We need to start again
So what is our Climate Change Minister, James Shaw, going to do now that the UN has halved to only 2.5°C its prediction of global temperatures by the year 2100, on the basis of recent science?
The collapse of long-standing global warming expectations is largely the result of the UN’s belated rejection of the most extreme scenario of future emission levels – known as Representative Concentration Pathway 8.5, or RCP8.5. This unrealistic input to climate models has for many years applied a massive upward distortion to the calculation of likely future temperatures.
Minister Shaw was alerted to this pending bombshell only recently. He co-leads the Green Party that has long claimed that climate change is an existential threat to the world order and his ideology lies at the heart of all of the climate change estimations and policies that have been put out by the government during his time in the Climate Change portfolio.
All that now has to change given that the United Nations Framework Convention on Climate Change (UNFCCC) has now banished RCP8.5 (and its successor SSP5-8.5) from all its policy-making at COP27. For good measure, it has also dropped the RCP6.0 scenario, and is now focussing on an envelope between 2.6 and 4.5 – a new addition, RCP3.4.
Even taken in isolation, the long-awaited abandonment of the extreme RCP8.5 is the most important and consequential climate change story of the last decade.
Based on advice from the NZ Climate Commission, prior to COP26 in Glasgow, Minister Shaw promised a net 50% reduction of New Zealand’s 2005 gross emissions by 2030. This extremely ambitious, and economically painful, pathway to 571 M tonnes of long-term gases was calculated by reference to BAU global temperatures of 4.5°C by 2100, and relied heavily upon modelling of the effects of RCP8.5.
We now know all those calculations were based on wrong assumptions. As were the endless calculations and model runs which underpin New Zealand’s First Emissions Reduction Plan, its First National Climate Risk Assessment and First National Adaptation Plan.
Other Government publications such as “Coastal hazards and climate change: Guidance for local government” and interim guidance on the use of new sea-level rise projections, all being heavily reliant on RCP8.5, can no longer stand.
Tens of thousands of work hours of highly-paid public servants have been invested in all of this modelling and central planning – which has been variously described as “economic transformation”, a “just transition” or the “great reset”.
The theory was great but like all modelling, when the underlying baseline assumptions have proved to be wrong then the whole theory is no longer supportable and the conclusions of the modelling must be thrown out on that basis.
Government’s advisers, acting rationally, will have no choice but to change their minds now that the basic assumptions used in their modelling have been proven wrong, as advised by UNFCCC.
Every government promise, every target, every carbon budget, and every quantified policy to mitigate future global warming will now require a thorough review. The models must be re-worked.
But it’s not all bad news. The silver lining to this paradigm shift in climate science is that the Labour government can extend its petrol price subsidy with a clear conscience; hopefully, businesses will be allowed to do business rather than spend time estimating potential losses from future climate policies and the Reserve Bank can finally turn its attention back to monetary policy.
The UN’s COP27 announcement effectively concedes that there is no “climate emergency”. The extent of the risk is that global temperatures over the next 80 years are expected to rise at around the same barely perceptible average pace as the last 80 years – about 0.017°C per year.
Based on this we need to go back and start over again using the proven science that the UN has just published. Our government’s promises, targets, carbon budgets, and policies to mitigate future global warming were all based on science that is now proven to have been wrong and therefore will now require a thorough review.