Numbers show how pollution has changed Earth

http://poststar.com/news/national/numbers-show-how-pollution-has-changed-earth/article_342305e6-7aa7-11e4-8dd7-9379d3ac6fb9.html

By SETH BORENSTEIN—Associated Press
Dec. 3, 2014

In the more than two decades since world leaders first got together to try to solve global warming, life on Earth has changed, not just the climate. It has gotten hotter, more polluted with heat-trapping gases, more crowded and just downright wilder.

The numbers are stark. Carbon dioxide emissions: up 60 percent. Global temperature: up six-tenths of a degree. Population: up 1.7 billion people. Sea level: up 3 inches. U.S. extreme weather: up 30 percent. Ice sheets in Greenland and Antarctica: down 4.9 trillion tons of ice.

“Simply put, we are rapidly remaking the planet and beginning to suffer the consequences,” said Michael Oppenheimer, professor of geosciences and international affairs at Princeton University.

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extreme weather has noticeably increased over the years, said Debby Sapir, who runs the center and its database. From 1983 to 1992, the world averaged 147 climate, water and weather disasters each year. Over the past 10 years, that number has jumped to an average 306 a year.

In the United States, an index of climate extremes — hot and cold, wet and dry — kept by the National Oceanic and Atmospheric Administration has jumped 30 percent from 1992 to 2013, not counting hurricanes, based on 10-year averages.

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The globe has broken six monthly heat records in 2014 and 47 since 1992. The last monthly cold record set was in 1916.

So the average annual temperature for 2014 is on track to be about 58.2 degrees, compared with 57.4 degrees in 1992. The past 10 years have averaged a shade below 58.1 degrees — six-tenths of a degree warmer than the average between 1983 and 1992.

The world’s oceans have risen by about 3 inches since 1992 and gotten a tad more acidic — by about half a percent — thanks to chemical reactions caused by the absorption of carbon dioxide, scientists at NOAA and the University of Colorado say.

Every year, sea ice cover shrinks to a yearly minimum size in the Arctic in September — a measurement that is considered a key climate change indicator. From 1983 to 1992, the lowest it got on average was 2.62 million square miles. Now the 10-year average is down to 1.83 million square miles, according to the National Snow and Ice Data Center.

That loss — an average 790,000 square miles since 1992 — overshadows the slight gain in sea ice in Antarctica, which has seen an average gain of 110,000 square miles of sea ice over the past 22 years.

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The effects of climate change can be seen in harsher fire seasons. Wildfires in the western United States burned an average of 2.7 million acres each year between 1983 and 1992; now that’s up to 7.3 million acres from 1994 to 2013, according to the National Interagency Fire Center.

And some of the biggest climate change effects on land are near the poles, where people don’t often see them. From 1992 to 2011, Greenland’s ice sheet lost 3.35 trillion tons of ice, according to calculations made by scientists using measurements from NASA’s GRACE satellite. Antarctica lost 1.56 trillion tons of ice over the same period.

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“Overall, what really strikes me is the missed opportunity,” Andrew Dessler, a climate scientist at Texas A&M University, said in an email.

“We knew by the early 1990s that global warming was coming, yet we have done essentially nothing to head off the risk. I think that future generations may be justifiably angry about this.”

“The numbers don’t lie,” said Michael Mann, a climate scientist at Penn State. “Greenhouse gases are rising steadily and the cause is fossil fuel burning and other human activities. The globe is warming, ice is melting and our climate is changing as a result.”