Post 2015: Global Action for an Inclusive and Sustainable Future

6.3.1 Atmosphere and global warming
there is a broad academic and policy consensus
that increased greenhouse gas (GHG) emissions
and atmospheric concentrations have led to rising
global temperatures. In fact, 2000–2009 was the
warmest decade since records began in the mid-
19th century. current models project that GHG
emissions could double over the next 50 years,
which would lead to at least a 3°c rise in the global
temperature by the end of the century (unEp,
2012b). the oEcD (2012) projects a smaller
increase in GHG emissions by 2050 (50%), but
also projects that the global temperature could rise
between 3°c and 6°c by 2100. a key contributing
factor is the level of energy-related carbon-dioxide
(co2) emissions, which is expected to grow by 70%
by 2050 (oEcD, 2012). these trends could have
substantial economic impacts.
Some estimates suggest that a 2.5°c temperature
increase from pre-industrial levels could generate
economic damages equivalent to 1–2% of world
GDp by 2100. these values rise significantly under
alternative scenarios: 2–4% of world GDp with a
4°c temperature increase, and 10–11% of global
GDp with a 6–7°c increase (unEp, 2012a). the
environmental, social and economic consequences
of such scenarios would be catastrophic.
the main effects of a significant long-term rise
in global temperature include changes to rainfall
patterns, rising sea levels and greater intensity and
frequency of extreme weather events. Flood and
drought-related disasters have risen by 230% and
38% respectively between the 1980s and 2000s,
while the costs of adaptation and mitigation of
these events are also expected to soar (unEp,
2012a). the poorest regions are expected to be
the worst affected by the consequences of climate
change (cline, 2007). africa and asia, in particular,
will experience reduced agricultural productivity
and food security, increased water stress, floods
and droughts, and the spread of diseases such as
cholera (Ipcc, 2007). Small island development
states (SIDS), especially in the caribbean and
pacific regions, are also extremely vulnerable to
environmental shocks. climate change will also
cause significant biodiversity losses.
Increased air pollution could generate large
economic losses, for instance by lowering agricultural
yields and accentuating the impacts described
above. moreover, it would aggravate its already large
impact on global health, in particular respiratory
diseases. air pollution is expected to become the
main environmental cause of premature deaths
by 2050, overtaking unsafe water and sanitation
(oEcD, 2012). this is partly due to increased traffic
and industrial emissions, which raise pollution
concentrations in urban areas, but also due to high
domestic pollution from biomass cooking stoves.
there has been some progress in protecting the
stratospheric ozone. For example, the measures taken
under the 1987 montreal protocol were instrumental
in drastically reducing the consumption of ozonedepleting
substances, which in turn have led to a
significant decline in their concentration in the
stratosphere since 1994 (unEp, 2012a). this is an
encouraging illustration of how a global agreement
can lead to successful results.
6.3.2 Land
about one-third of the world’s land surface is
currently used for agricultural production, with
another third occupied by forests, and a fifth by
savannahs and grasslands. the remaining land is
sterile or unproductive, with cities covering only
1% of the global land mass (Hertel, 2010).
the increasing pressures on land are due partly to
competing demands for food, animal feed, fuel, fibre
and raw materials, which aggravate deforestation
and desertification (unEp, 2012b). the factors
underlying these trends include population growth,
changing consumption patterns associated with
improved living standards and the search for
alternative sources of energy.
poSt-2015: Global actIon For an IncluSIvE anD SuStaInablE FuturE
Some estimates
suggest that a
2.5°C temperature
increase from preindustrial
levels
could generate
economic
damages
equivalent to
1–2% of world
GDP by 2100.
These values rise
significantly
under alternative
scenarios: 2–4% of
world GDP with a
4°C temperature
increase, and
10–11% of global
GDP with a 6–7°C
increase.
95