The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for assessing the most recent scientific research on climate change. It was established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) in 1988 to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts.
The IPCC is organised in three Working Groups and a Task Force that focus on specific aspects of climate change. The IPCC does not undertake new research, but examines published and peer-reviewed literature to develop a comprehensive assessment of scientific understanding which is published in IPCC Assessment Reports.
Fifth Assessment Report
The IPCC publishes Assessment Reports every six to seven years, with the IPCC First Assessment report published in 1990. The Fifth Assessment Report is being published in stages across 2013 and 2014.
Each of the three Working Groups contributes to the development of Assessment Reports:
- The Working Group I report, The Physical Science Basis, was released on 27 September 2013;
- The Working Group II report, Impacts, Adaptation and Vulnerability, was released on 31 March 2014;
- The Working Group III report, Mitigation of Climate Change, was released on 13 April 2014; and
- A Synthesis report of the content in all three Working Group reports will be released in October/November 2014.
Working Group I – The Physical Science Basis
The Working Group I report finds that there is strong evidence that the Earth’s climate system is changing, and there is now stronger evidence than ever that human activities are the primary cause.
Other key findings include:
- There is robust evidence that multiple components of the Earth’s climate system are changing, including rising global air and ocean temperatures, widespread melting of snow and ice, rising global average sea level, and changes in many extreme events.
For the first time, the IPCC provides estimates of the total allowable global emissions of carbon in order to limit temperature rise to 2°C above pre-industrial levels.
- The likely total allowable global emissions are about 1,000 billion tonnes of carbon. By 2011, around half of this budget had already been emitted.
- If emissions of greenhouse gases other than carbon dioxide (eg. methane and nitrous oxide) are accounted for, the likely allowable emissions are reduced to about 790 billion tonnes of carbon
- If emissions continue to track at the top of IPCC scenarios, global temperature could rise by between 3.2°C and 5.4°C by the end of the century (relative to a 1850-1900 baseline). If emissions track along the lowest scenario, then global average temperature could rise from 0.9-2.3°C by the end of the century (relative to a 1850 -1900 baseline).
- We are already observing the consequences of a changing climate in Australia and elsewhere around the world.
- Scientific understanding of sea level rise has improved and projections of global average sea level rise are higher than in previous IPCC reports.
Working Group II – Impacts, Adaptation and Vulnerability
The Working Group II report highlights the increasing evidence of a number of climate change risks facing Australia and the world. Some climate change risks have already materialised, and are having widespread and consequential impacts.
Other key findings include:
- Australia will face increasing risk from climate change. Some impacts are unavoidable but others can be managed by a combination of adaptation and effective global mitigation.
- Capacity to manage climate change risks to built assets such as houses, bridges and roads, as well as human activities in Australia is generally high, but natural systems have limited capacity to adapt to the rate of climate change.
- Risks from ocean warming and acidification have increased over the last century and are projected to continue to rise. This will have significant impacts on marine ecosystems and coastal communities.
- Without adaptation, further changes in climate are expected to have substantial impacts on Australia’s water resources, coastal ecosystems, oceans, infrastructure, health and agriculture.
Working Group III – Mitigation of Climate Change
The Working Group III report highlights the global nature of climate change and the need for international cooperation.
Key findings include:
- Greenhouse gas emissions continue to rise globally with trends at the high end of projected levels for the last decade.
- Economic and population growth continue to be the main drivers for increases in emissions
- The ambition of 2020 emissions reductions targets set by countries under the United Nations Framework Convention on Climate Change is unlikely to achieve the agreed global goal of limiting global temperature rise to 2 degrees Celsius.
- Limiting global temperature rise to 2 degrees Celsius (~430-480ppm CO2e) will require large-scale changes of the global energy system as well as cuts in greenhouse gas emissions over the coming decades, with significant up-scaling of zero and low carbon energy supply by 2050.
The reports represent the international consensus on climate change in literature that has been extensively peer-reviewed and published in scientific journals.
The Fifth Assessment Report is available from the Intergovernmental Panel on Climate Change.
Special Report on Extreme Events
In 2012 the IPCC released the Special Report for Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX report) which brings together the latest research on climate change and extreme events.
Key findings from the SREX report include:
- It is virtually certain that the world will experience a decrease in cold extremes and an increase in the frequency and magnitude of warm extremes over the 21st century.
- It is very likely that mean sea level rise will contribute to upward trends in extreme sea levels in the future.
- It is likely that the frequency of heavy precipitation will increase over many areas of the globe.
- Key findings from the SREX report for Australia include:
- Australia has already observed an increase in warm days and a decrease in cold days. This trend is projected to continue with large scale increases in the number of days over 35 degrees Celsius and 40 degrees Celsius and an increase in heatwave duration.
- Extreme rainfall events are projected to increase.
- Tropical cyclones are likely to become more intense and shift southwards; however the frequency of tropical cyclones could remain unchanged or even decrease.
- Since the 1950s there has been an observed increase in drought over the south west and south east of Australia with projections indicating this could continue.
- In south-east Australia, the frequency of very high and extreme fire danger days is expected to rise by 15-70 per cent by 2050. The fire season is expected to lengthen.
The most effective adaptation and disaster risk reduction actions for extreme events are those that offer development benefits in the relatively near term, as well as reductions in vulnerability over the longer term.
- Intergovernmental Panel on Climate Change facts
- Intergovernmental Panel on Climate Change website
- Special Report for Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX report)
- CSIRO Climate Response