Paul

A revised Holocene sea-level curve for the southeast coast of New South Wales, Australia, is presented
based on a review of previously published geochronological results for fossil molluscs, organic-rich
mud, mangrove roots and fixed biological indicators. It is supplemented by new radiocarbon and amino acid
racemization-derived ages on fossil molluscs from transgressive sandsheet facies in back-barrier settings within
shallow incised valleys along the southern coast of New South Wales. This data base has been limited to fossils
with accurate descriptions of their facies associations and stratigraphic relationships to present mean sea
level. Results show that sea level during the Holocene marine transgression rose to between −15 and −11 m at
9400–9000 cal. yr BP. Sea level then rose to approximately −5 m by 8500 cal. yr BP and to approximately
−3.5 m between 8300 and 8000 cal. yr BP inundating shallow incised valleys resulting in the deposition of
shell-rich transgressive sandsheets within shallow incised bedrock valleys. Present sea level was attained
between 7900 and 7700 cal. yr BP, approximately 700–900 years earlier than previously proposed. Sea level
continued to rise to between +1 and +1.5 m between 7700 and 7400 cal. yr BP, followed by a sea-level highstand that lasted until about 2000 cal. yr BP followed by a gradual fall to present. A series of minor negative
and positive oscillations in relative sea level during the late-Holocene sea-level highstand appear to be superimposed over the general sea-level trend. However, the precise nature of the oscillations are difficult to quantify because of problems associated with accurately determining palaeotidal and wave regimes, climatic
conditions and the antecedent morphology of the shallow marine environments during the mid Holocene.

Holocene sea-level change on the southeast coast of Australia: a review

Craig R. Sloss
School of Earth & Environmental Sciences, University of Wollongong, Wollongong NSW 2522, Australia, c.r.sloss@massey.ac.nz

The Holocene, Vol. 17, No. 7, 999-1014 (2007)DOI: 10.1177/0959683607082415

Colin V. Murray-Wallace

School of Earth & Environmental Sciences, University of Wollongong, Wollongong NSW 2522, Australia

Brian G. Jones

School of Earth & Environmental Sciences, University of Wollongong, Wollongong NSW 2522, Australia

Melting Arctic Ocean sea ice may have been caused by a reversal in the ocean’s circulation that had been going on for about a decade, scientists from NASA and the University of Colorado said.

Rocky Mountain News: ‘Ocean circulation may contribute to warming’

A study of the world’s power stations has shown the extent to which developed countries produce more carbon dioxide per head than emerging economies.

Australians were found to be the world’s worst polluters per capita, producing five times as much carbon from generating power as China.

The US came second with eight tonnes of carbon per head – 16 times more than that produced by India.

BBC News website: ‘Australians named worst emitters’

Two events loom on the horizon that might settle the issue once and for all; one shaped by human hands, one entirely natural.

At Cern, the giant European physics facility, an experiment called Cloud is being constructed which will research the notion that cosmic rays can stimulate the formation of droplets and clouds. There may be some results within three or four years.

By then, observations suggest that the Sun’s output may have started to wane from its “grand maximum”.

If it does, and if Henrik Svensmark is right, we should then see cosmic rays increase and global temperatures start to fall; if that happens, he can expect to see a Nobel Prize and thousands of red-faced former IPCC members queuing up to hand back the one they have just received.

But if the Sun wanes and temperatures on our planet continue to rise, as the vast majority of scientists in the field believe, the solar-cosmic ray concept of global warming can be laid to eternal rest.

BBC News website: Sun and global warming: A cosmic connection?

The delay in autumnal leaf coloration and leaf fall in trees is caused by rising levels of carbon dioxide (CO2) in the atmosphere and not by increased global temperatures, suggests a new study by researchers at the University of Southampton.

In recent years, woodland autumnal colour changes have been occurring later in the season whilst re-greening in spring has been occurring earlier. During the last 30 years across Europe, autumnal senescence – the process of plant aging where leaves discolour and then fall – has been delayed by 1.3 – 1.8 days a decade. To date, this has been explained by global warming, with increasing temperatures causing longer growing seasons.

However, while a strong correlation has been observed between increased global temperatures and earlier spring re-greening and bud break, the correlation between autumn leaf colour change and fall and temperature trends in 14 European countries is weak.

Over the 30 years that progressive delays in autumnal senescence have been observed, atmospheric CO2 has risen by 13.5 per cent. Experimental studies show that increased atmospheric CO2 affects plant physiology and function, influencing a myriad of processes.

The Southampton researchers undertook two large forest ecosystem experiments in which poplar (Populus) trees in separate plots were exposed to either ambient or elevated levels of CO2 from planting to maturity. The elevated concentration was at 550 parts per million, proposed as representative of concentrations that may occur in 2050. Changes in the tree canopy were measured by remote sensing.

The trees exposed to elevated CO2 retained their leaves for longer and also experienced a smaller decline in end of season chlorophyll content, resulting in a greener autumn canopy relative to that in ambient CO2.

Professor Gail Taylor, of the University’s School of Biological Sciences, explains:
‘The research data provide compelling evidence in terms of both the leaf and canopy that autumnal senescence in such forest ecosystems will be delayed as the atmospheric concentration of CO2 continues to rise, independent of increased temperatures.

‘Photosynthesis and canopy greenness are maintained for longer in elevated CO2. This is because a CO2 rich atmosphere allows the tree to generate carbon rich compounds that are known to prolong the life of leaves. These compounds may have a positive effect for carbon balance and stress tolerance but may also have a negative effect on the control of dormancy.

‘When trees keep their leaves for longer, they continue to photosynthesise but trees also need to set bud and if they don’t do that, it makes them susceptible to frost and other weather events. A key question now is whether we should be selecting trees which are better adapted to coping with increasing levels of CO2, perhaps considering different varieties and species to plant, rather than using locally sourced seed, as is current practice,’ she continues.

The study also provides the first insight into changes in the genetic make-up of Populus that can account for this shift to delayed senescence. Using cDNA microarrays, the researchers looked at approximately 20,000 genes and have identified a suite of genes that are switched on during delayed senescence in elevated CO2.

News Release from the University of Southampton:

New research suggests delay in autumn colour is caused by increased atmospheric CO2 not global warming