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| A new report from the IPCC says that climate change -- if left unchecked -- will increase the likelihood of severe, pervasive and irreversible impacts for people and ecosystems. |
Human influence on the climate system is clear and growing, with impacts
observed on all continents. If left unchecked, climate change will
increase the likelihood of severe, pervasive and irreversible impacts
for people and ecosystems. However, options are available to adapt to
climate change and implementing stringent mitigations activities can
ensure that the impacts of climate change remain within a manageable
range, creating a brighter and more sustainable future.
These are among the key findings of the Synthesis Report released by
the Intergovernmental Panel on Climate Change (IPCC) on Nov. 2, 2014.
The Synthesis Report distils and integrates the findings of the IPCC
Fifth Assessment Report produced by over 800 scientists and released
over the past 13 months -- the most comprehensive assessment of climate
change ever undertaken.
"We have the means to limit climate change," said R. K. Pachauri,
Chair of the IPCC. "The solutions are many and allow for continued
economic and human development. All we need is the will to change, which
we trust will be motivated by knowledge and an understanding of the
science of climate change."
The Synthesis Report confirms that climate change is being registered
around the world and warming of the climate system is unequivocal.
Since the 1950s many of the observed changes are unprecedented over
decades to millennia. "Our assessment finds that the atmosphere and
oceans have warmed, the amount of snow and ice has diminished, sea level
has risen and the concentration of carbon dioxide has increased to a
level unprecedented in at least the last 800,000 years," said Thomas
Stocker, Co-Chair of IPCC Working Group I.
The report expresses with greater certainty than in previous
assessments the fact that emissions of greenhouse gases and other
anthropogenic drivers have been the dominant cause of observed warming
since the mid-20th century.
The impacts of climate change have already been felt in recent decades on all continents and across the oceans.
The more human activity disrupts the climate, the greater the risks.
Continued emissions of greenhouse gases will cause further warming and
long-lasting changes in all components of the climate system, increasing
the likelihood of widespread and profound impacts affecting all levels
of society and the natural world, the report finds.
The Synthesis Report makes a clear case that many risks constitute
particular challenges for the least developed countries and vulnerable
communities, given their limited ability to cope. People who are
socially, economically, culturally, politically, institutionally, or
otherwise marginalized are especially vulnerable to climate change.
Indeed, limiting the effects of climate change raise issues of
equity, justice, and fairness and is necessary to achieve sustainable
development and poverty eradication. "Many of those most vulnerable to
climate change have contributed and contribute little to greenhouse gas
emissions," Pachauri said. "Addressing climate change will not be
possible if individual agents advance their own interests independently;
it can only be achieved through cooperative responses, including
international cooperation."
"Adaptation can play a key role in decreasing these risks," said
Vicente Barros, Co-Chair of IPCC Working Group II. "Adaptation is so
important because it can be integrated with the pursuit of development,
and can help prepare for the risks to which we are already committed by
past emissions and existing infrastructure."
But adaptation alone is not enough. Substantial and sustained
reductions of greenhouse gas emissions are at the core of limiting the
risks of climate change. And since mitigation reduces the rate as well
as the magnitude of warming, it also increases the time available for
adaptation to a particular level of climate change, potentially by
several decades.
There are multiple mitigation pathways to achieve the substantial
emissions reductions over the next few decades necessary to limit, with a
greater than 66% chance, the warming to 2 degrees C -- the goal set by
governments. However, delaying additional mitigation to 2030 will
substantially increase the technological, economic, social and
institutional challenges associated with limiting the warming over the
21st century to below 2ºC relative to pre-industrial levels, the report
finds.
"It is technically feasible to transition to a low-carbon economy,"
said Youba Sokona, Co-Chair of IPCC Working Group III. "But what is
lacking are appropriate policies and institutions. The longer we wait to
take action, the more it will cost to adapt and mitigate climate
change." The Synthesis Report finds that mitigation cost estimates vary,
but that global economic growth would not be strongly affected. In
business-as-usual scenarios, consumption -- a proxy for economic growth
-- grows by 1.6 to 3 percent per year over the 21st century. Ambitious
mitigation would reduce this by about 0.06 percentage points. "Compared
to the imminent risk of irreversible climate change impacts, the risks
of mitigation are manageable" said Sokona.
These economic estimates of mitigation costs do not account for the
benefits of reduced climate change, nor do they account for the numerous
co-benefits associated with human health, livelihoods, and development.
"The scientific case for prioritizing action on climate change is
clearer than ever," Pachauri said. "We have little time before the
window of opportunity to stay within 2ºC of warming closes. To keep a
good chance of staying below 2ºC, and at manageable costs, our emissions
should drop by 40 to 70 percent globally between 2010 and 2050, falling
to zero or below by 2100. We have that opportunity, and the choice is
in our hands."
Comprehensive assessment
The Synthesis Report, written under the leadership of IPCC Chair R.K.
Pachauri, forms the capstone of the IPCC Fifth Assessment Report. The
first three volumes, based on outlines approved by the IPCC's 195 member
governments in October 2009, were released over the past fourteen
months: The Physical Science Basis in September 2013, Impacts,
Adaptation and Vulnerability, in March 2014 and Mitigation of Climate
Change in April 2014.
IPCC reports draw on the many years of work by the scientific
community investigating climate change. More than 830 coordinating lead
authors, lead authors and review editors from over 80 countries and
covering a range of scientific, technical and socio-economic views and
expertise, produced the three working group contributions, supported by
over 1000 contributing authors and drawing on the insights of over 2,000
expert reviewers in a process of repeated review and revision. The
authors assessed more than 30,000 scientific papers to develop the Fifth
Assessment Report. About 60 authors and editors drawn from the IPCC
Bureau and from Working Group author teams have been involved in the
writing of the Synthesis Report. Their work was made possible by the
contributions and dedication of the Synthesis Report Technical Support
Unit.
"I would like to thank the hundreds of experts from the world's
scientific community who have given freely of their time and expertise
to produce the most comprehensive assessment of climate change yet
undertaken," said Pachauri. "I hope this report will serve the needs of
the world's governments and provide the scientific basis to negotiators
as they work towards a new global climate agreement."
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