IPCC Special Report on Global Warming of 1.5°C - Summary for Policymakers

The Paris Agreement adopted by 195 nations at the 21st UN Conference of the Parties (COP21) in 2015 responds to climate change by “holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels.” In turn, the UNFCCC invited the Intergovernmental Panel on Climate Change (IPCC) to provide this Special Report on the impacts of global warming of 1.5°C above pre-industrial levels. The report offers an assessment of these impacts, and describes various mitigation and adaptation pathways by which global temperature rise could be held to 1.5°C. The IPCC focused also on sustainable development and poverty eradication as system transitions that can be enabled by an increase of adaptation and mitigation measures. This Summary for Policy Makers (SPM) distills the key findings of the Special Report.

The report offers a summary of the global scale of impacts that are occurring and are projected to occur at each warming scenario. Some of the many general while significant findings include the following:

Countries that ratify the Paris Agreement submit pledges - or Nationally Determined Contributions agreements - as to how they will address climate change and limit GHG emissions. Analyses have concluded that these pledges are not sufficient enough to limit global warming to 1.5°C above pre-industrial levels.

We have already reached approximately 1.0°C of global warming above pre-industrial levels, and global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate.

“Reaching and sustaining net-zero global anthropogenic CO2 emissions and declining net non-CO2 radiative forcing would halt anthropogenic global warming on multi-decadal timescales.”

The risks and impacts of global temperatures reaching 1.5°C rather than 2°C above pre-industrial levels are found to be less severe. The report summarizes these findings for mean temperatures, drought, heavy precipitation, and sea level rise. These risks are detailed as to the impacts on natural, managed and human systems. Specifically for: Warm water corals, Terrestrial Ecosystems, Tourism, Mangroves, Small scale low latitude fisheries, Arctic Region, Coastal flooding, Fluvial Flooding, Crop Yields, and Heat-related morbidity and mortality.

Some of the results are explained further, for example, "the likelihood of an Arctic Ocean free of sea ice in summer would be once per century with global warming of 1.5°C, compared with at least once per decade with 2°C. Coral reefs would decline by 70-90 percent with global warming of 1.5°C, whereas virtually all would be lost with 2ºC."

The full report describes Climate-Resilient Development Pathways (CRDPs) which can offer strategies to achieve both socially equitable and low-carbon futures through sustainable development. The capacity to avoid climate change impacts on sustainable development, eradication of poverty and reducing inequalities would clearly be greater if global warming were limited to 1.5°C rather than 2°C, and when mitigation and adaptation synergies are maximized.

Examples of existing programs that provide guidance on CRDPs are given, such as the Transition Movement from Europe, which promotes equitable and resilient communities through low-carbon living, food self-sufficiency and citizen science.

The Special Report assesses the geophysical, environmental-ecological, technological, economic, socio-cultural and institutional dimensions of feasibility of adaptation pathways to limit climate risk. Increasing investment in physical and social infrastructure is found to be essential to the future resilience and the adaptive capacities of societies.

Broad scale adaptation options that can reduce the risks of climate change are reviewed. However, IPCC has determined that there are "limits to adaptation and adaptive capacity for some human and natural systems at global warming of 1.5°C, with certain associated losses."

Adaptation options exist that reduce human and natural systems climate vulnerability, are synergistic with sustainable development, and will support decreased global warming - such as:

  • food and water security
  • reducing disaster risks
  • improving health conditions
  • maintaining ecosystem services
  • reducing poverty and inequality

Furthermore, adaptation options that also mitigate emissions can provide synergies and cost savings in most sectors and systems. For example, as when land management reduces emissions and disaster risk, or when low carbon buildings are also designed for efficient cooling.

Limiting the impacts of climate change will depend on system transitions that the IPCC suggests can be “enabled by an increase of adaptation and mitigation investments, policy instruments, the acceleration of technological innovation and behavior changes.”


Publication Date: October 8, 2018

Related Organizations:

  • The Intergovernmental Panel on Climate Change (IPCC)

Resource Category:

Resource Types:

  • Assessment
  • Climate science


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