Evaluating the Performance of Past Climate Model Projections

Abstract

Retrospectively comparing future model projections to observations provides a robust and independent test of model skill. Here we analyze the performance of climate models published between 1970 and 2007 in projecting future global mean surface temperature (GMST) changes. Models are compared to observations based on both the change in GMST over time and the change in GMST over the change in external forcing. The latter approach accounts for mismatches in model forcings, a potential source of error in model projections independent of the accuracy of model physics. We find that climate models published over the past five decades were skillful in predicting subsequent GMST changes, with most models examined showing warming consistent with observations, particularly when mismatches between model‐projected and observationally estimated forcings were taken into account.

The COVID-19 lockdowns: a window into the Earth System

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“…The resulting climate impacts can be projected decades and even centuries in advance, revealing the long-term consequences of today's actions. Earlier predictions have already materialized and can now be observed (Hausfather et al , 2020). Extreme events, like the 2007–2010 drought in Syria, were significantly more likely to occur because of global warming (Kelley et al , 2015).…”

Perception and risk of Covid-19 and climate change: investigating analogies in a common framework

“…If these latter phenomena shall happen, temperature should increase dramatically and the new pathway shall not be easily influenced by human interventions. This nonlinear increase of temperature will be recognized only in the next future decades, following model results. Nevertheless, the GCMs' ability to reconstruct past climate as a result of anthropogenic influences, the robustness of these results (Mazzocchi & Pasini, 2017) and their good performance in past projections (Hausfather et al, 2019) let us be confident about their capability to obtain reliable projections under future behaviour of these human forcings, too. The quasi-linear temperature evolution observed in the last century should not mislead us and push to delayed actions, exactly as happened with the initial small number of deaths in Covid-19 epidemic. Temperature increase, as Covid-19 epidemic, shows inertia, which in this case is due to the long persistence time of CO 2 in the system (at least several decades) and to the slow response time of the oceans.…”

“…This nonlinear increase of temperature will be recognized only in the next future decades, following model results. Nevertheless, the GCMs' ability to reconstruct past climate as a result of anthropogenic influences, the robustness of these results (Mazzocchi & Pasini, 2017) and their good performance in past projections (Hausfather et al, 2019) let us be confident about their capability to obtain reliable projections under future behaviour of these human forcings, too.…”