Executive Summary
Engineers should plan for weather and climate changes because many infrastructure assets last long enough for hazard statistics to shift during the design life, which can invalidate stationary assumptions embedded in legacy design inputs (ASCE, 2026). The practical engineering response is to treat hazards as time-varying, test designs against a range of plausible future conditions, and document assumptions in the basis of design so projects remain defensible through permitting, peer review, and handover (ASCE, 2026). This approach is policy-agnostic and aligns with ASCE’s recommendation that projects with 20-plus-year design lives consider changing statistics and that 50-to-100-year assets anticipate ranges of continuing change (ASCE, 2026).
What The ASCE Technical Note Emphasizes
ASCE’s January 22, 2026 technical note states that civil engineers working on projects with design lives of 20 years or more should consider changes in weather and climate statistics across many hazards, and that the need for this planning holds regardless of government policy changes (ASCE, 2026). The note also points engineers to the Climate Adaptation Engineering Bulletin No. 3 figures as a concise way to communicate observed, long-running changes to stakeholders and decision-makers (ASCE, 2026; ASCE CACC, 2024b).
Why Design Life Changes The Reliability Math
A short-lived asset can often be designed with historical frequency estimates and still perform as expected, but a long-life asset effectively experiences multiple hazard regimes over its service life, which changes the probability of exceedance even if the governing equations remain the same (ASCE, 2026). ASCE provides a practical framing: 20 years is a useful threshold for explicitly considering changing statistics, and 50 to 100 years is where engineers should anticipate a range of future conditions rather than a single deterministic input (ASCE, 2026).
Stationarity Versus Nonstationarity In Engineering Inputs
Stationarity assumes the statistical properties of hazards such as extreme precipitation, temperature, and coastal water levels do not materially change over time, which is why legacy design maps and frequency products are often treated as fixed inputs. Nonstationarity recognizes that these statistics can drift over multi-decade periods, so the same exceedance probability can correspond to different physical loads at different points in an asset’s life (ASCE CACC, 2024a; NOAA, n.d.). This distinction matters because agencies and professional bodies are increasingly developing datasets and guidance that explicitly address time-varying extremes (NOAA, n.d.).
Observed Indicators Engineers Can Cite In Project Files
ASCE’s Climate Adaptation Engineering Bulletin No. 3 compiles historical indicators across Earth systems to show consistent change in measurements relevant to engineering practice, which supports design narratives that must be evidence-based rather than rhetorical (ASCE CACC, 2024b). The bulletin summarizes observed increases in land surface air temperature since the late 1800s, increases in sea surface and marine air temperatures since the 1920s, continuing sea level rise since late-1800s records, and decreases in summer Arctic sea-ice extent since about the 1960s, along with more recent-record indicators such as increasing tropospheric temperature and ocean heat content since about the 1970s and declining glacier mass balance since the 1940s (ASCE CACC, 2024b).
Range-Based Design As A Professional Norm
When ASCE recommends anticipating ranges of continuing change, the engineering implication is that a single “best estimate” design point often does not reflect uncertainty for long-life infrastructure, especially when consequences of failure are high (ASCE, 2026). In practice, range-based design means selecting a reference condition for baseline sizing and permitting, stress-testing performance under higher plausible future hazards, and then choosing robustness now or adaptability later based on consequence, retrofit feasibility, and lifecycle cost (ASCE, 2026).
Precipitation Frequency And IDF Curves As Critical Inputs
Many civil engineering calculations scale directly with rainfall intensity or depth, making stormwater, culvert, and drainage designs especially sensitive to changes in intensity-duration-frequency inputs (ASCE CACC, 2024a). ASCE’s precipitation bulletin highlights IDF as a critical design input and discusses how practice is moving from stationary assumptions toward nonstationary thinking as trends become clearer and are expected to continue, particularly for assets with 50-to-100-year lives (ASCE CACC, 2024a). When the IDF curve drifts, peak flow estimates, storage requirements, surcharge frequency, and level-of-service outcomes drift with it, even if the hydraulic model and methodology do not change (ASCE CACC, 2024a).
