Road to curb temperature rises

The goal of the 2015 Paris Climate Conference, COP21, is to achieve a legally binding, international agreement to keep average global temperatures no more than 2°C above pre-industrial temperatures*
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Global mean temperatures above pre-industrial levels

1850-1900 Average temperature 13.7°C
1.0°C Temperature rise expected to surpass 1°C in 2015
2.0°C 2010: 193 nations sign Cancun Agreements committing governments
to “hold increase in global average temperature below 2°C above pre-industrial levels”
2.7°C Forecast warming† by 2100 even if all COP21 pledges are implemented
3-5°C Warming on existing emissions-reduction policies. Low-lying island states at risk from rising sea levels
4-5°C Forecast rise by 2060 if current emissions levels continue

*Accurate assessment of temperatures in 1750s – when industrial revolution began – is difficult. To overcome problem, climatologists use average temperatures recorded between 1850 and 1900. †United Nations Synthesis report on aggregate effect of Intended Nationally Determined Contributions (INDCs) 
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Sources: UK Met. Office Hadley Centre, Climate Action Tracker, WMO
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