Abstract
Abstract. A new energy balance model (EBM) is presented and is used to study paleoclimate transitions. While most previous EBMs only dealt with the globally averaged climate, this new EBM has three variants: Arctic, Antarctic and tropical climates. The EBM incorporates the greenhouse warming effects of both carbon dioxide and water vapour, and also includes ice–albedo feedback and evapotranspiration. The main conclusion to be inferred from this EBM is that the climate system may possess multiple equilibrium states, both warm and frozen, which coexist mathematically. While the actual climate can exist in only one of these states at any given time, the EBM suggests that climate can undergo transitions between the states via mathematical saddle-node bifurcations. This paper proposes that such bifurcations have actually occurred in Paleoclimate transitions. The EBM is applied to the study of the Pliocene paradox, the glaciation of Antarctica and the so-called warm, equable climate problem of both the mid-Cretaceous Period and the Eocene Epoch. In all cases, the EBM is in qualitative agreement with the geological record.
Highlights
For approximately 75 % of the last 540 million years of the paleoclimate history of the Earth, the climate of both polar regions was mild and free of permanent ice-caps (Cronin, 2010; Crowley, 2000; Hubert et al, 2000)
The goal of this section is an exploration of the underlying causes of abrupt climate changes that have occurred on Earth in the past 100 million years, using, as a tool, the energy balance model (EBM) developed in Sect
This paper presents a new energy balance model (EBM) for the climate of Earth, one that elucidates the distinctive roles of carbon dioxide and water vapour as greenhouse gases, and the role of ice–albedo feedback, in climate change
Summary
For approximately 75 % of the last 540 million years of the paleoclimate history of the Earth, the climate of both polar regions was mild and free of permanent ice-caps (Cronin, 2010; Crowley, 2000; Hubert et al, 2000). The principal contribution of this paper is a simple climate EBM, based on fundamental physical laws, that exhibits bistability, hysteresis and bifurcations We propose that these three phenomena have occurred in the paleoclimate record of the Earth and they help to explain certain paleoclimate transitions and puzzles as outlined above. 2.650 and 6.590 × 10−2, respectively 270 to 1600 ppm 0.5 to 0.85 0 to 1, function of μ 0 to 1, function of δ and TS 0.3729 1 − (1 − ηW)(1 − ηC )(1 − ηCl) 0.07424 m2 kg−1 0.05905 m2 kg−1 6.49 × 10−3 K m−1 and 2.38 × 10−5 m−1, respectively 9 km (poles), 17 km (Equator), 14 km (global) 2.2558 × 106 m2 s−2 461.5 m2 s−2 K−1 611.2 Pa 101.3 × 103 Pa 9.81 m s−2 (1.52 × 10−6)kCPA/g = 1.166 × 10−3 Lv/(RWTR) = 17.89 kWPWsat(TR)/(γ RWTR) = 12.05 the change in global mean temperature produced by a doubling of CO2 in the model, starting from the pre-industrial value of 270 ppm For this EBM, the ECS is determined to be T = 3.3 ◦C, which is at the high end of the range accepted by the IPCC (IPCC, 2013)
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