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300 scientists warn about Trump's CCS + records for lightning + atmospheric rivers

#1
C C Offline
More than 300 scientists warn over Trump's climate change stance
https://www.yahoo.com/news/more-300-scie...52198.html

EXCERPT: Hundreds of top scientists warned on Tuesday against Republican presidential nominee Donald Trump's vow to pull the United States out of the Paris climate-warming accord if elected in November. The 375 members of the U.S. National Academy of Sciences, including 30 Nobel Prize winners, said in an open letter that a U.S. abandonment of the agreement would make it far harder to develop global strategies to lessen the impact of global warming...



WMO rules on longest distance and longest duration lightning flashes
https://www.sciencedaily.com/releases/20...165610.htm

RELEASE: A World Meteorological Organization committee of experts has established two new world records for the longest reported distance and the longest reported duration for a single lightning flash in, respectively, Oklahoma (United States of America) and southern France.

The lightning flash over Oklahoma in 2007 covered a horizontal distance of 321 kilometers (199.5 miles). The lightning event over southern France in 2012 lasted continuously for 7.74 seconds, the WMO evaluation committee found. "Lightning is a major weather hazard that claims many lives each year," said WMO Secretary-General Petteri Taalas. "Improvements in detecting and monitoring these extreme events will help us improve public safety."

It is the first time that lightning has been included in the official WMO Archive of Weather and Climate Extremes, which is maintained by the WMO Commission for Climatology and documents details of records for heat, cold, wind speed, rainfall and other events. Full details of the assessment are given in an Early Online Release posting of the article published on 15 September. The article will be formally published in an upcoming issue of the Bulletin of the American Meteorological Society. Dramatic improvements in lightning remote sensing techniques have allowed the detection of previous unobserved extremes in lightning occurrence and so enabled the WMO committee to conduct a critical evaluation.

The WMO evaluation committee judged that the world's longest detected distance for a single lightning flash occurred over a horizontal distance of 321 km (199.5 miles) using a maximum great circle distance between individual detected VHF lightning sources. The event occurred on 20 June 2007 across the state of Oklahoma. The committee also accepted the world's longest detected duration for a single lightning flash as a single event that lasted continuously for 7.74 seconds on 30 August 2012 over Provence-Alpes-Côte d'Azur, France.

"This investigation highlights the fact that, because of continued improvements in meteorology and climatology technology and analysis, climate experts can now monitor and detect weather events such as specific lightning flashes in much greater detail than ever before," said Randall Cerveny, chief Rapporteur of Climate and Weather Extremes for WMO. "The end result reinforces critical safety information regarding lightning, specifically that lightning flashes can travel huge distances from their parent thunderstorms. Our experts' best advice: when thunder roars, go indoors," he said.

The investigating committee was composed of lightning and climate experts from the United States, France, Australia, Spain, China, Morocco, Argentina, and the United Kingdom. As part of their evaluation, the committee also unanimously agreed that the existing formal definition of "lightning discharge" should be amended to a "series of electrical processes taking place continuously" rather the previously specified time interval of one second. This is because technology and analysis have improved to the point that lightning experts now can detect and monitor individual lightning flashes with lifetimes much longer than a single second.

Validation of these new world lightning extremes (a) demonstrates the recent and on-going dramatic augmentations and improvements to regional lightning detection and measurement networks, (b) provides reinforcement to lightning safety concerns that lightning can travel large distances and so lightning dangers can exist even long distances from the parent thunderstorm, and © for lightning engineering concerns.

A full list of weather and climate extremes is available at the WMO Archive of Weather and Climate Extremes (http://wmo.asu.edu/). This includes the world's highest and lowest temperatures, rainfall, heaviest hailstone, longest dry period, maximum gust of wind, as well as hemispheric weather and climate extremes



Atmospheric rivers come into focus with high-res climate model: Pineapple Express could linger, become more intense
https://www.sciencedaily.com/releases/20...162212.htm

RELEASE: A high-resolution climate model based at the National Center for Atmospheric Research (NCAR) is able to accurately capture the ribbons of moist air that sometimes escape the sodden tropics and flow toward the drier mid-latitudes, allowing scientists to investigate how "atmospheric rivers" may change as the climate warms.

These rivers in the sky can unleash drenching rains when they crash onto land. Because these downpours can alleviate droughts and also cause damaging floods, scientists are keenly interested in how their frequency, intensity, or path may be altered with climate change. But standard-resolution climate models have had difficulty realistically simulating atmospheric rivers and their impacts.

