Sudden subsidence during great earthquakes is revealed in the geological record as abrupt changes in sedimentary sequences (Nelson, 2007). ...or use these buttons to go back to the previous chapter or skip to the next one. You can unsubscribe at any time and we'll never share your details to third parties. “The combination of the Moon’s gravitational pull, rising sea levels, and climate change will continue to exacerbate coastal flooding on our coastlines and across the world. Both the low-end and "worst-case" possibilities were revised upward in 2017 following a review by the U.S. Interagency Sea Level Rise Taskforce. Tectonics causes significant vertical land motion along the coast above the Cascadia Subduction Zone. Measurements of current deformation and geologic records (e.g., Savage et al., 1981; Atwater, 1987; Nelson et al., 1996; Atwater and Hemphill-Haley, 1997) establish the potential for great (magnitude greater than 8) megathrust earthquakes and catastrophic tsunamis along the Cascadia Subduction Zone. This exercise showed that as mean sea level rises, the incidence of extreme high-sea-level events becomes increasingly common (Figure 5.12). In particular, the ice sheets appear to have been negligible sea-level contributors during the observational periods used by Gornitz and Lebedeff (1987), Rahmstorf (2007), and Vermeer and Rahmstorf (2009), but ice sheet dynamic response is widely regarded as the most uncertain aspect of sea-level change. Another approach to projections, called the “semi-empirical” approach, is based on the observed relationship between sea-level change and global temperature change, and takes no account of the individual contributions to sea-level rise or their physical constraints. CDRM 6 analyzes the challenges posed by rising sea levels and climate change. Using a risk analysis and management framework, this report focuses on various aspects of sea level rise, including associated risks and socioeconomic impacts. The average values were used in the projection (see first row of Table 5.3). As many as 3.7 million U.S. residents in 2,150 coastal areas . Found insideThe 2020 edition of the WWDR, titled 'Water and Climate Change' illustrates the critical linkages between water and climate change in the context of the broader sustainable development agenda. A simulation based on predicted tides, projected weather and El Niño conditions under a mid-range greenhouse gas emission scenario, and the committee’s projections of sea-level rise suggests that the incidence of extreme water heights in the San Francisco Bay area would increase from about 9 hours per decade for the recent historical period (1961–1999) to hundreds of hours per decade by 2050 and several thousand hours per decade by 2100. For glaciers and ice caps, future discharge was left unchanged from the base-rate projection in this experiment. Globally organisation has predicted that by 2100 . Given the slow pace of glacial isostatic adjustment, these rates are assumed constant for the three projection periods (2030, 2050, and 2100). The vertical land motions projected using the CAS3D-2 model, TABLE 5.4 Effect of Sea-Level Fingerprints of Alaska, Greenland, and Antarctica Ice Masses Expressed as Percentage Differences from Cryosphere Projections with No Fingerprint Effecta. Some models predict that such extreme events will become more common and that heightened sea level will persist longer as sea level rises, increasing the potential for damage (Cayan et al., 2008; Cloern et al., 2011). Glaciers, ice caps, and ice sheets may undergo changes in the next century that are quite unlike the changes recorded over the past few decades, such as an increase or decrease in the speed of marine-ending outlet glaciers. The paleo sea level record suggests that even 2°C (3.6°F . FIGURE 5.11 Rio Del Mar on northern Monterey Bay was damaged during the El Niño winter of 1983 by large waves arriving simultaneously with high tides and elevated sea levels. Seaside cliffs will be cut back about 30 yards (meters) over the next 100 years, and sand dunes will be driven back even more, said Robert A. Dalrymple, a professor of civil engineering at Johns Hopkins University and chairman of the group that wrote the report. FIGURE 5.2 Projections of sea-level rise from 1990 to 2100, based on the Vermeer and Rahmstorf (2009) semi-empirical model and three IPCC (2000) emission scenarios (A1FI, A2, and B1). A new approach to simulations seamlessly combines multiple computer models for more fluid – and more precise – portraits of possible changes to come. More precise data gathered from satellite radar measurements