It looks like global carbon emissions hit a peak

IT SEEMS like every day we read a new story with dire news about climate change. Specialists now warn that it will be impossible to hold global warming below 2 degrees Celsius, even with the carbon-emissions limits required by the recent Paris round of climate talks. Some environmentalists warn darkly that we must choose between saving the planet or capitalism. But I have some very good news to report. In 2015, global carbon emissions actually fell.

This isn't an occasion for complacency. The fall might be a temporary blip. Even if it's not, emissions represent the amount of additional carbon that is added to the atmosphere every year - that carbon builds up, so to really halt climate change we will need to decrease emissions drastically, not just halt their growth. But I feel that some climate writers are being too quick to dismiss the decline in emissions. Brad Plumer, one of the best in the business, writes that we should regard the drop as a temporary pause rather than a true peak. He notes that much of the emissions pause came from slowing economic growth in China, which reduced coal use. Since China is now the planet's biggest carbon emitter by far, that made a huge difference. But China's growth will probably rebound, and many other developing countries such as India and Indonesia are waiting to take up the baton of rapid industrialisation. When they do, they probably will fuel their development the same way all other countries have - by burning coal. So we're not out of the woods yet. But there are reasons to think that Mr Plumer is being too pessimistic. There are three major factors that will conspire to hold down carbon emissions in the decades ahead. One is technological, one is economic and one is political.

The technological force is, of course, the rapid progress in solar energy and battery storage technologies. Both appear to be decreasing in cost along smooth exponential paths. This suggests that there's some kind of self-replicating process going on. In the case of solar and batteries, that process is probably a learning curve - making more solar panels and batteries helps manufacturers discover how to make them ever more efficiently. That process has already made solar a cost-effective option in many areas, even without government subsidies. And if current trends continue, it will be cheaper than building new fossil-fuel plants in most regions of the world. Batteries, meanwhile, will help solar replace fossil fuels at night as well as when the sun isn't shining. They will eventually also allow electric cars to replace petrol-burning ones, further cutting into carbon emissions.