Carbon dioxide and warming

“Thus adding carbon dioxide to the atmosphere warms it a bit and leads to more water vapour and hence more warming.”

This is a direct quote from the New Zealand climate authority NIWA, in a media release after the formation of the newly formed ‘New Zealand Climate Science Coalition’ in May.

This NIWA statement sounds to me like early 1990’s IPCC inspired scares about a positive feedback and the threat of runaway warming. Is it not obvious that climate history of the last million or so years is one of repeated runaway COOLING, lurching the planet into a series of ice ages. I see no evidence for runaway warm periods, so it is obvious that the climate system incorporates feedback mechanisms that largely negate the effect NIWA is trying to express.

The NIWA statement follows.

Media Release
Why we need an IPCC
2 May 2006
The newly formed ‘New Zealand Climate Science Coalition’ is claiming that human activities have contributed only 3.2 percent of the current carbon dioxide in the atmosphere. This is wrong.

In fact, about 25 percent of the current levels of carbon dioxide in the atmosphere results from human activities.

The coalition’s claim is a prime example of the value of having a checking process like the Intergovernmental Panel on Climate Change (IPCC).

The IPCC represents a strong, balanced, thorough approach to assessing the science of climate change. The best climate scientists from around the world produce summaries of the latest knowledge. These summaries are then reviewed extensively by hundreds of other scientists.

NIWA principal scientist Dr David Wratt is a review editor for the forthcoming report of IPCC Working Group 1, which deals with the physical science behind global climate change. He says “I have to ensure that the lead authors have carefully considered every comment made by every reviewer. Even though the lead authors are demonstrated experts in their fields, what they write has to withstand heavy scrutiny. The IPCC produces a rigorous assessment of the science – an audit, if you like.”

The IPCC’s Fourth Assessment of climate change is due out next year. The reports are currently undergoing the second round of review.

For more information, contact:
Dr David Wratt
Tel: 04 386 0588
Mob: 021 349 742


Carbon dioxide vs water vapour

Water vapour is the largest contributor to the natural greenhouse effect, which has kept the planet at liveable temperatures. The computer models used by climate scientists to produce scenarios for climate change take the effect of water vapour into account.

However, the fact there is much more water vapour than carbon dioxide in the atmosphere does not mean that changes in carbon dioxide concentration are irrelevant to global climate. You may have much more flour than arsenic in your bread, but the arsenic can still make you very sick.

There are huge sources of water vapour around the world (eg evaporation from the oceans). When concentrations of water vapour in the atmosphere get too high, the water vapour condenses into cloud droplets and falls as rain. So, it’s not possible to keep adding water vapour on its own.

But water vapour is contributing to global climate change. This is because the amount of water the atmosphere can hold depends broadly on temperature. When the atmosphere warms up (eg due to increased concentrations of other greenhouse gases), it can hold more water vapour. Thus adding carbon dioxide to the atmosphere warms it a bit and leads to more water vapour and hence more warming.

Can changes in global temperatures be attributed to changes in solar activity?

Some temperature changes in first half of 20th century were probably due to changes in the sun, but solar effects cannot explain the more recent warming. Solar output in the second half of the 20th century fluctuated slightly with the 11-year sunspot cycle but showed little long-term trend.

The role of the Intergovernmental Panel on Climate Change (IPCC)

The role of the IPCC is: To assess on a comprehensive, objective, open and transparent basis the scientific, technical and socio-economic information relevant to understanding the scientific basis of risk of human-induced climate change, its potential impacts, and options for adaptation and mitigation. The IPCC also produces documents outlining methodologies and guidelines for reporting greenhouse gas emissions.

The IPCC assessments are based on information contained in peer-reviewed literature and, where appropriately documented, in industry literature and traditional practices. The assessment reports are expected to be policy-relevant but not policy-prescriptive.

Who writes and reviews the IPCC reports?

The reports are written by teams of authors, which are nominated by governments and international organisations, and selected according to their expertise. The reports go through a rigorous scientific and technical review process:

The first-order drafts are circulated for review to specialists with significant expertise evidenced by publications in the field.
Second-order drafts are then prepared, taking into account the expert review comments, and distributed for review to governments as well as again to the expert reviewers. Final drafts are then prepared, and presented to plenary meetings for acceptance of their content.

Who decides what goes into the Summaries for Policymakers?

Summaries for Policymakers (SPMs) are generally written in more accessible language than the main reports. They are the documents most likely to be read by media, politicians, and interested laypeople.

The SPMs are prepared concurrently with the main reports and undergo a simultaneous expert and government review. They are approved line by line in plenary sessions attended by government representatives. Lead author representatives from the chapters are present, and any changes must be with their concurrence (to ensure an SPM is consistent with its underlying scientific-technical report).

Structure of the IPCC

The IPCC has three Working Groups. Working Group I assesses the scientific aspects of the climate system and of climate change. Working Group II addresses the vulnerability of socio-economic and natural systems to climate change, the positive and negative consequences of climate change, and options for adapting to them. Working Group III assesses options for limiting greenhouse gas emissions and otherwise mitigating climate change. There is also a Task Force on National Greenhouse Gas Inventories.

The IPCC meets in a plenary session about once per year, to which all governments belonging to the United Nations or WMO (World Meteorological Organisation) may send representatives. These plenary sessions decide on the IPCC’s structure, principles, procedures and work programme, and elect the IPCC Chair and the Bureau. Plenary sessions also agree on the scope of IPCC reports and accept the reports.

The IPCC Bureau assists the IPCC Chair with planning, co-ordinating, and monitoring progress in the work of the IPCC. To undertake these tasks it meets two to three times per year. Bureau members generally also attend plenary meetings of the IPCC, as members of their country’s delegations. WMO Regional Association Five (South West Pacific) has three members on the Bureau: Dr Sutamihardja (Indonesia) is a vice-chair of Working Group III, Dr Geoff Love (Australia) is a vice-chair of Working Group II, and Dr David Wratt, New Zealand is a vice-chair of Working Group I.

Who funds the IPCC?

IPCC activities, including travel costs for experts from developing countries and countries with economies in transition, are financed through voluntary contributions from governments. The World Meteorological Organisation, United Nations Environment Programme, and the UN Framework Convention on Climate Change provide additional support.

2 thoughts on “Carbon dioxide and warming”

  1. That the IPCC would use the simplistic description of the water vapour and cloud/rain formation that I learned as a ten year old is surprising, but then to use it as a feedback mechanism in argument is unbelievable !

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