Department of Earth Sciences

The PALAVAS Hypothesis

PALAVAS tests the hypothesis that the efficiency of weathering and atmospheric CO₂ removal is strongly linked to the age of volcanic landscapes.

Fresh volcanic terrains provide abundant reactive material and experience rapid erosion, promoting intense chemical weathering. As landscapes mature, the supply of fresh rock declines and weathering rates are expected to decrease. We investigate whether this evolution follows predictable trajectories and how it varies with rock type and climate.

Why It Matters

Tropical volcanic islands play a key role in Earth's long-term climate system. Under warm and humid conditions, the weathering of volcanic rocks consumes atmospheric CO₂, helping to regulate climate over millions of years.

However, volcanic islands change through time. Newly formed volcanic landscapes are steep, dynamic, and highly reactive to weathering. As islands age, their topography becomes more subdued, erosion rates decline, and weathering processes evolve. Understanding how these changes unfold over the lifetime of a volcanic island is essential for quantifying the role of volcanic terrains in the global carbon cycle. 

How do tropical volcanoes influence Earth's climate over geological timescales?

The PALAVAS project investigates how the weathering and erosion of volcanic rocks regulate the global carbon cycle and contribute to the long-term removal of atmospheric CO₂. By studying tropical volcanic islands across the Indian Ocean and Caribbean, we seek to understand how landscape evolution controls the ability of volcanic terrains to act as natural climate regulators.

Study Areas: Réunion and Guadeloupe

PALAVAS focuses on two tropical volcanic islands: Réunion in the Indian Ocean and Guadeloupe in the Caribbean. These islands provide ideal natural laboratories for investigating how weathering and erosion evolve through time.

Both islands contain volcanic rocks of different ages, allowing researchers to compare young and old landscapes. They also experience strong rainfall gradients, which makes it possible to evaluate how climate influences weathering and erosion processes.

While Réunion is dominated by basaltic hotspot volcanism, Guadeloupe represents volcanism associated with a subduction zone. By comparing these contrasting settings, PALAVAS can assess how rock composition, landscape age, and climate interact to control long-term weathering rates and carbon dioxide consumption.