NASA's press release on the stunning melt event in Greenland where 97% of the surface melted (Note: not mass or volume. A relatively thin layer melted.) downplayed the severity of the event by implying that it was a cyclical weather event that occurs every 150 years. I omitted the paragraph mentioning the "150 year events" from my initial post because I thought it was inconsistent with the climate of the past 2000 years and was misleading. Now, it appears to me from the PBS interview below that NASA management may have coached the young scientist to mention the 150 year "cycles" for political purposes to downplay the possible connections to global warming.
"Ice cores from Summit show that melting events of this type occur about once every 150 years on average. With the last one happening in 1889, this event is right on time," says Lora Koenig, a Goddard glaciologist and a member of the research team analyzing the satellite data. "But if we continue to observe melting events like this in upcoming years, it will be worrisome."Tom Wagner, NASA scientist and manager, gave an excellent interview on PBS except for omitting discussion of the recent years' trend of warming, melting and darkening. He made this melt event sound like it was caused by a semi-cyclical weather event which occurs, on average, every 150 years. Moreover, he admits to having coached the young scientist to write about this "150 year" melt event. In fact, melt events have occurred at a much lower frequency than every 150 years over the past 4000 years. Melt events were much more frequent than every 150 years from 4000 to 8000 years before present when the summer sun was a lot hotter in the Arctic than it is now. Averaging the warm period that happened 4000-8000 years ago with the cool period of the past 4000 years "created" the 150 year "cycles".
Koenig and Wagner refer to a classic paper on Greenland ice cores to support their claim of an approximate 150 year period, but the first paragraph of the paper's conclusion makes clear that the climate was warmer 4000 to 8000 years ago, with far more frequent melt events.
CONCLUSIONSMelt Events over the past 10,000 years at the Greenland SummitThe frequency of melting at the GISP2 site in central Greenland has decreased significantly from a maximum about 7000-7500 BP. This could have been caused by a
change in summer temperature variability over time, but probably represents a cooling of summer temperatures.Calibration of this signal suggests that the cooling has been within a few tenths of a degree of 1.3° C. We interpret available ice-flow-modeling results as indicating little change in ice-surface elevation through the atmospheric lapse rate over this time, so the signal is probably climatic rather than glaciological .
Fig. 1. Melt against age (upper panel) and July insolation against age (lower panel) for the GlSP2 site. Years containing melt features are shown by thin dotted lines. The heavier textured line is the 100 a running mean of melt frequency (number of melt features per 100 years), and the heavy black line is the 1000 annum running mean. The lower panel shows deviation of July insolation )from modern values in cal cm2/d, )from Berger (1978, 1979); positive values indicate more insolation than today. Note: right hand side is 10,000 before 1950, left hand side is 1950 (figure was hard to copy).
New York Times Reporter and Blogger Andrew Revkin then slammed NASA for using the word "unprecedented" in the title of their press release instead of challenging NASA on the confabulated 150 year semi-cycles. Revkin and the Times, didn't stop there. He then took a shot at Dr. Joe Romm of the Center for American Progress and "hyperventilating" progressive science bloggers.
July 25, 2012, 1:25 pmThe problem for Revkin is that Romm was correct. NASA was reluctant to tie the melt event to climate change, most likely for political purposes. The usual climate change denial bloggers jumped on Revkin's story and slammed "climate alarmists". Of course, none of these attackers went back and reviewed the original figures and sources.
‘Unprecedented’ Greenland Surface Melt – Every 150 Years?
By ANDREW C. REVKINThe flow of news releases and background science content from NASA is generally excellent, but the space agency badly blew it earlier this week with this headline, which has now reverberated around the Web: "Satellites See Unprecedented Greenland Ice Sheet Surface Melt."
Unprecedented means "never done or known before." Yet the news release beneath the headline directly undercuts that description of this melting event, saying that it is rare -- the last wide surface melt was in 1889, recorded in separate ice cores at the Greenland ice-sheet summit and in the northwestern part of the vast frozen expanse -- and has happened roughly every 150 years over a long stretch of centuries, as recorded deeper in the ice. (Here's a figure from a 1994 Science paper pointing to a series of such melt layers, reflecting summer warmth. Please see the postscript below for the key reference, provided by Lora Koenig of NASA.)
