12:00 〜 12:15
[AOS19-06] Analysis of Sea level rise, Extreme coastal water levels and Vertical land motions produced by tectonic forces along the South American Pacific Coast
キーワード：sea level rise, extreme coastal water levels, vertical land motions, global warming
South American Pacific coasts (SAPC) behavior is subjected to oceanographic and tectonic conditions and those triggered by anthropogenic and climate change. The uncertainty about Extreme Coastal Water Levels (ECWL) which are defined as ECWL=RSLC+AT+SS+R2% Relative Sea Level Change (RSLC) Astronomical Tides (AT), Storm Surge (SS), and Waves Run-up (R2%), remains high worldwide, and along the SAPC studies analyzing them are scarce. A key factor for the region is the Vertical Land Motions (VLM) by tectonic processes, primarily due to the subduction of the Nazca plate beneath the South American plate. This process results in long-term uplift/subsidence rates of approximately 1 to 10 mm/yr, comparable in magnitude with sea level rise. This study aims to comprehend the regional SLR, historical ECWL, and future projections along the SAPC, considering interactions with tectonically induced VLMs.
Relative sea level (RSL) shows a strong dependency on local conditions. Analysis exhibits that if the global mean sea level (GMSL) is analyzed, presents a positive trend varying from 1.9 to 2.7 mm/yr, consistent with values reported in the Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC2 019). However, RSL trends derived from tide gauge records along the SAPC showed significant spatial variability, ranging from -5 to 20 mm/yr. If we analyze SSP585 projected SLR, for 2080-2100 is highest at middle latitudes (22-30°S) with values between 0.75-0.95 m, followed by lower latitudes (0-15°S) where values oscillate from 0.66-0.73 m. The lowest SLR projections for the same period occur at middle-high latitudes (45-55°S) with 0.50 m.
For the 1993-2019 period, historical ECWLs were assessed by combining measurements and numerical modeling. ECWL variability exceeds values over 5 m with a median value of 2.58 m ± 092 m, with trends strongly influenced by sea level anomalies (SLA) while R2% is the main contributor. Projections for the 2020-2100 period indicate changes in wave characteristics variability affecting R2%, and RSLC of about 0.5 to 1 m (medium confidence).
VLM trends were obtained integrating tide gauge and satellite altimetry data. The analysis reveals that long-term uplift/subsidence rates at tide gauge locations are larger than CMIP-6 projections for 2005-2020. Moreover, VLM rates exhibit greater variability than trends observed in ECWLs. To validate these findings, InSAR data were used to generate time series for five major cities along the SAPC over five ten-year periods. These results were then compared to values obtained from the satellite and tide gauge combination.
In conclusion, when comparing linear trends, both RSL and ECWL are strongly influenced by SLA. However, future projections highlight the crucial role of changes in wave characteristics for ECWL evolution. In the case of VLM, trends can exceed SLA contributions. Additionally, if earthquake-induced vertical displacements (coseismic displacements) are considered -an aspect currently under investigation- these could further alter projected trends, significantly affecting flood and erosion risks along SAPC coastlines.
Relative sea level (RSL) shows a strong dependency on local conditions. Analysis exhibits that if the global mean sea level (GMSL) is analyzed, presents a positive trend varying from 1.9 to 2.7 mm/yr, consistent with values reported in the Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC2 019). However, RSL trends derived from tide gauge records along the SAPC showed significant spatial variability, ranging from -5 to 20 mm/yr. If we analyze SSP585 projected SLR, for 2080-2100 is highest at middle latitudes (22-30°S) with values between 0.75-0.95 m, followed by lower latitudes (0-15°S) where values oscillate from 0.66-0.73 m. The lowest SLR projections for the same period occur at middle-high latitudes (45-55°S) with 0.50 m.
For the 1993-2019 period, historical ECWLs were assessed by combining measurements and numerical modeling. ECWL variability exceeds values over 5 m with a median value of 2.58 m ± 092 m, with trends strongly influenced by sea level anomalies (SLA) while R2% is the main contributor. Projections for the 2020-2100 period indicate changes in wave characteristics variability affecting R2%, and RSLC of about 0.5 to 1 m (medium confidence).
VLM trends were obtained integrating tide gauge and satellite altimetry data. The analysis reveals that long-term uplift/subsidence rates at tide gauge locations are larger than CMIP-6 projections for 2005-2020. Moreover, VLM rates exhibit greater variability than trends observed in ECWLs. To validate these findings, InSAR data were used to generate time series for five major cities along the SAPC over five ten-year periods. These results were then compared to values obtained from the satellite and tide gauge combination.
In conclusion, when comparing linear trends, both RSL and ECWL are strongly influenced by SLA. However, future projections highlight the crucial role of changes in wave characteristics for ECWL evolution. In the case of VLM, trends can exceed SLA contributions. Additionally, if earthquake-induced vertical displacements (coseismic displacements) are considered -an aspect currently under investigation- these could further alter projected trends, significantly affecting flood and erosion risks along SAPC coastlines.