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Abstract:
On 19th August 1983 CSIRO issued a press release beginning with these words: "An intensive mathematical analysis of rainfall data for southeastern Australia over 140 years provided no evidence that cloud seeding operations had any effect on rainfall" Dr. Neville Fletcher .... said today. True, it didn't. It was designed not to and the publicity received by the announcement has ensured that "rainmaking" has been subsequently regarded as a total failure. The reason for this incorrect statement will be mentioned and a more reasonable assessment attempted. Standard statistical analysis methods suggested three experiments that were successes (more than 10% increase in rain with 95% confidence levels) and four failures. However, the statistical analyses used will be shown to be inappropriate, having been built on the false assumption that seeding only affected rainfall downwind on the day of seeding. There are in fact after-effects on the concentration of airborne natural cloud-seeding particles (ice nuclei) that last for many months. The only alternative for assessing the results has some uncertainties but has consistently shown that six of the eight CSIRO experiments were successful, as also were two subsequent seeding operations in Tasmania.
Examining the experiments in detail has produced strong evidence of the after-effects of seeding, some of them negative, some of them positive in terms of rainfall increase. There is also evidence of enhanced rain over an area greater than the target area. Some possible causes of these effects are offered in the light of more recent discoveries concerning mechanisms of rain formation.
The possibility that the new information could allow us to enhance rainfall far more cheaply than in the past, and the pitfalls that would have to be avoided, will also be discussed.
Abstract:
A clear fingerprint has emerged of global climate change caused by increased greenhouse gas emissions. Scepticism of the potential for greenhouse gases to alter our climate is akin to doubting that the earth is round. Uncertainty remains nonetheless of how climate change will manifest itself in the Southern Hemisphere. In this talk I will discuss possible responses of the coupled ocean-atmosphere-ice system to climate change, with a focus on the midlatitude and polar regions of the Southern Hemisphere. This will include a review of recent advances in our understanding of how weather systems, ocean currents, Antarctic sea-ice, sea-level, extra-tropical cyclones, and rainfall will respond to anthropogenic climate change.
About the speaker:
Matthew England is the recipient of the AMOS 2005 Priestley Medal which is awarded biennially for excellence in meteorological and oceanographic research. He is recognised as an international leader in both Southern Ocean dynamics and ocean tracer modelling. In 2004 he was awarded the Australian Academy of Sciences Frederick White Prize. Currently he is an ARC Federation Fellow and Director of the Climate and Environmental Dynamics Laboratory at UNSW.
Abstract:
Climate change is being increasingly communicated and discussed in the context of extreme events and dangerous impacts in an effort to highlight its importance and scale. The notion of climatic change has transformed from a gradual and linear “weak signal” towards non-linear and catastrophic representations, particularly related to the possibility of abrupt or sudden climate change. This seminar reports on two Tyndall Centre projects which aimed to understand ‘expert’ and ‘lay’ perspectives of ‘Dangerous’ Climate Change.
The first project aimed to elicit interpretations of ‘dangerous anthropogenic interference…’ from leading international climate experts through a mental models approach. This is a robust qualitative technique which seeks to investigate and understand how a respondent understands and thinks about an issue or situation. This method is commonly used to develop risk-specific communications tailored to particular situations, by identifying for a particular hazard both accurate and inaccurate beliefs held by expert and lay individuals in a target population. These models were encapsulated in a “meta” influence diagram, denoting three conceptualisations of danger in relation to climate change: (i) human influence upon the climate system; (ii) impacts upon natural and human communities; and (iii) threat to the status quo, especially in the form of mitigation measures and related costs. These conceptualisations raise questions about how experts bring to bear their knowledge, values and understanding of climatic and social systems in articulating such discourses and the utility of using such subjective policy terms.
A second study investigated the strategy of communicating climate change impacts as ‘abrupt’ or ‘dangerous’ to the public. It tests evidence which suggests that whilst the lay public have increased concern over climate change, overall, behavioural reactions are not affected. In some cases, a distancing from the causes and effects of climate change may result. A controlled experiment examined this conflict of opinion by exposing a sample of subjects to two different experiences; the film “The Day After Tomorrow” and a compendium of scientific literature relating to climate change and abrupt climate change. Findings indicate that the majority of respondents from all treatments perceive climate change as a violent and catastrophic threat. Whilst in general neither treatment results in a significant difference in response between the groups, some evidence for a distancing effect does emerge. This suggests that when the perceived threat is greater than the ability to cope, fear reactions can instigate message rejection through defensive responses. This study contributes to emerging theory on the roles of experiential processing, affect, and imagery, in risk perception and decision-making and, it is hoped, to the development of climate change communication towards a more effective end.
