There is now too much mounting evidence for anyone to doubt the scientific view that human activity is creating irreparable planetary damage. Sustainable Engineering Society president David Hood outlines the most likely scenarios to occur if average global temperatures continue to rise.
Humans cannot survive on a planet where the global average temperature rises beyond 4° Celsius – our bodies simply cannot sustain self-cooling for more than six hours in a wet bulb temperature of 35°C.
A global average rise of 4°C will certainly result in weather events where continental temperatures will exceed that scenario regularly.
Even containing warming to a global average rise of 2°C, which by the way has been internationally agreed, will result in severe climate effects requiring adaptation and societal adjustments of immense economic impact.
Interestingly however, while the world may have accepted the need to adapt to a 2°C rise, our failure to mitigate the causes is pushing us to a rise well beyond 2°C.
As PricewaterhouseCoopers, the World Bank and the International Energy Agency (not normally known for their “tree hugging”, “hippy”, or leftist culture) have all suggested, “it’s too late for 2°C”.
So, let’s look at the likely effects on society of a couple of global average temperature rise scenarios:
A 2°C rise doesn’t simply mean an extra 2°C each and every day. The number of extremely hot days will increase with very significant health impacts, but weather variability will also increase.
There will still be cold days in winter, and the slowing, or even stopping of the Great Ocean Conveyor, particularly the Gulf Stream, will undoubtedly see more snow and ice over the UK and Europe in winter.
The added moisture held in a hotter atmosphere will mean more intense rainstorm events and greater incidence of severe flooding (as we are already experiencing), but severe dry spells will also characterise the new climate.
This will see increasing numbers of very intense firestorms during hot dry spells.
A 2°C average global rise will expand the oceans, which together with melt water from declining glaciers and land ice sheets will see sea level rises of at least half a metre, most likely more.
The east coast of Australia could see rises of up to one metre (the sea level rise will not be uniform due to gravitational variances around the planet).
And, of course, the loss of Arctic sea ice, already in record summer retreat, could open up vast areas for oil and gas extraction to burn and assist in warming the planet even further, not to mention new shipping routes to speed up trade and economic growth adding to what some are now calling the Arctic Death Spiral.
Speaking of death spirals, our very own Great Barrier Reef, already under massive threat from industrialisation, will be doomed under a 2°C average rise.
Extreme heat events will now be causing unparalleled health impacts. Sea level rises will result in the loss of infrastructure on a massive scale, with inundation from average rises of over one metre resulting in a massive wave of “climate refugees” around the world as displaced people seek higher land with increasingly scarce food and fresh water.
There will now be massive global food shortages, as many of the world’s current food bowls will have long ago dried up.
The great ice sheet melt will now focus on the Antarctic ice mass, which with a 4°C rise will begin its slow but vast disintegration, eventually resulting in 70m or more sea level rises.
The Arctic will be ice-free all year round.
As the tundra will now be rapidly thawing, fermentation of the tundra bogs will be releasing methane at an alarming rate.
Methane is significantly more intense as a greenhouse gas, and warming will now accelerate rapidly – the beginning of a feedback that will unlock enormous stores of methane from methane clathrate deposits currently locked under the world’s oceans.
Massive species extinction is now assured.
A 6°C global average temperature rise doesn’t bear thinking about. I doubt humans will survive. ?
About the author
Adjunct Professor David Hood was the president of Engineers Australia in 2012 and a panellist at the CCN Live Conference 2013.