Sea-Level and Climate Change

This paper presents an evaluation of the global and regional consequences of climate change for heat extremes, water resources, river and coastal flooding, droughts, agriculture and energy use. It presents change in hazard and resource base under different rates of climate change (representative concentration pathways (RCP)), and socio-economic impacts are estimated for each combination of RCP and shared socioeconomic pathway. Uncertainty in the regional pattern of climate change is characterised by CMIP5 climate model projections. The analysis adopts a novel approach using relationships between level of warming and impact to rapidly estimate impacts under any climate forcing. The projections provided here can be used to inform assessments of the implications of climate change. At the global scale all the consequences of climate change considered here are adverse, with large increases under the highest rates of warming. Under the highest forcing the global average annual chance of a major heatwave increases from 5% now to 97% in 2100, the average proportion of time in drought increases from 7% to 27%, and the average chance of the current 50 year flood increases from 2% to 7%. The socio-economic impacts of these climate changes are determined by socio-economic scenario. There is variability in impact across regions, reflecting variability in projected changes in precipitation and temperature. The range in the estimated impacts can be large, due to uncertainty in future emissions and future socio-economic conditions and scientific uncertainty in how climate changes in response to future emissions. For the temperature-based indicators, the largest source of scientific uncertainty is in the estimated magnitude of equilibrium climate sensitivity, but for the indicators determined by precipitation the largest source is in the estimated spatial and seasonal pattern of changes in precipitation. By 2100, the range across socioeconomic scenario is often greater than the range across the forcing levels.

Section: Climate Forcings and Increases In Temperature And Sea Levelmentioning

confidence: 66%

The global and regional impacts of climate change under representative concentration pathway forcings and shared socioeconomic pathway socioeconomic scenarios

Arnell

Lowe

Bernie

et al. 2019

“…Therefore, semi-empirical projections should be viewed as lower limits which do not fully represent the high-end tail. However, recent work showing agreement between the process-based GMSL projections preferred by the IPCC's Fifth Assessment Report (Church et al 2013) and a semi-empirical model calibrated to the last two millennia (Kopp et al 2016a) suggests that semiempirical models are particularly well suited to examining temperature scenarios, such as those consistent with the Paris Agreement, in which the focus is on relatively short-term (next 100-200 years) and small (less than 2.0 • C) temperature changes.…”

Section: Semi-empirical Model Development and Calibrationmentioning

confidence: 99%

Global mean sea-level rise in a world agreed upon in Paris

Bittermann

Rahmstorf

Kopp

et al. 2017

Although the 2015 Paris Agreement seeks to hold global average temperature to 'well below 2 • C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5 • C above pre-industrial levels', projections of global mean sea-level (GMSL) rise commonly focus on scenarios in which there is a high probability that warming exceeds 1.5 • C. Using a semi-empirical model, we project GMSL changes between now and 2150 CE under a suite of temperature scenarios that satisfy the Paris Agreement temperature targets. The projected magnitude and rate of GMSL rise varies among these low emissions scenarios. Stabilizing temperature at 1.5 • C instead of 2 • C above preindustrial reduces GMSL in 2150 CE by 17 cm (90% credible interval: 14-21 cm) and reduces peak rates of rise by 1.9 mm yr −1 (90% credible interval: 1.4-2.6 mm yr −1 ). Delaying the year of peak temperature has little long-term influence on GMSL, but does reduce the maximum rate of rise. Stabilizing at 2 • C in 2080 CE rather than 2030 CE reduces the peak rate by 2.7 mm yr −1 (90% credible interval: 2.0-4.0 mm yr −1 ).

“…We use them as possible 'what-if'-scenarios. Le Bars et al included contributions from thermal expansion, Greenland and Antarctic ice sheets, glaciers and ice caps, and land water storage, similar to Church et al [27] but assuming DeConto and Pollard [29] projections for Antarctica, where hydro-fracturing and ice cliff failure lead to a rapid destabilization of the ice sheet. The sea level contributions are modulated by their spatial fingerprints representing gravitational, rotational and the short-term (elastic) earth response to mass loading changes [63].…”

Section: Slr Scenariosmentioning

confidence: 99%

“…The sea level contributions are modulated by their spatial fingerprints representing gravitational, rotational and the short-term (elastic) earth response to mass loading changes [63]. The regional redistribution of ocean water due to changes in winds, ocean currents and local steric effects from the CMIP5 models [27,64,65] are taken into account to translate the global mean SLR to regional SLR along the Dutch coast. A Monte Carlo method is used to propagate the uncertainty between individual sea level contributors and the total sea level [66].…”

Section: Slr Scenariosmentioning

confidence: 99%

“…Similar to other coastal zones, the Dutch Delta Program relies on SLR-assessments from the Intergovernmental Panel on Climate Change (IPCC), which are further tailored to local scenarios [24]. Over the past decades, SLR scenarios from the IPCC were fairly stable, envisaging a global mean SLR up to 1.1 m between 1990 and 2100 [25,26] with a likely range (representing at least 66% probability) of 0.26-0.98 m in the IPCC Fifth Assessment Report [27]. In the recent Special Report on Oceans and Cryosphere in a changing Climate (SROCC) [28], the upper bound of the likely range was adjusted upwards to 1.1 m in 2100 for a high emission scenario (Representative Concentration Pathway (RCP) 8.5).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Adaptation to uncertain sea-level rise; how uncertainty in Antarctic mass-loss impacts the coastal adaptation strategy of the Netherlands

Haasnoot

Kwadijk

Alphen³

et al. 2020

111

Uncertainties in the rate and magnitude of sea-level rise (SLR) complicate decision making on coastal adaptation. Large uncertainty arises from potential ice mass-loss from Antarctica that could rapidly increase SLR in the second half of this century. The implications of SLR may be existential for a lowlying country like the Netherlands and warrant exploration of high-impact low-likelihood scenarios. To deal with uncertain SLR, the Netherlands has adopted an adaptive pathways plan. This paper analyzes the implications of storylines leading to extreme SLR for the current adaptive plan in the Netherlands, focusing on flood risk, fresh water resources, and coastline management. It further discusses implications for coastal adaptation in low-lying coastal zones considering timescales of adaptation including the decisions lifetime and lead-in time for preparation and implementation. We find that as sea levels rise faster and higher, sand nourishment volumes to maintain the Dutch coast may need to be up to 20 times larger than to date in 2100, storm surge barriers will need to close at increasing frequency until closed permanently, and intensified saltwater intrusion will reduce freshwater availability while the demand is rising. The expected lifetime of investments will reduce drastically. Consequently, step-wise adaptation needs to occur at an increasing frequency or with larger increments while there is still large SLR uncertainty with the risk of under-or overinvesting. Anticipating deeply uncertain, high SLR scenarios helps to enable timely adaptation and to appreciate the value of emission reduction and monitoring of the Antarctica contribution to SLR.