About the speaker:
Tom Lowe’s career began with a degree in Forestry Management from the University of Aberdeen. This allowed him to develop a practical grounding in environmental and natural resource management. An interest in the socio-cultural implications of environmental decision-making led him to carry out a Masters in Environment and Development at the University of East Anglia. Following a one year internship with the IUCN’s (International Union for Conservation of Nature and Natural Resources) Species Survival Programme in Cambridge, Tom returned to the University of East Anglia, this time as a research associate, based jointly between the Tyndall Centre for Climate Change Research and the Centre for Environmental Risk. His research has centred upon the notion of ‘dangerous’ climate change; issues relating to its use in policy and effects upon public perceptions. Tom is currently carrying out research as part of the Bushfire CRC’s ‘Building resilient communities’ program whilst also continuing to work for the Tyndall Centre as a consultant.
Abstract:
Modelling is an essential part of marine science. In the marine biological sciences, statistics and statistical models are commonplace. In physical oceanography, numerical models are more often used to understand coastal upwelling processes, large scale ocean dynamics, thermodynamics, ocean-atmosphere interaction, and ocean climate variability and change. Increasingly, numerical models have also become more widely used to understand ocean biogeochemical cycles. Choosing an appropriate model for a particular marine science application is not necessarily easy. Considerations in this choice include: identifying and resolving the processes that are important and/or that we want to understand, the relevant time and space scales of these processes, the modelling approach/philosophy (e.g., conceptual, statistical, deterministic (most commonly, numerical models)), model complexity (a hierarchy from simple box models through to state-of-the-art eddy-resolving ocean general circulation models), and available computer resources. This presentation will discuss results from some recent collaborative studies of ocean processes and climate variability by the author, his students and collaborators, using simple-to-intermediate complexity ocean models. Some thoughts will be provided regarding the appropriateness and limitations of these simpler models in the hierarchy.
About the speaker:
Neil Holbrook is currently senior lecturer in atmospheric science at Macquarie University, Sydney. He completed his undergraduate degree at the University of Sydney (1986-89) majoring in applied mathematics and marine sciences, gaining first class honours in physical oceanography. During 1990, he was employed as a research assistant at the University of Sydney and spent two months as a vacation scholar at CSIRO Division of Oceanography in Hobart. He completed his PhD in physical oceanography in the Marine Studies Centre/School of Mathematics and Statistics at the University of Sydney (1991-94). He was a postdoctoral researcher in the Climatic Impacts Centre (CIC), Macquarie University (Oct 1994 – Jan 1996) and spent three months as a visiting scientist at the National Center for Atmospheric Research (NCAR), Boulder, Colorado, USA. In 1996, he was appointed lecturer in atmospheric science at Macquarie University. His primary research interests include large-scale ocean and atmosphere dynamics, interannual-to-decadal upper ocean variability, simple-to-intermediate complexity modelling of the ocean (and atmosphere), and long time scale (centennial-to-millennial) climate change. He has authored and co-authored over 20 peer-review articles in international journals. His current and recent roles/honours include: Executive Secretary of the International Commission on Climate of IAMAS/IUGG [2003-2007]; Associate Editor of the Australian Meteorological Magazine [2001-2006]; Fellow (elected) of the Australian Meteorological and Oceanographic Society (AMOS) [2004-present]; Chair [1998-99, 2004] and Vice-Chair [2002-03] of AMOS Sydney Centre.
Abstract:
The planetary waves are the main extratropical atmospheric circulation patterns, directing, and interacting with, temporal and spatial-varying weather systems. Changes in the planetary waves invariably affect local climate characteristics. Understanding the variable pattern of the planetary waves could give insights into some local and temporal weather patterns, like for instance the occurrence of blocking highs and other persistent wind anomalies.
The drivers for changing the planetary waves are found in variations in the heat balance. With the Earth warming up at an alarming rate, it is expected that meridional heat transport will change. Changes in the meridional circulation will result in changes in the planetary wave structure. Such processes cannot be investigated with observations and we have to make use of climate models. Climate simulations and studies into past climates can help us understand what might happen to the planetary waves under different heat balance scenarios.
This talk will present some of the presenter’s findings of the characteristics of the Southern Hemisphere planetary wave patterns in a climate simulation under Last Glacial Maximum forcings. That presentation will automatically evolve into an analysis of the characteristics, changes and variability of the present day planetary waves in the Southern Hemisphere. Can we predict what might happen to the large-scale circulation patterns in the future?
About the speaker:
I obtained my MSc in geophysics in 1990 at the Rijksuniversity of Utrecht, the Netherlands, on the topic “Unbending and bending of the subducted lithosphere and the implications for intermediate depth seismicity”.
Upon finishing my MSc, I migrated to New Zealand (March 1990). I have worked for 7 years as a field and laboratory technician in geomorphology and hydrology at the School of Earth Sciences, Victoria University of Wellington. In 2001 I decided to do my PhD in atmospheric science on the topic “An investigation into New Zealand’s climate during the Last Glacial Maximum: A climate modelling approach”. I received my PhD in May 2006.
Upon several other memberships, I am a member of the Geophysical Society of New Zealand and the Meteorological Society of New Zealand. I was a committee member of the Meteorological Society since 2001, co-editor of the Society’s journal in 2004, and secretary of the Society for the last 4 years.