Are we heading for 6° temperature rise?

Liz Kalaugher in Environmental Research Web: Climate scientist Kevin Anderson believes scientists at the interface of climate and policy may have used naive assumptions when modelling for a 2°C target.

They say never judge a book by its cover, but chances are a lecture entitled "Real clothes for the emperor: facing the challenges of climate change" will be fairly down-to-earth. That proved to be the case when Kevin Anderson of the Tyndall Centre for Climate Change Research at the University of Manchester, UK, gave the Cabot Annual Lecture 2012 in Bristol, UK, in November 2012.

In response to an audience member who commented that most climate scientists were simply trying to pay their bills, Anderson said "I don't think it's OK to walk past a mugging on the way to pay the mortgage. Climate scientists need to be good citizens too. Our science tells us we are killing people in poor parts of the world by putting our lights on and we need to make people think about that. Scientists need to start standing up for what they believe in. By staying quiet we are legitimizing it."

Back in 2011, Anderson published a paper in the Philosophical Transactions of the Royal Society A on how he felt today's integrated assessment models, which combine climate data with economic data, are dangerously flawed. Why? Because they are based on "naive" assumptions for factors such as emission growth rates and the date of emission peaks, they limit annual energy-emission reduction rates to between 2 and 4%, and assume uptake of geoengineering as well as a high penetration of nuclear power alongside untested carbon-capture and storage technologies.

"Because integrated assessment models typically use similar and inappropriate sets of assumptions, they repeatedly come up with the same narrow and fundamentally flawed answers," Anderson told environmentalresearchweb at the time. In his November talk, on the topic of emission growth rates used in models that were lower than real-world growth rates, he said "We've always underplayed everything we possibly can – we've done exactly what the sceptics said but in reverse."

..."With few exceptions the scenarios out there hide or massage historical emissions and emission trends," said Anderson. "So they change the framing of where we are today. They underestimate short-term growth out to the peak of emissions. The peak choice is Machiavellian at best. No-one thinks that we're going to peak in 2016 and yet virtually every model will peak in 2016, which gives you a nice answer for your policymaker."...

This map shows the average of a set of climate model experiments projecting changes in surface temperature for the period 2050-2059, relative to the period from 1971-1999. Future greenhouse gas emissions were fed into the climate models to project future temperature changes. In this temperature projection, emissions are based on the Intergovernmental Panel on Climate Change's emissions scenario "A2" (see Special Report on Emissions Scenarios for more information on the A2 scenario). Public domain