The mind balks at predictions of rising sea levels that threaten, in the not-distant future, to drown or dramatically alter Connecticut's treasured shoreline and lowlands. How distant? How altered? What should be done? What would it cost, and who would pay?

The global emergency of climate change is right now the agenda of COP24, a two-week, 200-nation conference in Katowice, Poland. The meeting follows up on the 2015 Paris climate conference and calls for delegates to review the detailed measures countries plan to take for reducing their carbon emissions. The Trump administration has said it will pull the United States out of the Paris agreement in 2020, but for now U.S. delegates are present.

It's urgent that competing international interests agree to actions that could slow the overheating of Earth, described in a report released this week as "a speeding freight train" in 2017 that is expected to have gained even more momentum in 2018. Scientists have shown evidence carbon dioxide emissions are a major factor in the warming of the planet that is responsible for melting ice caps and glaciers. The melt adds to ocean volume and thus raises sea levels, including right here.

The current estimate for these waters is 20 inches by 2050. NOAA predicts that by next April, high tide flooding in the Northeast will be 60 percent higher than 20 years ago and double what it was 30 years ago. The mind balks.

Coastal states like Connecticut and its cities and towns have no choice but to prepare for the threat to access roads, bridges, beaches, homes, public spaces and buildings. In two installments last month, the Connecticut Mirror described the challenges and a limited number of actions already being taken by state and local government, the University of Connecticut and other partners such as CIRCA, Connecticut Institute for Resilience and Climate Adaptation. Some towns, like Stonington, have undertaken their own coastal resilience plans.

Given the lessons learned from damage caused by storms Irene (2011) and Sandy (2012) and the increasingly frequent instances of "sunny day flooding," decision-makers have choices such as these:

a. Put it back the way it was. This is the federal policy under which FEMA continues to reimburse property owners in flood-prone areas.

b. Abandon it and move to higher land. The idea upsets people, but west of the Connecticut River some have already been reimbursed for the move.

c. Set aside funds now and start building both the public will and the infrastructure to handle conditions still some years off.

"All of the above" is the only answer. The response to rising sea levels in the state is not an either-or choice between drastic measures and reconstruction after damage. Resiliency is the plan we make for coping with conditions we cannot prevent, both before and after something happens. It requires managing risk with every means available.

Managed risk includes getting people used to the idea that the coming conditions will affect everyone, whether by lost beaches, swamped septic systems or useless bridges, or houses on stilts that can only be reached, on many days, by boat.

While it may seem obvious that rebuilding in repeatedly flooded areas is foolish, some planners say that it may serve well as an interim step that allows the marketplace to gradually shift real estate values away from shoreline property. That may seem most fair to most people, and it avoids drastic action before the need becomes clear. It will allow time to work out new decision making roles for state and local government. Under the state's home rule arrangements, building codes, for example, are written by the state and enforced by the towns, which retain zoning authority and collect property taxes.

Connecticut cannot ignore the vanishing of its shoreline, even though it comes at a time when the state is feeling fiscally throttled. If the predictions are even close to correct, no greater and relatively rapid changes have ever occurred to Connecticut in its history as a state or a colony. This generation must act if it is to hand on Connecticut as previous generations have known it, lived it, loved it.

The Day editorial board meets with political, business and community leaders to formulate editorial viewpoints. It is composed of President and Publisher Timothy Dwyer, Executive Editor Izaskun E. Larraneta, Owen Poole, copy editor, and Lisa McGinley, retired deputy managing editor. The board operates independently from The Day newsroom.