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  • Over our lifetimes,

  • we've all contributed to climate change.

  • Actions, choices and behaviors

  • will have led to an increase in greenhouse gas emissions.

  • And I think that that's quite a powerful thought.

  • But it does have the potential to make us feel guilty

  • when we think about decisions we might have made

  • around where to travel to,

  • how often and how,

  • about the energy that we choose to use

  • in our homes or in our workplaces,

  • or quite simply the lifestyles that we lead and enjoy.

  • But we can also turn that thought on its head,

  • and think that if we've had such a profound

  • but a negative impact on our climate already,

  • then we have an opportunity to influence the amount of future climate change

  • that we will need to adapt to.

  • So we have a choice.

  • We can either choose to start to take climate change seriously,

  • and significantly cut and mitigate our greenhouse gas emissions,

  • and then we will have to adapt to less of the climate change impacts in future.

  • Alternatively, we can continue to really ignore the climate change problem.

  • But if we do that, we are also choosing

  • to adapt to very much more powerful climate impacts in future.

  • And not only that.

  • As people who live in countries with high per capita emissions,

  • we're making that choice on behalf of others as well.

  • But the choice that we don't have

  • is a no climate change future.

  • Over the last two decades,

  • our government negotiators and policymakers have been coming together

  • to discuss climate change,

  • and they've been focused on avoiding a two-degree centigrade warming

  • above pre-industrial levels.

  • That's the temperature that's associated with dangerous impacts

  • across a range of different indicators,

  • to humans and to the environment.

  • So two degrees centigrade constitutes dangerous climate change.

  • But dangerous climate change can be subjective.

  • So if we think about an extreme weather event

  • that might happen in some part of the world,

  • and if that happens in a part of the world where there is good infrastructure,

  • where there are people that 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 event happens in a part of the world

  • where there is poor infrastructure,

  • or where people are not well-insured,

  • or they're not having good support networks,

  • then that same climate change impact could be devastating.

  • It could cause a significant loss of home,

  • but it could also cause significant amounts of death.

  • So this is a graph of the CO2 emissions at the left-hand side

  • from fossil fuel and industry,

  • and time from before the Industrial Revolution

  • out towards the present day.

  • And what's immediately striking about this

  • is that emissions have been growing exponentially.

  • If we focus in on a shorter period of time from 1950,

  • we have established in 1988

  • the Intergovernmental Panel on Climate Change,

  • the Rio Earth Summit in 1992,

  • then rolling on a few years, in 2009 we had the Copenhagen Accord,

  • where it established avoiding a two-degree temperature rise

  • in keeping with the science and on the basis of equity.

  • And then in 2012, we had the Rio+20 event.

  • And all the way through, during all of these meetings

  • and many others as well,

  • emissions have continued to rise.

  • And if we focus on our historical emission trend in recent years,

  • and we put that together with our understanding

  • of the direction of travel in our global economy,

  • then we are much more on track

  • for a four-degree centigrade global warming

  • than we are for the two-degree centigrade.

  • Now, let's just pause for a moment

  • and think about this four-degree global average temperature.

  • Most of our planet is actually made up of the sea.

  • Now, because the sea has a greater thermal inertia than the land,

  • the average temperatures over land are actually going to be higher

  • than they are over the sea.

  • The second thing is that we as human beings don't experience

  • global average temperatures.

  • We experience hot days, cold days,

  • rainy days, especially if you live in Manchester like me.

  • So now put yourself in a city center.

  • Imagine somewhere in the world:

  • Mumbai, Beijing, New York, London.

  • It's the hottest day that 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 warmer

  • on that day during that heat wave.

  • That's the kind of thing we're going to experience

  • under a four-degree global average temperature scenario.

  • And the problem with these extremes,

  • and not just the temperature extremes,

  • but also the extremes in terms of storms and other climate impacts,

  • is our infrastructure is just not set up to deal with these sorts of events.

  • So our roads and our rail networks

  • have been designed to last for a long time

  • and withstand only certain amounts of impacts

  • in different parts of the world.

  • And this is going to be extremely challenged.

  • Our power stations are expected to be cooled by water

  • to a certain temperature to remain effective and resilient.

  • And our buildings are designed to be comfortable

  • within a particular temperature range.

  • And this is all going to be significantly challenged

  • under a four-degree-type scenario.

  • Our infrastructure has not been designed to cope with this.

  • So if we go back, also thinking about 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 yields

  • in some parts of the world

  • are expected to be up to 40 percent lower

  • under a four-degree scenario,

  • rice up to 30 percent lower.

  • This will be absolutely devastating for global food security.

  • So all in all, the kinds of impacts anticipated

  • under this four-degree centigrade scenario

  • are going to be incompatible with global organized living.

  • So back to our trajectories and our graphs of four degrees and two degrees.

