The planet could warm 7°F this century if current trends continue

The Intergovernmental Panel on Climate Change (IPCC) projects that if we continue to produce most of our energy from fossil fuels, especially coal without carbon capture, the Earth’s average surface temperature will rise by about 7°F by the year 2100.[[ For details, see figure SPM.5, Scenario A1FI p. 14, in IPCC, 2007: Summary for Policymakers. (PDF) In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.]]

The reason is that fossil fuels add carbon dioxide to the atmosphere, and carbon dioxide plays a major role setting the Earth’s temperature. The projected temperature rise could lead to a wide range of possible effects, including sea level rise, an increase in extreme weather events, the melting of ice caps and glaciers and the melting of permafrost.

The figure of 7°F is not an absolute prediction; it is a best estimate, within the limits of scientific uncertainty. The IPCC says that the actual increase is likely to be somewhere between 4.3°F and 11.5°F. Whatever the exact number turns out to be, the warming will likely be uneven across the globe, with some areas, such as the US, getting warmer than the average and some less.