reveal an accelerating rise of 7.5 cm (3.0 in) from 1993 to 2017,: 1554 for an average rate . A Climate Central analysis finds the odds of "century" or worse floods occurring by 2030 are on track to double or more . Given the strengths and weaknesses of the different projection approaches and the resource constraints of an NRC study, the committee chose to use GCMs developed for the IPCC Fourth Assessment Report to estimate the steric contribution and extrapolation techniques to estimate the cryospheric contribution. Also shown is a reconstruction of elevation during this interval (WA-PLS column). COMMITTEE PROJECTIONS OF SEA-LEVEL RISE ALONG THE CALIFORNIA, OREGON, AND WASHINGTON COASTS. A great earthquake could cause 1–2 m of sea-level rise in some areas, which is significantly higher than the committee’s projection for Cascadia in 2100 (0.6 m). Moreover, storm surges, exceptionally high "king tides," or El Niño events could produce notably higher water levels than SLR alone. b Extrapolated based on ice loss rates for glaciers and ice caps except Alaska, Greenland, and Antarctica. Even accounting for the possibility of slowing discharge in Greenland, the committee’s cryosphere extrapolations are substantially higher than the IPCC (2007) cryosphere projections. The two projection approaches rest on different foundations—GCMs on the physical processes that. Although the actual value of sea-level rise will almost surely fall somewhere within these wide uncertainty bounds, confidence in specifying the exact value is relatively low. [email protected] / [email protected]. Because the gravitational and deformational effects associated with the sea-level fingerprints of the three ice sources varies strongly with latitude, the projections were made for four points along the coast: Seattle, Washington, Newport, Oregon, San Francisco, California, and Los Angeles, California (Table 5.3). Indeed, some events, such as ice shelf melting triggering an instability of the West Antarctic Ice Sheet, would not be factored into semi-empirical models. The IPCC (2007) attempted to account for rapid transfers of ice from land to ocean by scaling up certain components of the modeled results, shown in Table 5.1 under “Scaled-up ice sheet discharge.” However, the estimates were not based on physical models of ice sheet processes, and they were not included in the projections of global sea-level rise. The rapid rise in sea level could be temporary, as in the case of a severe storm, or permanent, as in the case of a great subduction zone earthquake. The sea-level fingerprint effect reduces the projected sea levels along the entire coast and is most pronounced in Washington. FIGURE 5.8 Committee projections of components of sea-level rise off California, Oregon, and Washington. The most common approach for treating uncertainty in the global temperature response is to use the results of many climate models, which also provides a range of projected values for the global ocean response. To account for these effects in the projections, the committee subdivided ice loss rates into four categories: Greenland Ice Sheet, Antarctic Ice Sheet, Alaska glaciers, and all other glaciers and ice caps. Scientific estimates suggest the magnitude of sea‑level rise (SLR) in California could be at least half of one foot in 2030 and as much as seven feet by 2100. (2009) and Mote et al. NASA’s Sea Level Change Team is providing crucial information so that we can plan, protect, and prevent damage to the environment and people’s livelihoods affected by flooding.”, “It’s the accumulated effect over time that will have an impact,” said Phil Thompson, an assistant professor at the University of Hawaii and the lead author of the new study, entitled "Rapid increases and extreme months in projections of United States high-tide flooding," published last month in Nature Climate Change. IPCC (2000) Emission Scenarios. The steric and dynamical ocean components (blue swath in Figure 5.8) were extracted from the ocean data provided by Pardaens et al. These include: climate patterns such as the El Nino, effects from the melting of modern and ancient ice sheets, and geologic processes, such as plate tectonics. The local steric and wind-driven components were determined from the same CMIP 3 global ocean models used to calculate the steric contribution to global sea-level rise. a Rates provided by Kelin Wang, Geological Survey of Canada, using the CAS3D-2 model described in Chapter 4. b Rates were averaged from an ensemble of 16 GIA models (see Table 4.3) and are represented so positive GIA means falling relative sea level. For the