Darwin glacier melts away – From a Glaciers Perspective

Darwin Glacier on 8-29-2022 in Sentinel False Color image with area reduced to 0.026 km². No longer a glacier there is still relict ice clinging to the slope, in the next six weeks further melt reduced volume significantly.

Darwin Glacier on July 19, 2022 with the moraine that the glacier was in contact with in the 1990s-yellow dots, and curent margin green dots. The blue arrows indicate rock area emerging as glacier thins. Slope has steepened and bergshrund is melting out (sierralara.com, image)

The Sierra Nevada, California has a number of small glaciers that have clung to the north facing slopes of the High Sierra. Darwin Glacier is one of those glaciers on the north side of Mount Darwin. named for Charles Darwin. The glacier is in Kings Canyon National Park and drains into the San Joaquin River.

In 1903 the glacier had an area of 0.25 km², declining 40% by 1948, 0.14 km² Basagic and Fountain (2011). The glacier expanded beginning in the 1970s and ending in the 1990s, with an area of 0.157 km² in 1976 (GLIMS), and then had declined slightly in 2001 had an area of 0.135 km², 5-10% greater than in 1948. In 2004 area loss was increasing with the area measured in the field by Basagic and Fountain (2011), at 0.114 km² .

With a steep slope of ~30 degrees, the glacier depends on snow sloughing/avalanching off the north face of Mount Darwin and piling up against a moraine. Retreat from this moraine after 2004 has led to steepening of the glacier with less snowcover retained on its surface. From 2004 to 2022 the glacier rapidly lost volume and area. In 2014 the glacier area had declined 50% to 0.057 km² (GLIMS), in 2018 the glacier area was 0.048 km². The particularly warm summers of 2021 and 2022 led to further rapid decline to 0.038 km² in 2021 and 0.026 km² in 2022. At this time Darwin Glacier and was no longer a glacier with less than 20% of relict ice left from 2004, and with movement having ceased. The glacier bergshrund is also melting out. Bare rock was was also being exposed at several areas amidst the glacier area in 2022.

Just to the south Mount Fiske Glacier has disappeared as well, along with the glacier that was in the cirque on the north side of Mt. Mendel. The high snowfall winters of 2023 and 2024 have been offset by continued warm summers, preventing any significant volume increase.

**Darwin and Mt. Fiske Glacier on 1976 USGS Topographic map with areas of 0.16 km² and 0.08 km² respectively.**

**Darwin Glacier in 2018 Sentinel false color image with an area of 0.048 km².**

**Darwin Glacier and Fiske Glacier no longer have sufficient area to qualify as glaciers at 0.026 km² for Darwin Glacier and 0.008 km² for Fiske Glacier. No retained snowcover in 2021 or 2022.**

**Darwin Glacier on August 29, 2021 in Sentinel false color image. There is no retained snowcover and area has declined to 0.036 km².**

**Darwin Glacier on August 28, 2024 in Sentinel false color image. There are two areas where area loss from 2022 is evident, despite 60% of the glacier still having snow cover.**

These losses are similar to those observed on Whitney Glacier, Mount Shasta. The NCEI NOAA Division 5 climate data for this area indicates that meltseason temperatures have been the primary cause of the recent decline, though declining accumulation season precipitation has been as well, see bottom.