LASER TALK: What the Latest IPCC Report is Telling Us

The Intergovernmental Panel on Climate Change has released the first installment of its latest report. It says that there is now 95 percent certainty that human activity is causing global warming.

Here are some of the key findings from the report:

• Sea levels are likely to rise 1 meter (3 feet) by the end of the century if greenhouse gas emissions continue at current rates.
• The past 3 decades are the hottest since the start of the Industrial Revolution in 1850.
• In the past two decades, the Greenland and Antarctic ice sheets have steadily lost mass,(1) and glaciers are shrinking across the world.
• The concentration of greenhouse gases in the atmosphere has increased to levels unprecedented in the last 800,000 years.

While the rate of warming has slowed over the past 15 years, this should be viewed as a temporary reprieve, not a long-term trend. Ocean absorption of heat may be contributing to this slowdown.

Thomas Stocker, a co-lead on the IPCC report said, “That doesn’t mean that the ocean saves us from global warming. It means that there would be much more powerful (shorter-term) global warming if it wasn’t for the ocean.”

The report outlines four scenarios for warming throughout the century. The only scenario that prevents temperature increases from exceeding 2 degrees Celsius is one where carbon emissions are substantially reduced. In a nutshell, we have a “carbon budget” of 1 trillion tons, more than half of which has already been spent. At current rates, we’ll exceed this tipping point by 2040.

(1) Darryl Fears, “New study affirms ice-sheet-loss estimates in Greenland, Antarctica,” The Washington Post, 29 Nov. 2012, http://articles.washingtonpost.com/2012-11-29/national/35585200_1_sea-level-rise-sea-level-rise-greenland-and-antarctica

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