The inaccurate headline and burst of hyperventilating coverage and commentary (with some exceptions, like this new post by Climate Central) have already provided fodder for those whose passion or job is largely aimed at spreading doubt about science pointing to consequential greenhouse-driven warming.
This is unfortunate because the NASA release otherwise provided a fascinating, timely description of an unusual event, along with the historical context, as in this line:
"Ice cores from Summit show that melting events of this type occur about once every 150 years on average. With the last one happening in 1889, this event is right on time," says Lora Koenig, a Goddard glaciologist and a member of the research team analyzing the satellite data. "But if we continue to observe melting events like this in upcoming years, it will be worrisome."
But subtlety and reality don't play well in some circles. Koenig's careful description of the science and the uncertainty about what the future holds prompted a public spanking from the Center for American Progress climate blogger Joe Romm, who charged her with "scientific reticence" -- alluding to NASA scientist James Hansen's paper criticizing sea-level researchers for being overly cautious in 2007 conclusions about the possible rate of sea rise in this century. (At the time, scientists focused on ice sheets and sea level pushed back on Hansen's complaints.)
Here's how an obscure, relatively coherent, but dead wrong, conservative blogger responded to the mangled science reporting. I cite this right wing blog post because it is a rational response to NASA's and the Times' misleading reports.
Skeptics put the freeze on NASA ‘hot air’ about Greenland iceJoe Romm then proceeded to hand Revkin his backside with a strong assist from NASA climatologist Gavin Schmidt.
by HeidiFoxNews
NASA’s claim that Greenland is experiencing “unprecedented” melting is nothing but a bunch of hot air, according to scientists who say the country’s ice sheets melt with some regularity.
A heat dome over the icy country melted a whopping 97 percent of Greenland’s ice sheet in mid-July, NASA said, calling it yet more evidence of the effect man is having on the planet.
But the unusual-seeming event had nothing to do with hot air, according to glaciologists. It was actually to be expected.
“Ice cores from Summit station [Greenland’s coldest and highest] show that melting events of this type occur about once every 150 years on average. With the last one happening in 1889, this event is right on time,” said Lora Koenig, a Goddard glaciologist and a member of the research team analyzing the satellite data.
And yet Dr. Jason Box, a leading Greenland expert with “19 expeditions to Greenland since 1994, more than 1 year camping on the inland ice,” used the following headline on his blog, Meltfactor.org, “Greenland ice sheet record surface melting underway.” Hard for something to be a record if it isn’t unprecedented.That's right. There was one melt event in the past 700 years. There were only 6 in the past 2000. Four of those 6 event happened in the 450 year long Medieval Climate Anomaly aka the medieval warm period. There is no 150 year cycle of melt events. This summer's melt was exceptional. It is not just a freak weather event because it is part of a decade of very rapid warming across the Arctic.The most thorough response comes from NASA’s own Gavin Schmidt in a comment posted on the NY Times story (one he confirmed with me):
The NASA results are clearly unprecedented in the satellite record (and this is obviously what was being referred to), and come at the tail end of a strong increasing trend in summer surface melt area (as seen in data from the Steffen and Tedesco groups).
However, we know Greenland was warmer than today at many intervals in the past – the Early Holocene (from isotopes and borehole temperatures), the last interglacial, the Pliocene etc. so there is no claim that this is something that has never happened in the history of the planet.
Furthermore, the ‘every 150 years’ quote is very strange. The data on Summit melt layers – (discussed in the paper you reference http://www.igsoc.org/... ) and more easily visible here:http://www.gisp2.sr.unh.edu/... – indicates that the [1889] event was actually the only event in the last ~700 years, and there have only been 6 in the last 2000 years (4 of which were associated with the Medieval Climate Anomaly btw 750 and 1200AD). Hardly a frequently recurring ‘cycle’!
The all-Holocene average that Koenig is referring to includes the warmer Early Holocene where orbital variability was driving warmer northern high latitude summers — and which is not relevant to the expected frequency in today’s climate.