00:11Over our lifetimes,we've all contributed to climate change.Actions, choices and behaviorswill have led to an increasein greenhouse gas emissions.And I think that that'squite a powerful thought.But it does have the potentialto make us feel guiltywhen we think about decisionswe might have madearound where to travel to,how often and how,about the energy that we choose to usein our homes or in our workplaces,or quite simply the lifestylesthat we lead and enjoy.But we can also turnthat thought on its head,and think that if we've hadsuch a profoundbut a negative impacton our climate already,then we have an opportunity to influencethe amount of future climate changethat we will need to adapt to.
01:08So we have a choice.We can either choose to startto take climate change seriously,and significantly cut and mitigateour greenhouse gas emissions,and then we will have to adapt to lessof the climate change impacts in future.Alternatively, we can continue to reallyignore the climate change problem.But if we do that, we are also choosingto adapt to very much more powerfulclimate impacts in future.And not only that.As people who live in countrieswith high per capita emissions,we're making that choiceon behalf of others as well.But the choice that we don't haveis a no climate change future.
01:52Over the last two decades,our government negotiatorsand policymakers have been coming togetherto discuss climate change,and they've been focused onavoiding a two-degree centigrade warmingabove pre-industrial levels.That's the temperature that's associatedwith dangerous impactsacross a range of different indicators,to humans and to the environment.So two degrees centigradeconstitutes dangerous climate change.
02:21But dangerous climate changecan be subjective.So if we think aboutan extreme weather eventthat might happenin some part of the world,and if that happens in a part of the worldwhere there is good infrastructure,where there are peoplethat are well-insured and so on,then that impact can be disruptive.It can cause upset, it could cause cost.It could even cause some deaths.But if that exact same weather eventhappens in a part of the worldwhere there is poor infrastructure,or where people are not well-insured,or they're not havinggood support networks,then that same climate change impactcould be devastating.It could cause a significant loss of home,but it could also causesignificant amounts of death.
03:06So this is a graph of the CO2 emissionsat the left-hand sidefrom fossil fuel and industry,and time from beforethe Industrial Revolutionout towards the present day.And what's immediately striking about thisis that emissionshave been growing exponentially.If we focus in on a shorterperiod of time from 1950,we have established in 1988the Intergovernmental Panelon Climate Change,the Rio Earth Summit in 1992,then rolling on a few years,in 2009 we had the Copenhagen Accord,where it established avoidinga two-degree temperature risein keeping with the scienceand on the basis of equity.And then in 2012, we had the Rio+20 event.And all the way through,during all of these meetingsand many others as well,emissions have continued to rise.And if we focus on our historicalemission trend in recent years,and we put that togetherwith our understandingof the direction of travelin our global economy,then we are much more on trackfor a four-degree centigradeglobal warmingthan we are for the two-degree centigrade.
04:23Now, let's just pause for a momentand think about this four-degreeglobal average temperature.Most of our planetis actually made up of the sea.Now, because the sea has a greaterthermal inertia than the land,the average temperatures over landare actually going to be higherthan they are over the sea.The second thing is that weas human beings don't experienceglobal average temperatures.We experience hot days, cold days,rainy days, especially if you livein Manchester like me.
04:54So now put yourself in a city center.Imagine somewhere in the world:Mumbai, Beijing, New York, London.It's the hottest daythat you've ever experienced.There's sun beating down,there's concrete and glass all around you.Now imagine that same day --but it's six, eight,maybe 10 to 12 degrees warmeron that day during that heat wave.That's the kind of thingwe're going to experienceunder a four-degree globalaverage temperature scenario.
05:26And the problem with these extremes,and not just the temperature extremes,but also the extremes in terms of stormsand other climate impacts,is our infrastructure is just not set upto deal with these sorts of events.So our roads and our rail networkshave been designed to last for a long timeand withstand onlycertain amounts of impactsin different parts of the world.And this is going to beextremely challenged.Our power stationsare expected to be cooled by waterto a certain temperatureto remain effective and resilient.And our buildingsare designed to be comfortablewithin a particular temperature range.And this is all going to besignificantly challengedunder a four-degree-type scenario.Our infrastructure has not beendesigned to cope with this.
06:13So if we go back, also thinkingabout four degrees,it's not just the direct impacts,but also some indirect impacts.So if we take food security, for example.Maize and wheat yieldsin some parts of the worldare expected to be up to 40 percent lowerunder a four-degree scenario,rice up to 30 percent lower.This will be absolutely devastatingfor global food security.So all in all, the kindsof impacts anticipatedunder this four-degree centigrade scenarioare going to be incompatiblewith global organized living.
06:54So back to our trajectories and our graphsof four degrees and two degrees.Is it reasonable stillto focus on the two-degree path?There are quite a lot of my colleaguesand other scientistswho would say that it's now too lateto avoid a two-degree warming.But I would just liketo draw on my own researchon energy systems, on food systems,aviation and also shipping,just to say that I think there is stilla small fighting chanceof avoiding this two-degreedangerous climate change.But we really needto get to grips with the numbersto work out how to do it.
