A5036551272- Geology and Paleoclimatology Research
- Cryospheric studies and observations
- Methane Hydrates and Related Phenomena
- Climate variability and models
- Winter Sports Injuries and Performance
- Climate change and permafrost
- Geochemistry and Elemental Analysis
- Geological Studies and Exploration
- Geological formations and processes
- Isotope Analysis in Ecology
- Landslides and related hazards
- Arctic and Antarctic ice dynamics
- Oceanographic and Atmospheric Processes
- Marine and coastal ecosystems
- Pleistocene-Era Hominins and Archaeology
- Geophysics and Gravity Measurements
- Paleontology and Stratigraphy of Fossils
- Meteorological Phenomena and Simulations
- Marine and environmental studies
- Tree-ring climate responses
- Atmospheric and Environmental Gas Dynamics
- Geochemistry and Geologic Mapping
- Polar Research and Ecology
- Peatlands and Wetlands Ecology
- Groundwater and Isotope Geochemistry
University of Leeds
2016-2025
National Centre for Atmospheric Science
2024
The University of Western Australia
2022
University of Bristol
2008-2013
Abstract. The Last Glacial Maximum (LGM, ∼ 21 000 years ago) has been a major focus for evaluating how well state-of-the-art climate models simulate changes as large those expected in the future using paleoclimate reconstructions. A new generation of used to generate LGM simulations part Paleoclimate Modelling Intercomparison Project (PMIP) contribution Coupled Model (CMIP). Here, we provide preliminary analysis and evaluation results these experiments (PMIP4, most which are PMIP4-CMIP6)...
The 8.2 ka event was a period of abrupt cooling 1–3 °C across large parts the Northern Hemisphere, which lasted for about 160 yr. original hypothesis cause this has been outburst proglacial Lakes Agassiz and Ojibway. These drained into Labrador Sea in ∼0.5–5 yr slowed Atlantic Meridional Overturning Circulation, thus North region. However, climate models have not able to reproduce duration magnitude with forcing without including additional centennial-length freshwater forcings, such as...
The BRITICE‐CHRONO consortium of researchers undertook a dating programme to constrain the timing advance, maximum extent and retreat British–Irish Ice Sheet between 31 000 15 years before present. campaign across Ireland Britain their continental shelves, North Sea included 1500 days field investigation yielding 18 km marine geophysical data, 377 cores sea floor sediments, geomorphological stratigraphical information at 121 sites on land; generating 690 new geochronometric ages. These...
Abstract Abrupt climate changes in the past have been attributed to variations Atlantic Meridional Overturning Circulation (AMOC) strength. However, exact timing and magnitude of AMOC shifts remain elusive, which continues limit our understanding driving mechanisms such variability. Here we show a consistent signal 231 Pa/ 230 Th proxy that reveals spatially coherent picture western circulation over last deglaciation, during abrupt millennial-scale transitions. At onset observe an early...
Abstract. The last deglaciation, which marked the transition between glacial and present interglacial periods, was punctuated by a series of rapid (centennial decadal) climate changes. Numerical models are useful for investigating mechanisms that underpin change events, especially now some complex can be run multiple millennia. We have set up Paleoclimate Modelling Intercomparison Project (PMIP) working group to coordinate efforts transient simulations facilitate dissemination expertise...
Significance Peatlands are organic-rich wetlands that have acted as globally important carbon sinks since the Last Glacial Maximum. However, drivers of peat initiation poorly understood. Using a catalog radiocarbon dates combined with simulations past climates, we demonstrate in deglaciated landscapes North America, northern Europe, and Patagonia was driven primarily by warming growing seasons rather than any increase effective precipitation. In Western Siberia, which not glaciated, climatic...
Abstract Elucidating the source(s) of Meltwater Pulse 1a, largest rapid sea level rise caused by ice melt (14–18 m in less than 340 years, 14,600 years ago), is important for understanding mechanisms and links with abrupt climate change. Here we quantify how much what North American sheet could have contributed to driving an model two transient simulations last 21,000 years. Ice perturbed physics ensembles were run account uncertainties, constraining extent volume reconstructions ago...
Understanding the role of sediment-water interactions in oceanic cycling neodymium (Nd) isotopes is essential for its reliable use as a modern and palaeoceanographic tracer ocean circulation. However, exact processes that control Nd are poorly defined require an up-to-date knowledge sources, sinks transformation this to within (e.g. per GEOTRACES core mission). We propose considerable improvement Nd-source identification by providing extensive compilation published terrestrial marine...
Abstract. Paleoclimatic records provide valuable information about Holocene climate, revealing aspects of climate variability for a multitude sites around the world. However, such data also possess limitations. Proxy networks are spatially uneven, seasonally biased, uncertain in time, and present variety challenges when used concert to illustrate complex variations past climate. assimilation provides one approach reconstructing that can account diverse nature proxy while maintaining...