NOAA Atlas 15 And The Shift Toward Nonstationary Frequency
NOAA describes Atlas 15 as the next U.S. precipitation frequency atlas, providing spatially continuous estimates and covering storm durations from minutes to 60 days across commonly used exceedance probabilities (NOAA, n.d.). NOAA also states that Atlas 15 is intended to account for future temporal trends through 2100 and to incorporate nonstationary statistical methods and climate model information, which is a meaningful shift in how engineers may justify precipitation frequency inputs in design narratives and reviews (NOAA, n.d.).
What The Atlas 15 Timeline Means For Active Projects
NOAA’s Atlas 15 page indicates that preliminary estimates for the contiguous United States are planned for early 2026 for peer review and feedback and that published estimates are expected in 2026, with non-CONUS products following after (NOAA, n.d.). For engineering governance, this creates a transition window in which teams should clearly document which dataset version was used, what stationarity assumption it embeds, and how differences were handled in sensitivity checks and risk discussions (NOAA, n.d.).
Sea Level Rise As A Moving Boundary Condition
For coastal and tidally influenced assets, sea level rise is a changing boundary condition that can affect overtopping frequency, groundwater levels, corrosion environments, and access disruptions over time. NOAA’s 2022 sea level rise technical report resources highlight key takeaways including expectations of about 10 to 12 inches of sea level rise along the U.S. coastline over the next 30 years and a substantial increase in flood frequency over that same period, which has direct implications for lifecycle performance and operations planning (NOAA, 2022).
A Practical Climate-Aware Workflow Engineers Can Execute
A climate-aware process begins by defining service life, performance requirements, and consequence of failure, because these choices determine how conservative the design should be and whether staged upgrades are acceptable (ASCE, 2026). The next step is translating “climate” into specific design inputs such as precipitation frequency curves, flood elevations, extreme water levels, and temperature design days, then selecting authoritative sources and making assumptions visible in the basis of design (ASCE, 2026; NOAA, n.d.). Finally, the engineer tests performance across a plausible envelope of futures and chooses robust design or adaptive pathways with a documented rationale grounded in consequence, feasibility, and lifecycle cost, which supports stakeholder decisions without requiring political agreement (ASCE, 2026; ASCE CACC, 2024b).
Conclusion
Engineers should plan for weather and climate changes because infrastructure design lives are often long enough that hazard statistics can change during the asset life, so nonstationarity must be managed like any other time-dependent uncertainty (ASCE, 2026). ASCE provides practical thresholds and communication tools, while NOAA’s Atlas 15 program signals a shift toward nonstationary precipitation frequency products that will influence how engineers select and justify IDF inputs (ASCE, 2026; NOAA, n.d.). Done well, climate-aware design is not a political statement but a traceable set of inputs, checks, and documentation that protects safety, service, and lifecycle value under evolving conditions (ASCE, 2026).
Sources
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American Society of Civil Engineers. (2026, January 22). Why engineers should plan for weather and climate changes. Civil Engineering Source.
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American Society of Civil Engineers, Committee on Adaptation to a Changing Climate. (2024, September 12). Climate Adaptation Engineering Bulletin No. 2: Predicting future precipitation intensity, duration and frequency. ASCE Collaborate.
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American Society of Civil Engineers, Committee on Adaptation to a Changing Climate. (2024, December 20). Climate Adaptation Engineering Bulletin No. 3: Documented historic indicators of climate change. ASCE Collaborate.
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National Oceanic and Atmospheric Administration, National Weather Service, Office of Water Prediction. (n.d.). Welcome to the NOAA Atlas 15 informational page. NOAA Water Prediction.
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National Oceanic and Atmospheric Administration. (2022). Global and regional sea level rise scenarios for the United States: Updated mean projections and extreme water level probabilities along U.S. coastlines. NOAA Technical Report (2022 Sea Level Rise Technical Report resources).
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