Sea Level Rise CoursePreview
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Lesson 3b. Digging into SLR Probabilities

2008 Study looked at multiple scenarios

IPCC in 2007 estimated .09 to 0.9 m SLR by 2100

What's been happening with sea level rise forecasts is that models keep getting adjusted for new information that tends to increase estimates of how much ice might melt in coming decades

No widely accepted method exists for probabilistic projections of SLR

Experts have been generally unwilling to assign probabilities to different levels of potential SLR, noting that we have no real basis for assigning probabilities

2017 It's all about probabilities

But if you can't differentiate between the probability of 2 feet, 6 feet, or 10 feet of SLR, you're not answering the questions people have

1800-2100 (2017) Revised global SLR scenarios

Bottom line conclusions

It was only in 2017 that NOAA came out with a study assigning probabilities, and it's worth noting that the probability of anything like 6-10 feet of SLR remains very small

2017 Probability of exceeding sea level rise scenario values

If you had to estimate the most likely level of SLR, it would be between 0.5 and 1.0 meters. But what should we do with the higher numbers, even if they're improbable?

For example, you would never get on an airplane that had a 1% chance of crashing, or even a .1 or .01% (still equivalent to 3 crashes a day). Small probabilities of large impacts matter! And that's where we are with SLR

1880-2100 (2014) Global SLR to 2100 based on IPCC scenarios

2010-2200 (2017) Global SLR scenarios by decade and for 2200

A lot of people are exposed. And there's a lot of uncertainty

So what can we say about the pace of sea level rise that risk-averse real estate market participants may want to assume?

1.5 feet by 2100 appears very likely under any emissions scenario. Would that be significant? Absolutely, especially given the interplay of tides and storm surges

SLR by scenario for several cities to 2060

But it could be a lot more. And we'll continue to learn a lot about what's happening in Greenland and Antarctica that could significantly revise the estimates.

So to summarize this thread

    1. There's a lot of uncertainty about the rate of SLR over the next several decades
    2. Estimates of possible SLR have increased dramatically in recent years
    3. Even the almost guaranteed levels of SLR would have major real estate impacts
    4. We'll learn a lot more in the next 20 years; as a coastal property owner are you feeling lucky?