Friday, March 4, 2016

Global Warming News Roundup: Missing Ice, Hot Satellites, New England Winters

Click on this graph to make it bigger and
easier to see. Arctic sea ice extent (light blue
line) has been mostly running at record
low levels so far this year.  
If you want global warming to reverse itself and things to start cooling off, this isn't going to be a blog post you want to read.

Things are still heating up dramatically, as the following roundup of climate news suggests.

Hot Arctic And Not Much Ice

As I reported earlier, the Arctic is having an incredibly warm winter.

New data released in the past week show that February continued the warm trend, with parts of the high Arctic as much as 29 degrees Fahrenheit warmer than normal, something that's not been seen before.

Not surprisingly, Arctic sea ice was at record low levels during most of February, says the National Snow and Ice Data Center.

A bit of colder air in parts of the Arctic froze up some northern seas, so now the ice is about tied with a record low extent, rather than well below the previous record as it had been for most of February.

This winter continues - and at least temporarily accelerates - the decline in the amount of sea ice up there in recent decades.

As I've noted previously, record or near record low ice extent in February and March doesn't necessarily portend record low sea ice up there in the summer, when it matters the most, but it does make that more likely.

Weirder Winters Where We Live

Related to the lack of ice up in the Arctic is a new study on New England winters that bolsters the evidence that the declining ice up by the North Pole is changing weather patterns im the mid-latitudes where most of us live.

We in New England have noticed the winters have gotten pretty crazy. We've had warm, nearly snow-free ones like this year, and bitterly cold, horribly snowbound ones like last year.

According to the Alaska Dispatch News:

"Scientists studied isotopes in precipitation samples collected since 1968 at the Hubbard Brook Experimental Forest in New Hampshire. The water isotopes -- the varying atomic structure of the hydrogen and oxygen that make up water -- identifies the precipitation that falls there durig all and winter as originating from the warming Arctic."

Over time, there has been an increase in the proportion of the precipitation that originate from water molecules in the Arctic.  
A loss of Arctic sea ice might be affecting the
jet stream, which in turn seems to be
making New England winters more extreme,
either cold and snowy or warm and dry.

This suggests that as the ice in the Arctic melts, it influences the jet stream, giving it bigger bulges to the north and bigger dips to the south.

That means there's more likely to be unusual bursts of record warm air heading north toward the Arctic under the bulges, and a greater likelihood of blasts of air coming direct from the North Pole southward to places like New Hampshire.

The fact that more isotopes are coming from the Arctic means there's bigger gyrations in the jet stream, making it easier for Arctic air to plunge south, and presumably, warm air return north to the Arctic.  

The bigger the bulges and dips in the jet stream, the more extreme the temperatures, and the stronger the storm systems get. No wonder winters have been getting so weird.

This water isotope study does not prove that the jet stream is getting wavier and weirder, but it builds on previous studies that suggest the same thing, says the Alaska Dispatch News.  

Even The Satellites Are Saying It's Warm

Climatologists still largely regard surface-based temperature measurements as the best way to measure climate trends. Satellite measurements have been around for decades, but many scientists suggest these readings from satellites underestimate the amount the Earth has warmed.

However, the latest readings for February, as derived from satellites, are off-the-charts warm.

According to Slate, satellite measurements suggested that February set new heights in atmospheric warmth, only to be outdone by the opening couple of days in March.

The satellite readings showed the northern hemisphere, at least, was a full 2 degrees Celcius above normal. That level is a somewhat arbitrary threshhold in which scientists say the world is in deep trouble from global warming.

Of course, that 2 degrees Celcius danger level would have to be sustained over time. People unanimously believe this level of warmth in the northern hemisphere will end very soon. At least for now.

It's remarkable in that it's the first time such a departure above normal has been observed. It's probably the first time it's been that warm in the northern hemspher since human civilization began thousands of years ago, according to Slate.

If warming continues, we'll get to that 2 degree Celcius above normal warmth again, then more and more frequently, until it's always two degrees above normal.

It will be interesting to see what the land-based global temperature analysis will be for February. Those numbers I think are closer to reality. But I bet they'll show another record hot month for the planet.

The latest satellite data is bad news for climate science deniers like Ted Cruz.

The Republican presidential candidate has consistently said that satellite data shows no warming like surface based analysis has. He's not quite right. The satellite data shows warming, but not as steep a climb as data from land based thermometers have shown.

Now, even the satellite data is showng a big jump, at least for now.

The Global Warming Slowdown Is Over

The satellite data gives even more credence to the idea that global warming is accelerating, at least for now.

Global warming appears to have slowed in much of the 2000s, up to the year 2013. notes Climate Central. 

Some climate scientists and activists pooh-poohed the apparently slowdown in the rate of warming, saying it masked increasing heat content in the oceans.

Maybe, but the fact remains that the rate of global warming did, in fact, slow down, despite a few reports to the contrary.  NOAA, for instance, said the warming continued apace, with no slow down.

Climate change skeptics seized on the slowdown by calling it a hiatus, and claiming global warming was over.

That was incorrect, but so was claiming the easing in the rate of global warming didn't exist. It did exist.

"We shouldn't sweep the early 2000s warming slowdown under the rug," said Penn State meteorology professor Michael Mann.

That's significant, coming from Mann, since he has been in the forefront of scientists warning about the consequences of climate change.

