Moreover, cleaning up electricity is only part of the battle.
Even though gas-fired heating and cooking can be at least as big a source of greenhouse-gas emissions, renewable heating gets minuscule attention.
Transport policy is erratic, too.
Carmakers may hit their goal of annual sales of 10m electric vehicles in a decade, but battery-powered road haulage, shipping and aviation are dreams.
A much-quoted claim that America could rely on wind, solar and hydro alone for its electricity has recently been witheringly criticised by a group of respected academics.
Most important, a 100% renewables target confuses means with ends.
The priority for the planet is to stop net emissions of greenhouse gases, especially carbon dioxide.
Putting too much emphasis on wind, solar and other renewables may block off better carbon-reduction paths.
After decades of investment, it is wrong to leave nuclear power off the table.
Carbon emissions in Germany actually rose because it chose to phase outnuclear power and so burned more coal.
New technologies, such as “direct air capture” systems designed to separate carbon dioxide from the air, may in time prove vital.
Likewise, greater energy efficiency could reduce emissions by even more than deploying renewables would.
Indians last year consumed twice as much energy from newly installed air conditioners as they produced from new solar farms.
More accurate metering of energy consumption could encourage companies and households to rein in power demand.
It would be better, as the Paris agreement urges, for countries to focus on reductions in emissions rather than to set goals for renewable energy.
Global emissions have stabilised in the past three years, which is encouraging.
But to stand a chance of mitigating global warming, they must start falling sharply and keep doing so for decades.
The world will move in that direction with the help of wind and solar.
It will not get there without big advances on every other front as well.
1.cleaning up 清洁
例句:This room needs cleaning up.
2.nuclear power 核武器
例句:Japan has announced plans for a sharp rise in its nuclear power generation.
3.air conditioner 空调
例句:The air conditioner of my room is not working.
4.block off 阻挡
例句:They had blocked off the fireplaces to stop draughts.