Dynamic mass loss from Greenland's marine-terminating peripheral glaciers (1985-2018)

Global glacier mass balance decreased rapidly over the last two decades, exceeding mass loss from the Greenland and Antarctic Ice Sheets. In Greenland, peripheral glaciers and ice caps (GICs) cover only similar to 5% of Greenland's area but contributed similar to 20% of the island's ice mass loss between 2000 and 2018. Although Greenland GIC mass loss due to surface meltwater runoff has been estimated using atmospheric models, mass lost to changes in ice discharge into oceans (i.e., dynamic mass loss) remains unquantified. We use the flux gate method to estimate discharge from Greenland's 585 marine-terminating peripheral glaciers between 1985 and 2018, and compute dynamic mass loss as the discharge anomaly relative to the 1985-98 period. Greenland GICs discharged between 2.94 +/- 0.23 and 4.03 +/- 0.23 Gt a(-1) from 1985 to 1998, depending on the gap-filling method, and abruptly increased to 5.10 +/- 0.21 Gt a(-1) from 1999 to 2018. The resultant similar to 1-2 Gt a(-1) dynamic mass loss was driven by synchronous widespread acceleration around Greenland. The mass loss came predominantly from the southeast region, which contains 39% of the glaciers. Although changes in discharge over time were small relative to surface mass-balance changes, our speed and discharge time series suggest these glaciers may quickly accelerate in response to changes in climate.