We already have clear evidence for climatechange with a 0.75°C rise in global temperaturesand a 22cm rise in sea levels during the 20th century. The Intergovernmental Panel on Climate Change predicts that globaltemperatures by 2100 could rise between 1.8°Cand 4.0°C, the range is due to the uncertainty ofhow much greenhouse gas we will emit over the next 90 years. Sea levels could rise between28cm and 79cm, more if the melting ofGreenland and Antarctica accelerates. Inaddition, weather patterns will become lesspredictable and the occurrence of extremeclimate events, such as storms, floods, heatwaves and droughts, will increase. In the UK, thescience behind this has been taken seriously,and uniquely has led to the introduction of thelong-term legally binding Climate Change Act.This Act provides a legal framework for ensuringthat the Government meets the target ofreducing greenhouse gas emissions by at least80 per cent by 2050, compared to 1990 levels. To do this, sustainable clean energy will beessential, because only through business andfinancial innovation, will it be possible to changethe fundamental way we produce and useenergy in the UK and the World.

The greenhouse The temperature of the Earth is determined by the balance between energy from the sunand its loss back into space. Most of theincoming solar short-wave radiation (mainly

International Sustainable Energy ReviewVolume 6, Issue 1, 2012

Professor Mark MaslinEnvironment Institute and Department of Geography, University College London

By 2030 global food and energy demand will have increased by 50 per cent andwater requirement will have increased by 30 per cent. This is partly due to the risein global population but is mostly caused by the rapid development of lowerincome countries. Add to this the increasing effects of climate change, whichdirectly threaten water and food security, and you have what Sir JohnBeddington (UK Government Chief Scientific Adviser) calls the ‘perfect storm’(see Figure 1). Hence climate change and sustainable energy are the key scientificissues of the 21st century2.

THE SCIENCE RATIONALE FOR

Enhanced globalinvestment insustainable energy

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Figure 1: John Beddington’s perfect storm

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ultraviolet radiation and visible ‘light’) passesthrough the atmosphere without interference.About one-third of the solar energy is reflectedstraight back into space6. The remaining energy

is absorbed by both the land and ocean, which isreleased as long-wave infrared or ‘heat’ radiation.Greenhouse gases such as water vapour, carbondioxide, methane, and nitrous oxide can absorbsome of this long-wave radiation, thus warmingthe atmosphere. This effect has been measuredin the atmosphere and can be reproduced timeand time again in the laboratory. We need thisgreenhouse effect because without it, the Earthwould be at least 35°C colder, making theaverage temperature in the tropics about -5˚C.Since the industrial revolution we have beenburning fossil fuels (oil, coal, natural gas)deposited hundreds of millions years ago,releasing the carbon back into the atmosphere,increasing the ‘greenhouse effect’ and elevatingthe temperature of the Earth. Essentially we arereleasing ancient stored sunlight back into theclimate system, thus warming the planet.

Anthropogenic climate change The first direct measurements of atmosphericCO2 concentrations started in 1958 at an altitudeof about 4000 metres on the summit of MaunaLoa in Hawaii; a remote site free from localpollution. To extend this record further back airbubbles trapped in ice have been analysed fromboth the Greenland and Antarctic ice sheets.These long ice core records suggest pre-

industrial CO2 concentrations were about 280parts per million by volume (ppmv). In 1958concentration was already 316 ppmv, and hasclimbed each and every year to reach over 391

ppmv by 2012. We have caused a level ofpollution in one century that occurred inthousands through the natural waxing andwaning of the great ice ages. Interestingly this

increase in carbon dioxide in the atmosphererepresents only half of the pollution we currentlygenerate. About a quarter is absorbed by the

oceans and another quarter by the landbiosphere. One of the great worries scientistshave is that this natural service may reduce in the future making the situation worse4.According to the IPCC (2007a)8, an increase ingreenhouse gases over the last 150 years hasalready significantly changed the climate;average global temperatures have risen 0.75°C,and we have seen a sea level rise of over 22cm,significant shifts in the seasonality andintensities of precipitation, changing weatherpatterns, and significant retreat of Arctic sea iceand nearly all continental glaciers. According toNASA, NOAA, the UK Met Office and theJapanese Meteorological Agency, the lastdecade has been the warmest for the last 150years (see Figure 2).

Future climate changes and impacts The IPCC (2007a)8 synthesised the results of 23 Atmosphere–Ocean General CirculationModels (AOGCMs), which are super computermodels of global climate, to predict futuretemperature rises. Because the future is not fixedthey used six emission scenarios for the next 90 years ranging from the global communitystrongly limiting carbon emissions or continuingin the ‘same vein’. They report that global meansurface temperature could rise by between 1.1°Cand 6.4°C by 2100, with best estimates being

1.8˚C to 4˚C (see Figure 3). The range of futuretemperatures is mainly due to the unknownpathway we will take in terms of carbon

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Figure 2: Comparison of four independent compilations of global land and sea temperatures over the last 150 years

Figure 3: Records of Northern Hemisphere temperatures variation over the last 1300 years, compared with the instrumental record (see Figure 2) and the future modeled temperatures (taken from IPCC 2007a)

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emissions over the next century. At the moment,despite the global recession, global carbondioxide emissions are rising at the levelpredicted by the most extreme ‘same vein’ IPCCemission scenarios. The models also predict anincrease in global mean sea level of between18cm and 59cm. If the contribution from themelting of Greenland and Antarctica is includedthen this range increases to between 28cm and79cm by 2100. All such predictions assume acontinued linear response between global

temperatures and ice sheet loss. This is unlikely,and sea level rise could thus be much higher(Hansen et al).

