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The University of Southampton
Interdisciplinary Research Excellence

Earth's Climate Evolution Event

Time:
16:00 - 17:00
Date:
22 May 2015
Venue:
NOC Southampton - Henry Charnock Lecture Theatre (Waterfront Campus).

For more information regarding this event, please email Laura Grange at ljg1n12@noc.soton.ac.uk .

Event details

Global warming deniers are fond of saying "the climate is always changing". Well, yes it is, but the questions are why, and how, and how much?

If we know the answers to the questions back through time we can begin to understand how variable our climate is, and what makes it so. We can then use that knowledge to explain what is happening now and to tell us what to expect in the future. Whatever we find will be an adjunct to what climate models tell us. Speculation about climate change began among natural philosophers towards the end of the 18th century. Developments in different branches of science and technology over  the ensuing decades eventually got us to the point of developing a coherent theory of climate change, supported by growing reams of data from technologies as diverse as satellites, drill ships, and ice cores, by the late 20th century. We have come a long way from the notion that erratic blocks of rock on British hills were deposited by Noah's flood. The past 30 years have seen especially dramatic advances in our knowledge of the variability of past climate change, and its causes, which provide the essential underpinning to understanding what our climate is doing now and may do next. Much of what we know comes from examining piston cores and drill cores of marine sediment, along with ice cores. That's not too surprising as the oceans cover 72% of the planet and ice covers a further 3%. A key message is that our climate operates within rather narrow envelopes. For instance, over the past 2000 years we have been at the cold end of the Holocene Neoglacial period, driven there by falling orbital insolation. Our climate has fluctuated about that orbitally driven Neoglacial mean due to solar variability, which, like orbital insolation, operates within a well constrained natural envelope. Peaks in solar output gave us the Medieval Warm Period and the warming from 1900 to 1945, but since 1960 solar output has been flat or in decline, while temperatures have gone on rising. The main two climate entities that are now outside the climate envelope of the past 2000 years are CO2 and temperature. This geologically based information is independent of numerical climate models, yet supports them.  While it has  been said that the past is another country, to paraphrase the philosopher George Santayana - those who ignore the past are doomed to repeat it

Speaker information

Dr Colin P. Summerhayes ,Scott Polar Research Institute, University of Cambridge,Emeritus Associate and Marine geologist and oceanographer

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