Manuel Chevalier

Manuel Chevalier
University of Bonn | Uni Bonn · Institute for Geosciences; Meteorology department

Ph.D.

About

64
Publications
23,085
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1,113
Citations
Additional affiliations
September 2020 - October 2023
University of Bonn
Position
  • PostDoc Position
February 2017 - January 2020
University of Lausanne
Position
  • PostDoc Position
January 2016 - December 2016
French National Centre for Scientific Research · Institut des Sciences de l’Évolution Montpellier (ISEM)
Position
  • PostDoc Position

Publications

Publications (64)
Article
Full-text available
Statistical climate reconstruction techniques are fundamental tools to study past climate variability from fossil proxy data. In particular, the methods based on probability density functions (or PDFs) can be used in various environments and with different climate proxies because they rely on elementary calibration data (i.e. modern geolocalised pr...
Preprint
Full-text available
A mismatch between model- and proxy-based Holocene climate change, known as the Holocene conundrum, may partially originate from the poor spatial coverage of climate reconstructions in, for example, Asia, limiting the number of grid-cells for model-data comparisons. Here we investigate hemispheric, latitudinal, and regional mean time-series as well...
Preprint
Full-text available
Here we describe the LegacyClimate 1.0, a dataset of the reconstruction of mean July temperature (TJuly), mean annual temperature (Tann), and annual precipitation (Pann) from 2594 fossil pollen records from the Northern Hemisphere spanning the entire Holocene with some records reaching back to the Last Glacial. Two reconstruction methods, the Moder...
Preprint
Full-text available
Statistical climate reconstruction techniques are practical tools to study past climate variability from fossil proxy data. In particular, the methods based on probability density functions (PDFs) are powerful at producing robust results from various environments and proxies. However, accessing and curating the necessary calibration data, as well a...
Data
Interpretations of fossil pollen data are often limited to broad, qualitative assessments of past climatic and environmental conditions (e.g. colder vs. warmer, wetter vs. drier, open vs. closed landscape). These assessments can be particularly imprecise in regions such as southern Africa, where botanical biodiversity is high, and there exists an a...
Article
The East Asian summer monsoon (EASM) precipitation is vital to hydrology, ecology and societal activities in the densely populated region of East Asia. However, its long-term evolution history and driving forces during the relatively warm Miocene remain unclear, even conflicting in some intervals. Here, we present a new, and quantitative record of...
Article
Full-text available
Charcoal identification and the quantification of its abundance in sedimentary archives is commonly used to reconstruct fire frequency and the amounts of biomass burning. There are, however, limited metrics to measure past fire temperature and fuel type (i.e. the types of plants that comprise the fuel load), which are important for fully understand...
Article
Full-text available
The southwestern Cape of South Africa is a particularly dynamic region in terms of long-term climate change. We analysed fossil pollen from a 25,000 year sediment core taken from a near-coastal wetland at Pearly Beach that revealed that distinct changes in vegetation composition occurred along the southwestern Cape coast. From these changes, consid...
Article
Full-text available
The Amazon forest is increasingly vulnerable to dieback and encroachment of grasslands and agricultural fields. Threats to these forested ecosystems include drying, deforestation, and fire, but feedbacks among these make it difficult to determine their relative importance. Here, we reconstruct the central and western Amazon tree cover response to a...
Article
Changes in lake status are often interpreted as palaeoclimate indicators due to their dependence on precipitation and evaporation. The Global Lake Status Database (GLSDB) has since long provided a standardised synopsis of qualitative lake status over the last 30,000 ¹⁴C years. Potential sources of uncertainty however are not recorded in the GLSDB....
Article
Full-text available
Fossil pollen records are well-established indicators of past vegetation changes. The prevalence of pollen across environmental settings including lakes, wetlands, and marine sediments, has made palynology one of the most ubiquitous and valuable tools for studying past environmental and climatic change globally for decades. A complementary research...
Article
Full-text available
The Eurasian (née European) Modern Pollen Database (EMPD) was established in 2013 to provide a public database of high-quality modern pollen surface samples to help support studies of past climate, land-cover and land-use using fossil pollen. The EMPD is part of, and complementary to, the European Pollen Database (EPD) which contains data on fossil...
Article
Full-text available
Across the glacial-interglacial cycles of the late Pleistocene (~700 k.y.), temperature variability at low latitudes is often considered to have been negligible compared to changes in precipitation. However, a paucity of quantified temperature records makes this difficult to reliably assess. In this study, we used the Bayesian method CREST (Climate...
Article
Full-text available
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Article
Full-text available
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Article
Full-text available
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Article
Full-text available
A comprehensive database of paleoclimate records is needed to place recent warming into the longer-term context of natural climate variability. We present a global compilation of quality-controlled, published, temperature-sensitive proxy records extending back 12,000 years through the Holocene. Data were compiled from 679 sites where time series co...
Article
Full-text available
A comprehensive understanding of the relationship between land cover, climate change, and disturbance dynamics is needed to inform scenarios of vegetation change on the African continent. Although significant advances have been made, large uncertainties exist in projections of future biodiversity and ecosystem change for the World’s largest tropica...
Preprint
Full-text available
