During the end of the 20th century, the Earth was the hottest it had been in 1400 years.
Natural processes had led the Earth through an overall cooling trend that lasted over 1000 years, but this trend reversed in the late 19th century, despite the continued presence of those natural processes.
Over the past century, the average global temperature has increased by 0.74°C, and over half of the increase occurred has occurred since 1979.
March 2013 marked the 337th consecutive month that the global average temperature was higher than the 20th century average.
397.34 parts per million - the amount of carbon in the Earth’s atmosphere as of March, 2013. Between 1993 to 2002, this number increased every year, at an average rate of 1.7 ppm. Between 2003 and 2012, the yearly average increase was 2.1 ppm.
Since 1000 AD, the carbon concentration in the atmosphere hovered around 280 ppm, until the industrial revolution in the latter 19th century, when that number began a dramatic increase. It broke past 350 ppm in 1988.
Ice coverage in the Arctic is declining at a rate of 2.5% per decade.
The ice at the margins of Peru’s Quelccaya ice cap, which took 1600 years to form, has melted in just 25 years.
Between 2004 and 2011, Canada’s Arctic glaciers have lost 580 gigatons of ice, in what may be an irreversible trend. Glaciers in the Andes have been melting at an increasing rate since the 1970s; the region in general has warmed 0.7°C over the last 50 years.
2012 was the hottest year on record in the United States. The average temperature was 1.8ºC higher than the average for the 20th century.
Pakistan’s wheat production from rain-fed land is expected to be 30% lower than usual in 2013, due to inclement weather likely related to climate change.
Pine beetles’ life cycles are regulated by heat. As the temperature has warmed, they have begun to produce two generations per year rather than one, and have invaded new habitats. This has reduced BC timber production by 10% since 2008.
“Many countries important to the United States are vulnerable to natural resource shocks that degrade economic development, frustrate attempts to democratize, raise the risk of regime-threatening instability, and aggravate regional tensions. Extreme weather events (floods, droughts, heat waves) will increasingly disrupt food and energy markets, exacerbating state weakness, forcing human migrations, and triggering riots, civil disobedience, and vandalism.” – James R. Clapper, US Director of National Intelligence, addressing Congress regarding his department’s 2013 Worldwide Threat Assessment report