A Pedagogical "Toy" Climate Model

TL;DR

This paper introduces a simple climate model demonstrating bistability between glaciation and warm states, aligning qualitatively with paleoclimatic data, and discusses potential climate stability issues.

Contribution

It presents a pedagogical toy model of climate bistability based on water vapor absorption, highlighting possible climate instability and the role of feedback mechanisms.

Findings

The model predicts two stable climate states: glaciation and interglacial periods.

Intermediate states are unstable, leading to abrupt climate transitions.

Present climate may be inherently unstable without stabilizing feedbacks.

Abstract

A "toy" model, simple and elementary enough for an undergraduate class, of the temperature dependence of the greenhouse (mid-IR) absorption by atmospheric water vapor implies a bistable climate system. The stable states are glaciation and warm interglacials, while intermediate states are unstable. This is in qualitative accord with the paleoclimatic data. The present climate may be unstable, with or without anthropogenic interventions such as CO$_2$ emission, unless there is additional stabilizing feedback such as "geoengineering".