Edited by Michael L. Bender, Princeton University, Princeton, NJ, and approved November 5, 2019 (received for review December 27, 2018)
The glaciers near Puncak Jaya, Papua, Indonesia, the last tropical glaciers in the Western Pacific Warm Pool, have recently undergone a rapid pace of loss of ice cover and a 5.4-fold increase in the rate of thinning, augmented by the strong 2015–2016 El Niño. Ice cores recovered in 2010 record approximately the past half-century of tropical Pacific climate variability and reveal the effects of El Niño–Southern Oscillation (ENSO). It appears that the regional warming has passed a threshold such that the next very strong ENSO event, which typically exacerbates the rising freezing levels and associated feedbacks such as reduced snow cover, could lead to the demise of the only remaining tropical glaciers between the Himalayas and the Andes.
The glaciers near Puncak Jaya in Papua, Indonesia, the highest peak between the Himalayas and the Andes, are the last remaining tropical glaciers in the West Pacific Warm Pool (WPWP). Here, we report the recent, rapid retreat of the glaciers near Puncak Jaya by quantifying the loss of ice coverage and reduction of ice thickness over the last 8 y. Photographs and measurements of a 30-m accumulation stake anchored to bedrock on the summit of one of these glaciers document a rapid pace in the loss of ice cover and a ∼5.4-fold increase in the thinning rate, which was augmented by the strong 2015–2016 El Niño. At the current rate of ice loss, these glaciers will likely disappear within the next decade. To further understand the mechanisms driving the observed retreat of these glaciers, 2 ∼32-m-long ice cores to bedrock recovered in mid-2010 are used to reconstruct the tropical Pacific climate variability over approximately the past half-century on a quasi-interannual timescale. The ice core oxygen isotopic ratios show a significant positive linear trend since 1964 CE (0.018 ± 0.008‰ per year; P < 0.03) and also suggest that the glaciers’ retreat is augmented by El Niño–Southern Oscillation processes, such as convection and warming of the atmosphere and sea surface. These Papua glaciers provide the only tropical records of ice core-derived climate variability for the WPWP.
Author contributions: L.G.T., E.M.-T., and R.D.S. designed research; D.S.P., L.G.T., E.M.-T., M.E.D., P.-N.L., B.W.B., V.N.M., P.G., V.Z., K.R.M., W.H., M.N.H., Y.K., D.G., G.S., and R.D.S. performed research; D.S.P., L.G.T., M.E.D., P.-N.L., J.P.N., J.F.B., U.S., A.F., and B.G.M. analyzed data; D.S.P., L.G.T., E.M.-T., and M.E.D. wrote the paper; D.S.P., L.G.T., V.N.M., P.G., V.Z., K.R.M., W.H., Y.K., D.G., G.S., and R.D.S. supported the ice core drilling project and collected ice core samples; D.S.P., L.G.T., K.R.M., W.H., M.N.H., Y.K., and G.S. measured the stake accumulation; M.E.D., and P.-N.L. conducted the ice core stable isotope, dust, and chemical analyses; and U.S. conducted the ice core tritium analysis.
The authors declare no competing interest.
This article is a PNAS Direct Submission.
Data deposition: The data reported in this paper have been archived at the National Center for Environmental Information (NCEI) National Oceanic and Atmospheric Administration (NOAA) World Data Center for Paleoclimatology: https://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets/ice-core; https://www.ncdc.noaa.gov/paleo/study/24351.
This article contains supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.1822037116/-/DCSupplemental.
Published under the PNAS license.
