My best argument against the Keystone XL pipeline goes like this:
Build instead a shorter pipeline through less sensitive habitat from the Dakota Bakkan fields through Omaha and Oklahoma to Gulf refineries. This reduces the hazards of proposed oil and gas rail shipment and terminal operations in the Pacific Northwest; reduces demand for off-shore drilling in the Gulf; fuels reach domestic markets, East and West Coasts and limited world markets. Yes, it's a compromise, one that most safely delivers fuels to domestic markets and doesn't rule out inevitable restrictions on fracking.
Alberta tar sands crude is is basic shipping fuel. Obama's trade policy promotes trade, therefore he supports the Keystone XL. The global economy undermines all lesser economies - national, state, regional and local. Globalization undermines a sustainable level of global trade the same way automobiles undermine fundamental modes of urban/suburban travel - walking, bicycling and mass transit - to the point where even driving fails to serve its own optimal function. Globalization makes every nation vulnerable to any disruption in the distribution of basic goods. In military terms, globalization is a strategy that enables enforced embargo and siege. Conclusion: Today's insensible level of globalization is the final solution to over-population.