Utilizing state of affairs based mostly stress testing to establish medium (2050) and long run (2100) sea degree rise dangers
This undertaking makes use of a state of affairs based mostly qualitative stress testing method to establish US coastal census tracts anticipated to adversely impacted by sea degree rise (SLR) within the medium (2050) and long run (2100). One Baseline and two ‘believable however extreme’ Adversarial eventualities have been designed protecting 1–7ft of sea degree rise.
The important thing observations by means of this evaluation have been that that outdoors of present FEMA excessive danger areas, there are ~3500 different census tracts alongside the contiguous US shoreline which might be anticipated to expertise a mean SLR improve of 1ft within the medium time period (by 2050). Long run (by 2100) an extra ~1660 census tracts are in danger for two–7ft of SLR. The observations for the medium time period are significantly essential provided that they’re anticipated to materialize irrespective of future emissions pathways or different local weather mitigation motion due the warming of the ocean that has already occurred because of local weather change³.
This undertaking predominantly makes use of Python knowledge evaluation libraries, e.g., pandas and geopandas in addition to some visualization libraries, e.g., matplotlib, seaborn. The code for this undertaking could be discovered right here. The information for this undertaking has predominantly been sourced from the US census bureau and from NOAA. Additional particulars could be present in Expertise and Knowledge part beneath
Why Coastal Actual Property and Why Sea Degree Rise?
About 40% of the US inhabitants, or ~128 million folks, reside in coastal counties¹. Whereas residential belongings typically have been battered by a slew of utmost climate occasions lately, e.g., hurricanes, wildfires and so forth., for these coastal residents, one other vital rising danger is flooding and property loss because of accelerated sea degree rise (SLR). Nonetheless, within the exploratory analysis for this undertaking, it was discovered that there could not but be a deep understanding of the total lengthen of potential SLR impacts. Due to this fact, this undertaking intends to carry consciousness to areas anticipated to be impacted within the medium time period (2050) and long run (2100) in varied eventualities of accelerated sea degree rise.
The Nationwide Oceanic and Atmospheric Administration (NOAA) is a number one US scientific company charged with monitoring oceanic and atmospheric conditions². Per NOAA’s 2022 Sea Degree Rise Technical Report³, sea ranges are presently rising at a considerably accelerated tempo in comparison with beforehand noticed ranges within the twentieth century: sea ranges alongside the contiguous US shoreline are anticipated to rise, on common, as a lot over the following 30 years (2020–2050) as they’ve during the last 100 years (1920–2020).
Over the long run (by 2100), SLR projections alongside the contiguous US shoreline range between 2–7ft on common in comparison with 2000 ranges. The variability in these projections is especially because of uncertainity about future inexperienced home fuel emission charges and resultant international warming, which is the important thing driver for SLR. Over the medium time period (by 2050), given the warming of the ocean that has already occurred because of local weather change³, contiguous US shoreline sea ranges are anticipated to rise between 1.3–2ft on common, irrespective of future emissions pathways or different local weather mitigation motion. Moreover, these increased sea ranges are additionally anticipated to trigger extra disruptive excessive tide flooding (HTF) occasions than occuring immediately: minor disruptive HTF occasions projected to extend from 3 occasions/yr in 2020 to >10 occasions/yr by 2050, and main harmful HTF occasions projected to extend from 0.04 occasions/yr in 2020 to 0.2 occasions/yr by 2050).
Venture Targets
In gentle of those projections for coastal sea degree rise for the contiguous US, the targets of this undertaking are twofold:
- To offer most people (potential dwelling patrons, mortgage lenders, et al.) a device to visualise the regional impacts of SLR over the medium time period (2050) and long run (2100). Sea degree rise is studied at varied severities starting from 1ft to 7ft.
- To offer particular info (FIPS codes) on the census tracts that may be impacted in every SLR severity state of affairs. Homebuyers and mortgage lenders can then issue on this census tract degree location info into their buy choices to entry how a lot of a haircut, if any, they wish to apply to their evaluation of property worth.
Situation Based mostly Method to Assess Lengthy Time period SLR Impacts
Over the long run, given the potential variability in SLR projections, this undertaking has been designed as a state of affairs based mostly qualitative stress take a look at. SLR eventualities have been designed based mostly on the rules utilized within the Federal Reserve Capital Stress Testing exercise⁴; one baseline state of affairs and two “believable however extreme” eventualities of SLR have been utilized to evaluate how the varied coastal counties/census tracts throughout the contiguous US could also be impacted at varied SLR ranges over the long term.
