Thursday, October 13, 2011

Climate Change on the Eastern Downs

For most of us, the big climate change question has moved past the bickering about whether it is or is not happening, and whether it’s really being caused by humans.
Now, the questions now are to what extent the people of the world (including us) will be able to keep the change itself within reasonable bounds, how those changes that we are unable to prevent will affect us, and how best to cope with those changes we cannot prevent.
There is general recognition that climate change is not something humans will ever be able to prevent completely.However, the that we can and should do something to reduce the speed and extent of the change is becoming more widespread. An increasing number of individuals are making the choice to live “greener”. Investment in “green” technologies is now widespread, and increasing. Insurance companies are deciding that gambling on "no change" is likely to cause them financial pain, and local governments in coastal areas are planning strategies for coping with sea level rise. The most recent evidence of the changing weight of opinion is shown by our federal government’s recent decision to pass the carbon bills, a move that would have seemed unthinkable only a few years ago.

I recently got hold of the Queensland Government’s 2010 document on the subject, and found it interesting to read their projections (based on climate modelling done by the CSIRO) on how climate change is predicted to affect our own district.
In a nutshell, The Darling Downs will be hotter and dryer.
Calculations (based on the notion that the world will succeed in controlling its greenhouse gas emissions, to some degree), show that on the Eastern Darling Downs, average temperature is likely to be 1°C higher by 2030, average rainfall down by three per cent, and evaporation up by 3-4%. Of course these rather conservative figures will all be exceeded if there is no change (or less change than these researchers hope for), to the current rate of increase in greenhouse gases.
Whatever happens, we can expect fewer frosts, dryer winters, more heat waves and higher evaporation levels.
Water restrictions will be imposed more frequently. Those water conservation techniques that we learned, so that we could go on gardening during our recent 20-year drought, will be needed more than ever.
We’ll need to focus more on choosing heat and drought-hardy species for our gardens. We will enjoy our gardens more if we give up trying to nurse along those plants that would die if we failed to give then regular watering. As a trade-off, we may be able to grow some plants from northern districts which have previously been hard to keep alive through winter.
Australian native plants have had a long history of coping with climatic extremes, so are suitable plants to choose for a garden which will survive through change.
We are likely to show more interest in shady but drought-hardy trees such as our local dry rainforest species, rather than Eucalypts. (We love them, but they don’t keep the heat out of the garden.)
Scrub Wilga Geijera salicifolia( a dry rainforest species) and an Ironbark, Eucalyptus sp. both growing well despite the complete lack of garden care, both equally drought hardy. The wilga wins, in terms of providing livable shade!
Natural regeneration of native plants is likely to result in a slow move of our local species’ ranges, from north to south, and from west to east. Birds and other wildlife will change with the vegetation. Those native plants (some of them already very rare) which survive because they grow on cooler mountaintops may find themselves pushed uphill to extinction. Our conservation attempts should focus on these species.
Weeds which are currently kept in check by our frosts may invade. The effect will probably be greatest with woody plants and grasses. Highly flammable species like green panic, which loves to grow on rainforest edges, will increasingly threaten ecosystems that have previously been able to avoid being burnt because their plants have some ability to resist catching fire. (Once set alight, however, these plants are killed.)
Fires are likely to increase, putting pressure on those ecosystems such as rainforests and scrubs whose plants die when burned, and allowing them to be replaced by fire-tolerant species such as grasses and Eucalypts. Meanwhile, householders are likely to want to replace very flammable species (especially Eucalypts and introduced conifers) with non-deciduous plants that have green canopies and a reputation for not catching fire easily. Burning off, a practice which reduces short-term fire risk, but promotes an ecology dominated by flammable trees and grasses, is likely to come under review.
Plant diseases are also likely to spread southwards. So will diseases which affect humans, especially those borne by mosquitos. We may need to become much more careful, as tropical gardeners are now, not to risk our own health (as well as that of, for example, our neighbour’s children), by being careless about having water in the garden.
Our creeks and rivers will run dry more often, with a decline in both water quality and the native species that depend on them. The country is already addressing this problem by reducing rights to harvest water for agriculture. The decisions as to who has a right to how much water is fraught with difficulty, but I do hope that the needs of native plants and animals will continue to be factored in, and balanced with the very reasonable desire by landholders to make a living from their land.
Groundwater supplies will not be replenished at the current rate. We may see more use of soil surface treatments (such as mulch) designed to allow water to soak into the ground rather than run off. Driveways and other outdoor paving might also be used for water harvesting.
We can expect to see more restrictions placed on the use of underground water, as the levels drop ever more rapidly. It’s not wise to spend money on a bore in the belief that it will continue to be possible to fill gardens with plants from wetter climates, and keep them green with unlimited free sprinkling.
We will see more intense storms, rainfall events, and hail. We shouldn’t be lulled, by calculations of dubious mathematical integrity, into believing that last year’s “inland tsunami” was a “once in a hundred year event”, (or some such flaky figure). Our homes and gardens need to be designed to cope with such destructive summer downpours as the one in 2010. (So does all our public infrastructure, but that’s another story.) On the plus side, it is well worth putting in effective roof gutters and extra tanks to harvest these summer windfalls and save them for the increasingly dry winters.
Crows Ash Trees Flindersia australis. This Toowoomba residence takes advantage of a cool site among old trees.Built for Australia's variable climate, this is a dry rainforest species which is likely to weather climate change gracefully.

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