Abstract. The Eurasian (née European) Modern Pollen Database (EMPD) was established in 2013 to provide a public database of high-quality modern pollen surface samples to help support studies of past climate, land-cover and land-use using fossil pollen. The EMPD is part of, and complementary to, the European Pollen Database (EPD) which contains data...
Article
Full-text available
The progress of science is tied to the standardization of measurements, instruments, and data. This is especially true in the Big Data age, where analyzing large data volumes critically hinges on the data being standardized. Accordingly, the lack of community-sanctioned data standards in paleoclimatology has largely precluded the benefits of Big Da...
Article
The Cape Floristic Region (CFR) is one of the world's major biodiversity hotspots, and much work has gone into identifying the drivers of this diversity. Considered regionally in the context of Quaternary climate change, climate stability is generally accepted as being one of the major factors promoting the abundance of species now present in the C...
Article
Full-text available
Despite being one of the world’s oldest deserts, and the subject of decades of research, evidence of past climate change in the Namib Desert is extremely limited. As such, there is significant debate regarding the nature and drivers of climate change in the low-latitude drylands of southwestern Africa. Here we present data from stratified accumulat...
Article
The field of quantitative palaeoclimatology has made significant progress in the past decades. However, this progress has been spatially heterogeneous and strong discrepancies – both in terms of quality and density – exist between Europe and North America and the rest of the world. The need to balance this distribution of quantified records has nev...
Article
Full-text available
As climate model uncertainties remain very large for future rainfall in the Sahel, a multi-centennial perspective is required to assess the situation of current Sahel climate in the context of global warming. We present here the first record of hydroclimatic variability over the past 1600 years in Senegal, obtained from stable oxygen isotope analys...
Data
This database contains all the presence records of plants, beetles, chironomids, foraminifera and diatoms contained in the GBIF database in October 2020. The coordinates of the presence records have been homogenised on a 0.25x0.25° grid, and corresponding bioclimatic values from the Worldclim2.0 database have been added. These data are formatted...
Data
Page 1: Senilia senilis raw isotopic and stratigraphic data. Dates of archaeological samples were obtained from Bacon age models. Page 2: 1600-yr Saloum shell d18O record calculated with a Monte Carlo resampling method (see Matlab code in supplementary information)
Presentation
Full-text available
In an age of digital data analysis, gaining access to data from the pre-digital era – or any data that is only available as a figure on a page – remains a problem and an under-utilized scientific resource. Whilst there are numerous programs available that allow the digitization of scientific data in a simple x-y graph format, we know of no semi-aut...
Article
Full-text available
The southern Cape is a particularly dynamic region of South Africa in terms of climate change as it is influenced by both temperate and tropical circulation systems. This paper presents pollen and microcharcoal data generated from a sediment core extracted from the coastal lake Eilandvlei spanning the last $8900 years. With an average sample resolu...
Article
Pollen, spores, and microscopic charcoal from a sediment core from Lake Ngami, in the Middle Kalahari, reflect paleovegetation and paleoclimatic conditions over the last 16,600 cal years BP. The location of Lake Ngami allows for the receipt of moisture sourced from the Indian and/or Atlantic oceans, which may have influenced local rainfall or long...
Article
Africa's southern Cape is a key region for the evolution of our species, with early symbolic systems, marine faunal exploitation, and episodic production of microlithic stone tools taken as evidence for the appearance of distinctively complex human behavior. However, the temporally discontinuous nature of this evidence precludes ready assumptions o...
Article
Full-text available
We quantified the degree to which the relationship between the geographic distribution of three major European tree species, Abies alba, Fagus sylvatica and Picea abies and January temperature (Tjan) has remained stable over the past 10,000 years. We used an extended data-set of fossil pollen records over Europe to reconstruct spatial variation in...
Article
This paper presents the first continuous pollen record from the southern Namib Desert spanning the last 50,000 years. Obtained from rock hyrax middens found near the town of Pella, South Africa, these data are used to reconstruct vegetation change and quantitative estimates of temperature and aridity. Results indicate that the last glacial period w...
Article
This paper highlights the importance of differentiating between precipitation amount and moisture availability (‘humidity’/‘aridity’) when considering proxy records of climate change. While the terms are sometimes used interchangeably, moisture availability is determined by both (i) precipitation amount and (ii) temperature, through its influence o...
Thesis
Full-text available
Southern African drylands are not suited for the application of climate reconstruction methods based on surface samples. Methods based on the co-existence approach, while still in their early days, are really promising, particularly those using probability density functions (pdfs) that have proven particularly valuable in certain cases as they can...
Article
Full-text available
SOFTWARE DOWNLOAD AT: www.hyrax.univ-montp2.fr Several methods currently exist to quantitatively reconstruct palaeoclimatic variables from fossil botanical data. Of these, probability density function (PDF)-based methods have proven valuable as they can be applied to a wide range of plant assemblages. Most commonly applied to fossil pollen data, t...
Article
Full-text available
A 425 cm core has been collected from the Gantang subalpine peat bog, in Pingnan County, Fujian Province of Southern China. High-resolution pollen analysis of the core has allowed for the reconstruction of past vegetation and climate changes over the last 50,000 years. Today, Fujian province is located in the eastern part of middle subtropical zone...

