Environmentalism and Immigration

A comprehensive immigration policy for the United States is conspicuous by its absence. Actually, the current immigration policies or lack thereof, has come under attack from many sides over the recent years.
As you all know, more than 3/4 of the annual net growth in the US population is attributed to immigration. A rough back of the envelope kind of a calculation would suggest that immigration is responsible for about 2 million out of the 2.75 million annual growth. That is the equivalent of a major new city every year!!!. Once that figure of 2 million is combined with the typical level of consumption that is associated with life in the US it becomes clear that the ecological impact of such an increase in the US population has global ramifications.
Based on the above some have advocated the adoption of strict immigration limits on purely ecological grounds. What is your personal point of view regarding such efforts? Can the world afford an additional 2-2.5 million US style consumers every year?