The average air temperature near the Earth’s surface has increased by about 1.33 degrees Fahrenheit over the past 100 years. The Intergovernmental Panel on Climate Change (IPCC) reports that “most of the observed increase in global average temperatures since the mid-20th century is most likely due to the observed increase in greenhouse gas concentrations via the greenhouse effect.”
These basic conclusions have been endorsed by at least 30 scientific societies and academies of science, including all the national academies of sciences of the major industrialized countries.
The main greenhouse gases are water vapor, carbon dioxide and methane. Atmospheric concentrations of carbon dioxide and methane have risen 31% and 149%, respectively, above pre-industrial levels since 1750. These levels are considerably higher than at any time during the last 650,000 years, the period of the that reliable data have been extracted from Antarctic ice cores.
The burning of fossil fuels has produced about 75% of the increase in carbon dioxide from human activity in the last twenty years. Most of the rest is due to changes in land use, particularly deforestation. Paleoclimatologist William Ruddiman has argued that human influence on global climate began about 8,000 years ago with the onset of clearing of forests to provide land for agriculture.
The IPPC projects an additional 2 to 11 degrees Fahrenheit increase in global average surface temperature during the 21st century. This rise will cause global sea level rise (estimated to be between 4 and 30 inches), and is expected to increase the intensity of extreme weather events and change the amount and pattern of precipitation. Other effects of global warming include changes in agricultural yields, retreating glaciers, depletion of the ozone layer, ocean acidification, species extinction, and increased ranges of disease vectors.
These factors are likely to pose significant geopolitical and security challenges as countries around the world compete for dwindling water and other natural resources. Changes in the world’s population are likely as rising sea levels threaten cities located in lower coastal areas. This can increase the likelihood of armed conflict, as national cohesion may be threatened by population loss or increased migration from affected areas.
Although these scientific facts and predictions are discouraging, there is reason for hope. Paul Hawken, in his book Blessed Malaise: How the World’s Greatest Movement Was Born and Why Nobody Saw It Coming, believes we are in the midst of a rise of world-changing activist groups, all “working towards ecological sustainability.” and social justice”.
This widely diverse global movement made up of many thousands of nonprofit and community organizations is neither ideological nor centralized, but a coalescence of spontaneous and organic responses to the recognition that environmental issues are issues of social justice.
This is highlighted by the awarding of the Nobel Peace Prize in 2007 to Vice President Al Gore and the Intergovernmental Panel on Climate Change for “their efforts to build and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such a change”.
We have the knowledge, the tools and the ingenuity to tackle this most serious challenge facing humanity. It will require a long-term vision, the political will to act and the ability to overcome national interests and cooperate on a global scale.
