"The findings of this study indicate that future levels of immigration will have a significant impact on efforts to reduce global CO2 emissions. Immigration to the United States significantly increases world-wide CO2 emissions because it transfers population from lower-polluting parts of the world to the United States, which is a higher-polluting country. On average immigrants increase their emissions four-fold by coming to America."
So, just by coming here, immigrants fart four times as much gas into the atmosphere? We must be feedin' 'em too well.
More at:
http://www.cis.org/GreenhouseGasEmissions