RICHARD SCHIFFMAN SEP 27 2013

The polar icecaps are melting faster than we thought they would; seas are rising faster than we thought they would; extreme weather events are increasing.

By Matt McGrath

The levels of gases in the atmosphere that drive global warming increased to a record high in 2012.

By David Shukman Science Editor, BBC News, in Svalbard

Scientists in the Arctic are warning that this summer's record-breaking melt is part of an accelerating trend with profound implications.

Norwegian researchers report that the sea ice is becoming significantly thinner and more vulnerable.

SOPHIA LI

Nathanael Massey

Forests may not help mitigate carbon dioxide pollution thanks to an uptick in CO2 emissions from decomposition

Our atmosphere traps some of solar radiation as a greenhouse, which increases the planet's temperature

Seth Borenstein

Arctic monitoring stations show carbon dioxide levels are now above 400 parts per million. Carbon dioxide is the chief climate-change gas and stays in the atmosphere for 100 years.

Barbara Fraser and The Daily Climate

Scientists used to think the Amazon was too wet to burn, but a warming Atlantic Ocean is drawing moisture away from the rainforest

Brian Vastag

With global efforts to reduce carbon dioxide emissions stalled, the United States and five other countries are starting a new program to cut other pollutants — including methane, soot and hydrofluorocarbons — that contribute to global warming.

The Keeling Curve