The US West Has Lost Nearly 400 Glaciers

2026 Briefing A 2026 PNAS study finds 398 glaciers in the lower 48 have vanished since mid-century and a third of the ice is gone. What it means for water. By Sustainability Awakening • Dr. Ahmad Mahmood

1,453 glaciers

Mid-century map USGS maps from the 1950s–80s showed 1,453 glaciers across the lower 48 states. Source: Fountain et al., PNAS 2026

398 glaciers are gone

Vanished 27% Share of mid-century glaciers that disappeared by about 2015. Source: PNAS 2026

A third of the area melted

Ice cover Mid-century 562 km² About 2015 367 km² Source: PNAS 2026

One third lost

Ice volume Before 19.7 km³ Now 13.2 km³ 89% of what is left sits in Washington’s North Cascades.

77% of the ice gone

Sierra Nevada Glaciers 94 → 64 Area 12.2 → 4.4 km² Source: PNAS 2026

Montana and Wyoming

Rockies Wind River, WY 116 → 74 Lewis Range, MT 176 → 145 Source: PNAS 2026

A double whammy

Why Hotter summers melt more ice, and winter rain replaces the snow that once fed it.

Late-summer water

Why it matters Glacier melt keeps streams cold in the driest weeks, vital for fish such as bull trout.

Only the tallest peaks

By 2100 Many remaining glaciers may be gone by 2100, surviving only on peaks such as Rainier and Hood. Source: Andrew Fountain, PSU

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Go deeper Read the full guide → Carbon Footprint Calculator Read the full glacier guide