A5043995720- Geology and Paleoclimatology Research
- Climate variability and models
- Tree-ring climate responses
- Meteorological Phenomena and Simulations
- Atmospheric and Environmental Gas Dynamics
- Pleistocene-Era Hominins and Archaeology
- Time Series Analysis and Forecasting
- Isotope Analysis in Ecology
- Species Distribution and Climate Change
- Marine and environmental studies
- Advanced Thermodynamics and Statistical Mechanics
- Fractional Differential Equations Solutions
- Cryospheric studies and observations
- Plant Water Relations and Carbon Dynamics
- Oil and Gas Production Techniques
- Environmental Impact and Sustainability
- Archaeology and ancient environmental studies
- Complex Systems and Time Series Analysis
- Ecology and Vegetation Dynamics Studies
- Climate Change Policy and Economics
- thermodynamics and calorimetric analyses
- Reservoir Engineering and Simulation Methods
- Ecosystem dynamics and resilience
- Geochemistry and Geologic Mapping
- Geomagnetism and Paleomagnetism Studies
Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung
2020-2024
University of Potsdam
2021-2022
McGill University
2015-2021
Tenneco (United States)
1986
Abstract. Here we describe LegacyClimate 1.0, a dataset of the reconstruction mean July temperature (TJuly), annual (Tann), and precipitation (Pann) from 2594 fossil pollen records Northern Hemisphere, spanning entire Holocene, with some reaching back to Last Glacial Period. Two methods, modern analog technique (MAT) weighted averaging partial least squares regression (WA-PLS), reveal similar results regarding spatial temporal patterns. To reduce impact on reconstruction, vice versa, also...
Abstract. A mismatch between model- and proxy-based Holocene climate change, known as the “Holocene conundrum”, may partially originate from poor spatial coverage of reconstructions in, for example, Asia, limiting number grid cells model–data comparisons. Here we investigate hemispheric, latitudinal, regional mean time series time-slice anomaly maps pollen-based annual temperature, July precipitation 1908 records in Northern Hemisphere extratropics. Temperature trends show strong latitudinal...
The relatively short observational record limits our ability to understand the long-term variability of key climate factors like temperature and hydroclimate. Climate models paleoclimate proxies appear have variabilities that diverge from each other at local long time scales. But it is unclear whether these divergences also apply hydroclimate fundamentally different than variability.Here we evaluate over Common Era using a model (the Community Earth System Model-Last Millennium Ensemble,...
Abstract. It is virtually certain that the mean surface temperature of Earth will continue to increase under realistic emission scenarios, yet comparatively little known about future changes in climate variability. This study explores variability over large range climates simulated by Coupled Model Intercomparison Project Phase 5 and 6 (CMIP5/6) Paleoclimate Modeling 3 (PMIP3), including time slices Last Glacial Maximum, mid-Holocene, idealized experiments (1 % CO2 abrupt4×CO2). These states...
Abstract Classical Energy Balance Equations (EBEs) are differential equations of integer order ( h = 1), here we generalize this to fractional orders: the Fractional EBE (FEBE, 0 < ≤ 1). In FEBE, when Earth is perturbed by a forcing, temperature relaxes equilibrium via slow power‐law process: 1 exceptional (but standard) exponential case. Our FEBE derivation phenomenological, it complements derivations based on classical continuum mechanics heat equation (that imply 1/2 for surface...
Abstract Future precipitation levels remain uncertain because climate models have struggled to reproduce observed variations in temperature‐precipitation correlations. Our analyses of Holocene proxy‐based correlations and hydrological sensitivities from 2,237 Northern Hemisphere extratropical pollen records reveal a significant latitudinal dependence temporal among the early, middle, late Holocene. These are largely consistent with patterns obtained transient simulations (TraCE21k). While...
Data assimilation techniques, such as the Kalman Filter, have enabled development of complete climate field reconstructions over last millennium, commonly referred to paleoclimate reanalysis. These techniques effectively integrate data, facilitating understanding and attribution past events. The resulting spatio-temporal fields are invaluable for studying teleconnections exploring dynamical links between variables locations in past. However, when observation network is sparse, or proxies...
Abstract. On scales of ≈ 10 days (the lifetime planetary-scale structures), there is a drastic transition from high-frequency weather to low-frequency macroweather. This scale close the predictability limits deterministic atmospheric models; thus, in GCM (general circulation model) macroweather forecasts, noise. However, neither noise nor climate fully realistic. In this paper we show how simple stochastic models can be developed that use empirical data force statistics and realistic so even...
Abstract Reliable climate projections at the regional scale are needed in order to evaluate change impacts and inform policy. We develop an alternative method for based on transient sensitivity (TCS), which relies a linear relationship between forced temperature response strongly increasing anthropogenic forcing. The TCS is evaluated (5° by 5°), made accordingly 2100 using high low Representative Concentration Pathways emission scenarios. find that there large spatial discrepancies from 5...
