Fire is the most ubiquitous
disturbance affecting terrestrial ecosystems, most prominent in savannas, Mediterranean
woodlands, and boreal forests.
is an important component of the Earth system affecting the vegetation, the
carbon cycle and the radiative forcing through fire emissions.
has the potential therefore to amplify or reduce initial climatic changes
through its different feedbacks on climate. However, tackling its exact influence on climate still remains challenging as fire varied in the past both at temporal and
spatial scales, responding to different climatic variability over different
To go beyond these issues, my main
aim is at identifying and quantifying the different controls of biomass
burning (fire) through time.
illustrating the different feedbacks of fire on climate (designed by A-L Daniau)
Figure illustrating natural controls of biomass burning
(designed by A-L Daniau)
Climatic conditions are the primary
control of the incidence of fire, but fire is also influenced by the nature
of the vegetation. Vegetation on the other hand depends itself of climate
changes on timescales from interannual
(vegetation productivity) to multi-millennial (vegetation dynamics and
distribution). Another superimposed control on fire is natural (by
lightning storms) or anthropogenic ignition. Humans have been put forward
to explain both increased and reduced periods of fire through fire use
intensification for ecosystem management. This can lead to an increase of
fire, as well as fire suppression by fragmenting landscapes and reducing
I examine how key climatic and
vegetation variables governed biomass burning in regions that are today
sensitive to fire, in particular the Mediterranean region and south-western
Africa. I analyse microcharcoal
particles preserved in long and continuous deep-sea
sedimentary sequences, focusing on orbital and millennial time
scales. This approach is worth to draw on changes in
biomass burning directly in relation with vegetation (pollen grains) and
climate at regional scale.