SLR and Vertical Land Movement for Cities

Version: 1.0

For more information about this web app please visit: https://www.climsystems.com/slr-cities-app

For more information about CLIMsystems and our products please visit: https://www.climsystems.com

Disclaimer

The data and maps in this tool illustrate the scale of potential sea level rise. The information provided should be used ONLY as a screening-level app. As with the application of all climate-change related data, assumptions are made on future greenhouse gas emissions. All potential changes in sea level should be verified through a range of methods. The data and maps in this tool are provided “as is,” without warranty to their performance, merchantable state, or fitness for any particular purpose. The entire risk associated with using the results as well as the performance of the data is assumed by the user. This App should be used strictly as a reference tool only and not for design, navigation, permitting, or other legal purposes in any jurisdiction.

Disclaimer

The data and maps in this tool illustrate the scale of potential sea level rise. The information provided should be used ONLY as a screening-level app. As with the application of all climate-change related data, assumptions are made on future greenhouse gas emissions. All potential changes in sea level should be verified through a range of methods. The data and maps in this tool are provided “as is,” without warranty to their performance, merchantable state, or fitness for any particular purpose. The entire risk associated with using the results as well as the performance of the data is assumed by the user. This App should be used strictly as a reference tool only and not for design, navigation, permitting, or other legal purposes in any jurisdiction.

Welcome to the Sea Level Rise with Vertical Land Movement for Cities app

The base map depicts the projected sea level rise for the world's oceans in 2100 from a baseline in 1995 which range from 0 to 200cm (colours in the left-hand legend). The map also shows the population densities around the world scaled for a range of 0-500 persons/km2 (colours in the right-hand legend), so vulnerable cities in coastal areas are easy to spot.

The projection for sea level rise is based on the Fifth Assessment Report of the IPCC and shows the results of an ensemble of 28 General Circulation Models (GCMs) using the greenhouse gas emissions from the Representative Concentration Pathway (RCP) 8.5 under a high climate sensitivity. All the sea level data has been processed following Intergovernmental Panel on Climate Change (IPCC) guidelines. It also takes local vertical land movement into account.

Working with the app

Zoom in (double click) to take a closer look and click any location to add a pin and see a graph of projected values for the years 2020, 2040, 2060, 2080 and 2100, as well as the monthly deviations from the yearly mean. As the tool is taking Vertical Land Movement into account, that rate (in mm/year) is shown as well. You will notice that at a certain zoom level, the App obfuscates the areas outside the coastal zone. This is to indicate that the information generated (by clicking on a certain location) is meant for coastal areas.

More info

Additional information on the data and methods used for generating the data can be found in the Assist menu and on the CLIMsystems website (www.climsystems.com).

We look forward to your feedback.

- The Team at CLIMsystems.

Want more?

The sea level rise app does a great job showing sea level rise all around the world, taking into account the local variations in the driving processes, including vertical land movement and seasonal deviations.

However, it cannot show the uncertainties that can stem from the pre-set choices that were made:

1. The current representative concentration pathway is RCP8.5. It is one of four defined by the IPCC (Intergovernmental Panel on Climate Change). It is the most extreme scenario.
2. The climate sensitivity selected is high. It describes how strongly the global climate system responds to an increase in greenhouse gases. More conservative choices are low and medium.
3. The model output selected is the median (or 50-percentile) from a 28 GCM (Generalized Circulation Model, or Global Climate Model) ensemble. Other choices could be 25 or 75-percentile and/or a different set of models.
4. The effect of vertical land movement (VLM) is included. As this is a spatial interpolation of a relatively sparse set of observations at specific locations, in many cases it is an approximation of the real value. When the actual VLM is known for a location, a better projection could be made.
5. Focus is on the highest sea level in the year for both the baseline and the projected year (2020, 2040, 2060, 2080 or 2100). To compare with existing studies, the average sea level of the year would normally be used.
6. Only levels at 2020, 2040, 2060, 2080 and 2100 are shown, while other time-horizons may be required for a specific study.
7. No provisions are made for extreme sea level changes because of storm surges. Especially when future storm intensities may shift and the result could be profound changes in water levels and subsequent impacts.

CLIMsystems has tools and provides services that can deal with all of the provisos given above:

• SimCLIM-for-ArcGIS/Marine toolbar can generate sea level rise projections for any year, for any of the four RCPs, for any of the three climate sensitivities (low, medium and high), for any GCM or ensemble of GCMs (for any percentile) with or without vertical land movement: https://www.climsystems.com/simclimarcgis/
• SimCLIM 2013 has a local sea level rise generator that accepts local observed vertical land movement and can produce time-series projections, while it accepts all the choices regarding RCP, climate sensitivity and GCMs and ensembles of any number of GCMs: https://www.climsystems.com/simclim/
• CLIMsystems offers a service whereby the storm surge component is added to the sea level rise projections using an extreme event approach; this requires local observed extreme sea level events which can be sourced through CLIMsystems and its partners: http://www.metocean.co.nz/

Rundown

Sea levels around the globe are rising because of climate change. Temperatures in the atmosphere are going up because of greenhouse gas emissions, causing an increase in the melting of land-ice, and more importantly, raising the temperatures of the oceans’ surface and deeper waters. As water warms it expands (known as the 'thermal expansion' component of sea level rise, in contrast to the land ice component).

Other processes play a role as well. A local lowering of air-pressure of 10 mbar causes local sea level to rise 10 cm. Changes in ocean-currents, and even changes in the distribution of floating ice-masses like those that are diminishing in the Arctic, can all contribute to variations in sea level rise around the planet.

All these elements are modelled and expressed in the Global Climate Models (GCMs) which are publicly available from the Fifth Assessment Report (AR5) of the Intergovernmental Panel for Climate Change (IPCC). The CMIP5-data (Coupled Model Intercomparison Project Phase 5) of 28 GCM have been used to generate outputs in this App.

There is another critical and often overlooked factor that determines how sea level rise is experienced locally: land also moves up or down. This is usually a slow process but its magnitude is comparable to sea level rise. Thus when land rises, it lowers the rate of sea level rise experienced at that specific coastline, but when land sinks it exacerbates the local effects of sea level rise.

The app shows a global map of the combined processes of local (absolute) sea level rise and local vertical land movement. The sea level rise values are taken as the median value of an ensemble of 28 GCM’s, under the assumption of the largest greenhouse gas emissions as described by the RCP8.5 scenario in AR5. It also assumes a high climate sensitivity.

The vertical land movement values were generated from direct observations of continuous GPS (Global Positioning Systems; the SONEL program), and from trend analysis of tidal observations (the PSMSL program).

When a location is clicked on the map, the App shows a ruler with five future years (2020, 2040, 2060, 2080 and 2100), the sea level rise at these years compared to the baseline year of 1995 (in cm), the local Vertical Land Movement (in mm/year), and the variation over the months (in cm).