By Paul Homewood
More uncritical reporting by the BBC of the latest climate nonsense:
Snowy mountain winters are being "squeezed" by climate change, according to scientists in California.
Researchers who studied the winter snowfall in the mountains there revealed that rising temperatures are reducing the period during which snow is on the ground in the mountains – snow that millions rely on for their fresh water.
They presented their findings at the American Geophysical Union meeting – the world’s largest gathering of Earth and space scientists.
"Our winters are getting sick and we know why," said Prof Amato Evan, from the Scripps Research Institute in San Diego, who carried out the investigation. "It’s climate change; it’s rising temperatures."
Prof Evan studied the annual cycle of snow and melt in the western US from the early 1980s to 2018.
He found that the length of time snow is on the ground there is continually "being squeezed" into a shorter period. And the early arrival of summer, he explained, is a driving force behind sometimes devastating wildfires.
"Particularly in a place like California where we get all of our precipitation during the winter time, that means that our summers are growing longer," he told BBC News. "And really what that means is our fire seasons are growing longer.
"We’ve got less snow, we’ve got a longer fire season, we’ve got infestations [of pests that thrive in warmer temperatures] – these ecological issues; it’s a kind of perfect storm of really bad outcomes, which then result in – in some cases – these massively dramatic fires."
Donal O’Leary from the University of Maryland, who presented his research on what he called the "significant relationship" between snow and wildfire, agreed.
Earlier snowmelt, he said, "is leading to more wildfires, particularly in places like the Sierra Nevada in California".
Mountain snow is also what millions of people rely on for fresh water supplies – in California, particularly, the reservoirs are refilled by annual snowmelt.
Other scientists who have looked at global climate models have seen similar results across much of the Northern Hemisphere. And researchers say this signal from the snowpack is clear evidence that the impacts of climate change are now playing out in the mountains.
https://www.bbc.co.uk/news/science-environment-46547064
Even the headline image is grossly misleading. Comparing one year with another is merely weather, year to year variations, but the BBC have used it to deceive people into thinking that these are permanent, ongoing changes.
As for the body of the report, the first question that has to be raised is why the study only goes back to 1980? After all, that marked the time when the PDO switched to warm phase. We know warm PDOs tend to coincide with higher rainfall for California, much of which of course falls as snow.
If we look at winter precipitation in California back to 1895, we find that there is absolutely no trend at all.
Of course, this is all precipitation, both rain and snow. But it is a strong indication that 1980 is an improper base point.
Taking February snow extent for North America as a whole, the trend is actually upward since records began in 1967.
https://www.ncdc.noaa.gov/snow-and-ice/extent/snow-cover/nam/2
And snow extent for March, although showing a slightly reducing trend does not seem to have changed much since 1980.
https://www.ncdc.noaa.gov/snow-and-ice/extent/snow-cover/nam/3
It is claimed that the NH as a whole shows similar trends, but again the data says otherwise, with seven out of the last ten years having snow extent above the 30-year average.
https://www.ncdc.noaa.gov/snow-and-ice/extent/snow-cover/nhland/2
As for wildfires, they used to be far worse in the US, until fire suppression began after the war:
https://notalotofpeopleknowthat.wordpress.com/2014/06/09/wildfires-were-much-worse-in-past/
The very same fire suppression that has led to the massive fires we now see. This is what the California Department of Forestry and Fire Protection has to say:
Before the twentieth century, many forests within California were generally open and park like due to the thinning effects of recurrent fire. Decades of fire suppression and other forest management have left a legacy of increased fuel loads and ecosystems dense with an understory of shade-tolerant, late-succession plant species. The widespread level of dangerous fuel conditions is a result of highly productive vegetative systems accumulating fuels and/or reductions in fire frequency from fire suppression. In the absence of fire, these plant communities accrue biomass, and alter the arrangement of it in ways that significantly increase fuel availability and expected fire intensity. As such, many ecosystems are conducive to large, severe fires, especially during hot, dry, windy periods in late summer through fall. Additionally, the spatial continuity of fuels has increased with fewer structural breaks to retard fire spread and intensity. The increased accumulations of live and dead fuels may burn longer and more completely, threatening the integrity and sustainability of the ecosystems.
https://notalotofpeopleknowthat.wordpress.com/2013/12/16/wildfires-not-caused-by-climate-change/
You would think that a science correspondent would have the gumption to check some of these facts out for herself. But this is the BBC.
via NOT A LOT OF PEOPLE KNOW THAT
December 13, 2018 at 09:33AM
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