cryospheric component, the projection is the extrapolation from observed changes and the range includes a possible additional dynamic contribution. In using the current rates of vertical land motion in its projections, the committee assumed that the CGPS spatial pattern and rates in the two tectonic regions would remain constant for 2030, 2050, and 2100. The committee’s global projections for 2100 are substantially higher than the IPCC’s (2007) projection, mainly because of a faster growing cryosphere component, and are somewhat lower than the Vermeer and Rahmstorf (2009) projections. However, vertical land motions can vary at length scales that are considerably smaller than the CGPS station spacing, so interpolation using the CGPS data carries substantial risk of spatial aliasing. Pfeffer et al. To obtain values, TABLE 5.3 Regional Sea-Level Rise Projections (in cm) Relative to Year 2000. a Projection indicates the mean and ± standard deviation computed for the Pacific coast from the gridded data presented in Pardaens et al. The content is provided for information purposes only. SOURCE: Figure 10.31 from Meehl et al. In addition, the CAS3D-2 tectonic model suggests that, in the absence of a great earthquake, the general vertical land motion pattern or trend in Cascadia will not change significantly in the coming century. Thus, the committee assumed that direct climatically-forced surface mass balance is the primary control on future changes in the loss rate of glaciers and ice caps. (2007) extrapolation techniques and the Pfeffer et al. Some studies project the cryospheric contribution by extrapolating current observations into the future, but the results depend on assumptions about the future behavior of the system. (2011) projection by a factor of 4. High-tide flooding is increasingly occurring in coastal areas around the United States. The overlying contour lines are of the sea-level distribution in the baselne control simulations, averaged over a 120-year period (contours are every 0.2m).SOURCE: Pardaens et al. (2011). (2011a) estimated a sea-level contribution from the ice sheets of 15 ± 2 cm by 2050 and 56 cm (with no stated uncertainty) by 2100. In addition, the variance about the quadratic curve was computed for 21-year intervals centered on 2030, 2050, and for the last 20 years of the time series. Ranges are the means for B1 and A1Fl using the scaling in Table 10.7 of IPCC (2007; see also Table 5.1 of this report): (B1/A1B) = (0.1/0.13); (A1Fl/A1B) = (0.17/0.13). In this book a CD is included containing color figures of wetlands and estuaries in different parts of the world. * Includes a CD containing color figures of wetlands and estuaries in different parts of the world. The variations listed above were intended to capture the general magnitude of plausible changes in ice dynamics. North of Cape Mendocino, the coast is experiencing mean uplift, so vertical land motion contributes negatively to relative sea-level rise (although uncertainties are large and include positive contributions), whereas the coast south. Figure 5.6 compares the ranges of sea-level rise projected by the committee, IPCC (2007), and Vermeer and Rahmstorf (2009). Extreme events can raise sea level much faster than projected above. However, projections are lower north of Cape Mendocino because the land is being pushed upward as the ocean plate moves under the continental plate along the Cascadia Subduction Zone. And sea level rise is accelerating at a dangerous pace. To provide a range of projections for all six scenarios, the committee used the ratios of thermal expansion projections from Table 5.1. In the first 3 months of 1983, the west coast of the United States experienced a sequence of strong storms, with the coincidence of El Niño conditions, high astronomical tides, and large waves producing record sea levels along virtually the entire coast (see “Changes in Ocean Circulation” in Chapter 4). Based on their new scenarios, global sea level is very likely to rise . In Washington and Oregon, a great earthquake would cause some areas to immediately subside and sea level to suddenly rise perhaps by more than 1 m. This earthquake-induced rise in sea level would be in addition to the relative sea-level rise projected above. The blue band represents the model results for combined global steric and local dynamical sea-level change, averaged between 32° and 49° latitude, from 13 GCMs. In addition, the duration of these extremes would lengthen from 1 or 2 hours in the historical period to about 6 hours by 2100. Sea level rise is the dominant driver of increased coastal flood risk, both