NOx emissions also causes global cooling through the formation of OH groups that destroy methane molecules, countering the effect of greenhouse gases. The effect can be significant. For instance, according to the OECD "the large NOx emissions from ship traffic lead to significant increases in hydroxyl (OH), which is the major oxidant in the lower atmosphere. Since reaction with OH is a major way of removing methane from the atmosphere, ship emissions decrease methane concentrations. (Reductions in methane lifetimes due to shipping-based NOx emissions vary between 1.5% and 5% in different calculations)." "In summary, most studies so far indicate that ship emissions actually lead to a net global cooling. This net global cooling effect is not being experienced in other transport sectors. However, it should be stressed that the uncertainties with this conclusion are large, in particular for indirect effects, and global temperature is only a first measure of the extent of climate change in any event."[13]
Got the above quote off wikipedia on NOx gasses. My thought on all of this is that our little TDI's get too good fuel milage and the tax our EPA backed government receives from each gallon of spent fuel is being missed Did I see some where earlier that there are only 500,000 of these vehicals in the USA and the EPA noticed us ? Not saying they shouldn't do their job... And I'm glad they do... I've been to West Africa and Haiti, and their polution is way beyond I mean WAY beyond ours here. But I have a question for those in the know. If a gallon of fuel is burned it can only produce so much NOx and no more right ? So if I burn one gallon and travel 50 miles and you burn two gallons to go 50 miles who put more NOx into the atmosphere ? Of course maybe you helped cool the earth better then I did ? Some how theres a money trail here...