas emissions, particularly CO2.

However, as shown in the 2005 National Research Council report “Radiative forcing of climate change: Expanding the concept and addressing uncertainties. Committee on Radiative Forcing Effects on Climate Change, Climate Research Committee, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies, The National Academies Press, Washington, D.C.”, which has been mentioned repeatedly on our web site, climate change is much broader than global warming.

Global warming is defined by a positive accumulation of heat (Joules) in the climate system, of which most occurs in the oceans (see Pielke Sr., R.A., 2003: Heat storage within the Earth system. Bull. Amer. Meteor. Soc., 84, 331-335). While surface temperature as also been used to define this heating, it has a range of problems with its use in this context, as we have discussed in our papers, and in earlier weblogs, with more to follow.

Human-caused climate change, however, involves forcings beyond the radiative forcing of the well-mixed greenhouse gases. As summarized in the 2005 NRC report, this includes the multiple influences of aerosols and of biogeochemically active gases, and land-cover changes. The regional changes from these forcings must be considered, even if there were no global warming from these forcings.

By conflating the terms “global warming” and “climate change”, we misinform policymakers, by leading them to believe that the radiative effect of the well-mixed greenhouse gases is the only major forcing of human-caused climate change. It is not. Dealing with climate change is a much more difficult issue than is captured by focusing on global warming.