The Royal Society is located just off Pall Mall in a glorious Nash terrace in one of London’s most exclusive areas. As we discuss the end of the world “as we know it” inside, Bentleys and Porches glide effortlessly past outside the window. The latest IPCC assessment AR5 implies that cuts in emissions of 80% are needed to keep temperatures below 2C. However, several of the scientists had actually just arrived on transatlantic flights and most are habitual globe trotters! Bob Ward and John Ashton were more interested in their battle of ideas which they feel must be won in the public arena against their policy enemies. These enemies appear to be the old economic order, energy companies, bankers, reactionary politicians, right wing pressure groups and especially climate skeptics. Somehow they are seemingly striving for some green revolution to overturn “outdated” growth economic models of the past and return to some low energy “sustainable” nirvana. To the bustling world outside, this message has about the same impact as a speaker in Hyde Park Corner screaming “repent now for the end of the world is nigh” ! Even worse their message comes over to the public more like “repent now and save the world 100 years after you are dead” !
Most scientists accept that we must move away from an over-reliance on fossil fuels. To get the message across to the public however, you need to give a positive vision of the future and not a negative one. It’s no good preaching that we should abandon cars and quit taking overseas holidays, while simultaneously lobbying politicians to increase taxes to impose exactly that end. Instead we need a realistic plan of how to achieve a low carbon society that does not destroy living standards. Basically this means a plan to generate 50% more power than we do today from non-carbon sources as efficiently as possible. For the UK this would means a future generating capacity of at least 100GW. I think there are only two solutions that could possibly achieve this.
1. Nuclear Power
2. Carbon Capture
Wind power can only ever provide a maximum average of ~10% of demand, because of its extremely low energy density. So we should be making a realistic plan and a vision of how a low cost secure electric future could be achieved. Present this to the public in a positive way and then get on with implementing it. All this can be achieved by 2050 without bankrupting the economy provided engineers and not activists are allowed to make the decisions.
The overall meeting was very well organised and the science sessions were fascinating also because they highlighted the areas of uncertainties that still exist simply because the Earth’s climate is so complex. It is only the politics which has become too polarized.
The first day: The overall review of the SPM by Thomas Stocker was I suspect a talk he had given to policy makers. There is a clear underlying IPCC branded message that they feel obliged to be portrayed to politicians. There was much talk about how to control the communication with the public. He diminished the importance of the recent pause hiatus stated that it would need to last for 3 decades before it meant anything at all. The evidence for AGW comes from the 3 decades 1970 – 1999 !
The hiatus in global warming itself was addressed by Joachem Marotzke in a very low key talk. IPCC confirms that there has indeed been a pause in warming that is also independent of cherry picking the start date. Are models able to reproduce the hiatus? Should they be even expected to do so he asked? All the models essentially fail to explain the hiatus despite including natural variation. 111/114 simulations predict too high trends.
In IPCC parlance this translates to : It is “extremely unlikely” that AR5 models can explain the hiatus in global warming (95% probability).
There has been a lot of discussion on Climate Audit about why AR5 dropped Fig 1.4 in the leaked draft which showed FAR,SAR, TAR and AR4 predictions significantly above the temperature measurements. Instead we got a washed out blended plot which seemed to include the hiatus data post 1998. Below is the real graph we should be studying showing direct comparison with CMIP5 model runs. The thick red curve is the multi-model mean which lies above the measurements.
In summary, the observed recent warming hiatus, defined as the reduction in GMST trend during 1998–2012 as compared to the trend during 1951–2012, is attributable in roughly equal measure to a cooling contribution from internal variability and a reduced trend in external forcing (expert judgment, medium confidence). The forcing trend reduction is primarily due to a negative forcing trend from both volcanic eruptions and the downward phase of the solar cycle. However, there is low confidence in quantifying the role of forcing trend in causing the hiatus, because of uncertainty in the magnitude of the volcanic forcing trend and low confidence in the aerosol forcing trend.
A detailed study of temperature data he claimed show that the hiatus is concentrated in winter months in the northern hemisphere. Gavin Schmidt proposed that soot emissions and aerosols from China may be to blame !
The consensus partial explanation for the hiatus is that it is half natural – solar cycle, aerosols & volcanoes, and half unknown. So in other words there is the basic assumption that the models are right and that if only nature didn’t occasionally screw things up for them the predictions would be just fine. But anyway for them this is irrelevant as the pause will soon stop and warming will continue advancing according to model predictions. I suspect and some floor comments noted that perhaps the hiatus could well last another 10 years partially due to PDO.
The arctic is loosing Ice. This year’s recovery was within the year to year variations but the trend is still downwards. It is expected that the Arctic will be ice free by 2050-2060.
Antarctica is loosing some ice mass yet is actually gaining in sea ice extent. Any overall reduction is small.
Sea level rise will be ~60 cm by 2100. This was not enough for some of the audience who wanted to use more scary figures measured in meters. Sea defense engineers and flood protection experts need best estimates of worst case values. Such worst case estimates would realistically be 90cm by the end of this century. Others preferred to continue to use the AR4 figures of over 1-2 m. What are the causes of the rise in sea level? 50% is due to the thermal expansion of oceans. Of the rest glacier melting was twice as large as that contributed from the arctic and antarctic combined !
Day 2: Clouds (David Randell)- Good informative talk…. more in the next post.