- the earth’s climate is changing
- the change is being caused by human activities, and
- its effects will worsen if no action is taken.
The Problem Is Real
The Intergovernmental Panel on Climate Change is the world’s foremost authority on the subject, drawing on the expertise of more than 2,500 scientists from 130 countries. Established by the World Meteorological Organization and the United Nations Environment Programme, the IPCC has coordinated four major assessments of global climate change, dating back to 1990. In its 2007 report, the panel concluded that global warming is now unequivocal and is “now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level.”
Globally, 11 of the last 12 years (1995 to 2006) rank among the warmest since 1850. The IPCC has also concluded that atmospheric carbon dioxide equivalents (the standard measurement for greenhouse gas emissions) increased from a relatively stable 280 parts per million to over 380 parts per million over the past 150 years. According to analysis of ice cores, current concentrations are the highest on record for the last 650,000 years. The IPCC also noted that “anthropogenic warming could lead to some impacts that are abrupt or irreversible, depending upon the rate and magnitude of the climate change… Climate change is likely to have some irreversible impacts.”