Search results: “Kopp”
Browse All Documents
1–3 of 3
From the extreme to the mean: Acceleration and tipping points of coastal inundation from sea level rise
From the extreme to the mean: Acceleration and tipping points of coastal inundation from sea level riseAmerican Geophysical Union (AGU) | December 18, 2014...Summary
Relative sea level rise (RSLR) has driven large increases in annual water level exceedances (duration and frequency) above minor (nuisance level) coastal flooding elevation...
Relative sea level rise (RSLR) has driven large increases in annual water level exceedances (duration and frequency) above minor (nuisance level) coastal flooding elevation thresholds established by the National Weather Service (NWS) at U.S. tide gauges over the last half-century. For threshold levels below 0.5 m above high tide, the rates of annual exceedances are accelerating along the U.S. East and Gulf Coasts, primarily from evolution of tidal water level distributions to higher elevations impinging on the flood threshold. These accelerations are quantified in terms of the local RSLR rate and tidal range through multiple regression analysis. Along the U.S. West Coast, annual exceedance rates are linearly increasing, complicated by sharp punctuations in RSLR anomalies during El Niño Southern Oscillation (ENSO) phases, and we account for annual exceedance variability along the U.S. West and East Coasts from ENSO forcing. Projections of annual exceedances above local NWS nuisance levels at U.S. tide gauges are estimated by shifting probability estimates of daily maximum water levels over a contemporary 5-year period following probabilistic RSLR projections of Koppet al.(2014) for representative concentration pathways(RCP) 2.6, 4.5, and 8.5. We suggest a tipping point for coastal inundation (30 days/per year with a threshold exceedance) based on the evolution of exceedance probabilities. Under forcing associated with the local-median projections of RSLR, the majority of locations surpass the tipping point over the next several decades regardless of specific RCP.
Global and Regional Sea Level Rise Scenarios for the United States
Global and Regional Sea Level Rise Scenarios for the United StatesNational Oceanic and Atmospheric Administration (NOAA) | January 19, 2017...Summary
The Sea Level Rise and Coastal Flood Hazard Scenarios and Tools Interagency Task Force, jointly convened by the U.S. Global Change Research Program...
The Sea Level Rise and Coastal Flood Hazard Scenarios and Tools Interagency Task Force, jointly convened by the U.S. Global Change Research Program (USGCRP) and the National Ocean Council (NOC), began its work in August 2015. The Task Force has focused its efforts on three primary tasks:
1) updating scenarios of global mean sea level (GMSL) rise, 2) integrating the global scenarios with regional factors contributing to sea level change for the entire U.S. coastline, and 3) incorporating these regionally appropriate scenarios within coastal risk management tools and capabilities deployed by individual agencies in support of the needs of specific stakeholder groups and user communities. This technical report focuses on the first two of these tasks and reports on the production of gridded relative sea level (RSL, which includes both ocean-level change and vertical land motion) projections for the United States associated with an updated set of GMSL scenarios. In addition to supporting the longer-term Task Force effort, this new product will be an important input into the USGCRP Sustained Assessment process and upcoming Fourth National Climate Assessment (NCA4) due in 2018. This report also serves as a key technical input into the in-progress USGCRP Climate Science Special Report (CSSR).
In order to bound the set of GMSL rise scenarios for year 2100, we assessed the most up-to-date scientific literature on scientifically supported upper-end GMSL projections, including recent observational and modeling literature related to the potential for rapid ice melt in Greenland and Antarctica. The projections and results presented in several peer-reviewed publications provide evidence to support a physically plausible GMSL rise in the range of 2.0 meters (m) to 2.7 m, and recent results regarding Antarctic ice- sheet instability indicate that such outcomes may be more likely than previously thought. To ensure consistency with these recent updates to the peer-reviewed scientific literature, we recommend a revised ‘extreme’ upper-bound scenario for GMSL rise of 2.5 m by the year 2100, which is 0.5 m higher than the upper bound scenario from Parris et al. (2012) employed by the Third NCA (NCA3). In addition, after consideration of tide gauge and altimeter-based estimates of the rates of GMSL change over the past quarter-century and of recent modeling of future low-end projections of GMSL rise, we revise Parris et al. (2012)’s estimate of the lower bound upward by 0.1 m to 0.3 m by the year 2100.
This report articulates the linkages between scenario-based and probabilistic projections of future sea levels for coastal-risk planning, management of long-lived critical infrastructure, mission readiness, and other purposes. The probabilistic projections discussed in this report recognize the inherent dependency (conditionality) of future GMSL rise on future greenhouse-gas emissions and associated ocean-atmosphere warming. In recognition of the different time horizons of relevance to different decision contexts, as well as the long-term GMSL rise commitment (lagged GMSL response) from on-going increases in ocean- atmosphere warming, GMSL rise and associated RSL change are quantified from the year 2000 through the year 2200 (on a decadal basis to 2100 and with lower temporal frequency between 2100 and 2200).
