Local bodies deserve better than an outdated guessGuest author | March 12, 2012
NZCSC chairman Barry Brill has suggested to Environment Waikato that its Regional Policy Statement (RPS) should not be influenced by the climate change ‘Guidance Manuals’ (here and here) issued by the Ministry for the Environment in early 2008. Like the IPCC’s Fourth Assessment Report (4AR), their recommendations have been overtaken by recent scientific papers and data. His submission notes that modelled projections of 21st century warming rely upon two components – emission volumes and climate sensitivity. Here is his comment regarding future CO2-e tonnages – or, in other words, emission volumes.
1. The IPCC Report (2007)
In 1998, the IPCC commissioned consultants – economists, futurists, statisticians, demographers, etc. – to establish story-lines of how the world might develop over the following century. This group eventually brought out a detailed book, the “Special Report on Emissions Scenarios” (“SRES”) of 40 diverse story-lines, any of which might conceivably capture the emissions profile of the 21st century.
Trenberth says the IPCC itself has no view as to the correctness of the Scenarios: “They are intended to cover a range of possible self consistent “story lines” that then provide decision makers with information about which paths might be more desirable… There is no estimate, even probabilistically, as to the likelihood of any emissions scenario and no best guess.”
These Scenarios are divided into the four families described on page 118 of the Manual. Six are selected as representative.
Emissions growth is driven by global population, economic output, energy intensity and fuel choice. In 2005, an all-party Select Committee of the UK House of Lords conducted a public enquiry into “The Economics of Climate Change”. Its unanimous report made some important findings, including:
“it seems wrong to attach equal credibility to the scenarios in general – and we believe the IPCC is now working on this issue.”
“We received a significant amount of evidence on the realism of the IPCC emissions scenarios:
· They may not be consistent with trends over the past 25 years. Total emissions are indeed increasing, but the rates of increase have slowed significantly, as has the carbon-intensity of the world economy.
· They are not capturing recent experience in their short term projections.
· There is an urgent need for a wholesale reappraisal of the emissions scenario exercise.”
The following table (from 4AR SPM3 page 13) shows the temperatures and sea levels at 2100 in each of the Selected Scenarios.
|Scenario||CO2-e (ppm)||Temp Range (°C)||Most Likely||Sea Level Range (cm)||Most Likely|
|B1||450||1.1 - 2.9||1.8°||18 - 38||28cm|
|B2||600||1.4 - 3.8||2.4°||20 - 43||29cm|
|A1T||600+||1.4 - 3.8||2.4°||20 - 45||30cm|
|A1B||750||1.7 - 4.4||2.8°||21 - 48||32cm|
|A2||950||2.0 - 5.4||3.4°||23 - 51||34cm|
|A1F1||1250||2.4 - 6.4||4.0°||26 - 59||39cm|
|Mean||770||1.7 - 4.4||2.7°||21 - 47||32cm|
2: Recent Information
A2 assumes that world population will grow to 15 billion, and still rising, by the end of the 21st century. In 2012, nobody believes this, and the Scenario should be omitted. The UN Population Division’s Bayesian model currently suggests that we are heading for a global peak of 9-10 million by 2070, followed by an uncertain but progressive reduction.
The A1F1 scenario assumes no technology changes in 100 years and an ever-increasing proportion of global energy being met by coal-burning, rather than natural gas or nuclear fuels. In 1998, nothing was known of 21st-century technologies that were about to make vast reserves of shale gas available to China, USA, India, Poland and many other countries. In 2010, the US Energy Department’s report on the massive world reserves of recoverable shale gas and shale oil, caused The Economist to react with a cover entitled “This Changes Everything!”
The SRES assumed that the 21st century would see no material change in the availability or price of fossil fuels – and no climate policies. We now know that these assumptions were wrong. In 1998-2000, the price of oil was in the vicinity of $14 per barrel while, in 2012, the price exceeds $100 per barrel.
It must be emphasised that multi-decade forecasts are almost invariably wrong. A striking illustration is provided by the “Annual Energy Outlook” published by the US Government’s Energy Information Administration (EIA), which predicted in 2004 that US carbon emission levels would rise by 37% between 2005 and 2025. In a January 2012 update, the EIA now estimates that US CO2 emissions in 2025 will be 6% lower than they were in 2005. Not only the quantity, but even the sign, has changed dramatically in just a few years.
Contrary to A1F1 assumptions, energy intensity is dropping worldwide, and at a spectacular rate.
Over 6 years have passed since “urgent” reappraisal was recommended by the House of Lords, and 12 years since the scenarios were invented. Energy intensity and female fertility have fallen further, oil and gas prices have rocketed, and there has been a long global recession.
For the 5AR due in 2013/14, the SRES are to be entirely replaced by four new models called Representative Concentration Pathways (“RCPs”). These do not pretend to be anything other than pure speculation.
· Re A2 and A1F1 scenarios: 10%.
· Other scenarios: 50%.