The Fourth National Climate Assessment sounded alarm bells about climate change’s effects, both current and future, upon its release last November by the U.S. Global Change Research Program.
Civil engineering, of course, is at the forefront of this discussion. After all, it is civil engineers – planning, designing, and constructing infrastructure – who have to account for these climate change effects.
But how can civil engineers anticipate something that is in a state of constant flux?
The ASCE Committee on Adapting to a Changing Climate has published a new manual of practice, Climate-Resilient Infrastructure: Adaptive Design and Risk Management, to help civil engineers answer that exact question.
The book’s editor, ASCE Distinguished Member Bilal Ayyub, director of the Center for Technology and Systems Management at the University of Maryland, and a designated reviewer of the Fourth National Climate Assessment on behalf of the National Academies, talked with ASCE News about the new manual of practice and why he remains optimistic in the face of global climate change.
ASCE News: Let’s start with the basic question: Why is this manual of practice something that the committee wanted to prepare?
Bilal Ayyub: According to the latest U.S. Census Bureau statistics, we put in place – into construction – about $1.3 trillion in infrastructure a year. And if you examine what we build every year, it would include, of course, bridges, buildings, power plants, and much more. And I can tell you, almost all of these projects most likely are not designed to account for a changing climate.
With a design life of 50 or 100 years, or even longer, these projects are going to experience greater hazards and more extremes than they are designed for.
We felt as a committee a sense of urgency that we needed to put together this manual of practice. And we were able to accomplish the task in 12 months.
ASCE News: Could you break down some of the background on the probabilistic methods that you used for the risk analysis in the book?
Ayyub: The design philosophy that we used in the manual of practice, or the design philosophy that we advocate for engineers to use, is what’s called “adaptive design.”
Historically, we designed to account for or consider uncertainty, but the nature of uncertainty has changed. Uncertainty was treated in previous and current practices as being randomness due to natural variability. And we could deal with that by reliability-based design, robust design, et cetera.
But now we have what we call deep uncertainty. And the way we are dealing with it is through projections. In order to determine, let’s say, what the sea level will be in the future, we have to make those assumptions about power-type use, consumption levels of power, population growth, and so on. These are projections. If there is a policy change, those projections will be different.
Hence, we needed to come up with a design philosophy that enables us to introduce what we call “real options” in the project, where in the future when we have to enhance the project or expand it or make its performance higher, we don’t need to start all over, but could just build on what we have.
ASCE News: And that’s really the essence of what this entire book is all about, allowing for those projections to be part of the design process going forward, right?
Ayyub: Exactly. So, the process starts by looking at our best estimate of what the hazard level is for the future. It could be, let’s say, the year 2100. Then we will design the project to meet our estimates of hazards and their extremes in the year 2100.
Ten years from now, we will reassess our projections for the year 2100. And if we find that they are off from what we projected 10 years ago, we will examine the options or the features that we embedded in the project to see whether we should enhance the performance level of that project.
The manual also includes technologies for climate resilience that are suitable for new as well as existing infrastructure. It covers the estimation of extremes in a non-stationary environment, and focuses on precipitation, sea level rise, and flooding as example hazards.
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ASCE News: When engineers get the manual, how would you suggest they use it to adapt and continue to adjust going forward in the future?
Ayyub: The manual provides a framework. It’s not like your typical standard, where there are look-up tables and it describes the framework and its outcomes in the context of adaptive risk management and lifecycle cost analysis.
This is a risk-based framework. It starts by defining the context for the design, including the hazards. And then it goes through determining extremes, then looking at lifecycle cost, unedifying and examining real options, the adaptive features, and the associated economics. And at the very end, it will recommend where the design should be and document the available options for future consideration and actions.
Now, what’s interesting is that those options – because they are part of the project – they could have an economic valuation, meaning for a buyer who would like to take over that project. It could be a building. And the fact that it has those features would be viewed as economically beneficial. So the market value should become higher as a result.
ASCE News: How do you feel as you look at the decades ahead for the world and for civil engineering?
Ayyub: I am optimistic. The only item which I don’t feel I have full control over is the timeline.
This manual is only a first step on a path that could take us several years until we fully develop standards. Eventually, we would like to have standards.
How long will it take us to get there? That’s uncertain. But I’m optimistic that it will happen. It is needed.
I still remember when we met as a committee to prepare the manual of practice, when I proposed it to the group. I asked the group in the room – and these are my exact words: “Would you like to make history? Then you need to join this effort.”
And it was met with overwhelming support from all the members. They felt that sense of urgency, that they could make an impact on the future.