Fact 1
The atmospheric CO2 concentration has risen strongly since about 1850, from 280 ppm (a value typical for warm periods during at least the past 700,000 years) to over 380 ppm. 1
CO2 is a gas that affects climate by changing the earth’s radiation budget: an increase in its concentration leads to a rise in near-surface temperature. This has been known since the 19th Century and is well-established physics. If the concentration doubles, the resulting global mean warming will very likely between 2 and 4°C (the most probable value is ~3ºC), with the remaining uncertainty due to climatic feedback effects. 2
Fact 2
CO2 is not coming from human activities alone—it also has natural sources such as volcanic eruptions. All animals exhale it too, so how can human activities be affecting the concentration of CO2 on a global scale?
“Natural processes emit large quantities of CO2 into the atmosphere, but they also remove it—at nearly identical rates. This balance maintained the concentration of CO2 at a stable level for thousands of years prior to the Industrial Revolution. In the case of global warming, the question is: What is causing the increase in CO2concentrations? The answer turns out to be incontrovertible. The isotopic composition of carbon in atmospheric CO2 provides a unique “fingerprint” that tells scientists that the lion’s share of the additional CO2 accumulating in the atmosphere is from the burning of fossil fuels”3.
Fact 3
“Amazonia is already damaged by deforestation. Climate change may magnify this impact by increasing the risk of fire. Other precious areas of high biodiversities, such as those in South Africa, may see major losses of species as habitat conditions change. Around the world, some animals and plants may benefit and flourish in a changing climate, while others are likely to suffer “4
Fact 4
The average combined global land and ocean surface temperature for January–December 2014 was the highest on record among all years in the 135-year period of record, at 0.69°C (1.24°F) above the 20th-century average. The 10 warmest years in the instrumental record, with the exception of 1998, have now occurred since 2000.5
1&2, Climate Change - State of the Science by Prof. Stefan Rahmstorf Potsdam Institute for Climate Impact Research 3, Are Humans Responsible for Global Warming? A REVIEW OF THE FACTS., AUTHORS James Wang, PhD and Bill Chameides, PhD Aprol 2007 4, Warming, Climate change – the facts. Page 5, MET Office., http://www-solar.mcs.st-and.ac.uk/~eric/TALKS/ClimateChange.pdf 5, NOAA., Global Analysis - December 2014 http://www.ncdc.noaa.gov/sotc/global/2014/12#temp