Not a big deal, imho. There are far bigger threats to the environment than all cars combined - just look at all those freight ships burning bunker fuel, coal power plants emitting more radioactivity than a decades old nuclear plant...
How can you state that with certainty?
edit: Reason for this is that burning sulphur in fuel produces sulphur dioxide, which when combined with rain or natural humidity, makes acid rain.
So, yeah. I don't think the cargo ships are villains or anything, but one of them is worth 50 million cars, for that specific type of emission. (cars would be higher, but they're regulated.). Generally it's turning around, different countries are requiring low sulphur fuel, in spite of the cost. The us was January, i think.
It's more like double the cost. Your point stands, though.
That may be true for local waters (iirc 12 nautical miles from the land). International waters, not so much.
Cows eat grass, not fossil fuels. Measuring the impact of agriculture vs. transportation should take the source of the pollutants into account.
Excluding the farm equipment and fossil-fuel-based fertilizer, cow burps form a natural closed loop. Meaning, grow corn or grass and it takes in greenhouse gasses from the soil and the air. Feed it to a cow and it releases those same greenhouse gasses.
Cows and plants by themselves are not actually contributing greenhouse gasses into the atmosphere in a manner that contributes to global warming. Meaning, if you're worried about cow burps or humans breathing... stop worrying about it. And if you're pointing out that animals emit greenhouse gasses... cool, but that is irrelevant to a rational discussion of emissions that lead to climate change.
For agriculture, the system becomes imbalanced when you add in the emissions of the industrial farm equipment and the shipping infrastructure to getting food from the farm to the the table. But that imbalance is what we're trying to address when we talk about transitioning to more fuel efficient vehicles or more sustainable farming practices (like not using fossil fuels in fertilizer).
So, mentioning agriculture as a polluter is typically a red herring. At first blush it seems reasonable because there are a lot of farm animals that emit greenhouse gasses. However, including agriculture in a discussion of emissions is usually disingenuous or misinformed.
> Excluding the farm equipment and fossil-fuel-based fertilizer, cow burps form a natural closed loop. Meaning, grow corn or grass and it takes in greenhouse gasses from the soil and the air. Feed it to a cow and it releases those same greenhouse gasses.
Plants take in CO2. Cows fart out methane. Methane is a much more potent greenhouse gas than CO2.
http://www3.epa.gov/climatechange/ghgemissions/gases/ch4.htm...
> Pound for pound, the comparative impact of CH4 on climate change is 25 times greater than CO2 over a 100-year period.
> Methane breaks down in the atmosphere to form carbon dioxide, ozone, and water, all of which absorb heat.
Almost every current article about cow burps cites a 2006 U.N. study saying that livestock accounted for 18% of methane pollution. That study was later called into question as being slightly exaggerated because it included pollution from farming infrastructure itself, not just the animals.
http://www.telegraph.co.uk/news/earth/environment/climatecha...
> The meat figure had been reached by adding all greenhouse-gas emissions associated with meat production, including fertiliser production, land clearance, methane emissions and vehicle use on farms, whereas the transport figure had only included the burning of fossil fuels.