Puerto Rico could be without power for six months because of Hurricane Maria. Large parts of Southeast Asia are struggling to rebuild after catastrophic flooding. And severe droughts have caused widespread famine in parts of Africa.

While none of these events can be directly tied to climate change, they give a sense of what’s to come if countries fail to take meaningful climate change action.

And they show how the damage caused by extreme weather can create snowballing economic disasters.

In fact, as the International Monetary Fund was preparing its annual assessment of world economies, it identified one looming obstacle to sustainable growth: climate change.

In a chapter released a month ahead of the publication of its World Economic Outlook, the IMF argues that poor countries stand to be most affected by climate change.

Take Action: Tell World Leaders to Help Millions Affected by Recent Hurricanes and Monsoon

Further, they say that the poorest countries have contributed the least to climate change and have the least resources for adaptation.

“Rising temperatures would have vastly unequal effects across the world, with the brunt of adverse consequences borne by those who can least afford it,” the IMF wrote.

The organization calls this disparity an injustice and asks wealthy nations to pay for adaptation efforts.  

“With advanced and emerging market economies contributing the lion’s share to the warming that has occurred so far and is projected to continue, helping low-income countries cope with its consequences is a humanitarian imperative and sound global economic policy,” they wrote.

Global Citizen campaigns on the Global Goals, which call for countries to invest in climate action programs. You can take action on this issue here.  

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Examples of the economic impact of climate change can already be seen around the world.

Without more resilient infrastructure, future natural catastrophes will cause greater damage, the IMF argues.

And the only way this infrastructure can be paid for is with assistance from wealthier nations.

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Beyond the “humanitarian imperative,” the IMF says there is an economic argument.

Climate change can greatly damage world economies by disrupting trade networks, weakening major manufacturing hubs, causing widespread displacement of people, and endangering natural resources, among other impacts.

To avoid these risks and ensure economic growth in the future, wealthy nations should pay for adaptation efforts, according to the IMF.  

The United Nations has a Green Climate Fund set up to do exactly that.

So far, the program has mobilized more than $10 billion in funds to help poor countries adapt to climate change, but it came under attack earlier this year when US President Donald Trump disparaged the concept and vowed to cancel future US payments.

Read More: 5 Consequences of Trump Dumping the Paris Climate Agreement

The US has emitted more greenhouse gases than any other nation in history, making it arguably the primary driver of climate change.

Reneging on its commitments to other countries seems to go directly against the IMF’s latest directive.

But as the IMF warns, the risks of climate change are not limited to poor countries:

“Climate changes threatens not only low-income countries – it threatens all countries.