Abstract. Monsoon is the major manifestation of seasonal cycle in tropical regions, and there a wide range evidence from marine terrestrial data that monsoon characteristics are affected by changes Earth's orbital parameters. We consider 3 periods Eemian Holocene present some analogy configuration terms obliquity precession. Simulations with IPSL_CM4 ocean-atmosphere coupled model allow us to discuss response Indian African amplitude insolation forcing. Results show precession plays large...
Geological data for the Early Eocene (56-47.8 Ma) indicate extensive global warming, with very warm temperatures at both poles. However, despite numerous attempts to simulate this warmth, there are remarkable data-model differences in prediction of these polar surface temperatures, resulting so-called 'equable climate problem'. In paper, first time an ensemble a perturbed climate-sensitive model parameters approach has been applied modelling climate. We performed more than 100 simulations...
Abstract Understanding what drove Northern Hemisphere ice sheet melt during the last deglaciation (21–7 ka) can help constrain how sensitive contemporary sheets are to greenhouse gas (GHGs) changes. The roles of orbital forcing and GHGs in have previously been modeled but not yet quantified. Here for first time we calculate relative effect these forcings on North American by driving a dynamical model (GLIMMER‐CISM) with set unaccelerated transient deglacial simulations full primitive...
Abstract The cause of a rapid change in Atlantic Ocean circulation and northern cooling at the onset Heinrich Stadial 1 ~18.5 ka is unclear. Previous studies have simulated event using ice sheet and/or iceberg meltwater forcing, but these idealized freshwater fluxes been unrealistically large. Here we use different approach, driving high‐resolution drainage network model with recent time‐resolved global paleo‐ice reconstruction to generate realistic forcing. We input this flux Hadley Centre...
Ice stream evolution is a major uncertainty in projections of the future Greenland and Antarctic sheets. Accurate simulation ice requires an understanding number "ingredients" that control location behaviour flow. Here, we test influence geothermal heat flux, grid resolution, bed hydrology on simulated streaming. The palaeo-record provides snapshots evolution, with particularly well constrained sheet being British-Irish Sheet (BIIS). We implement new basal sliding scheme coupled...
Abstract Our limited understanding of millennial‐scale variability in the context last glacial period can be explained by lack a reliable modeling framework to study abrupt climate changes under realistic backgrounds. In this article, we describe new set long‐run Last Glacial Maximum experiments where such shifts were triggered different snapshots ice‐sheet meltwater derived from early stages deglaciation. Depending on location and magnitude forcing, observe three distinct dynamical regimes...
Abstract Collapse of ice sheets can cause significant sea level rise and widespread climate change. We examine the climatic response to meltwater generated by collapse Cordilleran‐Laurentide saddle (North America) ~14.5 thousand years ago (ka) using a high‐resolution drainage model coupled an ocean‐atmosphere‐vegetation general circulation model. Equivalent 7.26 m global mean in 340 years, caused 6 sverdrup weakening Atlantic Meridional Overturning Circulation (AMOC) Northern Hemisphere...
Abstract The source or sources of meltwater pulse 1A (MWP‐1A) at ~14.5 ka, recorded widely distributed sites as a sea level rise ~10–20 m in less than 500 years, is uncertain. A recent ice modeling study North America and Greenland has suggested that the collapse an saddle between Laurentide Cordilleran sheets, with eustatic equivalent (ESLE) ~10 m, may have been dominant contributor to MWP‐1A. To test this suggestion, we predict gravitationally self‐consistent changes from Last Glacial...
Seawater 234U/238U provides global-scale information about continental weathering and is vital for marine uranium-series geochronology. Existing evidence supports an increase in since the last glacial period, but timing amplitude of its variability has been poorly constrained. Here we report two seawater records based on well-preserved deep-sea corals from low-latitude Atlantic Pacific Oceans. The started to before major sea-level rise overshot modern value by 3 per mil during early...
Abstract. The penultimate deglaciation (PDG, ∼138–128 thousand years before present, hereafter ka) is the transition from glacial maximum (PGM) to Last Interglacial (LIG, ∼129–116 ka). LIG stands out as one of warmest interglacials last 800 000 (hereafter kyr), with high-latitude temperature warmer than today and global sea level likely higher by at least 6 m. Considering transient nature Earth system, climate ice-sheet evolution were certainly influenced changes occurring during...
Palsas and peat plateaus are climatically sensitive landforms in permafrost peatlands. Climate envelope models have previously related palsa/peat plateau distributions Europe to modern climate, but similar bioclimatic modelling has not been attempted for North America. Recent climate change rendered many palsas/peat this region, their valuable carbon stores, vulnerable. We fitted a binary logistic regression model predict presence America by relating the distribution of 352 extant gridded...
Abstract. The last deglaciation (∼20–11 ka BP) is a period of major, long-term climate transition from glacial to interglacial state that features multiple centennial- decadal-scale abrupt variations whose root cause still not fully understood. To better understand this time period, the Paleoclimate Modelling Intercomparison Project (PMIP) has provided framework for an internationally coordinated endeavour in simulating whilst encompassing broad range models. Here, we present multi-model...