The world has the means to achieve the goal set out in the Paris climate accord—but the odds of doing so are long. Governments, organizations, and individuals should still double down on efforts to limit global warming, but at the same time, we all must plan for a hotter planet.

According to the consensus among climatologists, the upward trajectory of greenhouse gas emissions needs to be reversed by 2025 to hit the Paris target: to limit the global temperature increase by 2100 to well below 2°C higher than pre-industrial (late-19th-century) levels.

Technologies—including renewables, energy efficiency measures, and substitution of energy sources—are available to reverse the growth in emissions. But they must be deployed at scale, and doing so would require fast, forceful, and united action by governments and regulators worldwide, using all the levers at their disposal—well beyond current efforts. It would also call for a huge upfront investment: $19 trillion to $21 trillion from now until 2030, according to our estimates. Both requirements may be difficult to achieve in the scarce time we have left.

Economic disparities among countries are a large part of the problem. Our research confirms that even if China, the European Union, developed countries in Asia, and the US curbed their emissions, the Paris target would still be out of reach. Non-OECD emerging economies would also need to do the same. Yet although the investment required to implement the technologies would be manageable for rich OECD countries and China, most emerging economies, which would need to make a substantial part of the investment, would not be able to afford it on their own.

Climate scientists do not know for sure how warm the world will become or how quickly. While it is imperative that we don’t ease up on actions to curb climate change, companies, governments, and investors need to wake up to the likelihood of a hotter planet and factor that into their assumptions about the future.