Much of the skepticism about whether humans are causing climate change would probably go away if only the Neanderthals had invented a good, reliable thermometer. Whenever someone announces that this year or that season was the warmest or the third warmest or whatever on record, “on record” only goes back to the late 1800’s at best. That’s when accurate instrument measurements of temperature began. To obtain readings from before that time, scientists have to rely on proxy measurements — things like tree rings or pollen deposits or oxygen-isotope ratios that change as temperature changes. The famous (or infamous) “Hockey Stick” graph showing temperatures shooting up during the second half of the last century after hundreds of years of relative stability is based almost entirely on proxies — and records from ancient ice cores push the temperature record back hundreds of thousands of years further.
Drawings of different types
of foraminifera. Credit: NOAA.
With a few small exceptions, proxies for the past thousand years or so are in broad agreement regarding temperature trends, and now one more has been reported in the journal Geophysical Research Letters — but there’s a twist.
This proxy involves the shells of tiny sea creatures called foraminifera, or forams, which lived and died in the bottom waters of the Lower St. Lawrence Estuary, in eastern Canada. The shells are made of calcium carbonate, which contains oxygen drawn from the su...
Climate in Context: Can Wildfires Worsen Climate Change? Hermine Soaks Texas, Igor Lurks in Atlantic
Global warming is the most direct consequence of human-generated greenhouse gases, but it’s what the warming triggers—rising seas, melting ice, extreme weather and more—that actually causes the problems scientists worry about. One more item on that list is an increase in wildfires. This summer’s wildfires in Russia are just an example, they say, of what could be an all too common occurrence by later this century.
But if fires are a secondary effect of warming, there’s yet another, tertiary effect that’s now emerging into the scientific consciousness. Massive fires can send superheated air rising through the atmosphere, and under the right conditions, these rising columns of air can create so-called pyrocumulonimbus clouds that can reach all the way into the stratosphere. The clouds, called pyroCbs for short, can literally turn into artificial thunderstorms (cumulonimbus is the name given to typical thunderstorm clouds), or they can turbocharge existing storms.
A pyrocumulus cloud rises from the 2009 Station
Fire in California. Credit: Wikipedia Commons.
Now, thanks to a new investigation out of the Naval Research Laboratory it turns out that pyroCbs can also inject smoke particles into the stratosphere—particles that can augment the heating effect of greenhouse gases. Until recently, atmospheric scientists assumed that the atmospheric layer known as the tropopause, which se...
Daily Arctic sea ice extent as of September 6, 2010, along with daily ice extents for years with the four lowest minimum extents. Credit: National Snow and Ice Data Center.
Arctic Sea Ice Melt Season Winding Down, Ice Extent Now Third Lowest in Satellite Record
The National Snow and Ice Data Center (NSIDC) in Boulder, Colo. announced today that Arctic sea ice extent had declined to the third lowest in the satellite record, surpassing last year's seasonal minimum. However, sea ice extent is not as low as it was in 2007, when the seasonal minimum shattered records, and with just about two weeks remaining in the melt season, a new record low is not expected this year. According to the NSIDC, ice extent during the month of August was the second lowest in the satellite record, after 2007.
Notably, both the famed Northwest Passage and the Northern Sea Route are currently described as "largely free of ice," and the NSIDC reports that there are at least two expeditions that are attempting to take advantage of these conditions to accomplish a historical feat: circumnavigating the Arctic Ocean. One of the ships is helmed by the Norwegian explorer Borge Ousland, while the other – the Peter I yacht – hails from Russia.
According to NSIDC:
Average ice extent for August was 5.98 million square kilometers (2.31 million square miles), 1.69 million square kilometers (653,000 square miles) below the 1979 to 2000 averag...
Sea surface temperature departures from average (anomalies) for the
week of Aug. 22-28, 2010. Credit: IRI.
As we've demonstrated in this slideshow, the Atlantic Ocean is downright sizzling right now, with record-breaking water temperatures in some areas. This makes it more likely that there will be an above average number of hurricanes this season, including more major hurricanes of Category Three strength or above. And – as Hurricane Earl has demonstrated – it also increases the odds that major hurricanes will be able to maintain their intensity in areas they seldom frequent.
The above map of sea surface temperature anomalies from the last week of August shows the abundance of unusually warm water in the Atlantic, from the coast of Africa to southern New England. This is one of the reasons why the U.S. National Oceanic and Atmospheric Administration (NOAA) has predicted an above average hurricane season, and helps explain how Earl was able to stay so strong as it neared the Carolinas.
According to Weather Underground meteorologist Jeff Masters, Hurricane Earl became the third strongest hurricane to be observed so far to the north in the Atlantic Ocean when it maintained Category Four intensity on its approach to the North Carolina coastline earlier this week (it weakened steadily thereafter due to a combination of factors). On September 2 Masters wrote:
Only Hurricane Esther of 1961 and Hurricane Connie of 1955 made it fa...
Bryozoans that can be found on Southern Ocean
Continental Shelves. Credit: British Antarctic Survey.
During the last warm interval between the ice ages – a time, about 130,000-114,000 years ago, known as the Eemian period – the Earth got warmer than it is today, and sea level rose higher. And since we’re currently heading for warmer temperatures again, thanks in large part to human generated greenhouse gases, scientists are looking back at the Eemian for clues about what our own future might look like.
One more clue has just been published, in the journal Global Change Biology. Much of the rise in Eemian sea level – about five meters, or 16 1/2 feet higher than it is today – presumably came from ice melting off Greenland. But some probably came from Antarctica as well, and sea creatures known as bryozoans seem to confirm that idea.
Field researchers from the British Antarctic Survey have shown that colonies of bryozoans on opposite sides of the West Antarctic Sheet are more similar to each other than they are to bryozoans along the nearby coast. This suggests that they were in direct biological communication sometime in the past – suggesting in turn that a seaway once existed in a region that’s now buried under thousands of feet of ice. As the paper’s lead author David Barnes says in a press release on the British Antarctic Survey website:
“The West Antarctic Ice Sheet...