Environmental Engineering Reference
In-Depth Information
Broderick and Wood's chapter in this topic (see Chapter 4) considers the
comparative emissions of shale gas and other fossil fuels, so this chapter will
look at the other two issues.
Climate change is arguably the greatest existential threat that the world
currently faces. The most recent report from the Intergovernmental Panel on
Climate Change (IPCC), released in 2013,
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found that warming of the climate
system is unequivocal and, since the 1950s, many of the observed changes
are unprecedented over decades-to-millennia. The atmosphere and oceans
have warmed, the amounts of snow and ice have diminished, sea level has
risen and the concentrations of greenhouse gases (GHGs) have increased. It
is extremely likely that human influence has been the dominant cause of the
observed warming since the mid-20th century. This warming has already
increased the occurrence of some types of extreme weather events. Further
temperature increases will see the frequency of heavy rainfall events and very
hot days increase, with the severity increasing in proportion to warming. In
some regions there will be more droughts and floods, though a lack of data
prevents any firm conclusions on how the frequency will change globally.
Governments of developed countries, including the UK, have repeatedly
stated that, to avoid dangerous climate change, global temperatures must
rise by no more than 2 1C above pre-industrial levels. For example, the EU's
target is explicit that ''The EU must adopt the necessary domestic measures
and take the lead internationally to ensure that global average temperature
increases do not exceed pre-industrial levels by more than 2 1C''.
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Challenging though this is, it might not be enough. Since the 2 1C target
was first adopted, knowledge about climate change and its potential impacts
has progressed and many scientists now believe that potentially catastrophic
impacts will be felt at lower temperature rises. This is demonstrated by the
'Burning Embers' diagram, first produced by the Intergovernmental Panel
on Climate Change (IPCC) in 2001.
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This shows the likelihood of various
types of impact of climate change (risk of extreme weather events, risk of
large-scale discontinuities) for different global temperature rises. The up-
dated version of this diagram, produced in 2009, makes it clear that for a 2
1C temperature rise there are now substantial negative impacts associated
with extreme weather events and that there are now ''moderately significant''
risks of large scale discontinuities - risks which were thought to be ''very
low'' in 2001.
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Such evidence has led over 100 developing-country Govern-
ments to call for a maximum temperature rise of no more than 1.5 1C above
pre-industrial levels. The 'Burning Embers' diagram will be updated by the
IPCC in March 2014.
However, even accepting the 2 1C target, the carbon maths is clear: if we
are to keep the likely global temperature rise below 2 1C, we cannot afford to
burn unabated more than a small fraction of the world's current proven
fossil fuel reserves, let alone any as yet unproven reserves. Exploring for new
hydrocarbon resources is simply adding to the stock of already unburnable
carbon. The concept of 'unburnable carbon' started to gain traction in 2013
following important work by the Carbon Tracker Initiative.
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In the words of
