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Evidence and Response: the IPCC

Response: the IPCC

(Image: IPCC)

The Intergovernmental Panel on Climate Change : IPCC

“Climate change is widespread, rapid, and intensifying… Many of the changes observed in the climate are unprecedented in thousands, if not hundreds of thousands of years, and some of the changes already set in motion—such as continued sea level rise—are irreversible over hundreds to thousands of years.”          – IPCC Press Release 09 August 2021

Video 1: Climate Change 2021: The Physical Science Basis, the Working Group I contribution to the IPCC Sixth Assessment Report.

The process

Once it became clear that the world’s climate was changing, it was also evident that every aspect of life on Earth would be affected. The IPCC was formed to gather research from around the world, evaluate it, and use it to make predications about the impacts, with the objective of  ‘stablising greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic (human-induced) interference with the climate system’.

By gathering research from across all sectors, the IPCC is also able to see where there are gaps in knowledge, which in turn to direct research.

Each of the six Assessment Reports published since 1988 runs into several million words, are in several parts, and were collated over four to five years by scientists and researchers nominated by their respective governments (Fig. 1). This process ensures that:

  1. All member nations are represented
  2. There is time to include all relevant material
  3. A consensus is reached by all nations prior to each Assessment Report being released

Thousands of scientists and other experts around the world volunteer their time to write and review the draft reports. As these are long and technical to ensure the research is robust and comprehensive, there is also a summary report for policymakers. Delegates from all participating governmentsaround 120 including New Zealandcheck the summary report line-by-line, and all countries have to agree on the wording before the final report is published.

The Sixth Assessment Report now underway. The first report in this cycle, the Physical Science, is now published. The second report ‘Mitigation’ and third report ‘Impacts, Adaptation and Vulnerability’ will be published in 2022.

Fig. 1: The process or ‘cycle’ of each of the reports. The cycle of the sixth report is now underway and due to be completed in 2022. The first report in the sixth cycle, published August 2021, includes peer-reviewed science published prior to January 31, 2021. Research published after that date is not included due to the time it takes to collate and review material (Image: IPCC).

Criticisms of past reports being too conservative

Some assumptions in earlier reports have not (so far) come to pass; primarily:

  • Once governments knew the problems that climate change would bring, they would act quickly to replace fossil fuels. This is slowly happening, but not anywhere fast enough, and not by all governments. 
  • Technologies would be invented and installed to remove excess greenhouse gasses from the atmosphere. This technology exists, but is not cost effective.

Some nations rejected aspects of the science and implications of climate change, insisting on language in the summary reports that downplayed the scale and urgency of the problems.

It takes time, sometimes years to gather robust evidence, write research papers, and have that research published. Some research included in the IPCC may be more than a decade old, so by the time IPCC reports are released, information may already be superseded. For example, the 2001 Third Assessment Report included predictions about sea level rise and temperatures with the ‘worst case’ scenario regarded as ‘least likely’. On the eve of the Fourth Assessment Report in 2007, a study was published showing the temperatures were at the top end of the worst predictions, and sea levels were rising much faster (Fig. 2).

Most recent reports

The Fifth Assessment Report, which superseded earlier reports, was used as the basis of the Paris Agreement to keep global temperatures under 1.5°C. Interim reports focused on specific issues took into account more recent observations and research:

The Sixth Assessment Report, Climate Change 2021: The Physical Science Basis, was finalized on 6 August 2021. This includes and interactive map (Fig. 3) and an unequivocal warning: the science is indisputable.

Fig. 2 : Changes in key global climate parameters since 1973. Top: Monthly carbon dioxide concentrations; different colours are from different measuring stations. Middle: annual global-mean surface temperature; the grey area are IPCC projections). Bottom: sea-level data based on tide gauges and satellite altimeter; the grey area are IPCC projections.
Fig. 3: To see an interactive map, click on the image. This will take you to the IPCC website. This screengrab is an example of how you can enter specific information for regions (in this example, New Zealand/ land only) and check the projected temperature changes over time, based on different models and pathways (i.e. if and by how much we reduced emissions).

References and further reading