If no strict action is taken to reduce emissions, the increasing levels of greenhouse gases in the atmosphere might bring the climate system on the verge of a critical threshold.
According to studies, greenhouse warming could trigger a vicious cycle of feedback, in which carbon dioxide released from thawing tundra and increasingly fire-prone forests would drive global temperatures even higher.
Chris Field, director of the Carnegie Institution's Department of Global Ecology and co-chair of the IPCC Working Group 2, will address the above issues at a symposium titled "What Is New and Surprising since the IPCC Fourth Assessment?" at the annual meeting of the American Association for the Advancement of Science (AAAS) in Chicago.
"The data now show that greenhouse gas emissions are accelerating much faster than we thought. Over the last decade developing countries such as China and India have increased their electric power generation by burning more coal," said Field.
He added: "Economies in the developing world are becoming more, not less carbon-intensive. We are definitely in unexplored terrain with the trajectory of climate change, in the region with forcing and very likely impacts, much worse than predicted in the fourth assessment."
Also, new studies have revealed potentially dangerous feedback in the climate system that could convert current carbon sinks into carbon sources.
Field cited the condition in the tropical forests, where vast amounts of carbon are stored in the vegetation, which are resistant to wildfires because of their wetness. But warming temperatures and shifting rainfall patterns threaten to dry the forests, making them less fireproof.
According to estimates loss of forests through wildfires and other causes during the next century, could boost atmospheric concentration of CO2 by up to 100 parts per million over the current 386 ppm, which could further lead to devastating consequences for global climate.
Warming in the Arctic is expected to speed up the decay of plant matter that has been in cold storage in permafrost for thousands of years.
"There is about 1,000 billion tons of carbon in these soils. When you consider that the total amount of carbon released from fossil fuels since the beginning of the Industrial Revolution is around 350 billion tons, the implications for global climate are staggering," said Field.
He added: "The IPCC fourth assessment didn't consider either the tundra-thawing or tropical forest feedback in detail because they weren't yet well understood.
"But new studies are now available, so we should be able to assess a wider range of factors and possible climate outcomes. One thing that seems to be certain, however, is that as a society we are facing a climate crisis that is larger and harder to deal with than any of us thought. The sooner we take decisive action, the better our chances are of leaving a sustainable world to future generations."