The particular ranges of SLR chosen for every of those eventualities have been based mostly on the 2022 NOAA SLR Technical Report³. Particularly, three NOAA SLR long run ranges are thought of on this undertaking: Low (0.6m or approxiamtely 2ft), Intermediate (1.2m or approxiamtely 4ft) and Excessive (2.2m or approxiamtely 7ft); these projected SLR ranges have been mapped to the qualitative stress testing eventualities as proven beneath:
- A Baseline Situation the place sea ranges are projected to rise 2 ft
- An Adversarial Situation the place sea ranges are projected to rise 4 ft
- A Severely Adversarial Situation the place sea ranges are projected to rise 7 ft
The Baseline state of affairs is mapped to NOAA’s long run “Low” SLR projection of roughly 2ft. This low projection is anticipated to materialize even at low emission ranges with >92% certainity in any respect ranges of world temperature rise3. The Adversarial and Severely Advserse Situations are supposed to be “believable however extreme”. NOAA’s low time period “Intermediate” SLR of roughly 4ft and “Excessive” SLR of roughly 7ft, have been thought of for the Advserse and Severely Adversarial eventualities respectively. These excessive SLRs are related to increased inexperienced home fuel emissions and corresponding bigger will increase in international temperatures in comparison with pre-industrial ranges. Excessive eventualities of SLR larger than 2.5m (roughly 8ft) are now not thought of believable by 2100³ and so the utmost SLR degree thought of on this undertaking is the “believable however extreme” NOAA Excessive SLR of 7feet for the Severely Adversarial Situation.
Further Evaluation for the Medium Time period
Along with long run SLR impacts, this undertaking additionally analyzes census tracts anticipated to be impacted by SLR over the medium time period (2050). Over the medium time period, SLR is certain on the decrease finish by 1ft and on the upper finish by 2ft for the contiguous US. Current scientific developments have led to an improved understanding of the components driving SLR and due to this fact, there’s much more confidence on this narrower vary (no matter the longer term course of emission pathways)³. On account of this improve confidence within the SLR predictions over the medium time period, this undertaking doesn’t use a state of affairs based mostly method for the medium time period. As an alternative, all contiguous US coastal census tracts in danger for SLR of 1ft by 2050 are thought of in danger over the medium time period on this undertaking.
Evaluation of Present Dangers vs Rising Dangers
This undertaking analyzed 20 coastal states within the contiguous United States protecting ~200 coastal counties and ~22K coastal census tracts inside them. Every census tract was analyzed when it comes to whether or not is it presently recognized to be in danger, i.e., “Present Danger Areas”, vs. if it could possibly be in danger sooner or later over the medium to long run, i.e., “Rising Danger Areas”.
The primary a part of the undertaking concerned understanding present dangers. When it comes to sea degree rise, one of many easiest types through which it may present itself can be flooding. The Federal Emergency Administration Company (FEMA) has recognized areas which might be at excessive danger for flooding (FEMA floodplains)⁵ . This undertaking used FEMA excessive danger floodplains as a proxy for areas which might be presently recognized to be in danger for coastal flooding. On this undertaking, these areas are thought of “Present Danger Areas”.
The second a part of this undertaking delved into figuring out census tracts that could be in danger over the medium or long run. This undertaking leveraged sea degree rise info from NOAA to establish census tracts that would grow to be an rising danger over the medium time period (2050) or long run (2100), i.e., “Rising Danger Areas”. With the intention to higher perceive the severity of danger of rising sea leveles, rising danger was divided into 4 classes — one class protecting the medium time period* and three state of affairs based mostly long run categores:
- Rising Medium Time period Danger (1 ft SLR by 2050)
- Rising Lengthy Time period Danger in Baseline Situation (2ft SLR by 2100)
- Rising Lengthy Time period Danger in Adversarial Situation (4ft SLR by 2100)
- Rising Lengthy Time period Danger in Sev. Adversarial Situation (7ft SLR by 2100)
*as given there’s extra confidence within the SLR predictions, no state of affairs based mostly method is required over the medium time period.
Key Observations
The important thing observations by means of this evaluation have been that that outdoors of present FEMA excessive danger areas, there are ~3500 different census tracts alongside the contiguous US shoreline which might be anticipated to expertise a mean SLR improve of 1ft within the medium time period (by 2050) and long run (by 2100) an extra ~1660 census tracts are in danger for two–7ft of SLR.
