Humanity has long learned to live with extreme weather. Much of the Netherlands would be under water were it not for centuries of ingenious adaptation to the constant threat of flooding. Likewise, ancient communities on the banks of the Tigris and Euphrates developed ways to capture and direct excess water to nourish and protect fields.

But the number of places exposed to extreme weather will only grow. According to new research from the McKinsey Global Institute, ‘Advancing adaptation: Mapping costs from cooling to coastal defences’, the world spends dollar 190 billion per year on investments in 20 key adaptation measures that protect roughly 1.2 billion people. But three billion more people, over three-quarters of whom live in low-income regions, have only limited protection.

Extending developed-economy standards of protection to all exposed places would require $540 billion annually. That means there is a dollar 350 billion gap, 60% of which is needed to help low-income areas build greater resilience. Moreover, adaptation costs will rise. On current emissions trajectories, the world is likely to reach 2° Celsius above pre-industrial levels by about 2050, exposing an additional 2.2 billion people to heat stress and another 1.1 billion to drought, for example.

Our analysis finds that at 2°C warming, the world would need to spend $1.2 trillion annually to protect everyone exposed to climate hazards at developed-economy standards, or almost 1% of GDP in affected places, by 2050. More than three-quarters of that spending would go toward protecting against heat and drought.

That may sound expensive, but the benefits of that adaptation would exceed the cost by roughly seven times. Air conditioners not only protect but also improve the productivity of indoor workers. Cooling shelters save lives in heat waves. Irrigation prevents crops from dying in hot, dry conditions. Sea dikes shield assets along coastlines from flooding. If deployed effectively, such solutions deliver immense value.

But recognising that adaptation is a good investment does not guarantee that the money will be spent. After all, the world spends only one-third of what’s required today, and achieving developed-economy standards of protection at 2°C by 2050 will require 6.2 times as much as what is spent today. A lack of capacity to spend, competing priorities, collective-action problems, and other factors all threaten to hamper implementation.

Moreover, the challenges of scaling up adaptation could look very different in developed and developing countries. For example, the costs would be highest by far in Sub-Saharan Africa, reaching 3% of projected GDP in exposed places, or about 50% more than governments in the region spent as a share of GDP to service their external debt in 2024. The shares of GDP needed for protection at developed-economy standards by 2°C in the Middle East and North Africa and in India are somewhat lower; and in North America, they are lower still, totaling around 0.3% of GDP in exposed places.

Economic development can help improve the capacity to spend, but even if adaptation spending grew in lockstep with GDP growth, only about 60% of what is needed would be covered globally at 2°C. If lower-income regions were to increase spending in line with their anticipated economic growth, it would cover only one-quarter of the costs of adapting at 2°C. Moreover, the presence or absence of adaptation measures can itself influence the pace of economic development. Drought or flooding can slow income growth for smallholder farmers, and heat stress can affect the productivity of outdoor workers.

So, what can be done, and what role do different actors play? The good news is that many households can implement some adaptation measures on their own, particularly for heat. If made affordable, solutions like passive cooling (shade, natural ventilation, and so forth), reflective roofs, fans, or air conditioners can offer meaningful protection in many cases.

But governments also have an important role to play, especially in lower-income areas and communities. They can finance critical infrastructure like coastal protection, and establish cooling shelters to protect the public. They can also create incentives to adapt, by setting and enforcing standards that enhance resilience, while raising awareness of risks. And they can deploy targeted subsidies or procurement programmes to make adaptation more affordable for households and small firms.

At the same time, businesses, particularly large ones, can manage their own exposures, both directly and indirectly through their supply chains. They can also innovate to help make adaptation measures more affordable and effective, such as by offering better and cheaper cooling systems to address heat stress.

Finally, financial institutions can leverage existing instruments to fund adaptation, such as by providing project-level finance for infrastructure like sea dikes. Blended-finance approaches also could prove helpful in bridging viability gaps and attracting private capital, though more work is needed to scale these up. For developing economies, there are also opportunities to integrate adaptation into broader investments relating to energy infrastructure, transportation systems, or urbanisation. Embedding adaptation early in these projects is far cheaper than retrofitting or rebuilding down the road.

Effective adaptation can strengthen resilience, protect vulnerable communities, and support economic growth. The world has the tools, and the benefits are undeniable. The decisions we make today will shape our ability to thrive in the long term.

(Mekala Krishnan is a partner at the McKinsey Global Institute. Annabel Farr is a senior fellow at the McKinsey Global Institute. Kanmani Chockalingam is a senior fellow at the McKinsey Global Institute)

Project Syndicate