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For our November meeting we welcomed Jim Paine of Walnut Tree Nurseries. Jim and his wife Clare have been running their enterprise for about 20 years. The nursery specialises in flowering dogwoods and crab apples, but there are many other types of plant in their range both on site and on line. Jim came to talk to us about climate change. His talk was complemented with some very informative slides.
Jim started by clarifying a possible confusion between climate and weather: weather is the atmospheric stuff happening at a particular time, whereas climate is the averaging out of those different features of the weather into a stable pattern over a particular period. The United States Climate Data Center regards a 30 year period as the length of time over which data can be accumulated to arrive at an ‘average’ to determine the climate. Any anomalies in any period will simply be a variation in the weather. However, if there are sufficient anomalies that result in the averages changing - over a 30 year period - then that may be considered as a change in the climate.
The realisation of the possibly of climate change can be traced back to a number of people including the following: the mathematician Joseph Fourier (1768-1830) wondered why a planet doesn’t keep heating up as it receives sunlight. He reasoned that some of the heat absorbed was being re-emitted until a state of equilibrium was arrived at. He thought that the atmosphere acted like a sheet of glass over a box, a well-known experiment of the time. Fourier thus introduced the concept of the ‘greenhouse effect’. John Tyndal (1820-1893) made discoveries in the studies of infrared radiation and its effect on the physical properties of air. Svante Arrhenius (1859 – 1927) developed a theory to explain ice ages and their relationship to atmospheric carbon dioxide. He concluded that human production of the gas could cause global warming.
From this and subsequent work it became possible to calculate the amount of heat an object (like a rock or a planet) would absorb, so increasing its temperature. It could also be calculated how much heat it would radiate away, thus reducing its temperature. When heat in equals heat out the temperature of that object becomes stable. When the calculations were carried out to arrive at a temperature for the planet Venus it worked out to -33°C. Sadly for the calculation, Venus is actually +427C. The Earth should be -22°C, it is +22°C. Mars should be -57°C, it is -33°C. These contradictions can be attributed to their respective atmospheric proportions of greenhouse gasses, mostly carbon dioxide: Venus 96.5%, Earth 0.04%, Mars 95.97%. There are other factors, but making changes to the carbon dioxide levels will have a calculateable effect.
The Sunlight reaching the surface of the Earth is 90% visible (high energy) light, which is able to pass through the glass of, say, a greenhouse. This will heat up anything inside the greenhouse. Those heated contents will then re-emit non visible (low energy infra red) ‘light’, much as a house radiator emits heat. Infrared radiation is much less able to pass through glass. Again, when heat in equals heat out the temperature if the interior becomes stable. It’s worth remembering that high energy does not mean high intensity. High energy light is short wavelength; low energy light is long wavelength, regardless of the wattage.
For about 200 years, since the industrial revolution, increasing amounts of carbon dioxide have been released into the atmosphere. Using historical information it is possible to construct a mathematical model that fits the data. The validity of the model can be checked by making a ‘hindcast’. That is, feeding data into the model, running it backwards and seeing how accurately the result matches the known historical climate. When the model has been tweaked to make it fit the past it can then be run forward to make a forecast. The predictions of these models have been well publicised.
Project Drawdown has calculated the top 100 things we might do (as opposed to stop doing) to decrease the amount of greenhouse gasses we put into the atmosphere and thereby reduce global warming. These are the top 10 with the calculated number of gigatons (a billion tons) of CO2 saved: New non greenhouse gas type refrigeration fluids – 89, onshore wind energy production – 85, reduce waste – 71, a plant rich diet – 66, tropical forest restoration – 61, educating girls – 60, family planning – 60, solar farms – 37, silvopasture (combining forestry with animal pasture (see The Archers on Radio 4)) – 31 and roof-top solar panels – 25.
Jim concluded a very interesting and thought provoking talk with a question and answer session, or perhaps a discussion would be more accurate. He is developing presentations of other gardening related subjects. There are more details on these and the distinctive range of plants for sale on his website at https://www.wtgn.co.uk.
This months competition results:
First: Sue Thomas.
Second: Jane Dalton.
Third: Chris Dalton.
Fruit / Vegetables:
First: Chris Dalton.
Second: Jane Dalton.
Third: Sue Thomas.
First: Prue Szczepanowski.
Second: Sue Thomas.
Third: Ed Szczepanowski.
Our next meeting will be Wednesday 12th of December. This is our Christmas social. doors open at 13:30, to start at about 14:00.
First: Ed Szczepanowski.
Second: Chris Dalton.
Third: Patrick Alzetto.
Our next meeting will be Wednesday 13th of December at Hockham village hall. This is our Christmas Social. Food will be provided, but any members requiring chemical modification should bring their own. Exact details are a bit hazy, but aren’t surprises what Christmas is all about?
Doors open at 13:30. Proceedings might start at about 14:00.
Page Last Updated - 21/11/2018