I found a very interesting article about Polar Stratospheric Clouds and their impact on Polar Temperatures. It is about study regarding equable climates athmosphere. (Please ignore it, if it is already known
- I´m not an expert in that, and yes, it is a kind of OT)
https://www.seas.harvard.edu/climate/eli/research/equable/psc.htmlThe study of Peters and Sloan compared two scenarios (ECOCONTROL+PCCLOUD):
CO2 both at 560 ppm
- ECOCONTROL with methane rates at 0,7 ppm
- PCCLOUD with 10 ppm (what is the actual concentration at northern hemisphere?-sure it is higher than the global average of 1,7 ppm (?) and we do have quite more of nice gases...
Methane is taken because of its oxidization to form water vapor.
PCCLOUD led to a i
ncrease of winter temperatures of 25 °C in Northern Hemisphere (average? or North Pole ? - isn´t that clear)
Quote:
Peters and Sloan in 2000 presented another paper that investigated the impact of large amounts of greenhouse gases combined with PSCs. In this study, they performed two model experiments, just as Sloan and Pollard did. Both scenarios had carbon dioxide levels set at 560 ppm, which is 2 times the preindustrial level. The first situation, ECONTROL, had an atmospheric methane concentration of 0.700 ppm, the preindustrial amount, and did not have any PSCs. In the second case, named PCLOUD, methane levels were 10 ppm, which is 14 times the amount of preindustrial levels, and PSCs were prescribed as in the Sloan and Pollard study. The results showed a globally averaged mean annual temperature (MAT) increase of 3.4°C, and MATs in PCLOUD were warmer than ECONTROL by 12°C in the Northern Hemisphere and by 9°C in the Southern Hemisphere. However, in the Tropics, the MATs of PCLOUD was only warmer than that of ECONTROL by 2°C. Additionally, the cold-month mean temperature increased by 25°C in the Northern Hemisphere and by 18°C in the Southern Hemisphere. As a result, the study shows that the combined effects of PSCs and higher levels of greenhouse gases could raise polar temperatures while not affecting the Tropics substantially. Specifically, it reveals the impact of more methane and more PSCs on the climate and demonstrates that these two factors could have caused equable climates
One question they rise is how the methane could be there over the entire Eocene of 10 million years:
Quote:
"Although the study produced results supporting the idea that higher methane concentrations and more PSCs could have caused equable climates, there are two major problems with this idea. First of all, in the modern atmosphere, methane has a lifetime of roughly 7 years, while the Eocene polar warmth existed for about 10 million years (Kirk-Davidoff, Schrag, and Anderson, 2002). This fact makes it seem unlikely that methane could have persisted long enough to have caused an equable climate. Even if methane's lifetime increased during the Eocene, it is doubtful that methane levels were sustained at concentrations suggested in the Peters and Sloan study throughout the duration of the Eocene."
But what if there was a BIG circle of methane, we now miss because of the freezed poles? - Methane is stored in the hydrates, we now loose... and there is already found methane based live on the former dead seafloor. Methane is built if organic material decays under anaerobic conditions. Warm water in a world full of flooded wetland would be not a problem if we look at the current tendencies...
I also ask myself if the building up of methane hydrates couldn´t be a result of binacles, underwater icicles, that grow under sea ice during a normal -cold and silent- polar winter. They could have been a engine for cold, salty water reaching deeper waters. Now, if the weather is getting stormy and warmer they will also disappear. (And that could have effects on thermoholine circulation a well...)
http://www.mnn.com/earth-matters/wilderness-resources/stories/brinicles-what-icicles-deathJust some thought of a lurker watching a lot of material at the moment.