In a pair of studies published this summer in the journal Geophysical Research Letters, NCAR scientists Christine Shields and Jeffrey Kiehl tested to see if a high-resolution climate model could do a better job. They found that a version of the NCAR-based Community Climate System Model 4.0 (CCSM4) with a resolution twice as high as normal does a good job of capturing the frequency with which atmospheric rivers made landfall over the last century as well as their locations and associated storms.

Looking forward, the model projects that storms on the U.S. West Coast associated with a type of atmospheric river called the Pineapple Express, which sweeps moisture in from Hawaii, could linger and become more intense if greenhouse gas emissions are not mitigated. The studies also find that future changes to atmospheric rivers in general -- including a possible increase in the number that make landfall in Southern California -- will likely be dependent on how jet streams change in a warming world.

"Atmospheric rivers play an extremely important role in Earth's water cycle. At any latitude, they account for only 10 percent of the air but they transport as much as 90 percent of the water that is moving from the tropics toward the poles," Kiehl said. "Understanding atmospheric rivers is critical to understanding how the entire climate system works."

The how and why of future changes

Atmospheric rivers were first discovered in the 1990s, and much of the early research was focused at understanding their detailed structure and the dynamics of how they form. "We've gotten to a point in the science where we're able to track atmospheric rivers and detect them fairly well, and we can make some general statements about duration, intensity, and the precipitation associated with them," Shields said. "So the next step is really trying to understand how they might change in the future and, then, why they are changing."

Shields and Kiehl suspected that the high-resolution version of the CCSM4 would be useful for answering those questions for a couple of reasons. Because the model has a resolution of about 50 kilometers (31 miles), it does a better job of capturing narrower phenomena, like the rivers. It also represents the complex terrain on the land surface that can trigger the atmospheric rivers to release rain or snow. As the rivers plow into the mountains of California, for example, they're forced higher into the atmosphere, where the moisture condenses and falls to the ground.

As they'd hoped, the model did do a better job than a standard-resolution climate model at representing both the atmospheric rivers and their interactions with terrain. This allowed them to run the model forward to get a look at what rivers might do in the future if human-caused climate change continues unabated. What they found is that how -- and why -- atmospheric rivers change depends on the area of the world. "Changes to atmospheric rivers in the future track with what the jets are doing," Shields said. "And that depends on your region."

For example, the scientists found that the atmospheric rivers that hit California were influenced by changes to the subtropical jet, while atmospheric rivers that hit the United Kingdom were influenced by the polar jet.

While understanding these connections gives scientist important insight into what factors may impact atmospheric rivers in the future, it's still a challenge for scientists to project how atmospheric rivers may actually change. That's because climate models tend to disagree about how jets will shift regionally as the climate warms.

In the future, Shields and Kiehl plan to expand their analysis to other parts of the world, including the Iberian Peninsula. "The climate change picture and what's going to happen to these atmospheric rivers really matter," Shields said. "They are a critical component of the hydrology in many places in the world."
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#2
Magical Realist Offline
I posted that article about the 300 scientists on my Facebook page, and to my surprise got a comment from my sister saying they are saying that just to get funding. She evidently circulates rightwing denialist crap with other conservative posters. Or else get's all her information from Fox News. I said no, they actually do believe climate change is occurring and is manmade, and posted a link to the NASA website on it. She asks: "But will it really happen?" to which I said yes, if we keep going on at the present rate. I have never understood how anyone can OPPOSE reducing carbon emissions. Even if global warming wont happen until a thousand years, isn't it good for us to start slowing the trend? Ofcourse it is. How can anyone be FOR polluting the atmosphere? Easy I guess when you're the useful idiot of unfettered corporate greed and environmental destruction.
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#3
C C Offline
(Sep 25, 2016 08:04 PM)Magical Realist Wrote: I have never understood how anyone can OPPOSE reducing carbon emissions. Even if global warming wont happen until a thousand years, isn't it good for us to start slowing the trend? Of course it is. How can anyone be FOR polluting the atmosphere? Easy I guess when you're the useful idiot of unfettered corporate greed and environmental destruction.


It also introduces new "green technology" industries to replace whatever turf the old ones are fearful of losing. Ironically, in the future an eye will probably have to be kept on them, too, regarding matters which we might not have originally anticipated.
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