Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).Peer reviewe

How rapidly can ice sheets retreat?

Landforms across the mid-Norwegian seafloor reveal that a former ice sheet retreated at up to 600 metres per day at the end of the last Ice Age. Pulses of similarly rapid retreat could soon be observed across flat-bedded areas of the Antarctic Ice Sheet.This work was funded by the Humanities and Social Sciences Faculty Research Fund, Newcastle University (to C.L.B.) and the financial assistance (to F.D.W.C.) of the Prince Albert II of Monaco Foundation

West Antarctic Peninsula seasonal ice velocity products supporting "Seasonal land-ice-flow variability in the Antarctic Peninsula"

This dataset contains the seasonal ice velocity products calculated from SAR- and optically derived velocity fields of land ice draining to George VI Ice Shelf. The dataset is provided in TIFF image (.tiff) format.This research was undertaken while KB was in receipt of a United Kingdom Natural Environment Research Council PhD studentship awarded through the University of Cambridge C-CLEAR Doctoral Training Partnership (grant number: NE/S007164/1). This work was also produced with financial assistance (to FDWC) of the Prince Albert II of Monaco Foundation, and (to ICW) from the United Kingdom Natural Environment Research Council awarded to the University of Cambridge (grant number: NE/T006234/1). TN and JW acknowledge support from the European Space Agency through the Antarctic Ice Sheet Climate Change Initiative (CCI) program

West Antarctic Peninsula grounding line location datasets supporting "Seasonal land-ice-flow variability in the Antarctic Peninsula"

This dataset contains the location of the grounding line along George VI Ice Shelf (West Antarctic Peninsula), Wilkins Ice Shelf and Bach Ice Shelf (Alexander Island), as determined from a compilation of datasets, including double-differential interferometric synthetic aperture radar (DInSAR) from Sentinel-1 imagery acquired May-October 2020, Sentinel-1 grounding-line information from 2018 (Mohajerani et al., 2021) and the MEaSUREs 1994-1996 grounding line dataset (Rignot et al., 2016). The dataset is provided in ESRI Shapefile (.shp) format.This research was undertaken while KB was in receipt of a United Kingdom Natural Environment Research Council PhD studentship awarded through the University of Cambridge C-CLEAR Doctoral Training Partnership (grant number: NE/S007164/1). This work was also produced with financial assistance (to FDWC) of the Prince Albert II of Monaco Foundation, and (to ICW) from the United Kingdom Natural Environment Research Council awarded to the University of Cambridge (grant number: NE/T006234/1). TN and JW acknowledge support from the European Space Agency through the Antarctic Ice Sheet Climate Change Initiative (CCI) program

Inter-decadal climate variability induces differential ice response along Pacific-facing West Antarctica.

West Antarctica has experienced dramatic ice losses contributing to global sea-level rise in recent decades, particularly from Pine Island and Thwaites glaciers. Although these ice losses manifest an ongoing Marine Ice Sheet Instability, projections of their future rate are confounded by limited observations along West Antarctica's coastal perimeter with respect to how the pace of retreat can be modulated by variations in climate forcing. Here, we derive a comprehensive, 12-year record of glacier retreat around West Antarctica's Pacific-facing margin and compare this dataset to contemporaneous estimates of ice flow, mass loss, the state of the Southern Ocean and the atmosphere. Between 2003 and 2015, rates of glacier retreat and acceleration were extensive along the Bellingshausen Sea coastline, but slowed along the Amundsen Sea. We attribute this to an interdecadal suppression of westerly winds in the Amundsen Sea, which reduced warm water inflow to the Amundsen Sea Embayment. Our results provide direct observations that the pace, magnitude and extent of ice destabilization around West Antarctica vary by location, with the Amundsen Sea response most sensitive to interdecadal atmosphere-ocean variability. Thus, model projections accounting for regionally resolved ice-ocean-atmosphere interactions will be important for predicting accurately the short-term evolution of the Antarctic Ice Sheet.Carnegie Trust for the Universities of Scotland Carnegie PhD Scholarship Scottish Alliance for Geoscience, Environment and Society (SAGES) Prince Albert II of Monaco Foundation NSF Grant 2045075 European Space Agenc

Drivers of Seasonal Land‐Ice‐Flow Variability in the Antarctic Peninsula

Publication status: PublishedFunder: Prince Albert II of Monaco Foundation; doi: http://dx.doi.org/10.13039/501100011592AbstractLand‐ice flow in Antarctica has experienced multi‐annual acceleration in response to increased rates of ice thinning, ice‐shelf collapse and grounding‐line retreat. Superimposed upon this trend, recent observations have revealed that land‐ice flow in the Antarctic Peninsula exhibits seasonal velocity variability with distinct summertime speed‐ups. The mechanism, or mechanisms, responsible for driving this seasonality are unconstrained at present, yet detailed, process‐based understanding of such forcing will be important for accurately estimating Antarctica's future contributions to sea level. Here, we perform time‐series analysis on an array of remotely sensed, modeled and reanalysis data sets to examine the influence of potential drivers of ice‐flow seasonality in the Antarctic Peninsula. We show that both meltwater presence and ocean temperature act as statistically significant precursors to summertime ice‐flow acceleration, although each elicits an ice‐velocity response after a distinct lag, with the former prompting a more immediate response. Furthermore, we find that the timing and magnitude of these local drivers are influenced by large‐scale climate phenomena, namely the Amundsen Sea Low and the El Niño Southern Oscillation, with the latter initiating an anomalous wintertime ice‐flow acceleration event in 2016. This hitherto unidentified link between seasonal ice flow and large‐scale climatic forcing may have important implications for ice discharge at and beyond the Antarctic Peninsula in the future, depending upon how the magnitude, frequency and duration of such climate phenomena evolve in a warming world.This research was undertaken while KB was in receipt of a United Kingdom Natural Environment Research Council PhD studentship awarded through the University of Cambridge C-CLEAR Doctoral Training Partnership (grant number: NE/S007164/1). This work was also produced with financial assistance (to FDWC) of the Prince Albert II of Monaco Foundation, and (to ICW) from the United Kingdom Natural Environment Research Council awarded to the University of Cambridge (grant number: NE/T006234/1). TN, JW and SS acknowledge support from the European Space Agency through the Antarctic Ice Sheet Climate Change Initiative (CCI) program (ESA/Contract No. 4000126813/19/I-NB) and 4DAntarctica project (ESA/Contract No. ESA/AO/1-9570/18/I-DT)

