Increased tidal flooding is essentially guaranteed. Changes already set in motion by our past and present heat-trapping emissions will largely drive the pace of sea level rise and flooding over the next several decades.

Coastal communities must act with urgency to prepare for this rising threat — and there are many things we can do to help ensure enduring coastal communities.

Municipalities, with state and federal help, should prioritize and incentivize flood-proofing of homes, neighborhoods, and key infrastructure; curtail development in areas subject to tidal flooding; consider the risks and benefits of adaptation measures such as sea walls and natural buffers; and develop long-term plans based on the best available science.

The costs and challenges, however, are too great for municipalities to shoulder alone. A coordinated, well-funded federal response is also needed and should include both substantial investments in coastal resilience building, as well as action to deeply and swiftly reduce global warming pollution. This latter action may ultimately be the only reliable way to protect coastal communities over the long term – by slowing the pace of future sea level rise.

There is a hard truth about adaptation, however. It has fundamental limits — whether physical, economic, or social — and it can only fend off the impacts of sea level rise to a point.

As sea level rises higher, even our best protection efforts will not suffice in some areas in the face of rising tides, waves, and storm surges.

If it reaches limits of coastal adaptation, a community will face the prospect of shifting back from heavily impacted areas. These limits will arrive sooner in those areas exposed to greater risks, those with more fragile ecosystems and limited natural buffers, and those that are less well-off economically.

Leaders at all levels of government need to take seriously the risks facing people living along our coasts and the urgent need for action. We must prepare our communities for encroaching tides and other impacts of sea level rise even as we make a concerted effort to reduce the heat-trapping emissions that will determine the rate at which the ocean rises over the long term.