The earth’s atmosphere is made up of a delicately balanced layer of ‘greenhouse gases’. This layer acts like
a blanket, trapping enough heat to sustain life.
Humans are burning huge amounts of fossil fuels – adding more and more greenhouse gases to the atmosphere
and making this blanket thicker. This traps more and more heat, warming the globe and throwing our climate
Climate change is already underway.
Global change, including climate change, ecosystem shifts and biodiversity loss as a result
of explosive human population growth and consumption, is emerging as one of the most
important issues of our time (Vitousek, 1994). Climate change in particular appears to be
altering the function, structure and stability of the Earth’s ecosystems (Lovelock, 2009). It has
been marked by an 80% increase in atmospheric CO2 level and a 0.
According to the Intergovernmental Panel on
Climate Change, the impacts of climate chang
on the water cycle are already evident and
projected to increase substantially in the futur
Climate change impacts the quantity and qua
of freshwater resources and the frequency of
extreme events, such as floods and droughts
While climate change is only one of many
drivers increasing pressure on water resource
its impact is projected to be significant and to
accelerate over time. Climate change reinforc
and adds urgency to the case for good water
resources management more generally.
Plants are sessile organisms and as such must have mechanisms to deal with both abiotic
and biotic stresses to ensure survival. The term “abiotic stress” includes many stresses
caused by environmental conditions such as drought, salinity, UV and extreme
temperatures. Due to global climate change it is predicted that abiotic stresses will increase
in the near future and have substantial impacts on crop yields (Intergovernmental Panel of
Climate Change; http://www.ipcc.ch).
The Millennium Ecosystem Assessment (MA) was carried out between 2001
and 2005 to assess the consequences of ecosystem change for human well-being
and to establish the basis for actions needed to enhance the conservation and
sustainable use of ecosystems and their contributions to human well-being.
The world’s climate is changing. The scientific
evidence is incontrovertible: most of this change
is due to human activity, and the process is
speeding up as more and more carbon dioxide,
methane and other greenhouse gases are pumped
into the atmosphere.
The next 10 years are critical. Carbon dioxide
emissions must be cut rapidly. If they are, according
to the Intergovernmental Panel on Climate Change,
we may limit the rise in global temperatures to
two degrees centigrade.
The Review uses the results from one particular model, PAGE2002, to illustrate how
the estimates derived from these integrated assessment models change in response
to updated scientific evidence on the probabilities attached to degrees of temperature
rise. The choice of model was guided by our desire to analyse risks explicitly - this is
one of the very few models that would allow that exercise. Further, its underlying
assumptions span the range of previous studies.
The impacts of climate change ranging from sea level rise,
melting ice caps and glaciers, severe weather events,
drought, flooding, warming, subtle changes in ecosystems –
will impinge on every aspect of society and economic life.
The costs of inaction will more than outweigh the costs
of action. There is only a narrow window of opportunity
to redress the situation.
Climate change is increasingly recognized as one of the most critical
challenges ever to face humankind. With the release of the Fourth
Assessment Report of the Intergovernmental Panel on Climate Change
(IPCC), the international scientific community has significantly advanced
public understanding of climate change and its impacts.
The debate on climate change has shifted dramatically in recent years. There is
now unequivocal scientiﬁ c evidence – summarised in the 2007 report from the
Intergovernmental Panel on Climate Change (IPCC) – that global warming is happening;
that human actions are responsible; and that this poses an enormous threat to life on
Politicians, businesses and the public are increasingly aware of the problem and are
calling for urgent action to cut the man-made emissions of greenhouse gases (GHGs)
that cause climate change, in particular carbon dioxide (CO2)....
Greenhouse gases are accumulating in Earth’s atmosphere
as a result of human activities, causing surface air
temperatures and subsurface ocean temperatures to rise.
Temperatures are, in fact, rising. The changes observed over
the last several decades are likely mostly due to human activities,
but we cannot rule out that some significant part of
these changes is also a reflection of natural variability.
Human-induced warming and associated sea level rises are
expected to continue through the 21st century.
The most recent report by the Intergovernmental Panel on Climate Change (IPCC) states
that global warming will lead to “changes in all components of the freshwater system,” and
concludes that “water and its availability and quality will be the main pressures on, and issues
for, societies and the environment under climate change.”2
Nestlé’s chairman Peter Brabeck-
Letmathe puts it more bluntly, calling water availability a bigger challenge than energy security.
And so, for another six years at least, it is over. Thousands of
authors referring to vast numbers of papers have, in sometimes-
contested consultation with the governments that lend
their name to the process, provided the world with their best assessment
to date of humanity’s prospects and options in the matter of
The Intergovernmental Panel on Climate Change (IPCC) is far
from a perfect institution, but it is a necessary and a heartening one.
As recent weather events have illustrated, coastal
areas in both developing and more industrialized
economies face a range of risks related to climate
change (IPCC 2007a). Anticipated risks include an
accelerated rise in sea level of up to 0.6 meters or
more by 2100, a further rise in sea surface tempera-
tures by up to 3° C, an intensification of tropical
and extra tropical cyclones, larger extreme waves
and storm surges, altered precipitation and run-
off, and ocean acidification (Nicholls et al. 2007).
Indeed, most climate scientists now
suspect that the accumulation of these gases in the lower atmosphere has
contributed to the strong recent uptrend in world average temperature. In its
Third Assessment Report, published in 2001, the Intergovernmental Panel on
Climate Change (IPCC) stated: “There is new and stronger evidence that most of
the warming observed over the last 50 years is attributable to human activities”
During the twentieth century, world average surface temperature increased
by approximately 0.6°C (Figure 1.1).