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New Reports Show Impact of Manmade Global Warming

The influence of manmade global warming on the climate system continues to grow, with human fingerprints identified in more than two dozen climate “indicators” examined by an international research team — from air temperatures to ocean acidity — for a comprehensive annual “State of the Climate” report released Tuesday.

In a related study also released on Tuesday, climate researchers said manmade global warming is already shifting the probability of many extreme weather and climate events, making heat waves, droughts, and other events more likely to occur in some parts of the world. The study found that manmade global warming made the devastating Texas drought and heat wave of 2011, which was the most expensive drought in the Lone Star State's history, at least 20 times more likely compared to years with similar large-scale weather patterns in the 1960s. The report also tied other recent extreme events worldwide to manmade warming.

Together, the two reports amount to a comprehensive accounting of the present state of the climate system, over which mankind is now exerting a greater impact than ever before.

Drought map from June 2011, showing the intensifying drought in Texas and northern Mexico. Credit: NOAA.

“Every weather event that happens now takes place in the context of a changing global environment,” said deputy NOAA administrator Kathryn D. Sullivan in a press release. The reports were released during a time when extreme weather events have been making international headlines, with the U.S. having just experienced an historic heat wave that has withered crops. Drought has expanded across the lower 48 states, affecting 56 percent of the contiguous U.S., and Russia is burying the dead from flash flooding that struck Krymsk, a small town near the Black Sea. Through June, the U.S. has had its warmest 12-month period, warmest year-to-date on record, and also saw a string of deadly wildfires.

The “State of the Climate 2011” report, published by the National Oceanic and Atmospheric Administration (NOAA) and the American Meteorological Society (AMS), presents a peer reviewed tour through the weather and climate events of 2011. The overriding theme that emerges from the report is that the effects of human activities are readily evident, be it in the form of rising concentrations of greenhouse gases in the atmosphere — global carbon dioxide concentrations hit a new all-time high of 390 parts per million last year, and will cross the 400 ppm threshold worldwide by 2016 — to the inexorable increase in ocean heat content.

The report shows that a La Nina event, characterized by cooler-than-average sea surface temperatures, helped keep global average surface temperatures down compared to 2010, but it was one of the warmest La Nina years on record.

In the Arctic, which has been warming at twice the rate of the rest of the globe, 2011 had the second-lowest sea ice extent on record. Barrow, Alaska, located above the Arctic Circle, experienced a record 86 straight days when the temperature failed to drop below freezing.

The report also contains evidence from ocean salinity measurements that the global water cycle is intensifying. “The dry regions are getting drier and the wet regions are getting wetter,” Kate Willet, a senior scientist at the U.K. Met Office said on a conference call with reporters.

The other climate assessment, which was also released by NOAA and the AMS, represents a step forward in efforts to decipher how manmade global warming is influencing specific extreme weather and climate events.

Global average surface temperature departures from average during 2011. Credit: NOAA.

As the reports, along with prior studies, point out, some extreme events are much more likely to occur in a warming world. Researchers used different and largely novel approaches to analyze a half-dozen extreme weather and climate events that occurred last year, from the brutal Texas drought and heat wave to the deadly Thailand floods.

The report notes that global warming has already been playing a role in shifting the odds for several of these extreme events, including the Texas drought. The 2011 growing season was by far the warmest and driest in Texas history, and the drought was the worst one-year drought on record there as well, costing billions in agricultural losses.

The study concluded that, due to manmade global warming, La Nina-related heat waves are now 20 times more likely to occur in Texas than they were 50 years ago.

According to Peter Stott, who leads the Climate Monitoring and Attribution team at the U.K.’s Met Office, since manmade global warming is boosting average temperatures, it makes it more likely that certain thresholds will be reached or exceeded when a La Nina occurs. Weather patterns during La Nina years naturally tend to favor warmer and drier conditions in the Lone Star State.

“You’re [now] much more likely to have exceptional warmth,” in Texas during a La Nina year, Stott said.