historically and in . FIGURE 5.1 Thermal expansion contribution to global sea-level rise calculated by a range of models for three emission scenarios: A1B, A2, and B1. The American Institute of Aeronautics and Astronautics (AIAA) is honoring Jet Propulsion Laboratory Director Watkins and Autonomous Systems Manager Gross, plus two European partners, for work on the GRACE missions. Tebaldi et al. Jane J. Lee / Ian J. O’Neill "During those events, sea level is elevated as much as a foot above normal and then we've got typically larger waves coming in with the high tides," particularly in the Northwest, he said. Uncertainty ranges are 1 standard deviation from the model means, and the gray shading is an added ± 7 percent, representing uncertainty in the fit of the data. c Extrapolation based on ice loss rates and gravitational attraction effects for Alaska, Greenland, and Antarctica. However, an earthquake magnitude 8 or larger, which occurs in the region every few hundred to 1,000 years, would cause the land to drop and sea level to suddenly rise. The committee’s projected values for 2030 and 2050 also are comparable to those of Tebaldi et al., (2012), although the committee found a larger north-south difference in the magnitude of sea-level rise. Thus to estimate sea-level rise at a particular locations, these distributions need to be added to projections of the global-averaged rise. FIGURE 5.14 Stratigraphy and abundance of foraminifera in the sediment sequence recording the 1700 earthquake at Siuslaw River, Oregon. The lower estimate assumed that present-day loss rates continued unchanged in the future. Great Earthquakes Along the Cascadia Subduction Zone. (2011a) projected a large dynamic contribution to sea-level rise from the ice sheets on the basis of past observations. This uncertainty arises from an incomplete understanding of the global climate system, the inability of global climate models to accurately represent all important components of the climate system at global or regional scales, a shortage of data at the temporal and spatial scales necessary to constrain the models, and the need to make assumptions about future conditions (e.g., population growth, technological developments, large volcanic eruptions) that drive the climate system. Given the larger size of the Amundson Coast outlet glaciers, it is reasonable to hypothesize that any reversals will occur on longer timescales than the committee’s projections. (2011) projection. New work on the time-varying aspects of dynamic response of outlet glaciers, such as the modeling study of Price et al. "It all comes down to the better data you have, the better decisions you can make.". Consequently, the committee used CGPS data in its projections of sea-level rise for 2030, 2050, and 2100. This chapter describes methods for projecting global and regional sea-level rise, summarizes recent results, and presents the committee’s own projections for the years 2030, 2050, and 2100, relative to year 2000. One of The Observer’s ‘Thirty books to help us understand the world’ Recycle. Fly less. Eat less meat. These are some of the ways that we’ve been told we can save the planet. “But if it floods 10 or 15 times a month, a business can’t keep operating with its parking lot under water. They projected that glaciers and ice caps would be the largest source of new water to the oceans throughout the 21st century (Table 5.1). Only a few studies have attempted to project 21st century sea-level rise along the west coast of the United States. After 1930, as ocean warming and water expansion kicked in, the rate of sea . They projected results to 2080. (2007) and Rignot et al. Northern California, Oregon and Washington can expect a less dramatic increase about four inches by 2030 and two feet by 2100 because seismic activity is causing land to rise north of the San Andreas Fault, offsetting increasing sea levels, and drop south of it. (2010), ±1 standard deviation computed for 20-year windows across models, and the range was determined by scaling the A1B projections for 2100 to the low value of B1 and the high value of A1FI for A1B, from Table 5.1. b The cryospheric projection is an extrapolation from observed changes, ±1 standard deviation. (2008) estimated future sea-level rise off Washington for 2050 and 2100, dividing the coastline into three regions according to their vertical land motions. Added to the world be found at: http: //www.wiley.com/go/church/sealevel are in. The cycle, tides are amplified: high tides get lower global climate models forced by the Environment.... 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