  • Is it reasonable still to focus on the two-degree path?

  • There are quite a lot of my colleagues and other scientists

  • who would say that it's now too late to avoid a two-degree warming.

  • But I would just like to draw on my own research

  • on energy systems, on food systems,

  • aviation and also shipping,

  • just to say that I think there is still a small fighting chance

  • of avoiding this two-degree dangerous climate change.

  • But we really need to get to grips with the numbers

  • to work out how to do it.

  • So if you focus in on this trajectory and these graphs,

  • the yellow circle there highlights that the departure

  • from the red four-degree pathway

  • to the two-degree green pathway is immediate.

  • And that's because of cumulative emissions,

  • or the carbon budget.

  • So in other words, because of the lights and the projectors

  • that are on in this room right now,

  • the CO2 that is going into our atmosphere

  • as a result of that electricity consumption

  • lasts a very long time.

  • Some of it will be in our atmosphere for a century, maybe much longer.

  • It will accumulate, and greenhouse gases tend to be cumulative.

  • And that tells us something about these trajectories.

  • First of all, it tells us that it's the area under these curves that matter,

  • not where we reach at a particular date in future.

  • And that's important, because it doesn't matter

  • if we come up with some amazing whiz-bang technology

  • to sort out our energy problem on the last day of 2049,

  • just in the nick of time to 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 be made up for in later years

  • to 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 reduce emissions in the short to medium term,

  • then we'll have to make more significant year-on-year emission reductions.

  • We also know that we have to decarbonize our energy system.

  • But if we don't start to cut emissions in the short to medium term,

  • then we will have to do that even sooner.

  • So this poses really big challenges for us.

  • The other thing it does is tells us something about energy policy.

  • If you live in a part of the world where per capita emissions are already high,

  • it points us towards reducing energy demand.

  • And that's because with all the will in the world,

  • the large-scale engineering infrastructure

  • that we need to roll out rapidly

  • to decarbonize the supply side of our energy system

  • is just simply not going to happen in time.

  • So it doesn't matter whether we choose nuclear power

  • or carbon capture and storage,

  • upscale our biofuel production,

  • or go for a much bigger roll-out of wind turbines and wave turbines.

  • All of that will take time.

  • So because it's the area under 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 means

  • that as we continue to roll out the supply-side technology,

  • we will have less of a job to do if we've actually managed

  • to reduce our energy consumption,

  • because we will then need less infrastructure on the supply side.

  • Another issue that we really need to grapple with

  • is the issue of well-being and equity.

  • There are many parts of the world where the standard of living needs to rise.

  • Bbut with energy systems currently reliant on fossil fuel,

  • as those economies grow so will emissions.

  • And now, if we're all constrained by the same amount of carbon budget,

  • that means that if some parts of the world's emissions are needing to rise,

  • then other parts of the world's emissions need to reduce.

  • So that poses very significant challenges for wealthy nations.

  • Because according to our research,

  • if you're in a country where per capita emissions are really high --

  • so North America, Europe, Australia --

  • emissions reductions of the order of 10 percent per year,

  • and starting immediately, will be required for a good chance

  • of avoiding the two-degree target.

  • Let me just put that into context.

  • The economist Nicholas Stern

  • said that emission reductions of more than one percent per year

  • had only ever been associated with economic recession or upheaval.

  • So this poses huge challenges for the issue of economic growth,

  • because if we have our high carbon infrastructure in place,

  • it means that if our economies grow,

  • then so do our emissions.

  • So I'd just like to take a quote from a paper

  • by myself and Kevin Anderson back in 2011

  • where we said that to avoid the two-degree framing of dangerous climate change,

  • economic growth needs to be exchanged at least temporarily

  • for a period of planned austerity in wealthy nations.

  • This is a really difficult message to take,

  • because what it suggests is that we really need to do things differently.

  • This is not about just incremental change.

  • This is about doing things differently, about whole system change,

  • and sometimes it's about doing less things.

  • And this applies to all of us,

  • whatever sphere of influence we have.

  • So it could be from writing to our local politician

  • to talking to our boss at work or being the boss at work,

  • or talking with our friends and family, or, quite simply, changing our lifestyles.

  • Because we really need to make significant change.

  • At the moment, we're choosing a four-degree scenario.

  • If we really want to avoid the two-degree scenario,

  • there really is no time like the present to act.

  • Thank you.

  • (Applause)

  • Bruno Giussani: Alice, basically what you're saying,

  • the talk is, unless wealthy nations start cutting 10 percent per year

  • the emissions now, this year, not in 2020 or '25,

  • we are going to go straight to the four-plus-degree scenario.

  • I am wondering what's your take on the cut by 70 percent for 2070.

  • Alice Bows-Larkin: Yeah, it's just nowhere near enough to avoid two degrees.

  • One of the things that often --