TY - JOUR

T1 - A re-evaluation of the Earth's surface temperature response to radiative forcing

AU - Young, P.C.

AU - Geoffrey Allen, P.

AU - Bruun, J.T.

PY - 2021/5/17

Y1 - 2021/5/17

N2 - There is much current debate about the way in which the earth's climate and temperature are responding to anthropogenic and natural forcing. In this paper we re-assess the current evidence at the globally averaged level by adopting a generic 'data-based mechanistic' modelling strategy that incorporates statistically efficient parameter estimation. This identifies a low order, differential equation model that explains how the global average surface temperature variation responds to the influences of total radiative forcing (TRF). The model response includes a novel, stochastic oscillatory component with a period of about 55 years (range 51.6-60 years) that appears to be associated with heat energy interchange between the atmosphere and the ocean. These 'quasi-cycle' oscillations, which account for the observed pauses in global temperature increase around 1880, 1940 and 2001, appear to be related to ocean dynamic responses, particularly the Atlantic multidecadal oscillation. The model explains 90% of the variance in the global average surface temperature anomaly and yields estimates of the equilibrium climate sensitivity (ECS) (2.29 °C with 5%-95% range 2.11 °C to 2.49 °C) and the transient climate response (TCR) (1.56 °C with 5%-95% range 1.43 °C to 1.68 °C), both of which are smaller than most previous estimates. When a high level of uncertainty in the TRF is taken into account, the ECS and TCR estimates are unchanged but the ranges are increased to 1.43 °C to 3.14 °C and 0.99 °C to 2.16 °C, respectively.

AB - There is much current debate about the way in which the earth's climate and temperature are responding to anthropogenic and natural forcing. In this paper we re-assess the current evidence at the globally averaged level by adopting a generic 'data-based mechanistic' modelling strategy that incorporates statistically efficient parameter estimation. This identifies a low order, differential equation model that explains how the global average surface temperature variation responds to the influences of total radiative forcing (TRF). The model response includes a novel, stochastic oscillatory component with a period of about 55 years (range 51.6-60 years) that appears to be associated with heat energy interchange between the atmosphere and the ocean. These 'quasi-cycle' oscillations, which account for the observed pauses in global temperature increase around 1880, 1940 and 2001, appear to be related to ocean dynamic responses, particularly the Atlantic multidecadal oscillation. The model explains 90% of the variance in the global average surface temperature anomaly and yields estimates of the equilibrium climate sensitivity (ECS) (2.29 °C with 5%-95% range 2.11 °C to 2.49 °C) and the transient climate response (TCR) (1.56 °C with 5%-95% range 1.43 °C to 1.68 °C), both of which are smaller than most previous estimates. When a high level of uncertainty in the TRF is taken into account, the ECS and TCR estimates are unchanged but the ranges are increased to 1.43 °C to 3.14 °C and 0.99 °C to 2.16 °C, respectively.

KW - data-based mechanistic modeling

KW - equilibrium climate sensitivity

KW - global average surface temperature

KW - ocean heat exchange

KW - optimal identification and estimation

KW - Atmospheric radiation

KW - Atmospheric temperature

KW - Differential equations

KW - Stochastic models

KW - Stochastic systems

KW - Surface properties

KW - Uncertainty analysis

KW - Atlantic multidecadal oscillations

KW - Climate sensitivity

KW - Differential equation model

KW - Global temperatures

KW - Modelling strategies

KW - Oscillatory components

KW - Surface temperature anomalies

KW - Surface temperature variation

KW - Climate models

U2 - 10.1088/1748-9326/abfa50

DO - 10.1088/1748-9326/abfa50

M3 - Letter

VL - 16

JO - Environmental Research Letters

JF - Environmental Research Letters

SN - 1748-9326

IS - 5

M1 - 054068

ER -