The Chinese government announced on Monday that it would prohibit its airlines from paying a controversial “carbon tax” on flights to and from Europe imposed by the European Union, putting the continental regime in a tough bind as it seeks assistance from Beijing to tackle the region’s spiraling debt crisis. Unspecified retaliatory measures will be taken if the EU persists, according to Chinese officials, who say the taxes violate international treaties.

RioThis June's United Nations Conference on Sustainable Development (UN CSD) in Rio de Janeiro will largely sidestep discussions of climate-change theories as leaders perceive the subject to be too controversial, according to summit insiders seeking ambitious and wide-ranging agreements on the world’s future. What is being touted as the biggest political gathering of the year will instead focus on framing UN “green” goals in terms of economic prosperity and environmental necessity.

Ener1 Inc., which owns an electric car battery-maker that reaped a $118-million grant from the Obama administration, filed for bankruptcy protection Thursday. The New York-based company claimed defaults on its bond debt were spurred by rising competition from China and other countries. Ener1 listed $73.9 million in assets and $90.5 million in debt as of December 31 in Chapter 11 papers filed in U.S. Bankruptcy Court.

As environmental groups hail President Obama’s rejection of the Keystone XL pipeline, billionaire and prominent Democratic donor Warren Buffett (left) is set to reap a handsome reward from the decision. Buffett’s Burlington Northern Santa Fe LLC is a notable beneficiary — among other U.S. and Canadian railroads — of the move, as it is one of the railroads that will transport the Canadian oil if the pipeline isn’t approved.

House Republicans unleashed a barrage of criticism Wednesday during a House hearing on Chevrolet’s Volt electric car, after the head of the federal auto safety agency insisted that the vehicles are not dangerous. "The Chevrolet Volt is safe to drive and it has been safe to drive the whole time," David Strickland, head of the National Highway Traffic Safety Administration (NHTSA), told a congressional panel. "Not only would I drive it, I would [take] my wife, my mother and my baby sister along for the ride."