Ladies and Gentlemen!
In this corner, competing on behalf of people who claim that anthropogenic global warming is to blame for all recent extreme weather conditions . . .
Climate scientist Jake Crouch, climate scientist Michael Mann and NASA scientist James Hansen!
In the opposite corner, competing on behalf of people who deny that anthropogenic global warming is to blame for all recent extreme weather conditions . . .
Climatologist John Christy, meteorologist Cliff Mass and climatologist Roy Spencer!
The match begins . . .
Crouch and Mann make the first move:
WASHINGTON (AP) – This probably comes as no surprise: Federal scientists say July was the hottest month ever recorded in the Lower 48 states, breaking a record set during the Dust Bowl of the 1930s.
And even less a surprise: The U.S. this year keeps setting records for weather extremes, based on the precise calculations that include drought, heavy rainfall, unusual temperatures, and storms.
The average temperature last month was 77.6 degrees. That breaks the old record from July 1936 by 0.2 degree, according to the National Oceanic and Atmospheric Administration. Records go back to 1895.
“It’s a pretty significant increase over the last record,” said climate scientist Jake Crouch of NOAA’s National Climatic Data Center in Asheville, N.C. In the past, skeptics of global warming have pointed to the Dust Bowl to argue that recent heat isn’t unprecedented. But Crouch said this shows that the current year “is out and beyond those Dust Bowl years. We’re rivaling and beating them consistently from month to month.”
Three of the nation’s five hottest months on record have been recent Julys: This year, 2011 and 2006. Julys in 1936 and 1934 round out the top five.
Last month also was 3.3 degrees warmer than the 20th century average for July.
Thirty-two states had months that were among their 10 warmest Julys, but only one, Virginia, had the hottest July on record. Crouch said that’s a bit unusual, but that it shows the breadth of the heat and associated drought.
For example in 2011, the heat seemed to be centered mostly in Oklahoma and Texas. But this summer “the epicenters of the heat kind of migrated around. It kind of got everybody in the action this month,” Crouch said.
The first seven months of 2012 were the warmest on record for the nation. And August 2011 through July this year was the warmest 12-month period on record, just beating out the July 2011-June 2012 time period.
But it’s not just the heat that’s noteworthy. NOAA has a measurement called the U.S. Climate Extreme Index which dates to 1900 and follows several indicators of unusually high and low temperatures, severe drought, downpours, and tropical storms and hurricanes. NOAA calculates the index as a percentage, which mostly reflects how much of the nation experience extremes. In July, the index was 37 percent, a record that beat the old mark for July last year. The average is 20 percent.
For the first seven months of the year, the extreme index was 46 percent, beating the old record from 1934. This year’s extreme index was heavily driven by high temperatures both day and night, which is unusual, Crouch said.
“This would not have happened in the absence of human-caused climate change,” said Pennsylvania State University climate scientist Michael Mann. [Quote Source]
Spencer dodges the move by Crouch and Mann by producing a chart which shows that the highest daily temperatures took place in the 1930s.*
On his blog, Spencer states the following:
If we look at the 5-year running mean of the daily averages for July’s over the last 100 years, we see that while recent Julys have indeed been warm, it is questionable whether they rival the 1930s . And if we do the same 5-year averaging on July maximum temperatures, the 1930s were obviously warmer. So, all things considered (including unresolved issues about urban heat island effects and other large corrections made to the USHCN data), I would say July was unusually warm. But the long-term integrity of the USHCN dataset depends upon so many uncertain factors, I would say it’s a stretch to call July 2012 a “record”. [Quote Source]
Meanwhile, Christy makes his own counter-move:
A project which seeks to generate consistent and systematic weather maps back to 1871 (20thCentury Reanalyisis Project, http://www.esrl.noaa.gov/psd/data/20thC_Rean/) has taken a look at the three major indices which are often related to extreme events. As Dr. Gill Campo of the University of Colorado, leader of the study, noted to the Wall Street Journal (10 Feb 2011) “… we were surprised that none of the three major indices of climate variability that we used show a trend of increased circulation going back to 1871.” (The three indices were the Pacific Walker Circulation, the North Atlantic Oscillation and the Pacific-North America Oscillation, Compo et al. 2011.) In other words, there appears to be no supporting evidence over this period that human factors have influenced the major circulation patterns which drive the larger-scale extreme events. Again we point to natural, unforced variability (i.e. Mother Nature) as the dominant feature of events that have transpired in the past 130 years. [Quote Source]
