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An essay on the state of climate change science. The scientific uncertainties associated with climate prediction are the basis of most of the arguments about the significance of climate change 25and as well are the basis of much of the polarized public opinion on the political aspects of the matter.
Imagine a plume of smoke rising from a cigarette into some sort of flue. The stream of smoke is smooth enough for Essay on climate change in australia start, but suddenly breaks into random turbulent eddies whose behaviour is inherently unpredictable. We can in principle make closely spaced measurements all over the turbulent plume at some particular initial time, and then at regular steps forward in time into the future.
After the first time step, the model uses as its starting point the conditions predicted for the end of the previous step.
Predicting the actual value of the average rate of rise of the overall plume is still difficult. A tuneable parameter is a piece of input information whose actual value is chosen on no basis other than to ensure that theoretical simulation matches observation.
Normally it would be used to define something about the average state of the turbulent medium between the grid points of the forecasting model. The climate system is much like the smoke but is vastly more complicated. In principle at least we may be able to make a reasonable forecast of such things as the future global-average temperature and global-average rainfall by using a numerical model and a number of tuneable parameters obtained from observations of present conditions.
Forecasting smaller-scale averages becomes more and more problematic as the scale decreases. This qualitative conclusion is borne out by the year forecasts of global and regional rainfall produced by the various numerical climate models from around the world 1.
While the predicted global averages are reasonably consistent not necessarily correct, but at least to some degree consistent with each otherthe predictions for continental Australia for instance, where the overall average of measured rainfall is currently about mm per year, range from less than mm per year to greater than mm per year.
From which it would seem that long-term predictions of regional rainfall are probably little better than guesswork.
The World Meteorological Organization of the United Nations took its first steps towards establishing the World Climate Program in the early nineteen-seventies.
Among other things it held an international workshop in Stockholm to define the main scientific problems to be solved before reliable climate forecasting could be possible 2.
The workshop defined quite a number, but focused on the two that it regarded as the most important and fundamental. The first concerned an inability to simulate the amount and character of clouds in the atmosphere. The second concerned an inability to forecast the behaviour of oceans.
Oceans are important because they are the main reservoirs of heat in the climate system. They have internal, more-or-less random, fluctuations on all sorts of time-scales ranging from years through to centuries.
Many of the problems of simulating the behaviour of clouds and oceans are still there along with lots of other problems of lesser moment and for many of the same reasons as were appreciated at the time 26, Perhaps the most significant is that climate models do their calculations at each point of an imaginary grid of points spread evenly around the world at various heights in the atmosphere and depths in the ocean.
The calculations are done every hour or so of model time as the model steps forward into its theoretical future.
Problems arise because practical constraints on the size of computers ensure that the horizontal distance between model grid-points may be as much as a degree or two of latitude or longitude — that is to say, a distance of many tens of kilometres.
That sort of distance is much larger than the size of a typical piece of cloud. Even if experimental observations suggest that the models get the averages roughly right for a short-term forecast, there is no guarantee they will get them right for atmospheric conditions several decades into the future.
Among other reasons, small errors in the numerical modelling of complex processes have a nasty habit of accumulating with time. The work was discussed 3 by Dr Kip Hansen, who made the point that the results illustrate well the original finding by Edward Lorenz in the s using a weather model on an early computer: Again because of the grid-point business, oceanic fluctuations and turbulent eddies smaller than the distance between the grid-points of a model are unknown to that model.
This would not be a problem except for the point made earlier that eddies in turbulent fluids can grow larger and larger. All of the above is background to one of the great mysteries of the climate change issue.
Virtually all the scientists directly involved in climate prediction are aware of the enormous problems and uncertainties still associated with their product. It is therefore difficult to see how the Intergovernmental Panel on Climate Change the IPCC can maintain there is a 95 per cent probability that human emissions of carbon dioxide have caused most of the global warming that has occurred over the last several decades 4.
Bear in mind that the representation of clouds in climate models and of the water vapour which is intimately involved with cloud formation is such as to amplify the forecast global warming from increasing atmospheric carbon dioxide — on average over most of the models — by a factor of about three 5.Turnitin provides instructors with the tools to prevent plagiarism, engage students in the writing process, and provide personalized feedback.
The latest Technology news, reviews & opinion from The Age covering IT, Mobile, Internet, Social, Industrial & Research Technology and Science. Climate Change & Business Conferences 11th Australia-New Zealand Climate Change & Business Conference.
October Speaker powerpoint presentations can be viewed below. People all over the world are being affected by climate change, not just in Peru. California has had four years in a row of serious drought. There have been heat waves in Australia, New Zealand, Japan, Korea, China and in Europe.
Pay for essay writing online a fair price and choose an academic writer who will provide an original and complete well-researched college paper in return. We can write you a perfect assignment that ideally matches your requirements in no time.
We work day and night to offer you a service that exceeds your expectations. The Australian Government has recognised that greenhouse gas emissions cause climate change and are taking steps to fix the issue.
One strategy is the Kyoto Protocol. This is an international agreement of countries to reduce global greenhouse gas emissions over a five year period from