Four degrees hotter looks crook Ė letís get cracking
From the August 2011 edition of Agriculture Today.
Scientists speaking at the recent Four Degrees climate conference in Melbourne painted a grim picture of hotter temperatures, significant reductions in rain and up to 40% decline in production per unit area of core agricultural commodities.
Scenarios include increasing water scarcity and declining fruit and vegetable production in key irrigation areas, and falling wheat production.
CSIRO scientist Mark Howden says lower wheat production means lower wheat exports, even to the point of Australia being a net importer under some climate models.
We are already importing more fruit and vegetables than we export.
These climate-induced declines are likely to be exacerbated by increasing human population, explosions of weeds (note this edition’s front page), pests and pathogens in hitherto cooler production regions, wind and water erosion, and sea level rises in coastal areas.
Competition for agricultural land will intensify due to demand from urban and peri-urban growth, mining, carbon forestry, biofuels, solar farms, and biodiversity conservation.
A four degree increase may occur by the end of the century if greenhouse gas emissions stay high.
It would mean overall temperature increases of three to five degrees in coastal areas and four to six degrees inland.
It would mean up to 50% decline in annual rainfall in southern Australia, particularly in winter, leading to more droughts and marked increases in potential evaporation.
Current extreme weather events such as the 2009 bushfires and the 2011 floods would become more frequent.
The general rule is that small changes in mean temperature mean big changes in the extremes.
A warming of 4°C is likely to lead to increases in extremely high temperatures, extreme daily rainfall, extreme fire weather, large hail on the east coast, tropical cyclone intensity and extreme sea level events.
However these changes may be avoidable if we act to reduce global greenhouse emissions now.
So what are our options in agriculture?
Broadly, we need to reduce our greenhouse gas emissions as fast as possible, use agricultural lands to sequester more carbon, and grow biofuels.
We can fine-tune current management practices, develop new varieties and techniques more suitable for a hotter, drier climate, diversify enterprises, even transform operations to produce ecosystem services.
In NSW, many farmers have already shown remarkable ability to adapt.
All of us in agriculture can increase our capacity to adapt to a hotter, drier future, hopefully less than four degrees hotter if we act now.
You can listen to several of the presentations at the Four Degrees conference at www.fourdegrees2011.com.au/presentations