Hobart

Seminar Abstract

Friday 2 May 2008, 11.30am (Tas time)
CSIRO Auditorium, Hobart

Philip C Reid
University of Plymouth and
Sir Alister Hardy Foundation for Ocean Science, Plymouth, UK

Are observed rapid changes in the oceans a warning signal and will changes seen in the oceans lead to an acceleration of climate change?

The key role that the oceans and in turn their biology play in global change and the importance of these changes to mankind is poorly recognised as it is a huge and remote environment outside most people’s experience. We cannot see or easily measure what is happening below the surface and we know little about the biodiversity or the biological processes that are taking place in this vast and unexplored part of the world. Central to climate change is that it is the main reservoir of carbon dioxide storing 34,000 petagram (1 x 1015 g) of carbon in the deep ocean that has accumulated over thousands of years. The oceans are now known to be the dominant sink for atmospheric CO2. Marine plants comprise 50% of global primary production and a proportion of the CO2 transferred from the atmosphere is utilised during their photosynthesis. Each year part of this production that is not recycled in the upper layer sinks to great depth by a process known as the Biological Pump, removing 11 petagram of carbon from the productive surface layer. One secondary consequence of increasing levels of atmospheric CO2 is that sea water is becoming more acidic (pH). The pH scale is logarithmic and the observed and projected rate of change is rapid with expected major consequences for the many marine planktonic organisms that have calcareous body parts (and for coral reefs) that could in a 100 year time frame reduce the ability of the oceans to take up CO2 from the atmosphere and possibly further accelerate the growth of atmospheric CO2.

Results will be presented to show that ocean temperature, circulation and planktonic ecosystems in the North Atlantic (and where information is available, globally) are changing rapidly in concert and that there is evidence to suggest that the changes are an ocean wide response to global warming. There is also good evidence from flux measurements that there has been a reduction in the uptake of CO2 in the northern North Atlantic within the last two decades. To illustrate these changes in the first instance I will be showing exemplars from the results of the Continuous Plankton Recorder (CPR) survey. The Colour index of the CPR survey (chlorophyll, like the greenness of a lawn) has shown a substantial increase in season length and intensity and implies an increase in primary production in a wide belt across the North Atlantic and especially in shelf seas. Many other changes in the timing of seasonal events in the plankton have also been observed. Parallel increases in the benthos (the animals living on the bottom) imply that sedimentation from the plankton has also increased in the last decade. Coincident changes have occurred in fish stocks including large reductions in cod recruitment in the North Sea. These events that occurred after the mid 1980s have been termed a regime shift and are evident from the Baltic all the way across the Atlantic and may even be linked to changes in the ice cover in the Arctic Ocean. Superimposed on the changes associated with the regime shift has been a northerly movement of warmer water plankton on the eastern side of the Atlantic and a southerly movement of plankton characteristic of colder water in the western Atlantic. The rate of change has been substantial, 1000 km in only forty years in the eastern Atlantic with warmer water fish species showing a similar northerly movement. These changes are linked to increasing temperatures in the Atlantic moving northward towards the Arctic as part of what may be a global signal. Further evidence of this warning signal is the appearance of a Pacific planktonic plant (a diatom) in the Northwest Atlantic for the first time in 800,000 years by transfer across the top of Canada due to the rapid melting of Arctic ice in 1998. The evidence from the CPR survey will be backed up by observations of changes in abundance, timing and distribution of marine organisms that exist in other oceans and shallower seas. Finally, reference will be made to a WWF initiative to produce a report on the role that the oceans play through feedback mechanisms, that may accelerate or decelerate climate change.

My talk will be rounded off by placing the changes and their speed within the context of the recent report by the IPCC where global temperatures based on the mean of a wide range of models was predicted to be 3° C higher in 100 years time. None of these models include biology, which is so important and has been changing rapidly. Forecasts by a Norwegian model predict temperatures in latitudes similar to Scotland to be 6° C warmer in 70 years time. Mean temperature increases of these magnitudes have potential huge socioeconomic consequences. At present the world’s economy is booming and there has been no serious attempt to reduce the burning of fossil fuels and cement manufacture that reached close to 7,000 million tonnes of carbon in 2000, contributing to the rising levels of CO2 in the atmosphere. While per capita inputs of carbon have levelled off the human population is expected to increase by a half in the next 30 years to ~9 billion people so unless individual carbon use is reduced considerably levels will continue to rise. The plankton may be acting like a canary in a mine warning us of the changes ahead. We are not tackling the issues with the urgency and resources required. In particular there is an important need to develop a global observing system for the oceans and its ecosystems that is adequately funded to assess and quantify the rate of future change. This applies particularly to Australian waters where monitoring systems for the plankton are minimal at present. Mankind needs to rapidly change the way we live, conserve resources, adapt to the changes, develop local approaches, save energy and urgently develop mitigation measures.

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Location:
CSIRO = Marine Laboratories Auditorium, Castray Esplanade, Hobart

For further information, or to schedule a seminar, contact:
To schedule a seminar, contact:
Bernadette Sloyan, (Oceanographic seminars) CSIRO Marine and Atmospheric Research (03) 6232 5152
Thomas Kunz, (Biological seminars) CSIRO Marine and Atmospheric Research
(03) 6232 5076
Natalie Dowling, (Fisheries Modelling) CSIRO Marine and Atmospheric Research
(03) 6232 5148
Jillian Enraght-Moony, (seminar administrator) CSIRO Marine and Atmospheric Research (03) 6232 5320
Communications Manager, Antarctic Climate and Ecosystems CRC (03) 6226 2265
Margaret Hazelwood, Institute of Antarctic and Southern Ocean Studies (IASOS) University of Tasmania (03) 6226 2971

Last updated 21/07/09