Alexandra-Jane Henrot

University of Liège | ulg · Department of Astrophysics, Geophysics and Oceanography

Improving the model-based predictions of plant species under a projected climate is essential to better conserve our biodiversity. However, the mechanistic link between climatic variation and plant response at the species level remains relatively poorly understood and not accurately developed in Dynamic Vegetation Models (DVMs). We investigated the...

Paleogene vegetation changes in Primorye (Far East of Russia) are studied using the Plant Functional Types (PFT) Approach, for the first time applied on the large palaeobotanical records of this region. The palaeobotanical data for this reconstruction are based on the analysis of 30 palynofloras and 24 leaf floras covering the Early Palaeocene to L...

The Gulf Stream, as part of the Atlantic Meridional Overturning Circulation (AMOC), is known as a major driver of latitudinal energy transport in the North Atlantic presently causing mild winters over northwestern Eurasia. The intensity of the AMOC throughout the Neogene, prior to the final closure of the Central American Seaway (CAS) in the early...

The purpose of this study is to evaluate the eight ISIMIP2a biome models against independent estimates of long-term net carbon fluxes (i.e. Net Biome Productivity, NBP) over terrestrial ecosystems for the recent four decades (1971–2010). We evaluate modeled global NBP against 1) the updated global residual land sink (RLS) plus land use emissions (E...

A biogenic emission scheme based on the Model of Emissions of Gases and Aerosols from Nature (MEGAN) version 2.1 (Guenther et al., 2012) has been integrated into the ECHAM6-HAMMOZ chemistry climate model in order to calculate the emissions from terrestrial vegetation of 32 compounds. The estimated annual global total for the reference simulation is...

A biogenic emission scheme based on the Model of Emissions of Gases and Aerosols from Nature (MEGAN) version 2.1 (Guenther et al., 2012) has been integrated into the ECHAM6-HAMMOZ chemistry climate model in order to calculate the emissions from terrestrial vegetation of 32 compounds. The estimated annual global total for the simulation period (2000...

Dynamic vegetation models (DVM), such as CARAIB (“CARbon Assimilation In the Biosphere”) were initially designed to describe the dynamics of natural ecosystems as a function of climate and soil with the aim of studying the role of vegetation in the carbon cycle. But their characteristics allow numerous other applications and improvements, such as t...

Early Pleistocene vegetation dynamics in the Russian Far East (southern Primory'e) are studied using multiple quantitative techniques on various palaeobotanical organ types. Vegetation data for this time interval were obtained from a total of 8 macrofloras (fruits and seeds, woods, and leaves) and 18 microfloras collected from a 10 m thick, terrige...

It is well known that climate change affects the ecosystem structure and its functions. This can in its turn lead to permanent changes in the land structure. Likewise, the land use and land cover changes impact the local and regional climate. The interactions between these land surface changes and climate changes are studied within the project MASC...

The Miocene is a relatively recent epoch of the Earth’s history with warmer climate than today, particularly during the Middle Miocene Climatic Optimum (MMCO, approximatively 17-15 Ma). Although the cause of the warming is probably not only attributable to CO 2, but also to changes in orography and configuration of ocean gateways, this time interva...

Dynamic vegetation models (DVM) were initially designed to describe the dynamics of natural ecosystems as a function of climate and soil, to study the role of the vegetation in the carbon cycle. These models are now directly coupled with climate models in order to evaluate feedbacks between vegetation and climate. But DVM characteristics allow nume...

The interactions between land surface and climate are complex. Climate changes can affect ecosystem structure and functions, by altering photosynthesis and productivity or inducing thermal and hydric stresses on plant species. These changes then impact socio-economic systems, through e.g., lower farming or forestry incomes. Ultimately, it can lead...

The Miocene is a relatively recent epoch of the Earth's history with warmer climate than today. The Middle Miocene (Langhian, near 15 Ma) was particularly warm. Although the cause of the warming is presumably not only attributable to CO2, but also to the change in orography and configuration of ocean gateways, this time interval represents an ideal...

The middle Miocene is a crucial period for the evolution of apes, and corresponds to their appearance in Europe. The dispersion of apes was made possible by tectonic changes and the expansion of their habitat, which is (sub-) tropical forest, in Europe. The context in which the Middle Miocene Climatic Optimum occurred still lacks constraints in ter...

Significant climatic changes are currently observed and, according to projections, will be strengthened over the 21st century throughout the world with the continuing increase of the atmospheric CO2 concentration. Climate will be generally warmer with notably changes in the seasonality and in the precipitation regime. These changes will have major...

The simulation of paleovegetation with dynamic vegetation models requires an appropriate definition of plant functional types (PFTs). For several million year old time periods, such as the Miocene, analogue species must be defined and then classified into PFTs. Then, parameters for each plant type must be evaluated from the known present distributi...

A transient Holocene simulation is carried out with an Earth system model of intermediate complexity (Planet Simulator). The spectral model is based on the moist primitive equations conserving momentum, mass, energy and moisture. For this study, the Planet Simulator is used in T21/5L-resolution and coupled to the LSG (large-scale geostrophic)-ocean...

The aim of this research work is the development of a methodology for drawing past vegetation maps and palaeoclimatology reconstruction using observation based on fossil floras. For this purpose we use the coexistence approach (Mosbrugger and Utescher 1997), a well-established method for reconstructing past climate, and we develop a variational dat...

In a long-term climatic cooling trend, the Middle Miocene represents one of the last warm periods of the Neogene, culminating with the Miocene Climatic Optimum, MCO (17-15 My). Palynological studies suggest that the warmer climatic conditions prevailing during the MCO allowed warm forests types to expand poleward of the subtropical zone, with everg...

According to projections, over the 21st century, significant climatic changes appear and will be strengthened all over the world with the continuing increase of the atmospheric CO2 level. Climate will be generally warmer with notably changes in the seasonality and in the precipitation regime. These changes will have major impacts on the environment...

The Middle Miocene was one of the last warm periods of the Neogene, culminating with the Middle Miocene Climatic Optimum (MMCO, approximatively 17–15 Ma). Several proxy-based reconstructions support warmer and more humid climate during the MMCO. The mechanisms responsible for the warmer climate at the MMCO and particularly the role of the atmospher...

Many sensitivity studies have been carried out, using climate models of different degrees of complexity to test the climate response to Last Glacial Maximum bound- ary conditions. Here, instead of adding the forcings succes- sively as in most previous studies, we applied the separation method of U. Stein et P. Alpert 1993, in order to determine rig...

In a long-term climatic cooling trend, the Middle Miocene represents one of the last warm periods of the Neogene, culminating with the Miocene Climatic Optimum, MCO (17-15 My). Palynological studies suggest that the warmer climatic conditions prevailing during the MCO allowed warm forests to expand poleward of the subtropical zone, with evergreen f...

Many sensitivity studies have been carried out, using simplified GCMs to test the climate response to Last Glacial Maximum boundary conditions. Here, instead of adding the forcings successively as in previous studies, we applied the separation method of Stein and Alpert (1993), in order to determine rigourously the different contributions of the bo...

The atmospheric CO2 mixing ratio has fluctuated widely over the Phanerozoic, according to the estimates from available proxy records. Because atmospheric CO2 is a major greenhouse gas, these fluctuations should have led to significant climatic variations. The "classical" view is indeed that atmospheric CO2 has been the main driver of the Earth's cl...