Old news.
The master speaks:
The good news is that global dimming seems to be reversing itself, mainly because we’ve been cleaning up the environment. Measurements show that since 1990 or so, more sunlight has been reaching the earth’s surface, with about a 4 percent increase in the last decade. The bad news is that, because dimming threw off the measurements, global warming may have been underestimated and projections of long-term temperature increases may be too low.
FXMastermind:
I mentioned contrails in a different thread, but most people are contrail deniers, so yeah, it won’t matter at all.
Uh, the effects of contrails have been investigated and taken into account, are you talking about the loopy conspiracy theory?
http://www.skepdic.com/chemtrails.html
According to several paranoid conspiracy theorists (PCTs), chemtrails look like contrails but they are intentionally created by unknown people to poison us with unknown chemicals for some unknown reason (Thayer).
One PCT, William Thomas, claims that chemtrails are part of a “massive, covert government operation to delay global warming by increasing the amount of sunlight that is reflected back into space” (Sheaffer). That a government which, until recently, didn’t even acknowledge that global warming is a major concern would have a secret program to delay global warming is curious. Nevertheless, the PCTs believe that there has been a noticeable change in cloud formations over the past decade or two and that this is evidence that something sinister is happening. They may be right, but as one critic of the PCTs notes: if there has been a noticeable change in cloud patterns at high altitudes over the past ten to twenty years, the change may be due to global warming (Wickson).
The effects from contrails are as big as unknown as those from damning rivers. But both are direct and quick acting forcings that change things.
Now that is irrational. If they are big unknowns, how can you summarily declare them to be “quick and direct forcings”? In the case of reservoirs, yes, there is some likelihood that the change in the biosystem may have notable effects on atmospheric chemistry, but how quickly, and does it eventually balance out?
But really, fucking rivers, damn those things to hell.
FXMastermind:
I mentioned contrails in a different thread, but most people are contrail deniers, so yeah, it won’t matter at all.
Are you suggesting they play a role in climate change? I don’t think there are nearly enough of them. Cars are the problem, not airplanes.
The AMOUNT of change, as well as what the extent is, is an unknown. (according to the official story)
No, I am flat out telling you the science says contrails, as well as the invisible moisture and CO2 (which you can’t see) changes the stratospheric atmosphere, and not in some small way. Like the denial over deforestation, land use change and other issues, there is a lot of denial over contrails.
Contrail radiative forcing is difficult to obtain, even if contrail parameters like coverage, ice water content, crystal size etc. are known. A substantial respective uncertainty has been documented in literature.
Sensitivity of the shortwave to longwave ratio in contrail radiative forcing calculations with different radiation schemes - ADS
http://www.nature.com/news/2008/081231/full/news.2008.1335.html
FXMastermind:
No, I am flat out telling you the science says contrails, as well as the invisible moisture and CO2 (which you can’t see) changes the stratospheric atmosphere, and not in some small way. Like the denial over deforestation, land use change and other issues, there is a lot of denial over contrails.
OK, just to nail this down, you’re not saying some contrails are secretly chemtrails , you’re saying that contrails as commonly understood have a larger environmental impact than is commonly acknowledged – correct?
Maybe so. Wiki sez:
Contrails and climate
Contrails, by affecting the Earth’s radiation balance, act as a radiative forcing. Studies have found that contrails trap outgoing longwave radiation emitted by the Earth and atmosphere (positive radiative forcing) at a greater rate than they reflect incoming solar radiation (negative radiative forcing). Global radiative forcing has been calculated from the reanalysis data, climatological models and radiative transfer codes. It is estimated to amount to 0.012 W/m2 for 2005, with an uncertainty range of 0.005 to 0.0026 W/m2, and with a low level of scientific understanding.[4] Therefore, the overall net effect of contrails is positive, i.e. a warming effect.[5] However, the effect varies daily and annually, and overall the magnitude of the forcing is not well known: globally (for 1992 air traffic conditions), values range from 3.5 mW/m2 to 17 mW/m2. Other studies have determined that night flights are mostly responsible for the warming effect: while accounting for only 25% of daily air traffic, they contribute 60 to 80% of contrail radiative forcing. Similarly, winter flights account for only 22% of annual air traffic, but contribute half of the annual mean radiative forcing.[6]
September 11, 2001 climate impact study
The grounding of planes for three days in the United States after September 11, 2001 provided a rare opportunity for scientists to study the effects of contrails on climate forcing. Measurements showed that without contrails, the local diurnal temperature range (difference of day and night temperatures) was about 1 °C (1.8 °F) higher than immediately before;[7] however, it has also been suggested that this was due to unusually clear weather during the period.[8]
Condensation trails have been suspected of causing “regional-scale surface temperature” changes for some time.[9][10] Researcher David J. Travis, an atmospheric scientist at the University of Wisconsin-Whitewater, has published and spoken on the measurable impacts of contrails on climate change in the science journal Nature and at the American Meteorological Society’s 10th Annual conference in Portland, Oregon. The effect of the change in aircraft contrail formation on the three days after the 11th was observed in surface temperature change, measured across over 4,000 reporting stations in the continental United States.[9] Travis’ research documented an “anomalous increase in the average diurnal temperature change”.[9] The diurnal temperature range (DTR) is the difference in the day’s highs and lows at any weather reporting station.[11] Travis observed a 1.8 °C (3.24 °F) departure from the two adjacent three-day periods to the 11th–14th.[9] This increase was the largest recorded in 30 years, more than “2 standard deviations away from the mean DTR”.[9]
The September 2001 air closures are deeply unusual in the modern world, but similar effects have provisionally been identified from Second World War records, when flying was more tightly controlled. A 2011 study of climate records in the vicinity of large groups of airbases found a case where contrails appeared to induce a statistically significant change in local climate, with a temperature variance around 0.8 °C, suggesting that examination of historic weather data could help study these effects.[12]
But, I’m sure not one bit of that is news to anyone on the IPCC.
If I was a nutball going on about chemtrails, there would be no confusion, as those people seem pretty obvious.
Like, duh. In fact, the Allied leaders knew for sure that just flying over Germany leaving contrails would starve the Germans out, since constant contrails would have destroyed their ability to grow food. Of course it was cheaper and faster just to bomb them back to the stone age, so they never used the contrail idea. But they knew good and damn well contrails caused a huge effect, under the contrails.
A 2011 study of climate records in the vicinity of large groups of airbases found a case where contrails appeared to induce a statistically significant change in local climate, with a temperature variance around 0.8 °C, suggesting that examination of historic weather data could help study these effects.[12]
Like, duh. note the uncertainty, as well as weasel words used in almost every story about contrails.
You might think after 65 years of contrails, somebody might actually know what happens.
ralfy
April 9, 2014, 2:46pm
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