The impacts of global warming will increasesignificantly as the temperature of the planetrises6,8. The return period and severity of floods,droughts, heat waves and storms will increase.Coastal cities and towns will be especiallyvulnerable as sea-level rise will increasinglyaffect the magnitude of floods and stormsurges7. The increase of extreme climate eventscoupled with reduced water-security and food-security will have a severe affect on the publichealth of billions of people3.

So what level of climate change is ‘safe’? In February 2005 the British Governmentconvened an international science meeting inExeter, UK to discuss this very topic. Theirrecommendation is that global warming mustbe limited to a maximum of 2˚C above pre-

industrial average temperature16. Below thisthreshold it seems that there were both winnersand losers due to regional climate change, butabove this figure everyone seems to lose10.However with the failure to produce a newclimate treaty it now seems likely thattemperature rise will exceed this threshold. Atthe moment in the ‘business as usual’ emissionscenario we will hit 2˚C before 2050, which is notsurprising given the International EnergyAgency’s prediction of fossil fuel use over the

next 20 years (see Figure 4) including a 30 percent increase in oil, 50 per cent increase in coaland a 40 per cent increase in natural gas.

What’s the cost? So what is the cost of saving the world (which is,in effect, the cost of moving sustainable energyproduction worldwide)? According to the UKGovernment-commissioned Stern Review onThe Economics of Climate Change in 200617, if we do everything we can now and reduceglobal greenhouse gas emissions and ensure weadapt to the coming affects of climate change itwill only cost us 1 per cent of World GDP everyyear. However, if we do nothing then theimpacts of climate change could cost between 5 and 20 per cent of world GDP every year. Thesefigures have been disputed15 where the cost ofconverting the global economy to low carboncould cost more than 1 per cent GDP because

global emissions have risen faster than the worstpredictions. In response Stern recently revisedhis figure to 2 per cent world GDP. Others haveargued the costs could be offset by a globalcarbon trading system17, while some suggestthat the impacts and the associated costs ofglobal warming have been under-estimated byIPCC the Stern Report. Even if the cost-benefit ofsolving global warming is less than suggestedby Stern (2007), there is an undeniable ethicalcase of preventing the deaths of tens of millionsof people and the increase in human misery forbillions. If we look at the UK the Climate ChangeCommittee estimates that an 80 per cent cut incarbon emissions by 2050 would cost between0.5 per cent and 3.0 per cent of 2050 GDPdepending on how different technologiesdevelop. That would mean over the next 40 years we would be as rich in 2051 as wewould have been in 2050 if we had not reducedour carbon emission. This is a loss of one year’sannual salary increase in 40 years.

Solutions Climate change is the major challenge for ourglobal society. Despite all the benefits that fossilfuels have brought us we now need to replacethem with sustainable carbon-free renewable oralternative energy sources. This is essential, asthe power needs of humanity will continue toexpand due to the rapid development of China,India, and other countries. For example the IEAsuggest that at least 50 per cent of the world’senergy demand for 2030 has yet to be built(Figure 1, page 14). This energy expansion is notlimited to the developing world. In the UK, therewill need to be at least another 20PW of powergenerated by 2020. The global demand for fossilfuels is so strong and the price high. There is alsoconcern that we have reached ‘peak oil’ and thatthe world is now running out of this resource.This does, however, provide two other reasonswhy countries should adopt a less intensivecarbon-energy sector. First, because the era ofpower from gas and oil will soon be over, due toa combination of huge global demands anddwindling global reserves. Note, there is concernthat stock of high quality coal will be runninglow by the end of the century5. Second,countries have, in the 21st century, become veryaware of ‘energy security’; most developedcountries’ economies are heavily reliant on theimport of fossil fuels, making them veryvulnerable to international blackmail1.

Sophisticated political solutions are

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Figure 4: International Energy Authority recorded and predicted energy use by source, note the predicted 30 per cent increase in oil, 50 per cent in increase in coal and 40 per cent increase in natural gas by 2030

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required at all levels; ranging from a bindinginternational agreement regional, national andlocal policies. For example the EU EmissionsTrading Scheme is driving down EU emissions,while the UN Clean Development Mechanismtries to drive low carbon investment indeveloping countries12. At national level the UKis leading the world with the Climate ChangeAct. The Climate Change Committee, whichoversees UK Government policies, has proposeda pathway to achieve the 80 per cent reductionby 2050. Their proposal is that over the next 25years the UK decarbonise the majority of itselectricity generation. After that they willelectrify the countries transport networkincluding cars hugely increasing demand for lowcarbon electricity (Figure 5).

