I do not know about the global warming part, but the ant-capitalist part was on the money. In WALL-E, humans have left the earth, and have been floating around in space aboard some kind of self-sustaining craft for 700 years, becoming a homogeneous drone society. Humans grow fat and, apparently, stupid. They have no incentive or initiative to do anything beyond their own existence on board their nanny spacecraft.
From the article WALL-E: Economic Ignorance and the War on Modernity at the Ludwig von Mises Institute:
The startling aspect of life aboard the Axiom [the spacecraft] is its total homogeneity. Everyone is morbidly obese; everyone drinks fatty meal-replacement shakes; everyone rides around in automated carts instead of walking; no one engages in direct personal communication; no one exercises; everyone follows the BNL [Buy'n Large, supposedly a Wal-Mart/Bush conglomeration] corporation's fashion advice (when the announcements tell the people that "blue is the new red," all Axiom inhabitants switch their suit color from red to blue at the press of a button). Not only does this homogeneity mark one instant in time; it has been present all throughout the Axiom's seven centuries of travel through space. During that time, there has been no technological progress, no cultural innovation, and no noncosmetic changes in the aesthetic, philosophical, and political arrangements aboard the ship. Imagine in 2008 if nothing had changed in human affairs since the year 1308.
The humans in WALL-E are not portrayed as evil; they are polite and well intentioned, but ignorant and torpid. Strangely enough, the ship has an extensive information database about life and conditions on Earth, and nobody bothered to examine this easily accessible information for seven centuries, until the Captain suddenly has a burst of interest. Are we to assume that curiosity and elementary initiative are such rarities that they are exercised only once in 700 years?
WALL-E is egregiously wrong in assuming that technological conveniences such as easily accessible food, transportation, entertainment, and communication render all people lazy, indulgent, and devoid of initiative.
The humans decide (!) to return to the now-sparkling-clean earth to begin again as an agrarian society. No, really!
The great thing about the Pixar catalog has been its careful presentation of traditional values, such as family and friendship, in an entertaining story. Unfortunately, WALL-E appears to miss that mark by a wide margin.