Environmental Change A View From Downunder
RSNZ WELLINGTON BRANCH GEOLOGICAL SECTION & GEOLOGICAL SOCIETY of NZ
The Hochstetter Lecture 2007 – Environmental change: a view from downunder
Professor Paul Williams, The School of Geography, Geology and Environmental Science (SGGES), University of Auckland
'Downunder' in the title refers to both the underground and the Southern Hemisphere. The talk will be in two parts.
The first part explains how evidence for environmental change can be obtained from caves. The emphasis will be on the interpretation of the climatic archive contained in speleothems (stalagmites etc) and will be illustrated by examples drawn from studies around the world. A case will be made that speleothem archives are on track to supersede ice cores and marine cores in their importance, because they can be much better dated, are of much higher resolution, and contain more information. They are also available from every continent that is free of ice cover. The U/Th dating limit of ~0.5Ma has recently been extended by U/Pb and so dated speleothem records are now potentially obtainable for many millions of years.
The second part presents the evidence for climatic change obtained from New Zealand speleothems. It compares our palaeoclimate records with those obtained from elsewhere, and concludes that at the multi-millennial scale we appear to be in step with climate change on the planet, but at the millennial scale we show a marked independence with climate change in New Zealand sometimes leading that observed in the Northern Hemisphere by centuries and sometimes even thousands of years. Finally, a possible view of the future is offered by projecting forwards in time the climate cycles identified in speleothems – but would human-induced changes exacerbate or suppress the natural swings of climate?
About the Speaker:
Paul Williams was born in Bristol, graduating with a BA Hons (1961) from Durham University and PhD (1965) and ScD (1991) from Cambridge University. He taught from 1964 at the University of Dublin (Trinity College) and later was a Research Fellow at ANU, Canberra. He has been Professor at the University of Auckland (School of Geography, Geology and Environmental Science) since 1972. He has published on land use hydrology, coastal geomorphology and the Quaternary, although his chief area of research interest is karst, including landform evolution, hydrogeology, paleoenvironmental studies of speleothems, and applied work. He has undertaken field research in New Zealand, Australia, Papua New Guinea, Niue, Ireland, France, USA, Vietnam and China.
Tuesday 10 July 2007, 7:15 pm refreshments for a 7:30 pm start, Science House, Turnbull St, Thorndon. All welcome. Information: Alan Orpin, ph. 386 0356, email: firstname.lastname@example.org
Is climate change in the Southern hemisphere similar to Northern Hemisphere?
Are ice cores from Antarctica providing similar climate results as NZ data?
Most important archives are those that can be well dated. Stalagmites can be very well dated. Almost 6 readings per year - going waaaay back 600,000 years (using Uranium dating) and beyond.
You measure ratios of isotopes in O and C to give proxies of climate. Not simple, not a straight forward co-relation though.
Ratios are effected by temp and precipitation. Precipitation from sea filters out more of the isotopes.
But the relationship between ratios and rainfall is less direct in NZ than in Israel (which has more definite seasons).
Data from NZ stalagmites, tree rings and Antarctic ice cores shows Southern hemisphere has a "hockey stick" graph just like the Northern hemisphere.
He can demonstrate a relationship between insolation and his stalagmite derived climate data going back 600,000 years. The relationship is not 100% there are some quirks. And there seems to be a delay in some of the bumps and troughs.
We reached a solar activity max 20 years ago.
His data shows that when solar activity declined, then global temp declined.
NZ stalagmite and tree data shows much more variability than Antarctic ice core derived data.
He finished with: Sun spot activity has a significant contribution to temperature. (!)
First question was along the lines of; what about man-made climate forcing?
He kinda ducked the question by saying that he was sure man-made forcing was involved in global warming but didn't know how much.
The bloke sitting next to us was the NZ Govt climate change expert (forgot his name); he pointed out that the ICCP report said that solar activity was about 10% of the forcing. Paul W said "he thought it was in that order".
The next day this came out: New analysis counters claims that solar activity is linked to global warming