07:30So if you focus in on this trajectoryand these graphs,the yellow circle therehighlights that the departurefrom the red four-degree pathwayto the two-degreegreen pathway is immediate.And that's becauseof cumulative emissions,or the carbon budget.So in other words, becauseof the lights and the projectorsthat are on in this room right now,the CO2 that is going into our atmosphereas a result of thatelectricity consumptionlasts a very long time.Some of it will be in our atmospherefor a century, maybe much longer.It will accumulate, and greenhouse gasestend to be cumulative.And that tells us somethingabout these trajectories.First of all, it tells us that it'sthe area under these curves that matter,not where we reachat a particular date in future.And that's important,because it doesn't matterif we come up with some amazingwhiz-bang technologyto sort out our energy problemon the last day of 2049,just in the nick of timeto sort things out.Because in the meantime,emissions will have accumulated.So if we continue on this red,four-degree centigrade scenario pathway,the longer we continue on it,that will need to bemade up for in later yearsto keep the same carbon budget,to keep the same area under the curve,which means that that trajectory,the red one there, becomes steeper.So in other words, if we don't reduceemissions in the short to medium term,then we'll have to make more significantyear-on-year emission reductions.We also know that we haveto decarbonize our energy system.But if we don't start to cutemissions in the short to medium term,then we will have to do that even sooner.So this poses really bigchallenges for us.
09:17The other thing it does is tells ussomething about energy policy.If you live in a part of the world whereper capita emissions are already high,it points us towardsreducing energy demand.And that's becausewith all the will in the world,the large-scale engineering infrastructurethat we need to roll out rapidlyto decarbonize the supply sideof our energy systemis just simply not goingto happen in time.So it doesn't matterwhether we choose nuclear poweror carbon capture and storage,upscale our biofuel production,or go for a much bigger roll-outof wind turbines and wave turbines.All of that will take time.So because it's the areaunder the curve that matters,we need to focus on energy efficiency,but also on energy conservation --in other words, using less energy.And if we do that, that also meansthat as we continue to roll outthe supply-side technology,we will have less of a job to doif we've actually managedto reduce our energy consumption,because we will then needless infrastructure on the supply side.
10:20Another issue that we reallyneed to grapple withis the issue of well-being and equity.There are many parts of the world wherethe standard of living needs to rise.Bbut with energy systemscurrently reliant on fossil fuel,as those economies growso will emissions.And now, if we're all constrainedby the same amount of carbon budget,that means that if some parts ofthe world's emissions are needing to rise,then other parts of the world'semissions need to reduce.
10:52So that poses very significant challengesfor wealthy nations.Because according to our research,if you're in a country where per capitaemissions are really high --so North America, Europe, Australia --emissions reductions of the orderof 10 percent per year,and starting immediately,will be required for a good chanceof avoiding the two-degree target.Let me just put that into context.The economist Nicholas Sternsaid that emission reductionsof more than one percent per yearhad only ever been associatedwith economic recession or upheaval.So this poses huge challengesfor the issue of economic growth,because if we have ourhigh carbon infrastructure in place,it means that if our economies grow,then so do our emissions.So I'd just like to takea quote from a paperby myself and Kevin Anderson back in 2011where we said that to avoid the two-degreeframing of dangerous climate change,economic growth needs to be exchangedat least temporarilyfor a period of planned austerityin wealthy nations.
12:07This is a really difficultmessage to take,because what it suggests is thatwe really need to do things differently.This is not about just incremental change.This is about doing things differently,about whole system change,and sometimesit's about doing less things.And this applies to all of us,whatever sphere of influence we have.So it could be from writingto our local politicianto talking to our boss at workor being the boss at work,or talking with our friends and family,or, quite simply, changing our lifestyles.Because we really needto make significant change.At the moment, we're choosinga four-degree scenario.If we really want to avoidthe two-degree scenario,there really is no timelike the present to act.
13:01Thank you.
13:02(Applause)
13:11Bruno Giussani: Alice,basically what you're saying,the talk is, unless wealthy nationsstart cutting 10 percent per yearthe emissions now, this year,not in 2020 or '25,we are going to go straightto the four-plus-degree scenario.I am wondering what's your takeon the cut by 70 percent for 2070.
13:30Alice Bows-Larkin: Yeah, it's justnowhere near enough to avoid two degrees.One of the things that often --when there are these modeling studiesthat look at what we need to do,is they tend to hugely overestimatehow quickly other countries in the worldcan start to reduce emissions.So they make kind ofheroic assumptions about that.The more we do that,because it's the cumulative emissions,the short-term stuff that really matters.So it does make a huge difference.If a big country like China, for example,continues to groweven for just a few extra years,that will make a big differenceto when we need to decarbonize.So I don't think we can even saywhen it will be,because it all dependson what we have to do in the short term.But I think we've just got huge scope,and we don't pull those leversthat allow us to reducethe energy demand, which is a shame.
14:14BG: Alice, thank you for comingto TED and sharing this data.
14:17ABL: Thank you.
14:19(Applause)
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