A NASA study underscores the fact that greenhouse gases generated by human activity – not changes in solar activity – are the primary force driving global warming, the US space agency said. The researchers’ calculations, published in Atmospheric Chemistry and Physics, show that, despite unusually low solar activity between 2005 and 2010, the earth continued to absorb more energy than it returned to space.

Meanwhile, that study’s leader, James Hansen, and two colleagues say they have gathered data that shows the 2011 Texas heat wave and the deadly Moscow temperatures of 2010 were “a consequence of global warming because their likelihood was negligible prior to the recent rapid global warming”. Their conclusions are based on some 50 years of data, Hansen told InsideClimate News. (See a draft of their findings here.)

The world can no longer afford to ignore the environmental cost of economic growth and must redefine the concept of national wealth, Agence France-Presse cited a UN panel on global sustainability as saying. Continuing on the current path risks “irreversible damage to both ecosystems and human communities”, UN secretary-general Ban Ki-moon said at the release of a UN report seeking to broadly shape the agenda for the Rio+20 environmental conference in June.

Energy efficiency offers one of the best tools for tackling the world’s debt and social crises, according to EU climate commissioner Connie Hedegaard. “We must bring sustainable development from the margins of the economy to the mainstream of the global economic debate,” Reuters quoted Hedegaard as saying.

Shortages of a handful of rare minerals could slow the growth of renewable energy industries and affect countries’ chances of limiting greenhouse-gas emissions, The Guardian reported the global professional services firm PricewaterhouseCoopers (PwC) as telling the World Economic Forum. Because “rare earths”, used in a range of green technologies, are mined almost exclusively in China – which has set strict export quotas – they are becoming harder and more expensive to source.

In a survey of some of the largest clean-energy manufacturers, The Guardian added, 78% told PwC they were already experiencing instability in rare-metals supply, and most said they did not expect shortages to ease for at least five years. The PwC report called the scarcity a “ticking time bomb”.

A US judge ruled that Halliburton is not liable for some pollution claims arising from the 2010 Gulf of Mexico oil spill, Reuters said, setting back the oil giant BP’s effort to hold other companies responsible for part of the US$42 billion clean-up bill. Halliburton provided cementing services for BP’s ruptured Macondo oil well.

In an ongoing legal battle over Texaco’s alleged dumping of toxic oil-drilling wastes in the Ecuadorean jungle from 1964 to about 1992, a US appeals court blocked Chevron from using a New York law to try to bar a group of Ecuadoreans from collecting on a US$18 billion judgement, Bloomberg News reported. Chevron acquired Texaco in 2001.