If the downward trend continues — and if anything it seems to be accelerating — we’re just a few years from the point at which electricity from solar panels becomes cheaper than electricity generated by burning coal.
And if we priced coal-fired power right, taking into account the huge health and other costs it imposes, it’s likely that we would already have passed that tipping point.
Recently an observant reader pointed out that methane is 20 times more potent than CO2 when its impact is measured over a century. But in the short term it is a far greater problem. Over the space of two decades it is estimated to be at least 84 times more damaging than carbon dioxide.
2 degrees of warming means 0.24 to 2.14 percent lower GDP growth through 2100. Four degrees means 5 to 20 percent.