Geoscience Reference
In-Depth Information
14 Conclusion
Avoiding a Four Degree World
- Australia's Role
Peter Christoff
Despite years of international negotiations and growing public and scientific
concern, both global fossil fuel use and carbon dioxide emissions have continued
to increase at an accelerating rate. In May 2013, atmospheric concentrations
of carbon dioxide rose above 400 ppm for the first time in human history (see:
keelingcurve.ucsd.edu). Similar levels were last experienced some 3.2 to 5
million years ago, when global average temperatures were between 3°C and 4°C
warmer and as much as 10°C more at the poles and sea levels ranged between 5
and 40 meters higher than present.
The first 12 years of the 21st century were all among the top 13 warmest years
since 1850, when records began, and 2012 was the 27th consecutive year in
which the global land and ocean temperatures were above the 1961-1990 average
(WMO, 2013). Such warming has contributed in the northern hemisphere to
the record loss of Arctic sea-ice, intense drought in the United States and south-
eastern Europe, and major storms such as Hurricane Sandy (WMO, 2013: 3).
Even at current low levels of global average warming of around 0.8°C,
Australia is proving highly vulnerable to the impacts of climate change. The
summer of 2012/13 was the hottest on record (BoM, 2013a). At the same time,
in January 2013, extreme rainfall in Queensland and northern New South Wales
resulted in severe flooding (BoM, 2013b). As the Climate Commission noted in
its report The Angry Summer , 'Australia was hit by a series of extreme weather
events, including heatwaves, bushfires, intense rainfall and flooding, that caused
serious damage in many places … As a result, the resources required for our
society to deal with extreme weather is increasing' (CC, 2013: 1).
Despite international agreement that global warming should be kept below
2°C, the voluntary national mitigation pledges in the Copenhagen Accord 2009,
confirmed at Cancun in 2010, are insufficient to hold warming below the 2°C
threshold, much less the safer target of 1.5°C. Recent negotiations have paved
the way for a new international climate agreement to be finalized in 2015 and
come into effect by 2020. However, such an agreement is neither certain, nor
is it clear that its targets will be robust enough to keep warming below the 2°C
'guardrail'. In all, in the absence of a massive international effort and substantial
additional action by individual nations to greatly reduce emissions during the
next decade, we remain on a path to global warming of four degrees or more - a
 
 
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