The tipping point
The consensus amongst climate change experts, including the Intergovernmental Panel on Climate Change (IPCC) and NASA, is that the tipping point for Earth’s climate is a global temperature rise of 2 degrees centigrade above pre-industrial levels.
The tipping point is when global temperatures no longer simply rise in accordance with the amount of carbon dioxide (CO2), and other greenhouse gases, which we release into the atmosphere.
Its rise suddenly accelerates, beyond our ability to control, or even predict it.
This sudden acceleration is caused by rising temperatures triggering events that cause further rises in temperature.
For example, the already occurring disintegration of the West Antarctic and Arctic ice sheets are causing what was once a white surface (ice), which reflected sunlight without absorbing its heat, to become a dark surface (sea), which absorbs heat, and thus speeds up global warming.
Further, this occurrence accelerates the release of icebergs, formerly trapped in ice shelves, which then become more vulnerable to melting, so feeding into the above process.
These are often referred to as positive feedback loops.
Other examples include the dying rainforests, which formerly operated as ‘carbon sinks’ – that is, they absorbed vast quantities of CO2 – and, upon their demise, do the opposite and emit vast quantities of CO2, thus accelerating overall planetary temperatures.
Then there is the bark beetle, now settling in higher and higher latitudes, thanks to rising temperatures. These little beasts can now be found in Canada, Alaska and Siberia, where they consume trees, again turning a carbon sink into a carbon belcher.
NASA and the University of Columbia Earth Institute have studied what comes after the tipping point, using data from previous warming events in Earth’s history, satellite information to monitor changes already afoot, and computerised climate models.
In the words of Dr James Hansen, the NASA scientist who took the issue of climate change to the US Congress, “business-as-usual (in terms of man-made CO2 emissions) would be a guarantee of global and regional disasters.”
Some scientists argue that it is already too late, and we must prepare for life on a deeply damaged planet, thanks to the time lag in the way CO2 is absorbed into the atmosphere.
Most are a little more optimistic, and believe we can turn the corner in time, and live to see a reduced but viable future.
What would 2 degrees centigrade plus look like?
Some 350-600 million people would be fighting for adequate water supplies in Africa alone, while facing a 50 per cent drop in agricultural yield as soon as 2020.
In Europe and North America, extreme weather events in the vein of Hurricane Katrina would become more and more common.
In South America, rainforests would start to disappear and arid land increase.
In the south Pacific, entire nations would vanish beneath the sea.
Heard enough?
The tipping point is the point of no return. Let’s make sure we never get there.