From Vulnerability to Adaptation to Climate Change: Food for Thoughts in Social Sciences - Vulnerability of Coastal Ecosystems and Adaptation - page 230

6.2.2.1. Hazard
The nature of a hazard is often very complex. If it originates in a
particular environment, its expression as a physical process (winds,
swells, landslides, etc.) can occur within one or several of the three
great spheres air/land/sea. This is the case for cyclones, which start over
the ocean and generate on the coasts both violent winds and strong
swells with heavy rain. Volcanoes can also combine lava flows,
pyroclastic flows and landslides. So beyond the original nature of the
hazard (the cyclone, the volcanic eruption), it is mostly the unfolding of
physical processes which needs to be considered to account for the
transformation of an original hazard into a series of multiple secondary
hazards. The need for the combinatory approach is even more pressing
when considering the effects of climate change. Indeed, the rise in
temperatures is expressed over the long term by the acceleration of
glacier melting and an increase in the volume of oceanic mass (thermal
dilation process), i.e. by a rise in sea levels which, when associated with
other processes, leads to the exacerbation of the the impacts of extreme
events (e.g. storms) and of more gradual climatic changes (e.g.
salinization of groundwater and of soil). The challenge with climate
change is therefore to be able to take into account all the various
changes in the natural processes. This explains why we refer to the term
hazard here in its very broad meaning, which includes both the
processes and their one-off events (hazards).
From the point of view of timeframes, hazards can be either
isolated in time (e.g. violent thunderstorms, floods or even forest fires)
or diffuse and gradual. The issue of climate change combines both
mechanisms as the possibility of intensifying and exacerbating more
or less recurrent one-off events (droughts, heat waves, cyclones, etc.)
is an indication for more gradual changes both in terms of conditions
(temperatures, currents, precipitation, etc.) and in terms of resources
(water, fish, etc.). Climate change is therefore associated with a more
profound change of natural environments and indirectly, of the
contexts in which human societies develop. This introduces another
important element: the timescales of some hazards may be complex,
half-way between discrete in time and gradual. This is typically the
case for drought events whose incidence can vary from a few days to
several months, or even years, and which can result in a latent water