Clock Ticking On Climate Change Prevention

This is Scientific American 60-Second Earth. I'm David Biello. Your minute begins now.
Climate change is real.
Carbon dioxide from burning fossil fuels and clearing forests, among other human activities, is to blame.
And more and more of that global warming pollution is being dumped in the atmosphere each year.
So says the United Nations Intergovernmental Panel on Climate Change's new synthesis report released on November 2.
The synthesis reduces thousands of pages of scientific knowledge to their essence.
That essence, however, has hardly changed since the last synthesis report in 2007.
What has changed is the concentrations of greenhouse gases in the atmosphere, which have now touched 400 parts-per-million.
Pollution in the first decade of the 21st century grew twice as fast as it did in the last few decades of the 20th century.
The resulting global warming poses risks ranging from rising sea levels that drown inhabited coasts to crop failures from stronger heat waves and drought.
The IPCC has now offered a budget for how much pollution people can add to the atmosphere without too much climate change.
Unfortunately, humanity has already used more than half of that budget.
The world's nations are meeting in Lima this year in hopes of hammering out a global deal to combat climate change to be agreed upon in Paris in 2015.
The new report is a reminder to world leaders that the stakes, like the seas, are high.
Your minute is up, for Scientific American 60-Second Earth. I'm David Biello.