Sunday, 15 July 2012

Climate stuff from the week 9-15/7/12

New Scientist editorial: As Freak Weather Becomes The Norm, We Need To Adapt
'Climate change boosts odds of extreme weather'

If 2012 seems incredibly hot and dry to you, part of the impact might have been contributed by 2011 being oddly cold and wet.
'Back-to-back La Ninas cooled globe and influenced extreme weather in 2011'
"Four independent datasets show 2011 among the 15 warmest since records began in the late 19th century, with annually-averaged temperatures above the 1981–2010 average, but coolest on record since 2008"
"Carbon dioxide steadily increased in 2011 and the yearly global average exceeded 390 parts per million (ppm) for the first time since instrumental records began. This represents an increase of 2.10 ppm compared with the previous year. There is no evidence that natural emissions of methane in the Arctic have increased significantly during the last decade."
"Arctic sea ice extent was below average for all of 2011 and has been since June 2001, a span of 127 consecutive months through December 2011."
"temperatures in the tropical stratosphere were higher than average while temperatures in the polar stratosphere were lower than average during the early 2011 winter months. This led to the lowest ozone concentrations in the lower Arctic stratosphere since records began in 1979 with more than 80 percent of the ozone between 11 and 12 miles altitude destroyed by late March, increasing UV radiation levels at the surface."
"Even with La NiƱa conditions occurring during most of the year, the 2011 global sea surface temperature was among the 12 highest years on record."
"oceans were saltier than average in areas of high evaporation, including the western and central tropical Pacific, and fresher than average in areas of high precipitation, including the eastern tropical South Pacific, suggesting that precipitation is increasing in already rainy areas and evaporation is intensifying in drier locations."

Tough shit, climate change denial agnotists - the millennia-long pattern in Europe was one of a 0.3 degrees per millennium downward trend (cooling), which only exacerbates the contribution of fossil fuel pollution to get the current, decadal trend (warming).
"Climate change denialists, who have never accepted that we are in unusually warm times, will say "told you so". They may also claim that scientists are trying to have it both ways - whatever past temperatures were, they are still evidence of global warming today.
Yet once again, they would be misrepresenting the evidence. The new finding confirms the primacy of human-made carbon dioxide emissions in the warming of the past century. A long-term downward trend in temperature makes it even less likely that recent warming could be due to normal variability."

'Climate change may lead to fewer but more violent thunderstorms'
"This could have negative consequences in the form of flash floods, wild fires, or damage to power lines and other infrastructure"

'Further proof that rising temperatures lead to more algal blooms'
"Researchers from Denmark, Germany, the Netherlands, Norway and Sweden have shown that for the Baltic ecosystem, further global warming could lead to the development of more blue-green algal blooms amid the onset of lower oxygen conditions."

And also the net carbon emissions of forest soils. Although increased forest biomass overall would easily outweigh it, a trend of increasing temperatures shifts the carbon equilibrium toward the atmospheric store.

'Study sheds light on vulnerability of polar ice sheets to modestly warmer climate'
During the last inter-glacial period, ~125000 years ago, sea levels were 6-10 metres above current levels. but sea level rise is not uniform, because the tectonic plates rise and sink according to how heavy they are, meaning the loss of ice sheets on Greenland and Antarctica, for example, will cause them to rise, and sea levels to rise less around them, and more elsewhere.

'Antarctica faces major threats in the 21st century'
"Antarctica faces growing threats from global warming, loss of sea ice and landed ice, increased tourism, over-fishing in the region, pollution and invasive species creeping into the area.
One of the longer-term concerns that may present the greatest threat overall is the potential for oil, gas and mineral exploitation on the continent and in the surrounding ocean"

But, negative feedback effect might come into play, mitigating the changes there:
'Snow could offset global warming in Antarctica'
Fallen snowflakes start small, and this is when they scatter light best, and therefore have the highest albedo (they reflect most energy away).
As they lie, they link up with others, becoming bigger, so their albedo falls, and they reflect less energy.
But warming temperatures, as long as they do bring more snow overall, as predicted, will overlay the growing flakes on the ground, and maintain the high albedo of the Antarctic surface, reflecting energy back into space.
"in a climate scenario where the temperature of Antarctica rises by 3°C, heavier snowfall would increase the albedo by 0.4%. This would offset the 0.3% fall in albedo caused by the rising temperatures (positive feedback loop). Thus, despite significant warming in Antarctica, albedo will vary only very slightly over a large part of the continent."

Periods of rapid sea-level rise, 14600 and 8200 years ago, have been found to be caused by the topography of North America. Ice and snow grows thicker over mountains, where clouds deposit more precipitant, and less thick in the valleys between.
During melting periods, the valley snow melts, accelerated by the warming of high mountain snow and ice, which has a compound effect at warming the lowland snow and ice (Warmth from the sun, and from the uphill streams). The consequence of this is an accelerated melt of snow and ice in the valleys, leaving just snow caps behind, and causing a quicker rise in sea levels.

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