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Climate in Context: August 24, 2010

By Andrew Freedman and Michael D. Lemonick

Get Used to La Nina


Sea surface temperature anomalies for the first week of August,
2010. Blue areas indicate cooler-than-average temperatures.
Red areas are warmer-than-average. The area of cool
temperatures in the equatorial Pacific are characteristic
of La Nina conditions. 

Credit: NOAA Environmental Visualization Lab.

Following on the heels of the 2009/10 El Nino event, a moderate La Nina is underway in the Pacific Ocean, and is likely to continue through early 2011, according to an outlook released by the International Research Institute for Climate and Society (IRI) on August 19. La Nina is characterized by unusually cool water temperatures in the central and eastern equatorial Pacific Ocean, and warmer-than-average water temperatures in the western Pacific, with associated changes in air and water circulation. (This is in contrast to El Nino, which features warmer-than-average water in the central and eastern tropical Pacific).

La Nina conditions first emerged in mid-June and have strengthened since that time. Such conditions are evident in the map of sea surface temperature anomalies, or departures from average, below.

Sea surface temperature departures from average during the week of August 18. Credit: NOAA/NCDC.

The unusually warm water near Indonesia is harming coral reefs, according to a report detailed in the New York Times last week. "A striking rise in sea temperatures in wa...

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Climate in Context: August 20, 2010

By Alyson Kenward and Michael D. Lemonick

Extra CO2 May Not Be Such a Boon for Plants After All

Back in 2003, Steve Running, an ecologist and climate modeler at the University of Montana, co-authored a paper that analyzed changes in the uptake of carbon dioxide (CO2) by plants around the world (the technical term for this uptake is “primary production”). The paper showed that it had been increasing through the 1980s and 1990s. The reason, he says: “Warming global temperatures were leading to longer growing seasons” – which gave plants more time, on average, to suck in CO2.

Running and his Montana colleague Maosheng Zhao returned to the question recently, and since temperatures have continued to rise, says Running, “our hypothesis was that was that if you’re following the same logic, you should [see] a further enhancement in primary production.”

Instead, according to a new paper the pair authored in this week’s Science, there's been a trend reversal. Specifically, they found that while carbon uptake rose about six percent from 1982 to 1999, it’s since pulled back by about one percent.

“In higher latitudes,” Running says, “we’re still seeing lengthening of growing seasons.” Closer to the equator, though, and especially in the southern hemisphere, the warming has lead to major droughts – not exactly a recipe for healthy plants. What makes this study so compelling is that it was based on global satellite observations, not scattered local measurements. Runnin...

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Climate in Context: August 19, 2010

By Michael D. Lemonick and Alyson Kenward

And Now: Antarctic Sea Ice Update

Yesterday we told you that the sea ice coverage in the Arctic is currently running well below average, although not quite in record territory. Today, let’s flip the world upside down and look at Antarctica – what’s going on with sea ice down there? (Keep in mind that although it’s summer in the Arctic, it’s winter in the Southern Hemisphere). 

Well, according to a recent paper in the Proceedings of the National Academy of Sciences, an increase in Southern Ocean sea ice area that has been going on for three decades might come to an end, soon-ish; computer models project that global climate change could lead to declining sea ice surrounding Antarctic by the end of the century, if not earlier.

That Antarctic sea ice coverage has grown during the last 30 years doesn’t contradict the global trend of rising temperatures. In fact, warmer global temperatures have brought more moisture into the air, which has consequently increased precipitation in some parts of the world. And near the South Pole, of course, the temperatures are still cold enough that the extra precipitation falls as snowfall, which accumulates onto ice cover and helps shield it from solar radiation. Other air and ocean cycles have combined to build up Antarctic sea ice, in stark contrast to conditions in the Arctic.

As global temperatures climb even higher, however, much of that Antarctic precipitation is bound to...

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Climate in Context: August 18, 2010

Michael D. Lemonick

By Michael D. Lemonick

Arctic Ice Update

Every winter, the surface of the Arctic Ocean freezes pretty much solid (or, more precisely, the surface freezes), Every summer, some of that ice melts to expose open water — and for the past several decades, the amount of open water in late summer has gotten gradually, though somewhat erratically, larger. The biggest meltback was in 2007, and since then, the summer ice has rebounded slightly. It hasn’t been much of a rebound, though. During the summers of 2008 and 2009, the area covered by ice in mid-September (the annual low point) was a little more than in 2007, although still significantly less than the 1979-2000 average.

Now the National Snow and Ice Data Center (NSIDC) has come in with its latest report: as of two days ago, the ice at the top of the world covered about 5.95 million square kilometers of sea — about a half-million more than at this point in the summer of 2007, but about one and a half million less than what should be there at this point based on the 1979-2000 average.

On the chart below, the black line shows the long-term average; the dotted line is the record melt year of 2007, and the blue line represents this year so far. You can also see that only 2007 and 2008 had less ice than we’ve got this year. It’s the kind of “rebound” you’d expect if you dropped a half-deflated basketball on the gym floor.

Arctic sea ice extent during the 2007-2010 melt seasons (...

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Climate in Context: August 17, 2010

By Alyson Kenward

Editor's Note: This is the first installment of what will become daily, quick-hitting blog posts that will cover climate science and energy developments from our nonpartisan (yet still entertaining) perspective. 

Coal Ash Ruined My Sunday Night

Shouldn’t Sunday night, by default, be relaxing? After all, it’s the best time to recover from a fun-filled weekend and to prepare for the busy workweek ahead. Unfortunately, anyone who caught this Sunday’s repeat episode of “60 Minutes” probably wasn’t left with any calm feelings. In a segment titled "Coal Ash: 130 Millions Tons of Waste", correspondent Lesley Stahl informed viewers that there is virtually no regulation of the staggering amount of toxic waste byproduct known as coal ash that is generated each year in the burning of coal for electricity in the U.S.

After listing off the poisonous metals that are concentrated in coal ash, including arsenic, mercury, cadmium, thallium, selenium and lead, Stahl pointed out the careless ways in which coal companies dispose of it all – none of it made for an easy Sunday night. Scientists still need to figure out exactly how toxic coal ash is, but Stahl says the EPA is lagging behind with instituting regulations based on existing knowledge.

Stahl seems to have missed the mark on one very important point, however. When speaking with Jim Roewer, a coal lobbyist, about how 48 percent of electricity in America comes from coal, Stahl says, “we can’t get rid...

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Gallery

Strong El Niño Brings Warmer Global Temperatures Global average temperatures are generally higher in El Niño years vs. La Niña years.

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