How have the glaciers changed?

Ice lost each year, measured on the ground

Measuring a glacier's yearly gain or loss takes a team on the ice every year, so only a few glaciers have long records. These nine are the long yearly records in the North Cascades near us: South Cascade Glacier, measured by the USGS since 1959, and eight glaciers measured by the North Cascade Glacier Climate Project since 1984 or 1990, four of them on Mount Baker and Mount Shuksan. They stand in for the hundreds of glaciers no one measures every year, which share the same weather. Tap a bar to see that year.

Why glaciers matter in Whatcom County

Glaciers are the mountains' slowest water storage. Snow lasts into early summer; glacier ice keeps melting through August and September, when little rain falls and the snow is gone.

• Salmon. Glacier melt keeps rivers cool and flowing in late summer. A study with the Nooksack Indian Tribe found that during summer heat waves (2013–2021), flow in the glacier-fed North Fork rose by about a quarter while the rain-fed South Fork fell by about a fifth (Columbia Climate School, 2022).
• Drinking water. Bellingham tops up Lake Whatcom with water diverted from the Middle Fork of the Nooksack, the river that drains Mount Baker's Deming Glacier (City of Bellingham).
• Snow feeds the glaciers. A glacier grows when winter snow outlasts summer melt. For the snowpack itself, see Snow.

Reading this page

• Glacier outlines come from different methods and dates. The old outlines were drawn by hand on USGS topographic maps from aerial photos, and each map has its own date: from the 1950s to the 1980s. The newer outlines come from aerial imagery, mostly of 2015. Both were digitized by Portland State University and include permanent snowfields. The old maps tended to include seasonal snow, so small differences are within the error of the comparison; large ones are real.
• The 2025 outlines are whatcom.land's own estimate, from Sentinel-2 satellite images of 23 September 2025, measured the same way on 4 October 2015 and checked against the 2015 outlines (large glaciers agree within 1%). They show visible ice on one late-summer day. Ice buried under rock and gravel can't be seen from space, so those parts keep their 2015 outline: the estimate leans to too much ice, not too little. Leftover winter snow can hide the edge, and small patches are the least certain.
• Ice lost each year is a glacier's mass balance: winter snow added minus snow and ice melted in summer. It is written as a depth, like rainfall: the water lost, spread evenly over the glacier, so it says how much thinner the glacier got on average (divide by 0.9 for metres of ice). Times the glacier's area, it gives the volume. It is measured on the ground every year, at South Cascade Glacier by the USGS since 1959 and at four glaciers on Mount Baker and Mount Shuksan, and four more farther south, by the North Cascade Glacier Climate Project (Mauri Pelto) since 1984 or 1990. The glacier's year runs October to September, like a snow season, and is named for the year it ends.
• Area is in square kilometres. One km² is about 250 acres, or roughly 140 soccer fields.