Scientists from Australia’s leading climate research centres are urging farmers to accept the reality of climate change and to work collaboratively on farming systems that will cope with more El Ninos and a range of other challenging climatic factors.

They say continuing increases in the concentration of carbon dioxide in the atmosphere will have positive and negative effect on the growth patterns of crops, trees and pastures while changes in rainfall patterns – increases as well as increases – will impact directly on production.

Temperature increases are already leading to changes such as the planting dates for wheat; the period when frost can be expected in Emerald, in Central Queensland, has dropped from around 10 weeks in 1900 to around three weeks in 2000.

They say further temperature increases will also affect rotations, limiting canola’s spread north into Queensland, for instance, or encouraging cotton production further south than it is grown now.

Water figures largely in the scientists’ calculations – river flows, erosion and management of salinity. And crop management is likely to see many changes, with farmers in what are now the more favoured cropping regions perhaps learning from their counterparts already farming in marginal environments.

In turn farmers who are in marginal regions now might switch from their current grain/grazing mixed operations to pure grazing or even plantation forestry.

Joint authors of the paper are Holger Meinke and Roger Stone from QDPI/APSRU and Queensland’s Centre for Climate Applications respectively, CSIRO researchers Mark Howden and Roger Gifford and William Wright, from the Bureau of Meteorology in Melbourne.

Their collaborative research has had the financial backing of the Australian Greenhouse Office, the Grains and Cotton Research and Development Corporations, CSIRO and Queensland’s Department of Primary Industries. The work also had close links with international scientists through the Asia-Pacific Network for Global Change Research and United Nations and United States programs.

Dr Meinke presented the paper at the Fifth Australian Maize Conference in Toowoomba last week, telling delegates world scientific opinion – the Inter-governmental Panel on Climate Change (IPCC) – backed the reality of "greenhouse" gases and resultant global warming.

The IPCC believed that – without new, countering initiatives – globally averaged surface air temperature would warm by 1.5 to 6.0º C by 2100 relative to 1990.

A 1ºC rise in average temperature would make Melbourne’s climate more like that currently experienced by Wagga Wagga, a 4^ºC rise like that of Moree and a 6^ºC rise like that of Roma.

"Climate change is already affecting Australian cropping systems and the way we manage them, although in many cases we might not be aware that we are dealing with manifestations of climatic change." Dr Meinke said. " For example, the number of frost days and the dates of last frost across most of Australia have reduced considerably since the 1950s and this has already changed variety choice and planting dates for wheat. " Good risk managers can no longer afford to dismiss climate change as something to be considered in the distant future or as an issue that only concerns politicians."

Changes in the dates of first (black circles) and last (grey circles) frost at Emerald during the last century (expressed as a screen temperature of 2oC or lower).

Dr Meinke said study of the more complex, likely effects of climate change on crops in Australia was still in its early stages, although computer modelling had been effective in assessing the potential of management changes to help farmers adapt.

Options could include:

• changes in varieties and planting dates, successful already in Central Queensland, where frost risk to winter crops has fallen;
• changes in crop species, with the availability of soil and irrigation water a crucial issue;
• changing crop management itself, continuing developments like zero tillage and different plant configurations;
• erosion and salinity management, forced by the expected increase in rainfall intensity, which could tend to increase drainage in northern Australia;
• pest and disease management, with more reliance on integrated pest and area wide management, and
• more use of seasonal forecast information in management decisions to take advantage of good seasons and to prepare for the bad ones.

"While there’s some potential for us to reduce the human contribution to climate change, from a management perspective adaptation to climate change requires the same tools and approaches that we are already using successfully to manage climate variability," Dr Meinke said.

"This will to more efficient and sustainable cropping.

"We’re past the stage of debating whether climate change is actually happening; the challenge for Australian farmers now is to develop strategies to manage it, capitalise on the upsides and minimise the effect of the downsides.