The BBC has a nice summary of my talk yesterday at Aston University (the paper on which it was based is here in PDF), as well as some critical reactions:

The UK’s plans to cut emissions by 80% by 2050 are fundamentally flawed and almost certain to fail, according to a US academic.

Roger Pielke Jr, a science policy expert, said the UK government had underestimated the magnitude of the task to curb greenhouse gas emissions.

He added that it would be more effective to “decarbonise” economic growth rather than focus on targets.

Professor Pielke made his comments during a speech at Aston University.

Professor Pielke said that a country’s greenhouse gas trajectory was determined by three factors: economic growth; population growth; and changes in technology.

This meant, the academic from the University of Colorado suggested, that if people migrate to the UK and the economy boomed, it would be harder for politicians to achieve emissions cuts based on historic levels.

He calculated that the combined effects of possible population growth and economic growth could oblige the UK to increase energy efficiency and reduce carbon intensity of energy at an unprecedented annual rate of 5.4%.

The arguments against my analysis?

Professor Pielke’s intervention was rejected by economist Terry Barker, a lead author for the Intergovernmental Panel on Climate Change (IPCC).

“Pielke’s analysis does not tell us how fast an economy can de-carbonise, just how much it has done so in the past when there has been a weak carbon price,” he said.

“[His] proposals are diversionary; they fail to emphasise the scale of the no-regrets options available to reduce emissions at net benefit and they do not include potential changes in regulations on vehicles and power stations that could lead to rapid de-carbonisation.”

Professor Tom Burke from Imperial College London added: “These conclusions are a very marginal addition to our knowledge.

“The argument in his paper amounts to saying that getting 80% will be difficult. This is hardly news.

“There is nothing that supports the contention that the Climate Change Act will fail or that there are flaws in its basic conception or that there is an alternative approach which is better.

“No-one has said this would be easy.”

Debates like this will run throughout the year whilst the world staggers towards a climate change agreement to replace the Kyoto Protocol.

And there is some support:

Colin Challen MP, chairman of the All Party Parliamentary Climate Change Group, said: “This raises questions which I do not think have been factored into the thinking behind the Climate Change Act.

“The task (of cutting emissions by 80% from 1990 levels by 2050) is already staggeringly huge and, as we have seen, well beyond our current political capacity to deliver.

“Heathrow is a prime example of ducking the responsibility,” the Labour MP for Morley and Rothwell told BBC News.

“It is hard to see any tough choices being made in the current climate. A greater population implies more embedded CO2 emissions in imported goods, but the climate change committee is only empowered to consider domestic emissions.”

The UK Climate Change Act has a near term target, so we’ll know fairly soon if my analysis is itself on target, or is wrong.