University of Cambridge > Talks.cam > Cambridge Centre for Climate Science > A geological perspective on climate change: forcings, feedbacks and tipping points.

A geological perspective on climate change: forcings, feedbacks and tipping points.

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If you have a question about this talk, please contact Dr Alex Archibald.

Humanity is currently conducting an unprecedented climate experiment, the outcome of which is typically framed in terms of an equilibrium ‘climate sensitivity’. This term encapsulates the impact on global average temperature of an imposed energy budget imbalance and its associated feedbacks; it is a calibration of climate response to forcing. Although our current climate experiment is unprecedented in its origin, it will not be the first time that global climate has changed drastically in association with a carbon cycle perturbation. Indeed, in seeking observational constraints on climate sensitivity and the fundamental ‘ground rules’ of climate adjustment, much may be learned from the geological record of past climate change. This talk will explore two key aspects of the climate system that are emphatically underlined in the palaeoclimate record. The first is the importance of positive feedbacks that act to amplify relatively subtle perturbations to the earth’s energy budget, broadly as predicted by numerical models. The second is the context (i.e. climate) dependence of these positive feedbacks. Together, these two aspects of the climate system provide the necessary ingredients for the emergence of non-linear behaviour, or ‘tipping points’. What we see is a climate system whose resilience to perturbations depends sensitively on the history of previous perturbations. This could pose a significant challenge for accurate long-term climate prediction.

This talk is part of the Cambridge Centre for Climate Science series.

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