NASA scientist James Hansen attempts to pin down his opponents:
“Climate dice,” describing the chance of unusually warm or cool seasons, have become more and more “loaded” in the past 30 y, coincident with rapid global warming. The distribution of seasonal mean temperature anomalies has shifted toward higher temperatures and the range of anomalies has increased. An important change is the emergence of a category of summertime extremely hot outliers, more than three standard deviations (3σ) warmer than the climatology of the 1951–1980 base period. This hot extreme, which covered much less than 1% of Earth’s surface during the base period, now typically covers about 10% of the land area. It follows that we can state, with a high degree of confidence, that extreme anomalies such as those in Texas and Oklahoma in 2011 and Moscow in 2010 were a consequence of global warming because their likelihood in the absence of global warming was exceedingly small. [Quote Source]
Mass avoids being pinned down:
This week, with great fanfare, NASA scientist James Hansen and associates released a paper “The Perception of Climate Change” in the journal PNAS that claims that recent heat waves and droughts were caused by human-induced climate change. To quote their abstract:
” It follows that we can state, with a high degree of confidence, that extreme anomalies such as those in Texas and Oklahoma in 2011 and Moscow in 2010 were a consequence of global warming because their likelihood in the absence of global warming was exceedingly small.”
This paper (found here) has been quoted in hundreds, if not thousands, of media outlets and newspapers and has garnered the praise of many environmental advocacy groups.
The problem? Their conclusions are demonstrably false and their characterization of the science and statistics are deceptive at best. [Quote Source]
On his blog, Mass explains why Hansen and his associates are mistaken. Mass states the following:
So I think you can see that the global warming signal due to human-emitted gases could not possibly be more than 1F, and is probably much less. Yet the heat wave last summer, expressed as monthly anomalies, reached 7-8F over large portions of Texas and Oklahoma.
What can you conclude? Something other than global warming produced the lion’s share of the heat wave...and we know what it was: a major change in the circulation over the U.S. last summer.
Mass also states, “I believe that human-induced global warming is both observed, real, and a serious problem for mankind. So if anyone wants to call me a denier or some other ad hominem name, please refrain from such remarks.”
Wait a minute. There seems to be a complaint coming from the team of Christy, Mass and Spencer.
The complaint is that the team of Crouch, Mann and Hansen has a fourth member.
The referee is investigating.
Now the referee speaks:
“May I have your attention, please. Upon reviewing the beginning of the fight, it appears that there is a fourth member of the team of Crouch, Mann and Hansen. That fourth member is the Associated Press. Thus far, all statements from the team of Christy, Mass and Spencer have come directly from them, without any assistance from the mainstream media. Therefore, in order to give the two sides an equal number of participants, the following excerpt from the Christian Science Monitor is added on behalf of the team of Christy, Mass and Spencer”:
Given that July marked the fourth 12-month span in a row setting record temperatures, and that it may be the high point of a record hot year, links to global warming from greenhouse gas emissions have been noted by scientists as entirely plausible. Worth noting: while the US landmass represents only 4 percent of the globe, global average temperatures in June also amounted to the fourth hottest in recorded history.
But the record heat in the US can also be tied to naturally occurring weather patterns, including nuances in the rotation of the North Atlantic Oscillation, a climatic phenomenon that, with great variability, controls wind patterns across the US and how storms track across the North Atlantic.
In July, the oscillation, in essence, backed up massive high pressure systems moving across the US, leading to a pattern of searing hot days that stoked the natural processes that produce drought. [Quote Source]
So, the great tag-team climate battle continues, climate scientist against climate scientist, and you can observe it without paying for those premium cable channels.
Now, for people who can’t cope with the fact that climate scientists are indeed feuding about global warming, the following is offered:
*The highest temperature recorded in Oklahoma was recorded in 1934, when a record high temperature of 120° Fahrenheit was recorded in the community of Tishomingo [Source]. The highest temperature recorded in Texas was recorded in 1936, when a record high temperature of 120° Fahrenheit was recorded in the community of Seymour [Source].