There is also a need for massive investmentin sustainable energy generation and lowcarbon technology18, to provide the means ofreducing world carbon emissions. Thisinvestment should take many forms includingtax breaks and cost incentives, direct R&Dsupport, investment in universities and supplyline protection. We also need to realise that theword ‘sustainable’ is essential when looking atnew low carbon energy technology because alot of the new technology relies on metals andrare earth elements. In a world where climatechange is not going away and regional and

global politics will start to catch up with thescience we do need some enlightened forwardthinking policies to allow the high tech lowcarbon industries to bloom in the UK.

Conclusions The scientific evidence for climate change is unequivocal and it is due to us. A viewsupported by a vast array of learnedorganisations, including the Royal Society andAmerican Association for the Advancement ofScience. But cutting global emissions need notbe such a daunting task. If you divide theproblem into a number of wedges instead of huge insurmountable problems, really what we are faced with are lots of medium-sized challenges. Each ‘wedge’ has to save

1 gigatonne of carbon every year14. For example,one wedge would be doubling the efficiency of two billion cars from 30mpg to 60mpg, which is actually a very achievable aim, as carshave already been built that can easily do100mpg. Another could increase global windcapacity by 50 times the current level or solarpower by 700 times the current level. Anotherwould be to stop deforestation and double the current rate of new forest planting.Considering the currently level of politicalsupport and binding targets in the UK and Europe there is an extremely healthy

future in sustainable clean energy and suitableinvestment from the carbon markets, under -pinned by a clear scientific rationale.

References1. Bradshaw M, Global energy dilemmas: a geo-

graphical perspective, The Geographical Journal,2010;176:275–90

2. Corfee-Morlot, J., M.A. Maslin, J. Burgess “ClimateScience in the Public Sphere”, Philosophical TransactionsA of the Royal Society, doi:10.1098/rsta.2007.2084 (2007)

3. Costello, A., et al. (2009) UCL-Lancet Commission:Managing the Health effects of climate change, TheLancet, vol 373, 16th May, 1693-1733 (2009)

4. Friedlingstein P, Houghton RA, Marland G, Hackler J,Boden TA, Conway TJ et al. Update on CO2 emissions.Nature Geoscience 2010; 3(12):811-812

5. Heinberg R, Fridley D, The end of cheap coal, Nature,2010;468:367–9

6. Houghton, J. T. (2004) Global Warming: The CompleteBriefing (3rd edition) Cambridge University Press (2004)

7. J.C.R Hunt, M Maslin, P Backlund, T Killeen and H.J.Schellnhuber (eds.) ‘Climate Change and Urban Areas’,Philosophical Transactions of the Royal Society ofLondon, Series A, 365/1860 (2007): 2613 – 2776

8. IPCC, 2007a: Climate Change 2007: The Physical ScienceBasis, Contribution of Working Group I to the FourthAssessment Report of the Intergovernmental Panel onClimate Change, Solomon et al.(eds) CambridgeUniversity Press

9. IPCC, 2007b: Climate Change 2007: Impacts, Adaptation,and Vulnerability, Contribution of Working Group II tothe Fourth Assessment Report of the IntergovernmentalPanel on Climate Change, Parry et al.(eds) CambridgeUniversity Press

10. IPCC, 2007c: Climate Change 2007: Mitigation of ClimateChange, Contribution of Working Group III to the FourthAssessment Report of the Intergovernmental Panel onClimate Change, Metz et al.(eds) Cambridge UniversityPress

11. Maslin, M., Global Warming, A Very Short Introduction,OUP, p162, (2008) Maslin M.A., and J. Scott “Carbontrading needs a Multi-Level Approach?” Nature 475,445-447 (2011) doi:10.1038/475445a

11. Parry, M., J. Paluyokof, C. Hanson, and J. Lowe, Squaringup to reality, Nature, nature reports climate change vol.2 June 2008 p3 (2008).

12. Pacala S. and R. Socolow, Stabilization Wedges: Solvingthe Climate Problem for the Next 50 Years with CurrentTechnologies, Science, Vol. 305 no. 5686 pp. 968-972 (2004)

13. Pielke Jr, R., T. Wigley, and C. Green, Dangerousassumptions, Nature, Vol. 452, 3rd Ap.ril 2008, 531-532 (2008)

14. Schellnhuber, H.J. et al. 2006: Avoiding DangerousClimate Change (Cambridge University Press)

15. Stern, N., The Economics of Climate Change: The SternReview, Cambridge University Press, p692 (2007)

16. Walker, G. and D. King, The Hot Topic, Bloombury, p309 (2008)

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Mark Maslin is a Professor ofClimatology at University CollegeLondon (UCL). He is Co-Directorof the Environment Institute and Head of the Department ofGeography at UCL. He is also co-founder and Executive Directorof Carbon Auditors Ltd. His latestbook is the Oxford University Press

‘Global Warming: A Very Short Introduction’ whichhas sold over 40,000 copies.

BIOGRAPHY

Figure 5: UK Climate Change Committee suggested pathway to an 80% carbon emission reduction by 2050. Note the initial de-carbonisation of electricity generation and then the shift to electric based transport

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