Global warming does not cancel out natural variability. Many influences can lower, or raise global temperatures. While increasing amounts of carbon dioxide in the atmosphere would inevitably cause the heat to rise, those other natural processes can slow the rate of warming, or speed it up.

It appears that there was a natural cycle in the Pacific Ocean that increased trade winds, which in turn sank excess heat into the deep oceans, rather than letting it sit in the atmosphere. That meant the rate of warming in the lower atmosphere, where we live, kind of conked out as the 21st century opened, says Climate Central.

That natural cycle in the Pacific has pretty much moved on now. El Nino, another natural process, has apparently teamed up with the end of that Pacific cycle, means that global warming since the beginning of 2014 has accelerated to a rate faster than the average over the past few decades.

Which explains why we've been breaking global temperature records by large margins for the past couple of years.

The rate of global warming will continue to fluctuate. Nobody is sure how long the current really fast rate, which is going full steam, will continue. Will the inevitable end of El Nino, probably happening later this year, slow things down again? Or will temperatures keep racing upward and upward.

We'll have to wait and see.

Temperature measurements taken at the surface of the planet from 2001 to 2014 revealed a lull in the rate of global warming, sometimes called the “warming hiatus,” before spiking upward again. 2014 was the hottest year on record until the record was easily beaten in 2015.
Until 2009, scientists had little explanation for the phenomenon. By 2014, though, it was known that the slowdown was caused primarily by a phase in a slow-moving Pacific Ocean cycle, with fierce trade winds driving more heat than normal into ocean depths.
The slowdown at the planet’s surface coincided with a rise in temperatures in ocean depths, worsening sea-level rise.
“The temporary slowdown in no way implies that human-caused warming has ceased or slowed down,” Mann said. “It was temporarily masked by natural factors.”Several recent papers have called into question whether the surface warming slowdown was significant. Some of the disagreements boil down to semantics; others relate to interpretations of data.
Wednesday’s commentary lauded the advances in climate science that helped solve the mystery of the slowdown, while rebuking other scientists whose research has concluded that the slowdown was insignificant or unimportant.
“Given the intense political and public scrutiny that global climate change now receives, it has been imperative for scientists to provide a timely explanation of the warming slowdown,” wrote the 11 scientists, who are based in Canada, England, Australia and the U.S. “Despite recently voiced concerns, we believe this has largely been accomplished.”
One of the studies singled out in the commentary was produced by National Oceanic and Atmospheric Administration scientists led by Thomas Karl, who directs the agency’s National Climatic Data Center.
Karl’s team believes some historical records of ocean temperatures are flawed, and they corrected them accordingly.  The result of that analysis led them to conclude in a paper published last year in Science that warming during the early 2000s was “far more similar” to the longer-term trends “than previously estimated.”
That surprise finding prompted Rep. Lamar Smith, a Republican from Texas who is chairman of the House Committee on Science, Space and Technology, to aggressively push for access to the government scientist’s emails, part of an investigation that others have characterized as a witch hunt.
Smith has argued that the NOAA study was “expedited to fit” the Obama Administration’s “aggressive” climate policies — a claim the agency strongly denies.
Karl on Wednesday stood by his work, saying “there is no disagreement” that temperatures and warming rates vary between decades. “We showed that one could not claim that the long-term warming trend was significantly different from the shorter period,” he said.Wednesday’s commentary was a reminder that opposition to NOAA’s findings is not just from politicians and fossil fuel groups, but from researchers who are convinced that the warming slowdown was real — and worthy of a public conversation.
The new commentary included new analysis of temperature data that showed what the authors described as a “mismatch” between early-century rates of warming and rates projected by model simulations.
“We’re presenting results to support previous findings of reduced rates of surface warming,” said John Fyfe, a Canadian government climate scientist who coordinated publication of the commentary. “That essentially refutes the Karl et al. paper.”
Fyfe said he had “no doubt” that the commentary would be misused by climate science deniers, but that he had no hesitations about publishing it. “I don’t think we should be in the business of pandering to the climate deniers.”
Two other teams of scientists whose papers were critiqued in the commentary downplayed any differences in opinion, pointing to the consensus that global warming and natural variability both affected early-century surface temperatures.
“Their perspective is very much in line with our previously published work,” said Noah Diffenbaugh, one of four Stanford researchers who wrote a paper published last year in Climatic Change provocatively titled “Debunking the climate hiatus.” “Global warming has resulted in a long-term trend superimposed on natural climate variability.”
Another paper criticized in the commentary was published last year by the Bulletin of the American Meteorological Society. In it, three scientists led by University of Bristol cognitive psychology professor Stephan Lewandowskyconcluded that “there is no evidence that identifies the recent period” of warming as “unique or particularly unusual.”
That paper argued against the use of the term “global warming hiatus,” or “pause,” which is sometimes used to describe the recent global warming slowdown.
Wednesday’s commentary agreed that recent temperature trends have been framed “in an unfortunate way,” suggesting that “reduced rate of warming” or “temporary slowdown” would better describe them.
Although Lewandowsky’s paper was singled out in Wednesday’s commentary, he said it fundamentally addressed different scholarly questions.
“As far as we’re concerned, there’s no discrepancy,” Lewandowsky said. “They share our view that warming never stopped, and we don't actually disagree at all.”

“We shouldn't sweep the early 2000s warming slowdown under the rug,” said Penn State meteorology professor Michael Mann, one of 11 authors of the commentary published in Nature Climate Change.

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