Nature Quest: How High Will Sea Levels Rise?

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• Globally, sea levels are projected to be about 15 inches higher by 2050 compared to 1880s levels, a projection scientists are highly confident about for the next few decades.  Copied to clipboard!
• Regional sea level rise varies significantly across the U.S. due to factors like ocean currents, proximity to melting ice sheets, and local land movement (subsidence or uplift).  Copied to clipboard!
• While sea level rise in the immediate future (by 2050) is largely unavoidable, drastically cutting greenhouse gas emissions now can prevent catastrophic rise (3 to 10+ feet) after 2050.  Copied to clipboard!

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Listener Question Introduction

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(00:00:25)

• Key Takeaway: Peter Lansdale from Santa Cruz asked about sea level rise projections for the next few decades.
• Summary: The episode of Short Wave, part of the Nature Quest segment, addresses a listener question from Peter Lansdale in Santa Cruz, California. He is concerned about projected sea level rise and the potential damage to his coastal area. The hosts confirm the episode will cover projections, regional differences, and mitigation strategies.

Global and Near-Term Projections

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(00:04:01)

• Key Takeaway: Globally, oceans are projected to be 15 inches higher by 2050 than in the 1880s, a certainty due to thermal inertia.
• Summary: Globally, oceans are currently about nine inches higher than in the 1880s, and this rise is accelerating. By 2050, sea levels are projected to be about 15 inches higher worldwide. Scientists are highly confident in these near-term projections because the planet’s reaction to trapped heat involves a decades-long lag.

Santa Cruz Specific Forecast

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(00:05:30)

• Key Takeaway: Santa Cruz is expected to see about one foot of sea level rise by 2050 compared to the year 2000.
• Summary: For Santa Cruz specifically, scientists expect approximately one foot of sea level rise by 2050 relative to the year 2000 baseline. This is slightly less than the global average projection. The uncertainty range for this prediction is small, estimated at plus or minus a few inches.

Regional Variation Explained

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(00:06:50)

• Key Takeaway: Sea level rise rates vary regionally due to ocean currents, proximity to melting ice, and local land movement.
• Summary: Sea level rise is not uniform; for example, Galveston, Texas, faces upwards of two feet of rise by 2050, while Seattle faces less than one foot. This variation is caused by factors like ocean currents and the gravitational effects of melting ice sheets. Additionally, the expansion of ocean water due to heat absorption is a major driver of global sea level rise.

Land Movement Impact

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(00:09:43)

• Key Takeaway: Land sinking, such as on the Gulf Coast due to underground extraction, exacerbates sea level rise locally.
• Summary: The movement of land significantly contributes to differences in observed sea level rise along coastlines. If the land sinks while the water rises, the effective relative sea level rise is compounded. The Gulf Coast of the U.S. experiences some of the highest rates globally because land is sinking due to activities like oil extraction.

Mitigation and Future Choices

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(00:11:33)

• Key Takeaway: Stopping greenhouse gas emissions now will significantly reduce the severity of sea level rise occurring after 2050.
• Summary: While near-term sea level rise is largely locked in, pivoting to cleaner energy sources like solar and wind can prevent catastrophic rise beyond 2050. Avoiding extreme scenarios, which could mean 3 to 10 feet higher water levels, depends on current human choices regarding planet-warming pollution.