Climate change will be front and center at this week's United Nations Climate Summit. Late last year, the United Nations has released a benchmark study on the issue that further strengthens the suspicions many scientists already have -- that humans are making the Earth warmer which, in turn, is having disastrous impacts on everything from weather to sea levels.
Here's a look at climate change by the numbers:
95 percent -- How certain scientists now are that human activity has caused at least half of climate change in the last half-century.
90 percent -- How certain scientists were that human activity has caused at least half of climate change in the last half-century in 2007.
Other factors that could be contributing to climate change include changes in the sun's energy output, natural changes in greenhouse gas concentrations and natural changes in reflectivity like melting sea ice or increasing cloud cover, which affect how much energy enters the Earth's system.
10 to 32 inches -- The projected amount sea levels are now expected to rise by the end of the century.
7 to 23 inches -- The projected amount sea levels were expected to rise by the end of the century in 2007.
0.5 to 8.6 degrees -- How much average global temperatures are now expected to rise by the end of the century.
20 years -- The average period of time weather catastrophes, like Superstorm Sandy, are now expected to strike. Previously, these were called "storms of the century."
56.4 degrees -- The average global temperature in 1850.
58.2 degrees -- The average global temperature in 2012.
40 percent -- The percentage rise in the concentration of carbon dioxide in the atmosphere between the years 1750 and 2011.
275,000,000,000 -- The amount of ice in tonnes per year which "very likely" melted from the world's glaciers between 1993 and 2009.
2,000,000,000,000 -- The tonnes of carbon dioxide added to the atmosphere from fossil fuel burning, cement production, deforestation and land clearing between 1750 and 2011.
90 percent -- The percentage of extra energy in the climate system between 1971 and 2010 that has been taken up by warming oceans.