Network

Cited By

Projects

Projects (4)
Project
Development and applications of the probabilistic climate reconstruction method CREST.
Project
The Early-Career Network (ECN) of Past Environmental Global Changes (PAGES) aims to facilitate the exchange of ideas and skill sets in order to give early-career researchers the tools to excel in their research fields. The PAGES ECN will aid in the dissemination of information, establish vital scientific networks, and foster the development of ideas that can lead to future research collaborations and improved job prospects.
Project
In an age of digital data analysis, gaining access to data from the pre-digital era – or any data that is only available as a figure on a page – remains a problem and an under-utilized scientific resource. Whilst there are numerous programs available that allow the digitization of scientific data in a simple x-y graph format, we know of no semi-automated program that can deal with data plotted with multiple horizontal axes that share the same vertical axis, such as pollen diagrams and other stratigraphic figures that are common in the Earth sciences. STRADITIZE (Stratigraphic Diagram Digitizer) is a new open-source program that allows stratigraphic figures to be digitized in a single semi-automated operation. It is designed to detect multiple plots of variables analyzed along the same vertical axis, whether this is a sediment core or any similar depth/time series. The program is written in python and supports mixtures of many different diagram types, such as bar plots, line plots, as well as shaded, stacked, and filled area plots. The package provides an extensively documented graphical user interface for a point-and-click handling of the semi-automatic process, but can also be scripted or used from the command line. Other features of STRADITIZE include text recognition to interpret the names of the different plotted variables, the automatic and semi-automatic recognition of picture artifacts, as well an automatic measurement finder to exactly reproduce the data that has been used to create the diagram. Evaluation of the program has been undertaken comparing the digitization of published figures with the original digital data. This generally shows very good results, although this is inevitably reliant on the quality and resolution of the original figure.