The 0.3 m-2.5 m GMSL range for 2100 is discretized by 0.5-m increments and aligned with emissions- based, conditional probabilistic storylines and global model projections into six GMSL rise scenarios: aLow, Intermediate-Low, Intermediate, Intermediate-High, High and Extreme, which correspond to GMSL rise of 0.3 m, 0.5 m, 1.0 m, 1.5 m, 2.0 m and 2.5 m, respectively. These GMSL rise scenarios are used to derive regional RSL responses on a 1-degree grid covering the coastlines of the U.S. mainland, Alaska, Hawaii, the Caribbean, and the Pacific island territories, as well as at the precise locations of tide gauges along these coastlines. These scenario-based RSL values fill a major gap in climate information needed to support a wide range of assessment, planning, and decision-making processes. GMSL was adjusted to account for key factors important at regional scales, including: 1) shifts in oceanographic factors such as circulation patterns; 2) changes in the Earth’s gravitational field and rotation, and the flexure of the crust and upper mantle, due to melting of land-based ice; and 3) vertical land movement (VLM; subsidence or uplift) due to glacial isostatic adjustment (GIA, which also changes Earth’s gravitational field and rotation, as well as the overall shape of the ocean basin), sediment compaction, groundwater and fossil fuel withdrawals, and other nonclimatic factors. Key findings include:
* Along regions of the Northeast Atlantic (Virginia coast and northward) and the western Gulf of Mexico coasts, RSL rise is projected to be greater than the global average for almost all future GMSL rise scenarios (e.g., 0.3-0.5 m or more RSL rise by the year 2100 than GMSL rise under the Intermediate scenario).
* Along much of the Pacific Northwest and Alaska coasts, RSL is projected to be less than the global average under the Low-to-Intermediate scenarios (e.g., 0.1-1 m or less RSL rise by the year 2100 than GMSL rise under the Intermediate scenario).
* Along almost all U.S. coasts outside Alaska, RSL is projected to be higher than the global average under the Intermediate-High, High and Extreme scenarios (e.g., 0.3-1 m or more RSL rise by the year 2100 than GMSL rise under the High scenario).
Finally, the consequences of rising RSL are presented in terms of how the frequency of moderate-level flooding associated with a NOAA coastal/lakeshore flood warning of a serious risk to life and property may change in the future under the sea level scenarios. The elevation threshold used to classify such events by NOAA on their tide gauges varies along the U.S. coastline, but in general it is about 0.8 m (2.6 feet) above the highest average tide and locally has a 20% annual chance of occurrence. For example, using the flood-frequency definition, we find at most locations examined (90 cities along the U.S. coastline outside of Alaska) that with only about 0.35 m (<14 inches) of local RSL rise, annual frequencies of such disruptive/damaging flooding will increase 25-fold by or about (±5 years) 2080, 2060, 2040 and 2030 under the Low, Intermediate-Low, Intermediate and Intermediate High subset of scenarios, respectively.
Rising seas in California: An update on sea-level rise science$0.00
Rising seas in California: An update on sea-level rise scienceCalifornia Ocean Protection Council | April 22, 2017...Summary
Key findings of this report: Scientific understanding of sea-level rise is advancing at a rapid pace. Projections of future sea-level rise, especially under...
Key findings of this report:
Scientific understanding of sea-level rise is advancing at a rapid pace. Projections of future sea-level rise, especially under high emissions scenarios, have increased substantially over the last few years, primarily due to new and improved understanding of mass loss from continental ice sheets. These sea-level rise projections will continue to change as scientific understanding increases and as the impacts of local, state, national and global policy choices become manifest. New processes that allow for rapid incorporation of new scientific data and results into policy will enable state and local agencies to proactively prepare.
The direction of sea level change is clear. Coastal California is already experiencing the early impacts of a rising sea level, including more extensive coastal flooding during storms, periodic tidal flooding, and increased coastal erosion.
The rate of ice loss from the Greenland and Antarctic Ice Sheets is increasing. These ice sheets will soon become the primary contributor to global sea-level rise, overtaking the contributions from ocean thermal expansion and melting mountain glaciers and ice caps. Ice loss from Antarctica, and especially from West Antarctica, causes higher sea-level rise in California than the global average: for example, if the loss of West Antarctic ice were to cause global sea-level to rise by 1 foot, the associated sea-level rise in California would be about 1.25 feet.
New scientific evidence has highlighted the potential for extreme sea-level rise. If greenhouse gas emissions continue unabated, key glaciological processes could cross thresholds that lead to rapidly accelerating and effectively irreversible ice loss. Aggressive reductions in greenhouse gas emissions may substantially reduce but do not eliminate the risk to California of extreme sea-level rise from Antarctic ice loss. Moreover, current observations of Antarctic melt rates cannot rule out the potential for extreme sea-level rise in the future, because the processes that could drive extreme Antarctic Ice Sheet retreat later in the century are different from the processes driving loss now.
Probabilities of specific sea-level increases can inform decisions. A probabilistic approach to sea-level rise projections, combined with a clear articulation of the implications of uncertainty and the decision support needs of affected stakeholders, is the most appropriate approach for use in a policy setting. This report employs the framework of Kopp et al. (2014) to project sea-level rise for three representative tide gauge locations along the Pacific coastline: Crescent City in northern California, San Francisco in the Bay area, and La Jolla in southern California. These projections may underestimate the likelihood of extreme sea-level rise, particularly under high emissions scenarios, so this report also includes an extreme scenario called the H++ scenario. The probability of this scenario is currently unknown, but its consideration is important, particularly for high-stakes, long-term decisions.
Current policy decisions are shaping our coastal future. Before 2050, differences in sea-level rise projections under different emissions scenarios are minor but they diverge significantly past midcentury. After 2050, sea-level rise projections increasingly depend on the trajectory of greenhouse gas emissions. For example, under the extreme H++ scenario rapid ice sheet loss on Antarctica could drive rates of sea-level rise in California above 50 mm/year (2 inches/year) by the end of the century, leading to potential sea-level rise exceeding 10 feet. This rate of sea-level rise would be about 30-40 times faster than the sea-level rise experienced over the last century.
Waiting for scientific certainty is neither a safe nor prudent option. High confidence in projections of sea-level rise over the next three decades can inform preparedness efforts, adaptation actions and hazard mitigation undertaken today, and prevent much greater losses than will occur if action is not taken. Consideration of high and even extreme sea levels in decisions with implications past 2050 is needed to safeguard the people and resources of coastal California.