Other researchers looked at international events and came to different conclusions depending on the questions researchers asked and the specific event in question. For example, scientists looked into the shifting odds for two unusual months that the U.K. experienced in 2010 and 2011. The U.K. had a very warm November of 2011, and rare cold during December 2010, during which time much of Britain experienced a white Christmas.

The study found that, because of manmade global warming and other factors, cold Decembers are now half as likely to occur as they were 50 years ago, and warm Novembers are 62 times more likely to take place.

Other experts in the burgeoning field of “extreme-event attribution” took on the challenge of determining whether there was a global warming influence on the record Thailand floods of last year.

The floods were the worst to occur there since 1942, with some areas remaining submerged by 6 feet of water for more than two months, according to NOAA. The floodwaters damaged or destroyed many high tech manufacturing centers, leading to delays in shipping equipment such as laptop computers.

In this case, the researchers found evidence that the floods were manmade, but not because of climate change. The study concluded that the rainfall amounts were not actually unprecedented or that unusual for Thailand, and that industrial development, reservoir management policies, and other trends on the ground contributed to the flooding.

“The flooding was unprecedented but the rainfall that produced it was not,” Stott said.

Stott is working with an international team of scientists to advance extreme-event assessments, and has raised the possibility of eventually being able to conduct them in near-real time if the science advances far enough.


By Stee (Denver/CO/80205)
on July 11th, 2012

In real life, droughts were MUCH more severe in the 1950s and 1960s which anyone can verify by looking at the Palmer Drought Index Record. In addition to that, the number of record high temperatures in 2011 was less than 1925, despite the fact that there were more stations in 2011. More likely than not, 9 out of 10 people will read something like this and believe it without even a second thought because it’s lock step in line with their own dogma.

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By Steve Goddard (Fort Collins Colorado 80525)
on July 11th, 2012

The PDSI was much worse in the 1950s and 1960s, indicating that the author and reviewers didn’t check their facts.

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By Andrew
on July 12th, 2012

@Steve - the Texas State Climatologist has concluded that the 2011 Texas drought was the most intense one-year drought in that state’s history, based on multiple factors. Furthermore, no one is making the claim that the drought conditions across the U.S. are unprecedented. Just that there is more land area affected by drought now than was affected in the history of the Drought Monitor, which is a short dataset since it only goes back to 2000.

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By David F. (Toledo, OH 43607)
on July 13th, 2012


The Texas drought was the worst on record. Steven is known for taking liberty with facts, The link he posted above is a 12-month filter ending in May. In other words, it shows the average statewide PDSI for the period beginning in June of the previous year and ending the following May. For May 2012, the 12-month Texas state PDSI was -5.72, second lowest on record, behind only the -5.99 from June 1917 through May 1918. Moreover, moving back in time to the peak of the Texas, we see that the one-month average PDSI for Texas in August 2011 was an incredible -7.72, easily the lowest on record for the month of August, since records began in 1895.

In addition, some “skeptics” have argued the current heat and drought is no big deal. As an aside, I’m sure the farmers whose crops are withering will love to hear that it’s all hype. Unfortunately, it’s not hype. In fact, the objective PDSI, which is measure of drought based solely on temperature and precipitation trends for a given climate district, is even more ominous than the UN-L Drought Monitor. The most recent weekly PDSI can be viewed at the following link: Nationally, the current PDSI is classified as being in the lowest one percent, again based on records since 1895. It appears only the Dust Bowl drought of 1934 resulted in a more widespread low PDSI.

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By Hank Hilltopper
on July 16th, 2012

Climate change is a natural phenomenon. Climate change due to anthropogenic activities is not. Global warming is a theory based on anthropogenic activities. If only GWTs could provide specific data properly collected and analyzed, perhaps those data could be rigorously scrutinized and global warming could be knocked out of the ‘theory’ column.  But alas, to date, this hasn’t been done. Unfortunately, NOAA, AMS and TWC are promoting recent articles, reports, etc advocating the purported link between global warming and extreme weather events. Why? One only need read “The New Levithan.” When these recent articles/reports link extreme weather events using wildfires as an example, the articles/reports indicate a lack of validity and cause their integrity to be suspect; nearly all US wildfires originate due to human carelessness (anthropogenic activities), therefore not due to a weather event. Some additional data concerning CO2 emissions? Try the USEPA’s Greenhouse Gas Inventory Sheet for CO2 emissions, particularly CO2 emissions due to fossil fuel combustion, for the 5yr period 2006-2009.

