Drivers and consequences of climate change

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Drivers and consequences of climate change

Up until the mid-1950s, climate models demonstrated that global average temperature variability could be explained by natural factors such as the output from the sun and volcanic eruptions. However, from 1970 onwards only by adding greenhouse gas emissions (mainly carbon dioxide produced by human activity) to climate models could the recent, steep rise in temperature be accounted for.

According to the Australian Bureau of Meteorology, the 2001-2010 period marked Australia's hottest decade on record, with each decade since the 1940s warmer than the last. Red Cross researchers believe that Earth's stability and sustainability is under threat and they identify climate change as one of the main causes. Red Cross reports that the number of disaster events each year is rising steadily; from around 100 in 1975 to more than 400 in each of the last nine years.

CSIRO Fast Facts:

Ongoing changes in the climate and some sea level rise are now unavoidable

Australia is likely to become warmer, with less rainfall and more droughts in the south, uncertain rainfall changes in the north, more heat waves, less snow, more fires, more heavy rainfall events and more intense cyclones

Further increases in greenhouse gases are expected and this will accelerate changes in the climate

Our current dependence on fossil fuels for energy is threatening Queensland's iconic Great Barrier Reef. IPCC Working Group II (Impacts, Adaptation and Vulnerability) reported that the ocean has become more acidic, because of increased concentration of atmospheric carbon dioxide resulting from human activity. Since the Industrial Revolution, the surface ocean pH has dropped by about 0.1, which corresponds approximately to a 30% increase in acidity.

One third of the carbon dioxide we produce on land ends up in our oceans making them more acidic, which leads to brittle coral and seashells. The marine carbonate buffer system enhances the uptake of carbon dioxide in the ocean because carbon dioxide in the ocean becomes carbonate ions. However, this carbonate buffer system will reach saturation leaving an increasingly large proportion of man-made CO2 emissions in the atmosphere. Greenhouse gas emissions during the next few decades will significantly affect our future climate.

To stabilise atmospheric greenhouse gas concentrations, our emissions would need to peak and then decline. To stabilise carbon dixoide-equivalent concentration to 490 parts per million, or less, our emissions would have to peak before 2015, followed by a 50-85% reduction in emissions (from 2000 levels) before 2050.

However, even this scenario is likely to result in a 50% chance of exceeding 2ºC of global warming. Delaying peak emissions until 2020 would lead to a mean global warming of 3ºC.

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