The future - cooking the planet
Even allowing for some degree of scepticism as the link between the loss of arctic sea ice and the behaviour of the jet stream noted in Jeff Masters’ Scientific American article referred to earlier, clearly the world cannot safely wait to act until scientists fully understand how and why the climate is changing[1].
According to the Intergovernmental Panel on Climate Change, in order to keep warming below the dangerous 2 degree Celsius threshold, energy sources such as solar, wind and nuclear that emit low or zero levels of carbon dioxide, along with technologies that can capture and store carbon, must at least triple by 2050, and greenhouse gas emission must fall by 40 to 70% compared with 2010 levels. Otherwise, the earth could launch into a spiral of terrible storms, droughts, fire, famines, and extinctions.
For its fifth report (AR5) in 2014, the IPCC selected four greenhouse gas concentration (not emissions) trajectories known as Representative Concentration Pathways (RCPs) for climate modelling and research[2]. The RCPs were selected and defined by their total radiative forcing[3] pathway and level by 2100. They describe four possible climate futures, all of which are considered possible depending on how much greenhouse gases are emitted in the years to come and constitute projections not predictions[4].
The dotted line designated A1B denotes “business as usual”. The light grey area captures 98% of the range in previous Integrated Assessment Model (IAM) scenarios, and dark grey represents 90% of the range.
The PricewaterhouseCoopers chart below, illustrating current rates of “decarbonization” (reducing our use of carbon) compared with the rates needed to keep climate change in check, shows that at the present rate, we are destined to miss the 2 degrees C goal by 2 degrees C by the end of the century (reaching a total of 4 degrees Celsius increase)[5]. In order to avoid such an outcome, we’d have to cut 6.2 per cent of our emissions every year for the rest of the century – a huge task.
The PricewaterhouseCoopers chart below, illustrating current rates of “decarbonization” (reducing our use of carbon) compared with the rates needed to keep climate change in check, shows that at the present rate, we are destined to miss the 2 degrees C goal by 2 degrees C by the end of the century (reaching a total of 4 degrees Celsius increase)[5]. In order to avoid such an outcome, we’d have to cut 6.2 per cent of our emissions every year for the rest of the century – a huge task.
"We will literally cook the planet"
Certainly, something must be done because – keeping in mind that benchmark figure of 2 degrees C - if we were to continue on a “business-as-usual” basis and burn all the world's known fossil fuels, this would result in the release of the equivalent of 5 trillion tonnes of carbon dioxide and drive global temperatures 8 degrees warmer than pre-industrial levels by 2300.[6]
By 2300, global temperatures would range from 6.4-9.5 degrees warmer than pre-industrial times with a mean warming of 8.2 degrees. Arctic regions would warm by as much as 19.5 degrees. Rainfall changes would include increases of as much as fourfold in tropical areas, while more-temperate areas – such as parts of Australia, the Mediterranean and the Amazon – could have rainfall halved. Such climate changes, if realised, would have extremely profound impacts on ecosystems, human health, agriculture, economies and other sectors[7].
Not only would thawing permafrost in Arctic regions release huge amounts of greenhouse gases, existing carbon sinks, such as oceans and the tropics, would take in less carbon dioxide, leaving more of it the atmosphere. Last year, the Climate Council estimated that as much as 90% of Australia’s remaining fossil fuel reserves would have to remain in the ground, assuming the country did its bit to keep warming to within 2 degrees[8].
However, if fossil-fuel burning continues at a “business-as-usual” rate, such that humanity overall exhausts the reserves over the next few centuries, CO2 will continue to rise to levels of order of 1500 ppm. The atmosphere would then not return to pre-industrial levels even tens of thousands of years into the future. In the words of Dr Pep Canadell, executive director of CSIRO’s Global Carbon Project, "If we continue to ultimately burn all that we know to be in our fossil fuel reserves, we will literally cook the planet”[9].
[1] Jeff Masters, op cit, Scientific American, December 2014, 52 at 59.
[2] Foundation source for this material: Associate Professor Michael Box’, “Our Atmospheric Environment”, 6.1.1.
[3] The cumulative measure of human emissions of GHGs from all sources expressed in Watts per square meter.
