The planet has warmed about .74 degrees Celsius over the past
100 years, according to the IPCC. Eleven of the 12 years between 1995 and 2006
were the warmest since global temperature records were first kept in 1850. As a
result, polar ice caps are collapsing at alarming rates. Since 1978, the Arctic
ice has shrunk 2.7 percent per decade, according to the IPCC. A separate study
that recently surveyed 30 glaciers from around the world observed them melting
at record rates; an average rate of loss was 4.9 feet in 2006. That’s compared
to an average loss of about a foot a year between 1980 and 1999.
One obvious implication is a rise in sea level. Between
thermal expansion and collapsing polar ice caps, sea levels are expected to
rise at a drastic rate. Sea level on average since 1961 has risen globally at a
rate of 1.8 millimeters a year. Since 1993, it has risen 3.1 millimeters a
year. In future decades, average sea level will be a few feet higher than now
as glaciers continue to recede.
Greenhouse gases emitted by humans for the past 150 years will
continue to warm the planet for generations even if we stop fossil-fuel
combustion today. Unfortunately, anthropogenic greenhouse-gas emission rates
are still rising. Worldwide, emissions rose 70 percent between 1970 and 2005.
Emissions will rise by a projected 25 to 90 percent by 2030. China in
particular continues to build new coal-fired power plants on a weekly basis.
Before 1850, atmospheric carbon dioxide concentration was
about 280 ppm by volume, the same as the rate for the previous 10,000 years.
Today, that reading is 385 ppm. It will continue to rise with each passing
year.