There are strings of potential bottlenecks in the supply chains. Each stop point is a tree-like system where raw materials are conveyed from the system's farthest tendrils to sub-assemblers along its roots. The cumulative mileage traveled by all the parts of the product would probably reach the moon, according to Mims. Getting all of the suppliers to adapt to climate change would be a monumental achievement. Each point of vulnerability has the potential to send damaging ripples up and down the chain.

Seaports are vulnerable. Port authorities have three ways to deal with sea level rise. They can retreat to inland locations with river links to oceans, but only if they have the right conditions. Even if the sea dikes are strong enough to resist the rising ocean, they must be raised continually to keep up with sea level rise, and they only buy time until eventually being overtopped. Floodwater is diverted to coastal areas that are not protected by the dikes.

As sea level rise proceeds, port officials can raise by at least a couple of meters all their infrastructure so that the port can continue to function. The rate of the rise is so uncertain that choosing a cost-effective height for the increase is problematic. Raising wharves and other port infrastructure would leave ports, vital ground transportation links, and the residents of adjoining cities vulnerable.

In a paper published in Global Environmental Change, Becker and four colleagues concluded that raising 221 of the world's most active seaports by 2 meters would require 436 million cubic meters of construction materials, an amount large enough to create global. It would cost $60 billion to make 49 million metric tons of cement alone. In 2012 dollars, elevating the infrastructure of the 100 biggest US seaports by 2 meters would cost between $57 billion and 78 billion, which is equivalent to 69 billion to $103 billion in current dollars.

We're a rich country and we're not going to have enough resources to make all the required investments. The ports are going to be winners andlosers. I don't know if we're well equipped for that.

The long-term nature of sea level rise combined with the deficiencies and expense of the proposed solutions have prevented seaport managers from addressing the threat. A 2020 study in the Journal of Waterway, Port, Coastal, and Ocean Engineering was co-authored by Becker and found that only 29 percent of US maritime infrastructure engineers had a policy or planning document for sea level rise. The study said that the federal government's lack of guidance on sea level projections leaves engineers to make subjective decisions.