Impact of effective polarisability models on the predicted release dynamics of CH$_4$ and CO$_2$ from premelted ice

TL;DR

This paper investigates how different models of molecular polarizability affect predictions of greenhouse gas release dynamics from melting ice, focusing on Casimir--Polder forces acting on CH$_4$ and CO$_2$ molecules.

Contribution

It introduces a detailed theoretical framework showing the impact of various polarizability models on gas molecule behavior at melting ice surfaces.

Findings

Dispersion forces influence methane to move towards ice surface in complex models.

Carbon dioxide tends to be attracted to the nearest interface, either ice or air.

Different polarizability models yield contrasting predictions for gas release mechanisms.

Abstract

We present a theory for Casimir--Polder forces acting on greenhouse gas molecules dissolved in a thin water film. Such a nanosized film has recently been predicted to arise on th surface of melting ice as stabilized by repulsive Lifshitz forces. We show that different models for the effective polarizability of greenhouse gas molecules in water lead to different predictions for how Casimir--Polder forces influence the extraction of CH$_4$ and CO$_2$ molecules from the melting ice surface. In the most intricate model of a finite-sized molecule inside a cavity, dispersion potentials push the methane molecules towards the ice surface whereas the carbon dioxide typically will be attracted towards the closest interface (ice or air). Previous models for effective polarizability had suggested that CO$_2$ would also be pushed towards the ice surface. Release of greenhouse gas molecules from the surface of melting ice can potentially influence climate greenhouse effects.