[The] world [is] warming more quickly than before. First, the rate of warming we’ve measured over the world’s land and oceans over the past 15 years has been 40 percent higher than the rate since the 1970s, with the past nine years being the nine warmest years on record. Second, there has been acceleration over the past few decades in the total heat content of Earth’s oceans, where over 90 percent of the energy trapped by greenhouse gases in the atmosphere is accumulating. Third, satellite measurements of Earth’s energy imbalance — the difference between energy entering the atmosphere from the sun and the amount of heat leaving — show a strong increase in the amount of heat trapped over the past two decades.
It’s now clear that we can control how warm the planet gets over the coming decades. Climate models have consistently found that once we get emissions down to net zero, the world will largely stop warming; there is no warming that is inevitable or in the pipeline after that point. Of course, the world will not cool back down for many centuries, unless world powers join in major efforts to remove more carbon dioxide from the atmosphere than we add. But that is the brutal math of climate change and the reason we need to speed up efforts to reduce emissions significantly.
On that front, there is some reason for cautious hope. The world is on the brink of a clean energy transition. The International Energy Agency recently estimated that a whopping $1.8 trillion will be invested in clean energy technologies like renewables, electric cars and heat pumps in 2023, up from roughly $300 billion a decade ago. Prices of solar, wind and batteries have plummeted over the past 15 years, and for much of the world, solar power is now the cheapest form of electricity. If we reduce emissions quickly, we can switch from a world in which warming is accelerating to one in which it’s slowing. Eventually, we can stop it entirely.