[4] https://en.wikipedia.org/wiki/Representative_Concentration_Pathways
[5] http://www.pwc.co.uk/assets/pdf/low-carbon-economy-index-2014.pdf
[6] The result of a Canadian study, published in Nature Climate Change: “We would literally cook the planet”, Sydney Morning Herald, 24 May 2016; also at http://www.smh.com.au/environment/climate-change/burning-all-fossil-fuels-would-cook-earth-raise-temperatures-8-degrees-study-20160523-gp1ih3.html
[7] On the impact of climate change in Australia and its ecosystems, see the CSIRO’s 2007 report “Australian Climate Change Impacts – adaptation and vulnerability”, prepared under the auspices of the IPCC at http://www.ccma.vic.gov.au/soilhealth/climate_change_literature_review/documents/conferences/greenhouse_2007/071002_Hennessy.pdf
[8] www.smh.com.au/environment/climate-change/burning-all-fossil-fuels-would-cook-earth-raise-temperatures-8-degrees-study-20160523-gp1ih3.html
[9] Cited in Ibid.
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Certainly, something must be done because – keeping in mind that benchmark figure of 2 degrees C - if we were to continue on a “business-as-usual” basis and burn all the world's known fossil fuels, this would result in the release of the equivalent of 5 trillion tonnes of carbon dioxide and drive global temperatures 8 degrees warmer than pre-industrial levels by 2300.[6]
By 2300, global temperatures would range from 6.4-9.5 degrees warmer than pre-industrial times with a mean warming of 8.2 degrees. Arctic regions would warm by as much as 19.5 degrees. Rainfall changes would include increases of as much as fourfold in tropical areas, while more-temperate areas – such as parts of Australia, the Mediterranean and the Amazon – could have rainfall halved. Such climate changes, if realised, would have extremely profound impacts on ecosystems, human health, agriculture, economies and other sectors[7].
Not only would thawing permafrost in Arctic regions release huge amounts of greenhouse gases, existing carbon sinks, such as oceans and the tropics, would take in less carbon dioxide, leaving more of it the atmosphere. Last year, the Climate Council estimated that as much as 90% of Australia’s remaining fossil fuel reserves would have to remain in the ground, assuming the country did its bit to keep warming to within 2 degrees[8].
However, if fossil-fuel burning continues at a “business-as-usual” rate, such that humanity overall exhausts the reserves over the next few centuries, CO2 will continue to rise to levels of order of 1500 ppm. The atmosphere would then not return to pre-industrial levels even tens of thousands of years into the future. In the words of Dr Pep Canadell, executive director of CSIRO’s Global Carbon Project, "If we continue to ultimately burn all that we know to be in our fossil fuel reserves, we will literally cook the planet”[9].
[1] Jeff Masters, op cit, Scientific American, December 2014, 52 at 59.
[2] Foundation source for this material: Associate Professor Michael Box’, “Our Atmospheric Environment”, 6.1.1.
[3] The cumulative measure of human emissions of GHGs from all sources expressed in Watts per square meter.
[4] https://en.wikipedia.org/wiki/Representative_Concentration_Pathways
[5] http://www.pwc.co.uk/assets/pdf/low-carbon-economy-index-2014.pdf
[6] The result of a Canadian study, published in Nature Climate Change: “We would literally cook the planet”, Sydney Morning Herald, 24 May 2016; also at http://www.smh.com.au/environment/climate-change/burning-all-fossil-fuels-would-cook-earth-raise-temperatures-8-degrees-study-20160523-gp1ih3.html
[7] On the impact of climate change in Australia and its ecosystems, see the CSIRO’s 2007 report “Australian Climate Change Impacts – adaptation and vulnerability”, prepared under the auspices of the IPCC at http://www.ccma.vic.gov.au/soilhealth/climate_change_literature_review/documents/conferences/greenhouse_2007/071002_Hennessy.pdf
[8] www.smh.com.au/environment/climate-change/burning-all-fossil-fuels-would-cook-earth-raise-temperatures-8-degrees-study-20160523-gp1ih3.html
[9] Cited in Ibid.
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