Global Climate Change

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.

Even if human ingenuity and/or behavior resulted in the total cessation of anthropogenic GHG emissions tomorrow, the persistence of these gases in the atmosphere and the inertia of the geophysical, oceanic, and atmospheric processes that feed off global warming will result in a global mean surface temperature rise approaching at least 2 degrees C over the [Page 194]next century. Given the current rate of GHG emissions growth, in spite of any individual and collective reduction efforts, we are almost certain to cause much more warming still.

NASA satellites captured this image of the Larsen B ice shelf in Antarctica in 2000 before its rapid collapse in early 2002.

Source: NASA/Goddard Space Flight Center Scientific Visualization Studio

Unfortunately, the climatic effects that this warming will precipitate are not entirely understood. Computer models used to explain weather and climate phenomena are still limited in their predictive capacities. Aspects of the interactions among atmospheric, land, and ocean systems are still unknown or speculative, and we have no sense of what climatic “tipping points” lurk in the future that might drastically change climate patterns in a time frame that provides us with little or no time to adapt, much less mitigate them.