The evidence, the expert advice, common sense — they all point to a single unavoidable conclusion: Humankind has dragged its feet for so long on the looming crisis of climate change that it is no longer looming but is upon us, and will be impossible to undo. ¶ It would be foolish, of course, to rule out nascent or not-as-yet conceived technological advances that could claw back some of the carbon and other greenhouse gases we’ve already emitted. But it would be equally foolhardy to count on them. What is required, at a minimum, is a radical change, as quickly as possible, in the way the world produces and consumes energy. The goal is to eliminate most future emissions, especially of carbon, and to “capture” the carbon that is emitted so that it does not enter the atmosphere.

Of course that alone won’t solve all our planet’s climate problems. We will have to deal with the trouble we have already set in motion and which can no longer be averted. That means, for example, crafting approaches to handle the flow of migrants as regions of the world become uninhabitable, protecting people in low-lying lands from rising oceans, and preparing for the excessive heat, longer droughts, more ferocious hurricanes and other extreme weather events that will, among other things, threaten the global food supply.

But to keep the bad outcomes to a minimum, we must do what we can to not make the situation worse. That means continuing the fight to reduce emissions. A 2018 estimate put the annual cost to mitigate climate change if the world does nothing to curtail emissions at $500 billion per year by 2090 — and that’s just for the U.S. Globally, one estimate says, a temperature rise of 4 degrees Celsius would cost $23 trillion per year. We can’t let it get to that point.

The best way to keep human-generated carbon out of the atmosphere, where it and other greenhouse gases trap heat and drive up temperatures, is to not create it in the first place. The world has been making progress at this, but not nearly enough. In the United States, for instance, reliance on coal continues to decline, but in many cases, power plants that used to burn coal are now burning natural gas. That’s an improvement, yes, but it’s insufficient, since burning natural gas also releases carbon. Dishearteningly, total global emissions have actually increased substantially in the last two decades.

Here’s one heartening fact: In April, the amount of energy the U.S. is capable of producing from renewable sources for the first time surpassed what it can produce from coal, and the gap is expected to widen as more power comes from wind, solar and other renewables and more fossil-fuel plants are shut down.

But globally the view is more dour. China has worked to ratchet back on burning coal at home, but it has been building coal-fired power plants in other countries, hoping to extend its political and economic influence at the expense of the environment. That needs to stop.

By one estimate, about half of Africa does not have access to electricity. There and elsewhere, new power generation should not involve coal, but should be achieved with renewable sources. The developed nations must help build power grids in developing nations.

There have been international calls since the 1997 Kyoto Protocol for governments to end domestic subsidies for fossil fuels, particularly oil. But they haven’t. In the U.S., federal and state governments provide, in one conservative estimate, $20.5 billion a year in such subsidies — including industry-specific tax deductions and exemptions. About 80% of that money goes to the oil and gas industry and nearly all the rest to the coal industry. There are also more difficult to count consumption subsidies, including those that help low-income families pay for the fossil fuels that heat their homes. If poorer people need assistance, government should find ways to provide it that don’t incentivize the use of carbon.

What will our world look like in 15 years if we begin to do what we have to do? Charging stations for electric vehicles as plentiful as gas stations are now. A significant drop in gas-powered vehicles through phased-out production, and government-funded buyback programs. Millions of people working to create new power systems; the world needs cheaper and more efficient solar panels, bigger and more efficient energy storage systems, more utility-scale renewable production facilities and more efficient hydro- and geothermal technologies. Oil companies no longer wielding such disproportionate influence on policy. Perhaps they will have transitioned away from fossil fuels — or been superseded by new energy providers.

Sacrifice will be a part of this too. Doing the right thing will require shifts in employment, changes in consumer habits (cutting way back on meat consumption, for instance, reduces global carbon emissions). We will drive less, ride more public transit, use less air conditioning. Costs will undoubtedly rise for goods we’ve taken for granted.

Is this level of change unachievable? Perhaps. For the moment, at least, the politics are against us. President Trump and his supporters have moved the U.S. backward rather than forward. The recalcitrant oil and gas industry remains a powerful force too.

Yet the world has transitioned before. We thrived on whale oil until we decimated the whale population and discovered how to make kerosene from petroleum, and how to commercialize natural gas. This time the transition will have to happen a lot faster and will require more than just market forces. We’ll need more government intervention through even stronger pacts than the 2015 Paris agreement under which the world’s nations agreed to limit the global temperature rise.

It’s clear now that those promises will not be sufficient. But they provide a model upon which we must build as we steer ourselves away from, in essence, self-annihilation.