predicting the climate future

predicting the future - climate modelling 

Peter Cox presented what may have been one of the best videos to come out of the course so far, taking us on a tour of the Met Offices forecasting centre and explaining the massive amounts of computing power needed to develop climate models. The long term climate models use similar techniques to near future weather forecasting - but factor many more variables into the fantastically complex equations used to make projections of how our climate might change

The acid test for climate models is to run the parameters used for predicting future climate change through the system and see how well results correspond to the historic record. Interestingly, the model works very well up until the 1970's at which point observed warming increases far more rapidly than the model predicts - results for this period only correspond to the climate record when anthropogenic carbon is factored into the equation.

Given the close match between observation and modelling of past climate it's reasonable to suggest that the climate models predictions about future climate will be accurate. There are some unpredictable variables, including how much we are able to reduce emissions, and the ability of the bio-sphere and the world's oceans to absorb emissions that leave questions about exact outcomes.

The problem is can be overcome by creating a range of projections using different scenarios seen in this NASA Earth Observatory chart

The 5th assessment ignored other important variables like the carbon feedback from thawing permafrost, and methane clathrates  ("frozen" methane on the sea bed) that could be triggered by a warming climate - the US Blog Climate Progress regards the omission of carbon feedbacks from the IPCC 5th Assessment as "jaw dropping news" .

It's ironic that perhaps the biggest questions surrounding the IPCC 5th Assessment , who use the kind of modelling Peter Cox describes to produce their reports, is not that it exaggerates the scale of warming but that it is too conservative.

Some critics of the IPCC believe that it is under too much political pressure to tone down statements.

US educational science education site SPARK give the background to the way the IPCC develops it's reports,, saying:

"all language included in the reports (needs) support of all representatives before (inclusion)... ...Some participants feel that the reports are somewhat "watered down"... ... any claim even remotely contentious in the eyes of any participant was vetoed, and hence some important and largely agreed-upon aspects of the science were left out."

Former IPCC panelist Professor Michael Mann explains the political difficulties for the IPCC. Mann characterises the process of "hashing out the report with the input of world political leaders" as “a pretty tense negotiation at times". For example, he says,

"in 1995, during the second assessment report, when the IPCC first went on record stating that the impact of humans on climate had been detected, there was a three-day-long debate about what word should be used to describe the level of certainty about civilization’s role in climate change.

Several governments, including the government of Saudi Arabia, objected to the strength of the language that was being used and demanded essentially that it be watered down"

technology to the rescue???

Having established that it's almost certain human carbon emissions are affecting climate and gained a clear idea of what those effects will be the second topic was the possibility of using technology to mitigate the effects of climate change or to remove CO2, either by removing carbon dioxide from the system or by increasing the earth's surface albedo to reflect a proportion of solar radiation.




In theory, "removal" of carbon can be achieved by several methods.

Carbon capture and storage (CCS) extracts carbon dioxide  from exhausts of large plants like power stations and liquefy and store it in suitable geological strata. It's limitations are that it is very energy intensive process, driving up energy cost between 25 and 40%, and the risk of stored gas finding it's way back into the atmosphere. As yet there have been no successful demonstration of CCS in the UK and there are major concerns about liability and risks, described in this British Geological Survey report, which identifies geological instabilities, difficulties in monitoring and difficulties in finding commercial organisations prepared to develop the technology without government guarantees in the event of major failures. It's also interesting that  much of the lobbying effort for CCS appears to come from the fossil energy industry.

Mineralisation of Carbon Dioxide, although an energy intensive process (it would take three tons of crushed rock to remove one ton of CO2 from the atmosphere) offers is a possible technique. Mineralisation is the main natural route to carbon sequestration and the end product, carbonate rock, has none of the critical risks of storing liquid CO2. In this article, the work of Cambridge Carbon Capture is described - expanding mineralisation into industrial processes and using it to create commercially viable end products and giving an insight into the ways new technologies and ideas could help to provide climate solutions. As always with new thinking there are questions as to how much of a difference the ideas described would really make and how quickly, if ever, they will cross the bridge from theory to functional large scale plant.

Converting CO2 into fuel feedstocks - there's no such thing as a free lunch but carbon dioxide can be persuaded to form carbon monoxide that can in turn be used as a fuel - for example the University of Delaware has developed a nano-catalyst 3000 times more effective than conventional catalysts - while it doesn't remove CO2 it is a potential way of reducing new emissions. Another obvious way of recycling CO2 is via fuel crops. Bio-fuel and bio-mass are established technologies that use CO2 from the existing carbon cycle - but they have limited value - in the case of extensive palm oil plantations for example, because the fuel crops are grown at the expense of natural rain forest and in the west fuel crops competing for land with food crops - help drive up food prices and also deliver very poor overall energy returns on energy invested (EROEI).

There's also the possibility of sequestering CO2 in biomass and converting this into biochar which can be incorporated into soil, where it not only remains in a relatively stable form but also has good soil enhancement properties. Jim Haywood's presentation also suggested combining bio-mass power generation with CCS as the most "economically viable technique". Theoretically this is a good way of sequestering carbon but I'm not sure I agree with this view. I've already touched on the difficulties associated with this technology and in a country the size of the UK there are also serious questions about the quantity of bio-mass we can produce - David McKay writes in "Sustainability Without the Hot Air" that a minimum of 30% of biomass energy would be lost along the processing route - and that even with absurdly generous estimates of the land that could be made available for biomass it would make only a small contribution to overall energy demands - adding in a 25-40% increased energy cost for CCS would render biomass virtually worthless as a fuel.

Overall none of these technologies are entirely free from side effects and none would make really significant inroads into the huge amounts of new CO2 coming from fossil fuels each year.

The other path - reflecting incoming solar radiation is highly controversial for a number of reasons. Studies of the effects of high altitude particles from volcanoes and the smoke stack trails from shipping have shown that introducing materials into the atmosphere can cut temperatures.The technology involves techniques like seeding clouds to make them more reflective or creating "solar mirrors" in earth orbit to create overall global cooling - but it's a technology fraught with risk. It's known that it can reduce overall warming but no one knows how widespread use might affect specific weather systems - so, for example, if it forced a northward migration of wet zones the Amazon basin could dry out - putting one of the worlds biggest bio-carbon fixers at risk and turning it into a carbon emitter in the event of it dying. There are even greater risks associated with the technology - if it's use suddenly became impracticable the earth's temperature would rise very quickly with catastrophic effects on eco-systems.

Matthew Watson, writing in the Guardian suggest that despite the many controversies surrounding the technologies it would be foolhardy not to develop and understanding of how they could be used as a last resort. JackStilgoe takes the view that the IPCC is offering a ray hope to policy makers by even including a largely critical reference to the technology in it's report

In my view, there is a real danger to even pushing the door slightly ajar to climate engineering - it gives the "extract every drop" mob another propaganda get-out route. The stupidity of this technology is that we don't need to switch to a low carbon/renewable energy economy simply because of climate change. Continued investment in a technology and infrastructural model that depends on a finite resource is taking us up an economic dead end - a point well made in the 2010 UK Industry Taskforce on Peak Oil & Energy Security (ITPOES) report "The Oil Crunch".

There is more than enough energy and existing technologies to accelerate the decarbonisation of electricity generation right now. Given the weaknesses of geo-engineering and CCS it's by far the safest and most cost effective path - Caroline Lucas is one of many calling for the fight against climate change to be put on a war footing - though it's ironic that Greens continue to reject Nuclear Power - one of the lowest carbon energy options available to us.