As delegates gather in South Africa to determine what the world's nations should do about climate change, one might wonder how we're doing? After all, scientists have advised cuts to greenhouse gas emissions since at least the 1980s.

The latest accounting shows that global CO2 emissions have increased by nearly 50 percent in the past several decades. 2010 now stands as the year with the most greenhouse gas emissions ever. The results were published today in the journal Nature Climate Change.

Burning fossil fuels released more than 36 billion metric tons of CO2 last year, mainly due to growth in China and India combined with U.S. contributions. Ongoing deforestation is a big factor, too.

Looking back to the 1960s, nothing seems to have set back emissions for long, and that includes the latest Great Recession. Other studies show that we've burned roughly half of the fossil fuels we can if we don't want the climate to warm by more than 2 degrees Celsius.

In fact, we'll need zero or negative emissions at some point and emissions to peak sometime this decade to avoid any further warming. No time like the present.

—David Biello

[The above text is a transcript of this podcast.]