Cancun

Cancun failed us.  We the concerned citizens of our planet blue hoped Cancun could do three things for us: (1) set an objective of cutting atmospheric concentrations of CO2 to 350ppm or less; (2) close the "gigatonne gap"; and (3) require global emissions to peak no later than 2015.

1. 350
There is currently 389ppm of carbon in our atmosphere: a dense, invisible fog that transforms the earth into a steam bath.  Reducing this number to 350 would give us a good chance at limiting warming to 1.5 degrees celcius and restoring sea ice and glaciers that have already begun to melt, protect alpine water supplies and avoid levels of ocean acidification that destroy coral reefs and other fragile underwater ecosystems.

2. Gigatonne Gap: the elephant in the room
At the previous UNIPCC conference in Copenhagen, nations made pledges to keep their carbon emissions at a "lower level", political speak that ignores the dire reality of the convention's outcome.  The pledges will lead to a 650ppm - or roughly 3.5 degree celcius - increase in temperature by 2100.  Such a rise in temperature would be catastrophic.  It was hoped that cancun would have closed this "gigatonne gap" between a safe level (350ppm) and the pledged level (650ppm).

3. 2015
Of course it takes time to change a world of gas guzzlers and coal consumers and to find effective energy substitutes.  In order to meet the 350ppm target, it has been found that global emissions can peak no later then 2015.  It requires a 5.3% emissions reduction per year.  If we wait until 2020, we would have to reduce emissions by 9% annually, something that would be extremely difficult.