3 The IPCC 1990 Report
It was agreed at the first meeting of the IPCC that a new assessment of the whole
issue of anthropogenic climate change should be prepared. There had, of course,
been assessments before of the climate change issue, notably that resulting from
the Villach conference (SCOPE 29), again under the chairmanship of Bert Bolin
as mentioned in the introduction. The IPCC saw its task as updating previous
assessments, but with a difference. Previous assessments had involved relatively
few of the world’s leading climate scientists. Because of the global nature of the
issue that brought with it a large measure of international concern, the IPCC’s
ambition from the start was to involve as many as possible from the world
scientific community in the new assessment.
To assist in the preparation of the WGI report, a small Technical Support Unit
was set up within the part of the UK Meteorological Office at Bracknell which
was concerned with Climate Research. The report comprised eleven chapters
totalling over 300 pages dealing with different components of the scientific issue
together with a Policymakers’ Summary and an Executive Summary. Twelve
international workshops were held to address these different components. One
hundred and seventy scientists from 25 countries contributed to the report either
through participation in the workshops or through written contributions. A
further 200 scientists were involved in the peer review of the draft report. The
thorough peer review assisted in achieving a high degree of consensus amongst
the authors and reviewers regarding the report’s conclusions.
The Policymakers’ Summary (20 pages) together with its Executive Summary
(2 pages) was based on the conclusions presented in the chapters and was
prepared particularly to present to those without a strong background in science
a clear statement of the status of scientific knowledge at the time and of the
associated uncertainties. In preparing the first draft of the Policymakers’
Summary, the Lead Authors of the chapters were first involved; it was then sent
out for the same wide peer review as the main report. A revised draft of the
Summary was then discussed line by line at a Plenary Meeting of the Working
Group attended by government delegates from 35 countries together with Lead
Authors from the chapters, and the final wording agreed at that meeting.
A flavour of the style and content of the report is given by the first few
paragraphs of the Executive Summary which read as follows:
We are certain of the following:
E there is a natural greenhouse effect which already keeps the Earth warmer
than it would otherwise be.
E emissions resulting from human activities are substantially increasing the
atmospheric concentrations of the greenhouse gases: carbon dioxide,
methane, chlorofluorocarbons (CFCs) and nitrous oxide. These increases
will enhance the greenhouse effect, resulting on average in an additional
warming of the Earth’s surface. The main greenhouse gas, water vapour, will
Climate Change, the IPCC Scientific Assessment, eds. J. T. Houghton, G. J. Jenkins and J. J.
Ephraums, Cambridge University Press, 1990.
An Overview of the Intergovernmental Panel on Climate Change
3
It was agreed at the first meeting of the IPCC that a new assessment of the whole
issue of anthropogenic climate change should be prepared. There had, of course,
been assessments before of the climate change issue, notably that resulting from
the Villach conference (SCOPE 29), again under the chairmanship of Bert Bolin
as mentioned in the introduction. The IPCC saw its task as updating previous
assessments, but with a difference. Previous assessments had involved relatively
few of the world’s leading climate scientists. Because of the global nature of the
issue that brought with it a large measure of international concern, the IPCC’s
ambition from the start was to involve as many as possible from the world
scientific community in the new assessment.
To assist in the preparation of the WGI report, a small Technical Support Unit
was set up within the part of the UK Meteorological Office at Bracknell which
was concerned with Climate Research. The report comprised eleven chapters
totalling over 300 pages dealing with different components of the scientific issue
together with a Policymakers’ Summary and an Executive Summary. Twelve
international workshops were held to address these different components. One
hundred and seventy scientists from 25 countries contributed to the report either
through participation in the workshops or through written contributions. A
further 200 scientists were involved in the peer review of the draft report. The
thorough peer review assisted in achieving a high degree of consensus amongst
the authors and reviewers regarding the report’s conclusions.
The Policymakers’ Summary (20 pages) together with its Executive Summary
(2 pages) was based on the conclusions presented in the chapters and was
prepared particularly to present to those without a strong background in science
a clear statement of the status of scientific knowledge at the time and of the
associated uncertainties. In preparing the first draft of the Policymakers’
Summary, the Lead Authors of the chapters were first involved; it was then sent
out for the same wide peer review as the main report. A revised draft of the
Summary was then discussed line by line at a Plenary Meeting of the Working
Group attended by government delegates from 35 countries together with Lead
Authors from the chapters, and the final wording agreed at that meeting.
A flavour of the style and content of the report is given by the first few
paragraphs of the Executive Summary which read as follows:
We are certain of the following:
E there is a natural greenhouse effect which already keeps the Earth warmer
than it would otherwise be.
E emissions resulting from human activities are substantially increasing the
atmospheric concentrations of the greenhouse gases: carbon dioxide,
methane, chlorofluorocarbons (CFCs) and nitrous oxide. These increases
will enhance the greenhouse effect, resulting on average in an additional
warming of the Earth’s surface. The main greenhouse gas, water vapour, will
Climate Change, the IPCC Scientific Assessment, eds. J. T. Houghton, G. J. Jenkins and J. J.
Ephraums, Cambridge University Press, 1990.
An Overview of the Intergovernmental Panel on Climate Change
3