Introduction

Since the onset of the industrial revolution (c.1750), human activities have altered the atmospheric composition of the Earth, significantly impacting the terrestrial energy balance. The burning of fossil fuels has substantially increased the amount of particulate matter and concentration of greenhouse gases (GHGs), most notably carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), into the atmosphere. The overall impact of human industrial activities on global climate has been a pronounced warming effect, as GHG increases have enhanced the atmospheric greenhouse effect and reduced the amount of outgoing radiation from the earth. Although global climate change occurs with natural process (e.g., volcanic eruptions, insolation variability), the rate of change is much slower, occurring over millennia rather than the rapid anthropogenic induced climate changes observed over the past century with the modern industrial era. Global climate change impact scenarios have sparked an international debate on policy initiatives for balancing global climate change reduction measures with continued industrial development.

Background

“Climate change” is closely related to “global warming” but can be thought of as a more complex set of phenomena, many of which are directly dependent on global warming. Discussed elsewhere in this volume, global warming is a phenomenon that results from radiative forcing as a result of various gaseous and particulate substances in Earth's atmosphere. The increase in Earth's mean surface temperature is caused by warming of land, ocean, and/or atmosphere as a result of the amount of the sun's radiant energy that is not reradiated into space but absorbed by the Earth and it components.

Sources of this global warming are natural or anthropogenic. Absent human influence, naturally occurring GHGs (including carbon dioxide) and water vapor (in the form of clouds) provide a relatively stable radiative forcing that maintains the global mean surface temperature at a level conducive to human and other biological life. Abrupt warming may result from variations in solar radiation patterns. Abrupt cooling may result from the reflection back into space of greater amounts of solar radiation by dust resulting from volcanic activity.

Although isolated weather incidents cannot be directly linked to a changing climate because of the fundamentally chaotic nature of our climate, there is compelling evidence—much of it provided by National Aeronautics and Space Administration scientist James Hansen—that we are beginning to see the effects of global warming in global climate change. Among the numerous global reports documenting climate change effects:

The IPCC reported that 11 of the warmest years in the instrumental global surface temperature record occurred during 1995-2006.

A 2005 Harvard Medical School report concludes that “Climate change and infectious diseases threaten wildlife, livestock, agriculture, forests and marine life, which provide us with essential resources and constitute our life-support systems.”

In its assessment of 2007 global natural and man-made disasters, reinsurance giant Swiss Re highlighted IPCC Fourth Assessment Report conclusions that global warming is contributing to an increase in the severity of flood events (1970-2005).

The U.S. National Oceanic and Atmospheric Administration reported that the combined global land and ocean surface temperature for January 2009 was the seventh ...