2025
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Sea level trend 2025 → 2100
Risk Outlook
Select a city to see its projected sea-level risk and how the outlook changes by 2100.
How Today's Emissions Decide Tomorrow's Climate
A climate story
How Today's Emissions Decide Tomorrow's Climate
▶ Demo video linkHow can your choices change the climate?
↓Atmospheric CO₂ has reached 428.7 ppm which is higher than at any point in the last 800,000 years. But what does that number actually mean? PPM stands for parts per million: the count of CO₂ molecules in every million molecules of air. Scientists have tracked this figure continuously since 1958 at the Mauna Loa Observatory in Hawaii, producing the longest unbroken record of atmospheric CO₂ in history known as the Keeling Curve. The steady rise you see in that curve is driven primarily by burning fossil fuels (coal, oil, and natural gas) and by deforestation, which releases carbon stored in trees back into the atmosphere. Before the Industrial Revolution, CO₂ held steady at roughly 280 ppm for thousands of years. We are now at 428.7 ppm — a roughly 52% increase in under 200 years.
Since the Industrial Revolution, human emissions have driven global temperatures up nearly 1°C above pre-industrial levels. This warming is already reshaping coastlines, intensifying storms, and accelerating ice melt across the planet.
Climate scientists have modeled four possible futures depending on how aggressively humanity reduces emissions.
Each choice below represents 10 million Americans making a change. Watch how collective decisions shift our trajectory.
Rising temperatures aren't just a number on a chart. They translate directly into rising seas, threatening the homes, infrastructure, and lives of millions of Americans in coastal cities. Explore how each emissions scenario plays out city by city, decade by decade.
Two factors beyond warming oceans amplify risk: ice melt from Greenland and Antarctica adds water volume, while land subsidence — the gradual sinking of coastal ground from groundwater extraction — means some cities are simultaneously being approached by rising seas and sinking toward them. Toggle this on in the map below to see the difference.
Sea level trend 2025 → 2100
Select a city to see its projected sea-level risk and how the outlook changes by 2100.
The data tells a clear story: the globe is warming, seas are rising, and the choices we make collectively determine how severe those changes become. The difference between SSP1-2.6 and SSP5-8.5 is not a matter of fate, it is a matter of decisions made by governments, industries, and individuals over the next few decades. Every fraction of a degree avoided is real infrastructure protected, real communities kept whole, real futures kept open.
You've just walked through what the science shows: where we are, how we got here, where each pathway leads, and what it means for the places people live. The window for meaningful action is narrow, but it is still open. The question the data cannot answer is which future we choose to build.