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By Peggy (murfreesboro/TN/37128)
on July 19th, 2012

What caused the droughts prior to Global Warming?

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By geohydro2011
on August 7th, 2012

@stee and @steve: the PDSI is affected inordinately by high temperatures and tus is not the best measure of drought see
@hank: here is the empirically (not modeled) derived data you desire:

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By Robert Harmon (St. Augustine, FL)
on August 7th, 2012

Definition: Anthropogenic - caused or produced by humans. Hank ought to realize his skepticism and negativism in the face of so much worldwide studying of climate change is an anthropogenic event in itself - a human causing the dangerous delay of any worldwide momentum toward taking this topic seriously and producing irreversible tipping points caused by such ignorance and denial. Theory? I’ve got one - he’s a Republican!

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By Robert Harmon (St. Augustine, FL)
on August 7th, 2012

Hank reminds me of the pseudo intellectual who stands there arguing the exact weight of the stampeding elephant about to trample him.

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By Robert Harmon (St. Augustine, FL)
on August 7th, 2012

OK, you don’t have to post this but I just had an epiphany! I’ve finally figured it out. All the passionate climatologists are really in it for personal gain. They’re secretly buying up land at the edges of at risk cities around the world knowing that with increased ice melts they’ll make terrific marinas.

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By geohydro2011
on August 7th, 2012

@hank: I’m not sure that all US wildfires originate due to human carelessness—lightning initiates many wildfires. But these wildfires are accentuated due to institutionalized programs of fire suppression and exclusion (meant to help people) that have allowed many landscapes to accumulate surface and ladder fuels that would have been burned naturally had suppression/exclusion not been in place.

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By geohydro2011
on August 7th, 2012

@Peggy, drought is a term that has meaning to humans but before humans dominated the landscape, droughts or periods of high temperature and low precipitation would likely occur due to natural causes and thus be seen as part of the nature of things. Today drought is a term that is usually associated with crop failure and human suffering. Global warming affects not only temperature but also the hydrologic cycle and and thus a drought that occurred before warming would have been moderate in time and space now may morph into a severe drought.

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By Uwe Fritz
on August 9th, 2012

I feel that maybe some folks are missing the message that is trying to be relayed here and that is that the chance of certain events occuring are increased by global warming, and not necessarily caused by global warming.

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By Star Garnet (Ellensburg, WA 98926)
on October 19th, 2012

Virtual Premier

Welcome to our virtual premiere! We invite you to watch our new movie “The Boy Who Cried Warming.” Every Global Warming prediction, has proven to be science fiction. Uncover the truth as we expose the shepherds of Climate Change in this new controversial documentary. Enjoy the movie!

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By Jason (Arkansas)
on November 21st, 2012

This is what happens when we allow people like Al Gore, people with an agenda, to spread baloney like this.  I don’t know how many of you are engineers or engineering students; but, if you look at the THEORY of manmade climate change as a thermodynamic system, it makes absolutely NO sense.  Are humans using fossil fuels causing some sort of measurable temperature rise?  Probably.  Is it going to be enough to cause catastrophic changes in the Earth’s climate and cause mass extinctions of species?  Not likely.  And what’s all this crap about carbon dioxide?  Do none of you understand that NO LIFE exists without it?  If you’re worried about CO2 levels, go somewhere and plant a couple trees.  There are much more important issues facing the human species, at this point…such as the rate at which we use up our natural resources without much research or action in reducing usage or replacing said resources.  Don’t worry, hippies, good ol’ mother Earth isn’t gonna go bye-byes because someone drives an SUV.

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