The existence of anthropogenic climate change has firm scientific evidence, no matter what global warming denialists say with no evidence or with interests (Hansen, Sato, & Ruedy, 2012; Washington & Cook, 2011). Although many ill-informed politicians, self-interested organizations, and even some scientists in non-atmospheric circles tried to discredit science of climate change (Nordhaus, 2012), global warming represented by a figure called “hockey stick” is undeniable (Mann, 2012).
Recent estimates of Earth’s energy budget clearly indicate that
anthropogenic global warming is happening at annual net energy gain
rates of 0.6±0.4 W/m2 (i.e., 0.6 = 340.2 (incoming solar) − 239.7 (outgoing longwave radiation) − 99.9 (reflected solar) W/m2) over 2000-2010 (Stephens et al., 2012). To be more specific, the net energy imbalance was annually 0.9 ± 0.5 W/m2 over 2000-2005 (Trenberth &
and 0.58 ± 0.15 W/m2 over 2005-2010 (Hansen, Sato, Kharecha,
Schuckmann, 2011). This energy imbalance is mainly caused by burning
fossil fuels (Dukes, 2003), the vast majority of which had been stored
underground for millions of years before the Industrial Revolution
began to utilize coal steam engines from around 1760. Instead of
searching for alternative and more sustainable energy sources,
globalized energy industry is “ripping apart the earth” to extract more
fossil fuels (McKibben, 2012).
Because the environment is “warmer and moister than it used to be”
(Trenberth, 2012, p. 7), all weather events as well as extreme ones are
affected by the current climate change. Hurricane Katrina in August
2005 (Graumann et al., 2006) was a dramatic symbol of how human
inaction will worsen the climate change and harm humans themselves
(Karl, Melillo, & Peterson, 2009; Lynn, Healy, & Druyan, 2009).
Hurricane Sandy in October 2012 wreaked more havoc on lower Manhattan
in New York and shorelines in New Jersey by exacerbated storm surge due
to sea-level rise, which is undeniably caused by human induced global
warming (Gillis, 2012).
Therefore, sustainability cannot be achieved without climate change
mitigation. One of the most evident ways to minimize the adverse
effects of human activities is to minimize greenhouse emissions, as
suggested by the Intergovernmental Panel on Climate Change (IPCC) (Core
Writing Team, Pachauri, & Reisinger, 2007). The more we delay to
reduce greenhouse gas emissions drastically, the harder it becomes that
we contain global warming within manageable limits. However, time is
running out (Ranger et al., 2012; van Vliet et al.,
2012). The latest
estimation for the global carbon dioxide emissions in 2012 shows a
trend worse than the IPCC’s worst warming scenario (Peters et al.,
Although some recent studies indicate that imminent peak production
fossil fuels will eventually limit global CO2 emissions
2011; Vernon, Thompson, & Cornell, 2011), even their analyses can
be counter-argued by scientists’ analyses showing even fossil fuel
reserves that are significantly lower than IPCC scenarios can induce
catastrophic climate changes (for example, Kharecha & Hansen
(2008)). We have to prepare for worst cases by reducing emissions right
now (Oreskes, Stainforth, & Smith, 2010).
Then what should be our goal for climate change mitigation? It is
widely accepted that we have to confine global warming within 2 °C
above the pre-industrial global average temperature (Knopf, Kowarsch,
Flachsland, & Edenhofer, 2012; UNEP, 2010; UNFCCC, 2010). According
to the IPCC’s new climate change scenario called Representative
Concentration Pathways (Moss et al., 2008), the organization’s
in 2100 to limit global surface temperature change within 2 °C since
industrialization is 2.6 W/m2 of radiative forcing increase
industrialization and the CO2 equivalent concentration of
gas should be limited to 450 ppm (van Vuuren et al., 2012). By
definition, all values for the pre-industrial era should be based on
those of the year 1750 (Core Writing Team et al., 2007, p. 36).
However, climate models of the IPCC run their simulations by setting
the benchmark year as any year between 1765 and 1850, for there are not
a significant change in greenhouse gas concentrations during the period
(Meinshausen et al., 2011).
How much is the amount of greenhouse gas emissions that are
of the warming limit? It is recently estimated that we have to reduce
our CO2 emissions by more than 80% compared to a peak
stabilize a CO2 concentration at any chosen target level
century or so (Committee on Stabilization Targets for Atmospheric
Greenhouse Gas Concentrations, 2011).
Then what are we humans doing to achieve the target? Sadly, we are
doing enough, if not nothing. Although the Kyoto Protocol and its child
EU ETS have given us a small bit of hope, the skepticism of
environmentalists and scientists against any kind of selfless
negotiations between nations turned out to be right. Copenhagen Climate
Change Conference (COP15/CMP5) held in 2009 didn't produce any
tangible, legally-binding agreement between nations. Its outcome, the
Copenhagen Accord, just voiced the world’s agreed concern that global
average temperature 2 °C warmer than pre-industrial age was
unacceptable (UNFCCC, 2010).
The outcome of Durban Climate Change Conference (COP17/CMP7) held in
2011 was creation of an “Ad Hoc Working Group on the Durban Platform
for Enhanced Action” (“Durban Platform”). COP17 just promised that the
Durban Platform will prepare a legally binding protocol ratified by
countries no later than 2015. But this time, global leaders admitted
that holding global average temperature increase below 2 °C above
pre-industrial levels might not be sufficient to avoid anthropogenic
catastrophe and began to mention 1.5 °C (UNFCCC, 2012).
Today, I don’t have an answer about what we have to do for real
for global climate change mitigation. In my future post, I’ll search
for promising answers.
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