This is the conclusion on climate change from media baron Rupert Murdoch, as he tweeted yesterday. Crikey asked Dr Chris Weston from the Department of Forest and Ecosystem Science at the University of Melbourne to apply the Get Fact blowtorch to the tweets. Does Rupert’s science stack up?

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The scientific community has known since the early 1960s that rising concentrations of CO2 and other greenhouse gases would lead to rapid atmospheric warming and to changes in climate regimes, especially at the poles. Basically, a warmer atmosphere holds more water vapour and will lead to higher global rainfall as well as temperature increases in the oceans.

Since the 1960s this knowledge has been difficult for the broader community to grasp and accept, now we have confirmation of that approach via tweets from Rupert Murdoch.

There is an element of truth to his tweets. Science predicts a “CO2 fertilisation” stimulation of vegetation growth in response to rising CO2 and increased water and nutrient availability. Through photosynthesis, forests are systems that transform light energy from the sun into chemical energy in wood — from CO2 of the air plus water and nutrients.

Because CO2 is a gas in very low concentrations in the atmosphere, the process of photosynthesis is in part limited by the CO2 concentration of air diffusing into leaves from the atmosphere.

Murdoch’s tweet not only acknowledges the reality of rising atmospheric CO2, it also accepts a global vegetation impact. That’s real progress, a senior influential global citizen with major media influence accepts global impact of rising CO2. Or is it?

Taken together, these two tweets suggest that rising atmospheric CO2 and climate change is good for the world, and that humans should abandon limiting fossil fuels by developing non-CO2 polluting alternatives. This is a clear example of the habitually hopeful disposition that is part of human nature — and the denial that sits alongside it.

Humans do these traits well, but in this case the overwhelming scientific evidence points to major climate disruptions and impacts on human food systems and the economy from global warming brought on mainly by our adherence to energy systems that transfer carbon from coal, oil and gas directly to the atmosphere.

Rupert’s first tweet is “mostly true”, the second tweet is “utter bollocks” and when taken together they demonstrate a wanton disregard for the well-being of future generations and life on earth.

Changes in the intensity and timing of precipitation, extreme weather events and rising annual temperature trends are evidence of rapid climate change. So to is melting of polar region land and sea-ice and rising sea levels.

On balance these climate change impacts will cause negative disruptions to human food systems and to the infrastructure that supports human cultures, especially in low-lying coastal areas. Food production will become a more risky enterprise as weather extremes and shifting climate challenge the planning and infrastructure that supports agriculture.

Rapid climate change will bring about rapid shifts in biomes and their characteristic vegetation. During the rapid transition phase in many environments, impacts will be reflected in altered fire regimes that may be more destructive to human infrastructure and food systems. We may be seeing the early phase of this trend in the extensive and catastrophic fires in many parts of southern Australia since 2003.

As large areas of Australia experience an unprecedented heatwave this week, ask yourself what level of risk you are prepared to accept in gambling with Earth’s climate system against the best advice of the scientific community.

In terms of background, the anthropocene is a time span of humans’ track record in altering Earth’s vegetation, biodiversity and soils, and it applies to conditions prevailing over the last 10,000 years or so. Humans’ impact on earth’s systems has been evident since the rise of agriculture and has increased rapidly over the last 200 years since the industrial revolution and the attendant exponential human population growth.

Fortunately our knowledge and understanding of our planet, the life it supports and its big cycles of water, carbon and nutrients has also grown along with our influence on these cycles. Emerging from the abundance of new knowledge is the realisation that carbon dioxide (CO2) and other gases in our atmosphere act like a blanket to trap heat energy and maintain Earth’s temperature regime.

The spread of agriculture, cities and roads has reduced the area of Earth’s forests by about 20% since 1700 and in so doing has caused a net release of carbon from vegetation and soil to the atmosphere as CO2.

Since the 1940s, fossil fuels have rapidly become the major source of increased CO2 in the atmosphere and now account for about 75% of the additional CO2 released annually to the atmosphere by human endeavour. We know that humans have managed Earth’s resources to increase annual average atmospheric CO2 from about 250 parts per million (pm) in 1850 to 393.8 ppm in 2012.

Annual atmospheric CO2 increases are currently running at about 1.8 ppm so that even with the best global mitigation actions 600-1000 ppm is inevitable.

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Peter Fray
Peter Fray
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