Rapid, buoyancy-driven ice-sheet retreat of hundreds of metres per day.

Rates of ice-sheet grounding-line retreat can be quantified from the spacing of corrugation ridges on deglaciated regions of the seafloor1,2, providing a long-term context for the approximately 50-year satellite record of ice-sheet change3-5. However, the few existing examples of these landforms are restricted to small areas of the seafloor, limiting our understanding of future rates of grounding-line retreat and, hence, sea-level rise. Here we use bathymetric data to map more than 7,600 corrugation ridges across 30,000 km2 of the mid-Norwegian shelf. The spacing of the ridges shows that pulses of rapid grounding-line retreat, at rates ranging from 55 to 610 m day-1, occurred across low-gradient (±1°) ice-sheet beds during the last deglaciation. These values far exceed all previously reported rates of grounding-line retreat across the satellite3,4,6,7 and marine-geological1,2 records. The highest retreat rates were measured across the flattest areas of the former bed, suggesting that near-instantaneous ice-sheet ungrounding and retreat can occur where the grounding line approaches full buoyancy. Hydrostatic principles show that pulses of similarly rapid grounding-line retreat could occur across low-gradient Antarctic ice-sheet beds even under present-day climatic forcing. Ultimately, our results highlight the often-overlooked vulnerability of flat-bedded areas of ice sheets to pulses of extremely rapid, buoyancy-driven retreat.This work was funded by a Humanities and Social Sciences Faculty Research Fund, Newcastle University (to CLB) and a Junior Research Fellowship, Peterhouse College, University of Cambridge (to AM). This document was also produced with the financial assistance (to FDWC and JAD) of the Prince Albert II of Monaco Foundation

Antarctic Seabed Assemblages in an Ice-Shelf-Adjacent Polynya, Western Weddell Sea.

Ice shelves cover ~1.6 million km2 of the Antarctic continental shelf and are sensitive indicators of climate change. With ice-shelf retreat, aphotic marine environments transform into new open-water spaces of photo-induced primary production and associated organic matter export to the benthos. Predicting how Antarctic seafloor assemblages may develop following ice-shelf loss requires knowledge of assemblages bordering the ice-shelf margins, which are relatively undocumented. This study investigated seafloor assemblages, by taxa and functional groups, in a coastal polynya adjacent to the Larsen C Ice Shelf front, western Weddell Sea. The study area is rarely accessed, at the frontline of climate change, and located within a CCAMLR-proposed international marine protected area. Four sites, ~1 to 16 km from the ice-shelf front, were explored for megabenthic assemblages, and potential environmental drivers of assemblage structures were assessed. Faunal density increased with distance from the ice shelf, with epifaunal deposit-feeders a surrogate for overall density trends. Faunal richness did not exhibit a significant pattern with distance from the ice shelf and was most variable at sites closest to the ice-shelf front. Faunal assemblages significantly differed in composition among sites, and those nearest to the ice shelf were the most dissimilar; however, ice-shelf proximity did not emerge as a significant driver of assemblage structure. Overall, the study found a biologically-diverse and complex seafloor environment close to an ice-shelf front and provides ecological baselines for monitoring benthic ecosystem responses to environmental change, supporting marine management

Rapid, buoyancy-driven ice-sheet retreat of hundreds of metres per day

Rates of ice-sheet grounding-line retreat can be quantified from the spacing of corrugation ridges on deglaciated regions of the seafloor1,2, providing a long-term context for the approximately 50-year satellite record of ice-sheet change3,4,5. However, the few existing examples of these landforms are restricted to small areas of the seafloor, limiting our understanding of future rates of grounding-line retreat and, hence, sea-level rise. Here we use bathymetric data to map more than 7,600 corrugation ridges across 30,000 km2 of the mid-Norwegian shelf. The spacing of the ridges shows that pulses of rapid grounding-line retreat, at rates ranging from 55 to 610 m day−1, occurred across low-gradient (±1°) ice-sheet beds during the last deglaciation. These values far exceed all previously reported rates of grounding-line retreat across the satellite3,4,6,7 and marine-geological1,2 records. The highest retreat rates were measured across the flattest areas of the former bed, suggesting that near-instantaneous ice-sheet ungrounding and retreat can occur where the grounding line approaches full buoyancy. Hydrostatic principles show that pulses of similarly rapid grounding-line retreat could occur across low-gradient Antarctic ice-sheet beds even under present-day climatic forcing. Ultimately, our results highlight the often-overlooked vulnerability of flat-bedded areas of ice sheets to pulses of extremely rapid, buoyancy-driven retreat. </p