Climate adaptation, in one form or another, has been around for decades, if not centuries. Recent sustainability or resiliency efforts often address the same issues as climate adaptation. For firms and governments, it makes fiscal sense to ensure their operations can withstand storm surge or high wind—whether once every 100 years or once every three years.

Businesses, concerned about continuity of operation or pushed by insurers to be concerned about business continuity, are looking for ways to make their buildings and infrastructure more resilient to disruptive climatic events. "A lot of that focus will be on not resisting the impacts [of climactic events] but of being able to recover more quickly from such an event," says Bob Prieto, senior vice president of Fluor Corp.

The American Society of Civil Engineers adopted in 1990 a climate adaptation policy that supports government policy changes. The Army Corps of Engineers started working on climate adaptation in 2007, and federal agencies recently released extensive agency-specific climate adaptation plans.

Kate White, senior lead for global and climate change for the Army Corps of Engineers' Institute for Water Resources, likes to point out that planning for unknowns isn't totally foreign to engineers. Systems are always changing. Following the 1927 Mississippi River flood, engineers planned levees that were resilient enough to withstand the 2011 floods, she says.

Typically, however, engineers have based design criteria on historical records. But with changing weather patterns, "there's no longer a history that dictates the future," says Wallis-Lage of Black & Veatch. In several instances, infrastructure designed decades ago for worst-case scenarios now have exceeded those scenarios. And even in the best-case scenario, climate change is still going to require changing design standards, she says.

Designing for an uncertain future may be a tough sell for engineers, says James Neumann, an economist and lead author for IPCC on the economics of adaptation. "It's difficult for anyone to make that change of mind-set," he says.

Glenn Daiger, senior vice president of CH2M Hill, agrees, saying, "Design in many ways had become really mechanical. Now you have to look at risk and consider uncertainty. It's different than going to a book and looking up a chart and designing to that number."

ASCE is pondering changes to its lookup charts that would rely less on a lengthy historical record and more on recent records of weather events.

But such changes pose their own risks, says the Corps' Goran. If historical data isn't used as the basis to make design decisions and climate changes don't happen as expected, Goran says, "Are they putting their engineers and designers at risk? If [the data or decisions] don't play out and something else happens, have they spent their money wisely, and are they liable?"

However, climate norms are changing so rapidly that engineers can incorporate new data to reflect recent heavy rains, drought and extreme weather to design and help their clients prepare for climate change.

"Instead of just using historical precipitation data, we are able to introduce [clients] to some modeling techniques" that factor in new, potentially higher sea levels so clients can asses their risk better, says Joe Danko, global director of sustainable solutions for CH2M Hill. Alexandria, Va., went through such an assessment process with CH2M Hill to incorporate climate-change-based impacts on its stormwater system.