Geoscience Reference
In-Depth Information
The problems of unmitigated or weakly mitigated climate change will be for all
humanity.
The threats to the stability of the institutions that underpin modern civili-
zation will be the more difficult to manage because many of the shocks from
climate change will come in sudden large events or series of events. The risks
of sea level rise may suddenly be realized in an extreme climatic event - for
example, a storm surge from a cyclone in the sea of Bengal or across South-East
Asia. The risks to agriculture may be manifest sharply in the effects of drought or
flood in a number of major food-producing countries, causing global food prices
suddenly to rise way beyond anything in earlier experience. Such shocks would
pose special challenges to institutional stability.
Avoiding Four Degrees
The Australian Parliament in mid-2011 legislated a set of policies that extended
considerably the Australian contribution to the global mitigation effort. That
legislation embodies arrangements for increasing Australian mitigation ambition
over time in line with increasing global action. The set of Australian mitigation
policies introduced in recent years, including energy efficiency measures and the
Renewable Energy Target as well as carbon pricing, have slowed and could end
what had been a rapid increase in Australian emissions over a long period of
time. But the larger importance of the new Australian policies is the support that
they give to Australia in contributing its fair share in a global effort that increases
in ambition and effect over time.
Over two decades, the international community has groped its way towards an
international system for climate change mitigation that introduces a possibility
of holding temperature increases to around 2°C. However, global aggregate
emissions continue to rise. We no longer have time for such slow progress: the
concentrations of greenhouse gases are already approaching levels that are likely
over time to generate a 2°C increase in average temperatures. Emissions have
grown more rapidly since the turn of the century than the most widely used
scenarios developed in the 1990s had suggested, largely because growth was
stronger and more energy intensive and energy more emissions intensive than
had been anticipated (Garnaut et al., 2009). If temperature increases are going
to be kept to 2°C, there must be an early and large reduction in global emissions
trajectories.
In contrast to the world up to the 1992 Rio Earth Summit, emissions growth
in the 21st century was overwhelmingly concentrated in developing countries.
My own calculations on 'business as usual' emissions for the Climate Change
Review Update (Garnaut, 2011c; 2011b) suggested that in the absence of new
policy action to change established trends, developing countries would account
for the whole of the increase in global emissions from 2005 to 2030; developed
country emissions as a whole were expected to remain steady between 2005 and
2030. In the absence of policy action, China would account for 41 per cent of
global emissions in 2030 and developing countries 70 per cent. Whatever weight