We directly exploit the stochasticity of internal variability, and linearity forced response to make global temperature projections based on historical data a Green's function, or Climate Response Function (CRF). To problem tractable, we take advantage temporal scaling symmetry define CRF characterized by exponent
Abstract. Characterizing the variability across timescales is important for understanding underlying dynamics of Earth system. It remains challenging to do so from palaeoclimate archives since they are more often than not irregular, and traditional methods producing timescale-dependent estimates variability, such as classical periodogram multitaper spectrum, generally require regular time sampling. We have compared those using interpolation with interpolation-free methods, namely...
Variations in regional temperature have widespread implications for society, but our understanding of the amplitude and origin long-term natural variability is insufficient accurate projections. This especially case terrestrial variability, which currently thought to be weak over long timescales. By performing spectral analysis on climate reconstructions, produced using sedimentary pollen records from Northern Hemisphere last 8,000 years, coupled with instrumental data, we provide a...
Abstract The current global warming driven by human activities has been accentuated in Polar Regions due to the polar amplification, resulting large releases of ice that have impacts on circulation and sea level at scale. In Arctic, temperature increased three times rate, lead significant melt Greenland sheet decline. Yet, for Antarctica, impact is still poorly constrained given lack instrumental data decadal climate variability. Using a compilation 78 core records, we provide...
Abstract. We produce climate projections through the 21st century using fractional energy balance equation (FEBE): a generalization of standard (EBE). The FEBE can be derived from Budyko–Sellers models or phenomenologically application scaling symmetry to storage processes, easily implemented by changing integer order (derivative) term in EBE value. is defined three parameters: fundamental shape parameter, timescale and an amplitude, corresponding to, respectively, exponent h, relaxation...
Abstract. With rapid anthropogenic climate change future vegetation trajectories are uncertain. Climate-vegetation models can be useful for predictions but need extensive data on past validation and improving systemic understanding. Even though pollen provide a great source of this information, the is compositionally biased due to differences in taxon-specific relative productivity (RPP) dispersal. Here we reconstructed quantitative regional cover from global sedimentary set last 50 ka using...
Abstract With increased pressure from anthropogenic climate change, boreal forests are suspected to be approaching tipping points which could cause large-scale change in tree cover and affect global climatic feedback. However, evidence for this proposed is sparse relies heavily on observations short time scales remote sensing data space-for-time substitutions.&#xD;Here we make use of an extensive pollen set including over 450 records investigate the existence alternative stable forest...
Abstract. At scales of ≈ 10 days (the lifetime planetary scale structures), there is a drastic transition from high frequency weather to low macroweather. This close the predictability limits deterministic atmospheric models; so that in GCM macroweather forecasts, noise. But neither noise nor climate fully realistic. In this paper we show how simple stochastic models can be developped use empirical data force statistics and realistic even two parameter model outperform GCM's for annual...
Abstract. A mismatch between model- and proxy-based Holocene climate change, known as the conundrum, may partially originate from poor spatial coverage of reconstructions in, for example, Asia, limiting number grid-cells model-data comparisons. Here we investigate hemispheric, latitudinal, regional mean time-series well anomaly maps pollen-based annual temperature, July precipitation 1676 records in Northern Hemisphere extratropics. Temperature trends show strong latitudinal patterns differ...
Abstract. We produce climate projections through the 21st century using fractional energy balance equation (FEBE) which is a generalization of standard EBE. The FEBE can be derived either from Budyko–Sellers models or phenomenologically by applying scaling symmetry to storage processes. It easily implemented changing integer order (derivative) term in EBE value near 1/2. has two shape parameters: exponent H and relaxation time τ; its amplitude parameter equilibrium sensitivity (ECS). Two...
Abstract. Characterizing the variability across timescales is important to understand underlying dynamics of Earth system. It remains challenging do so from paleoclimate archives since they are more than often irregular and traditional methods produce timescale-dependent estimates such as classical periodogram multitaper spectrum generally require regular time sampling. We have compared those using interpolation with interpolation-free methods, namely Lomb-Scargle first-order Haar structure...
Global warming driven by human activities is expected to be accentuated in polar regions compared with the global average, an effect calledpolar amplification. Yet, for Antarctica, amplitude of still poorly constrained due short weather observations and largedecadal climate variability. Using a compilation 78 ice core records, we provide high-resolution reconstruction temperatures over thepast 1,000 years seven Antarctica direct evidence Antarctic amplification at regional continental...
Knowledge on natural climate variability is pivotal for making future projections. Previous studies demonstrated that centennial to millennial temperature lacking in model simulations and this bias spatially heterogeneous. Various mechanisms have been proposed might be important modulate low-frequency such as the ocean circulation, meridional gradient or external forcing sensitivity forcing, but evidence identify main driver(s) still debated. Here, we provide preliminary insights respective...