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climate and geology

Enhanced marine burial of terrestrial organic carbon through the Palaeocene–Eocene Thermal Maximum

by G.N.Inglis et al., June 16, 2026, Nature OPEN ACCESS

Abstract

The Palaeocene–Eocene Thermal Maximum (PETM) occurred ~56 million years ago and was characterized by large-scale carbon release and transient warming. Erosion and subsequent burial of terrestrial organic carbon in marine sediments could have sequestered organic carbon during the PETM—stabilizing global carbon and climate systems—yet direct evidence for this process is lacking. Here we present source-specific biomarker records from five globally distributed shallow marine sites and show that vascular plant and soil organic carbon contributed ~40–95% of total organic carbon in coastal sediments during the PETM. This is higher than modern marine sediments (~12–20% of total organic carbon) and indicates greater terrestrial organic carbon delivery to marine environments during warmer climates. We find that terrestrial organic carbon burial fluxes can increase ~10-to-50-fold during the PETM due to enhanced physical erosion and higher coastal sedimentation rates, implying that marine burial of terrestrial organic carbon sequestered excess carbon released during the PETM. Palaeoclimate model simulations do not account for enhanced delivery of terrestrial organic carbon into the marine realm and are thus missing an important carbon sink. Terrestrial organic carbon burial could act as a negative feedback during other hyperthermals and may aid the long-term (>10,000-year) recovery of the Earth syste

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Defining Temperature

by A. May, Aug 9, 2026 in WUWT

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Local temperature

This is the temperature used in climate and meteorological studies. It is the foundation of heat conduction, and hydrodynamics. One assumes local thermodynamic equilibrium over some volume and measures or assumes a local temperature for the volume. This is the logic used in the famous Navier-Stokes equations. This assumed “local equilibrium” is valid over small volumes (for example an “air parcel”) for short time periods. The problem with some climate models is that they assume “local equilibrium” for volumes and time periods that are too large and too long.

Discussion

Temperature is not a primitive mechanical property like mass; it is an emergent statistical property that characterizes the distribution of energy among degrees of freedom (Landau & Lifshitz, 1980). Mass can be measured independently of the rest of the universe or system and does not change as the system around it changes. Temperature follows from the 0th law of thermodynamics, which says:

If system A is in thermal equilibrium with system B,

and system B is in thermal equilibrium with system C,

then A is in thermal equilibrium with C.

The 0th law establishes that “temperature” is a meaningful physical quantity because thermal equilibrium is transitive. It does not define temperature, but it guarantees that temperature is meaningful and measurable. We often hear that temperature is transitive, but this is only true in laboratory settings or at equilibrium. Outside equilibrium, temperature can lose transitivity and different degrees of freedom can produce different temperatures. Transitivity is the basis of equilibrium temperature, but not all temperature measurements.

In summary, the thermodynamic definition of temperature applies only to equilibrium states, but physics uses many other temperature concepts like kinetic, effective, local, and generalized that are essential for describing real systems far from equilibrium. Restricting “temperature” to its equilibrium definition ignores the vast range of physical systems where temperature is well-defined and indispensable.