liveforphysics wrote:The cows in India alone are a larger greenhouse gas contributer than all of the gas burning transportation in the USA.
Besides, Like I said recently in another GW thread... all the carbon emitted by a cow was recently removed from the atmosphere by whatever plants the cow was eating. Net bovine atmospheric carbon impact = zero.
This is true. Plants absorb carbon from CO2 residing in the air, expelling O2 as a waste product. However, CO2 is emitted as a waste product by most carbon lifeforms who breath in O2, so it seems there was a historical balance. I kind of wonder how much the explosion of the human population, relative to all other species including plants, has unbalanced the historical cycle? The explosion in the human population has been made possible by amplifying food yields with modern technology and by advancing medical technology.
Here's a source that claims human breath emits about 8% of world-wide carbon emissions.http://www.thenewamerican.com/tech-mainmenu-30/environment/1022
The reason why I question the relationship between the human population and CO2 levels is how eerily similar the CO2 and human population curves are. Even back in 1900 when practically very little cars existed, this relationship still existed.
Carbon Dioxide history (Top graphic, carbon; Right side, 1500s to Now)http://nordpil.com/static/images/carbon_dioxide_and_temperature_historic_trends_full.png
You'll notice that the carbon started growing exponentially shortly after the 1800s.
You'll notice that the human population started growing significantly around the 1700-1800's which is an odd amount of timing.
So, in essence, I think the main cause behind the increase in carbon dioxide over the past two centuries is due to disproportionate human population growth due to advancing food and medical technologies. The industrial revolution and other carbon-based devices (Like cars) afterwards had a way of amplifying the carbon contribution of each person (It might have multiplied it upto 12 times, as the 8% human breath statistic might imply, but I think it's probably close to 4-8x. Whatever the case, it's clear the carbon contribution per person hasn't grown in a similarly exponential way as much as human population itself has.), but the root of the exponential growth of CO2 emission is human population.