Human influence on the climate system is clear and increasing: IPCC V Report
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Human influence on the climate system is clear and growing, and its impacts can be observed on all continents. If left unchecked, climate change will increase the likelihood of severe, widespread and irreversible impacts on people and ecosystems. However, there are options for adaptation to climate change, and rigorous mitigation activities can ensure that the impacts of climate change remain at a manageable level, creating a clearer and more sustainable future.
These are some of the main conclusions of the Synthesis Report released Sunday by the Intergovernmental Panel on Climate Change (IPCC).
The Synthesis Report presents and integrates the findings of the IPCC's Fifth Assessment Report produced by more than 800 scientists and published over the past 13 months: the most comprehensive assessment of climate change ever undertaken.
"We have the means to limit climate change," said IPCC Chairman R.K. Pachauri, who added that "the solutions are many and allow for continued economic and human development. All we need is the will to change, and we are confident that this will is motivated by knowledge and understanding of the science of climate change."
The Synthesis Report confirms that climate change is occurring worldwide and that warming of the climate system is unequivocal. Since the 1950s many of the observed changes have been unprecedented in recent decades to millennia. "Our assessment concludes that the atmosphere and ocean have warmed, snow and ice volumes have decreased, sea levels have risen, and carbon dioxide concentrations have increased to levels unprecedented for at least 800,000 years," said Thomas Stocker, Co-Chair of IPCC Working Group I. "We are now seeing a significant increase in the global climate system," he said.
The report expresses with greater certainty than in previous assessments the fact that greenhouse gas emissions and other anthropogenic drivers have been the dominant cause of the observed warming since the mid-20th century.
The impacts of climate change have already been felt in recent decades on all continents and oceans.
The greater the perturbation of human activity on the climate, the greater the risks. The report concludes that continued greenhouse gas emissions 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 Synthesis Report clearly states that many risks are particularly problematic for least developed countries and vulnerable communities, given their limited capacity to cope. Socially, economically, culturally, culturally, politically, institutionally and otherwise marginalized people are especially vulnerable to climate change.
Indeed, limiting the effects of climate change over time raises issues of equity, justice and equality and is necessary to achieve sustainable development and poverty eradication. "Many of the people most vulnerable to climate change have contributed and contribute little to greenhouse gas emissions," Mr. Pachauri said. "It will not be possible to tackle climate change if individual actors put their own interests first independently; positive results will only be achieved with collective responses, particularly from international cooperation."
"Adaptation can play a critical role in reducing these risks," said Vicente Barros, Co-Chair of IPCC Working Group II. "Adaptation is so important because it can be integrated into the development pathway and help in preparing for the risks we are already forced to face because of past emissions and current infrastructure."
But adaptation alone is not enough. To truly limit the risks of climate change, substantial and sustained reductions in greenhouse gas emissions are needed. And to the extent that mitigation reduces the rate and magnitude of warming, it also extends the time available for adaptation to a given level of climate change, potentially by several decades.
Many mitigation pathways lead to achieving the substantial emission reductions needed to limit warming to 2°C - the target set by governments - over the next few decades with a probability of success greater than 66%. However, the report states that if additional mitigation is delayed to 2030, the technological, economic, social and institutional challenges associated with limiting warming to less than 2°C below pre-industrial levels in the 21st century will increase significantly.
"The transition to a low-carbon economy is technically feasible," said Youba Sokona, Co-Chair of Working Group III. "But what is lacking are the right policies and institutions.
The longer we wait to act, the higher the cost of climate change adaptation and mitigation will be." The Synthesis Report concludes that estimates of mitigation costs vary, but overall economic growth would not be greatly affected. In business-as-usual scenarios, consumption - an indicator of economic growth - grows by between 1.6 and 3% per year over the 21st century. Ambitious mitigation would reduce those rates by about 0.06 percentage points. "Compared to the imminent risk of irreversible climate change impacts, the risks of mitigation are reasonable," Mr. Sokona said.
These economic estimates of the costs of mitigation do not consider the benefits of smaller climate change, nor the many co-benefits related to human health, livelihoods and development. "The scientific basis for prioritizing action on climate change is clearer than ever," said Mr. Pachauri. "We do not have much time left before the window of opportunity to stay within the 2°C margin of warming closes. To have a good chance of staying below 2°C at reasonable costs, we should reduce emissions by 40 to 70% globally between 2010 and 2050, and bring them down to zero or negative by 2100. We have the opportunity, and the choice is in our hands."
Read the IPCC press release on the report here
The report is available here:
Sources:
IPCC Final Report of November 1, 2014.
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