In early November, the Intergovernmental Panel on Climate Change (IPCC) released the Synthesis of its 5th Climate Assessment Report. With more than 800 scientists contributing, this is the most comprehensive assessment ever made of climate change.

The IPCC was established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Program (UNEP) with the mission of synthesizing and evaluating all documents published and whose scientific value Is widely recognized, on the theme of Climate. It is a question of knowing and understanding the evolution of the climate, the risks and the consequences linked to these changes as well as the possible adaptation and mitigation strategies.

Go to the IPCC website

According to the IPCC 5th report, “Climate change could have irreversible and dangerous impacts, but there are options to limit their effects.” This is a real invitation to urgent, comprehensive and concerted action. We propose to return here to the main conclusions of this document.

5ème Rapport_Synthèse

Human responsibility in climate change is now described as “extremely likely”

Since its first report in 1990, the IPCC has gradually been able to rely on increasingly sophisticated sources and scientific data, and has been able to deepen its analyzes with more efficient systems. While the first report in 1990 referred to a probable correlation between human activity and global warming, the responsibility for human activity and associated greenhouse gas (GHG) emissions in the observed upheavals is Clearly established in the latest IPCC document.

“The influence of human activities on warming of the atmosphere and ocean, changes in the global water cycle, snow and ice retreat, rising global average Of the seas and in the modification of certain climatic extremes. There has been some confidence in this since the Fourth Assessment Report. It is highly likely that human influence is the main cause of the warming observed since the mid-20th century.” Source : GIEC, 5ème rapport d’évaluation, Groupe de travail I

If we do not reverse the trend, the impacts could be dramatic, widespread and irreversible

The first consequence of the many GHG emissions generated by human activity is the gradual increase in temperatures since the middle of the 19th century.

Augmentation températures depuis 1850

Average global surface and ocean temperatures (Source: Presentation of the 5th Assessment Report, IPCC, 2014)

This has led to a series of upheavals: accelerated melting of glaciers, rising sea levels, acidification of the oceans, disruption of the precipitation cycle, and so on.

“According to our assessment, the atmosphere and oceans have warmed, the amount of snow and ice has decreased, sea levels have risen and carbon dioxide levels have increased to a level Unprecedented for 800,000 years. “

Source: IPCC Press Release, 2 November 2014

Impacts on humans and ecosystems are potentially catastrophic, with serious consequences such as increased risk of flooding in coastal areas, decreased food resources (in particular as a result of lower agricultural yields) and Increased risk of conflicts and population movements, increased poverty, the accelerated disappearance of certain species, …

Moreover, the least developed countries are particularly vulnerable and fragile in the face of the consequences of global warming.

The causes are multiple, but the use of fossil fuels remains the main cause of greenhouse gas (GHG)

The energy sector is responsible for more than a third of global GHG emissions. This is due in particular to a high consumption of fossil fuels, which are highly emitted in GHGs.

Emissions GES 2010

Source: Presentation of the 5th Assessment Report, IPCC, 2014

Limiting warming to the surface of the earth at + 2 ° C remains possible but will require significant efforts in terms of GHG emissions

The IPCC has developed various scenarios to determine the path to reduce our GHG emissions (in the chart below, in red the scenario following the current trend, in yellow the + 3 ° C scenario, in blue Scenario + 2 ° C).

Scénario 2°C

Source: Presentation of the 5th Assessment Report, IPCC, 2014

If we want to limit global warming to an increase of + 2 ° C (this is the target set by Governments under the UN Framework Convention on Climate Change), this will require a drastic reduction in global emissions Of GHG emissions.

“To have a chance of limiting the increase in global average temperature to 2 ° C, global greenhouse gas emissions will have to be reduced by 40 to 70% compared to 2010 by the middle of the century, and Eliminate almost completely by the end of the century. “

Source: IPCC Press Release, 2 November 2014

Opportunities to limit global warming

The IPCC has identified various measures that would allow us to limit global warming. Among those :

Mesures d'atténuation

Source: Presentation of the 5th Assessment Report, IPCC, 2014

The implementation of these measures is urgent.

Avec ou sans atténuation

Source: Presentation of the 5th Assessment Report, IPCC, 2014

According to Youba Sokona, co-chair of IPCC Working Group III:

“The longer we wait to make arrangements, the more costly will be the adaptation and mitigation of climate change.” Source: IPCC Press Release, 2 November 2014

Access the IPCC Press Release on the Synthesis of the 5th Assessment Report

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