Trephina Gorge, Central Australia
Climate Change – First Principles
After reading many badly written media reports I am going back to first principles of Climate Change. This began with Andrew Campbell, 2008. Managing Australian Landscapes in a Changing Climate: A climate change primer for regional Natural Resource Management bodies. Report to the Department of Climate Change, Canberra, Australia (downloadable from the author’s website, http://www.triplehelix.com.au/). Campbell is a firm believer in the ‘Greenhouse Effect’ driven by CO2 emissions and whether one is a skeptic, or agrees with the CO2 effect, he offers practical suggestions for mitigating climate change.
But first, some definitions.
“Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and numerous other meteorological elements in a given region over long periods of time.” http://en.wikipedia.org/wiki/Climate
Climate change is the variation in global or regional climates over time. It reflects changes in the variability or average state of the atmosphere over time scales ranging from decades to millions of years. These changes can be caused by processes internal to the Earth, external forces (e.g. variations in sunlight intensity) or, more recently, human activities. In recent usage, especially in the context of environmental policy, the term “climate change” often refers only to changes in modern climate, including the rise in average surface temperature known as global warming. In some cases, the term is also used with a presumption of human causation, as in the United Nations Framework Convention on Climate Change (UNFCCC).
Climate models use quantitative methods to simulate the interactions of the atmosphere, oceans, land surface and ice. They are used for a variety of purposes from study of the dynamics of the weather and climate system to projections of future climate. The most talked-about models of recent years have been those used to infer the consequences of increasing greenhouse gases in the atmosphere, primarily carbon dioxide (see greenhouse gas). These models predict an upward trend in the global mean surface temperature, with the most rapid increase in temperature being projected for the higher latitudes of the Northern Hemisphere. http://en.wikipedia.org/wiki/Climate#Climate_change
Global warming is the increase in the average temperature of Earth’s near-surface air and oceans since the mid-twentieth century and its projected continuation. Global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) between the start and the end of the 20th century. http://en.wikipedia.org/wiki/Global_warming
The trend shown below from the Australian Bureau of Meteorology confirms that we are experiencing increasing temperatures. Additional data and definitions are on http://www.bom.gov.au/climate/change/.
However, when checking out the ‘Annual Mean Temperature Anomaly’, I found slightly different information where the trend line is not so ominous.
See http://www.bom.gov.au/climate/change/amtemp.shtml
What is the cause?
External forcing of climate refers to processes external to the climate system (though not necessarily external to Earth) that influence climate. Climate responds to several types of external forcing, such as radiative forcing due to changes in atmospheric composition (mainly greenhouse gas concentrations), changes in solar luminosity, volcanic eruptions, and variations in Earth’s orbit around the Sun. Attribution of recent climate change focuses on the first three types of forcing. Orbital cycles vary slowly over tens of thousands of years and thus are too gradual to have caused the temperature changes observed in the past century.
The greenhouse effect is a natural warming process of the earth. When the sun’s energy reaches the earth some of it is reflected back to space and the rest is absorbed. The absorbed energy warms the earth’s surface which then emits heat energy back toward space as longwave radiation. This outgoing longwave radiation is partially trapped by greenhouse gases such as carbon dioxide, methane and water vapour which then radiate the energy in all directions, warming the earth’s surface and atmosphere. Without these greenhouse gases the earth’s average surface temperature would be about 35 ° Celsius cooler.
Australian BOM
Human activities such as deforestation and the burning of fossil fuels have increased the concentrations of greenhouse gases in the atmosphere. http://www.bom.gov.au/lam/climate/levelthree/climch/clichgr1.htm
http://en.wikipedia.org/wiki/File:Climate_Change_Attribution.png
In summary, the surface temperature of Australia is rising and greenhouse gasses are increasing. The greenhouse proponents sress that the two are linked. I now need to review why the sceptics dismiss the CO2 connection.
Today’s Podcast
There is a small controversy over school gardens in the USA. Caitlin Flanagan, “Cultivating Failure”, The Atlantic, Jan-Feb 2010, http://www.theatlantic.com/doc/201001/school-yard-garden has provoked comment with her thesis that school gardens are teaching students work skills that their migrant parents in California want to leave behind. School should be for better test scores and graduating on to college and a less labour intensive working life.
“The Edible Acre Project”, Agroinnovations, 11 January 2010, http://agroinnovations.com/index.php/en_us/multimedia/blogs/podcast/ is an interesting example of how school gardens have been woven into the curriculum rather than simply picking lettuce.
In this episode we continue with the theme of school gardens and farms. I am joined by Debbie Hillman of the Edible Acre Project, a project in a suburb just outside of Chicago Illinois. Debbie discusses the origins and implementation of the project, the role of a the farm/garden in education, and practical strategies for those looking to develop similar projects in their communities.