Climate change will add billions of dollars through the end of the century to the costs of maintaining and repairing Alaska's public roads, buildings and utilities, according to a new study published by the National Academy of Sciences.

Reducing carbon emissions will lessen that cost, says the study, led by the Environmental Protection Agency and released during the final weeks of the Obama administration. The study suggests that people have a role causing climate change, and also can slow or halt its potentially disastrous effects.

The study, published in the journal Proceedings of the National Academy of Sciences, estimates cumulative economic damages to public infrastructure through the 21st century from climate-driven changes in flooding, precipitation, permafrost thaw, freeze-thaw cycles and coastal erosion.

If carbon emissions continue at their current pace, the climate-related costs for maintaining and repairing public roads, pipelines, buildings, airports and rail lines will be $5.5 billion by 2099, the study says.

But if emissions are cut in line with the United Nations climate agreement reached in Paris in 2015, the costs would drop to $4.2 billion, according to the study. The Paris agreement commits to a global temperature rise of no more than 2 degrees Celsius. Reductions in global emissions at a level consistent with the Paris agreement would save Alaska $1.2 billion in infrastructure costs over the 21st century, according to the study results.

Not included in the study were costs to maintain docks and harbors or the trans-Alaska pipeline system, which is considered private infrastructure.

Flood damage to roads is expected to be the climate-related factor racking up the most economic damage, with permafrost thaw and effects on buildings expected to be the second-costliest category, the study says.

Even though the most dramatic climate warming has been measured in Alaska's far-north Arctic, the state's Interior region and parts of the state's Southcentral region are likely to incur the biggest costs from climate-related damages. Within developed Southcentral Alaska, the Prince William Sound area is expected to bear the highest climate-related infrastructure costs.

"Both these regions are expected to have more rain in the future, which could result in more flooding, thus increasing the impacts on the many roads found in boroughs in that area. For Fairbanks North Star (Borough), permafrost thaw damage to buildings also adds considerably to the costs," lead author April Melvin said in an email.

Costs are also expected to be relatively high in the Anchorage area, which has the highest density of people and public infrastructure

Climate-related infrastructure costs in the Aleutians East Borough are expected to be so small as to be indiscernible, but that is largely because of the dearth of public infrastructure there — not a lack of climate-change effects, the study said.

Melvin served as an American Association for the Advancement of Sciences policy fellow with EPA. She is no longer with EPA, and current EPA employees declined to comment on the study.

Co-authors included permafrost experts from the University of Alaska Fairbanks, as well as scientists from other organizations.

The climate-related infrastructure cost total estimated in the study was lower than that found in a previous analysis by a team mostly from the University of Alaska Anchorage. Melvin said her group used information from that earlier study, which put estimated cumulative costs through 2080 at $5.6 billion to $7.6 billion, but made different assumptions about how infrastructure would be maintained.

The UAA-led team modeled damages based on the shortening of the lifespan of infrastructure and more frequent replacement, so the costs were incurred largely due to replacement, she said by email. "In contrast, our model quantifies the costs required to maintain infrastructure through its usable life, with the damages from climate change coming in the form of additional maintenance and repair."

Climate change mitigation, the new study found, could dramatically lower costs — by about 25 percent to about 40 percent, the study found.

One specific case of costly climate-change damage occurred at the most famous national park in Alaska.

At Denali National Park and Preserve, permafrost thaw led to a massive landslide that blocked the park's sole road in the fall of 2013. That 600-foot-long slide peeled 30,000 cubic yards of debris off the slope at the Igloo Creek area of the Denali park road. It was one of a series of slides expected to become more common as temperatures rise in the region.

Protecting the Igloo Creek portion of road from similar slides in the future would cost $15,000 to $7.1 million, depending on the response strategy chosen, according to a study led by the Federal Highway Administration and discussed Thursday at the Alaska Forum on the Environment conference in Anchorage.

The cheapest option would be revegetating the collapsed Igloo Creek-area slope to make it more resilient to future landslide forces. The most expensive option would be building a tunnel to shelter the road from landslide debris.

Paul Schrooten, a National Park Service landscape architect who presented information about the study at the conference, said the agency is steadfast in its position that climate change in Alaska is real.

In Alaska, he noted, park lands have glaciers that are melting, permafrost that is thawing and vegetation that is transforming as temperatures rise.