China's formal climate target shows that the world's largest greenhouse emitter is determined to green its economy on an unprecedented scale - and that it can bring the rest of the world along for the ride.
Greenhouse emissions from the aviation industry are still largely unregulated. The prospect of regulations for US flights sounds like progress, but it won't happen without an elusive international consensus.
The Grattan Institute has reported that the costs of solar panels have outweighed the benefits by almost A$10 billion in Australia. But the real benefits of cutting greenhouse emissions are much larger.
Nuclear power isn't 'zero-emission', as many proponents claim. Factor in uranium mining, power plant construction, and other factors and it has similar emissions to wind power. But that's still lower than fossil fuels.
Federal environment minister Greg Hunt has hailed the first round of Emissions Reduction Fund auctions as a "stunning result". But extrapolating the numbers puts Australia behind on its carbon targets.
The Climate Change Authority has recommended Australia cut greenhouse gas emissions 30% below 2000 levels by 2025. While sensible, the government is unlikely to accept, and the target misses bigger opportunities to cut emissions.
The Guardian's divestment campaign is targeting charitable research trusts. John Quiggin says they have a moral duty to divest fossil fuels, regardless of the temptation to research technological climate fixes.
We have hit a new milestone in carbon dioxide levels: the average for February topped 400ppm. It's the first time this has happened in the northern winter, when levels are typically lower than in summer.