Professor Jim Watson, University College London: Air travel

Jim Watson: Good morning, everybody. I hope you slept well, et cetera and are ready to go at this other important part of our transport sessions. So air travel this morning. It's about 8% of the U.K's greenhouse gas emissions, so in itself, it's quite an important area of emissions and therefore an important area to consider how emissions could be reduced as part of meeting that net zero target. So I'm just going to make a few introductory remarks, give you a little bit of information to help, and a bit of context. And then the other speakers are going to go into a lot more detail, as Sarah's explained, about things like technologies, alternatives, fairness and some viewpoints about how we might reduce emissions from air travel. So the first thing to say is, air travel is treated a bit differently in a number of different ways, but there are two points I really want to make on this. One is that a lot of air travel is international, just like travel by boat as well. And because emissions reductions are agreed by governments at a national level, there have to be some special arrangements for activities that are meeting international airspace or international waters. So things that travel between two different countries. So because air travel is international and most of the emissions are international, then they are treated differently. Sometimes they're not included in the national accounts for emissions reduction, but we're being really careful in this assembly to actually to give you the international air travel emissions as well to make sure we're showing you the full carbon footprint.

So in terms of how we reduce it and who is responsible, the arrangements are a bit different than for many other areas of life. There are other reasons why it's different. If you remember, I'm going to show this slight again in a minute just in case you can't recall it,when I showed you the example of the Committee on Climate Change is pathway to how we meet Net 0, one of the areas where they foresaw as having quite a lot of emissions still happening in 2050 was air travel, and some of the reasons for that are summarised on that slide, and we'll get-- the other speakers will be able to tell you a lot more about these. So one is that technologies or fuels that can deliver really large reductions in air travel emissions are at quite an early stage, things like electric aircraft and alternative fuels. There are obvious safety considerations, you know, safety considerations in many years of life, but particularly their travel, which means if you're going to make changes of that kind, then there are very good reasons to be careful and cautious. And then, although you could say this last point for many other areas as well, there is a reluctance to reduce or limit how much air travel we do because of all sorts of economic and other reasons. You could say the same for road travel and the same for other things. But these are just some of the reasons why air travel is different to bear in mind as we go through this session.

The next thing I wanted to say was that most of our just to show you some numbers to illustrate that point that most of the emissions from air travel from the UK are from international flights. So this is a graph looking at three different years, 1990, 2005 and 2017. The scale up the side on the Y axis is the amount of emissions, greenhouse gas emissions. Hopefully, the difference is pretty clear. So the red bar is the international flights and blue is the domestic. So as it says on the slide, about 96% of the emissions from air travel come from international flights. So we don't really have that much emissions from domestic flights in the U.K. I think the other thing I'd emphasise from this slide is that certainly between 1990 on the mid-2000's, there was a very rapid growth in air travel emissions that became a really important issue, so you could see the real difference in the amount of emissions between those two years. That has since leveled off a bit, but there has been quite a big growth in the last 20 years in those emissions.

So in terms of impacts of air travel, this is really important, and one thing to note from the grafts have shown you for emissions, is that these showed that direct carbon dioxide emissions from the plane, so it's the same as the carbon dioxide emissions from other areas of life, whether it be a car or boiler or whatever. But actually there are other impacts from air travel on the climate which I've just summarised on this slide. Some of the other speakers of real experts in this area, so if you've got questions we can go into it in the Q and A discussion. So they are larger, most scientists agree that they're larger than just those direct CO2 emissions, those impacts on the climate. There are other emissions from planes which can have an effect, and one of those effects is, for example, affecting cloud formation in the atmosphere. So sometimes on particular days, when you see planes going across the sky, you'll see what's called contrails. Those of those trails that look like clouds, sort of tracks across the sky. So that's an effect on forming those clouds and there is some science which says, well, actually, that also enhances the greenhouse effect as it traps that heat in the earth more than it would do otherwise. So there are some more impacts to consider, but I think what we've emphasised here is that they're quite uncertain, they're quite difficult to measure, but they are going to mean that the impact of air travel is larger than those direct carbon dioxide emissions from the engine. So that's just something to bear in mind.

So this is just a reminder of the graph I showed you earlier at the introduction to all of the transport sessions, just showing you the example of the Committee on Climate Change is analysis for net-zero. So it shows you all transport emissions, including international air travel in international shipping on the left in 2017, and then on the right 2050. And just to really re-emphasise the fact that most of those emissions in 2017 have gone to almost zero by 2050, apart from those air travel emissions which are in green there. Now actually, the air travel emissions have reduced by 20% between 2017 and 2050 so there is a reduction. That's through some assumptions which other speakers will go into about include improvements in technology in some ways, and also demand. The amount of air travel we do, although it still grows, it grows more slowly than it has in the past. But a key question for you, I think, in the Assembly, is thinking about well is this kind of scenario which we think is plausible, this is something we want to recommend, or actually are the measures we want to consider which would reduce their trouble emissions further than the Committee on Climate Change? Or even not reduce them as much? So there's, you know, there's quite a lot to play for here in terms of discussing how much you think air travel should contribute to that target for net-zero.

Just a final slide just to reinforce this point about how much air travel we do, and the different assumptions that are made out there. So, as I said, the Committee on Climate Change is assuming a growth in the amount we fly between now and 2050 as part of their calculations. So they assume that that will go up by about 25% from today's levels. So that already means that the rate of growth is slowing, so because it's grown more rapidly in the past, as I've illustrated. But just to contrast that the government, the Department for Transport's latest forecast, their central forecast, is a growth that's much higher than that. That's a 50% increase in the amount we fly between now and 2050. So if we built that into the calculations, you'd end up with much higher emissions in 2050. So it's really just to, you know, explain this point that the all the Committee on Climate Change or those data, what we're using to illustrate a point, there are a range of views out there about how much air travel use will actually grow, or whether it needs to grow a tall. So that's again, something really important to bear in mind in the discussions today.

So finally, just a recap of what we're covering in terms of topics. So we're going to go on after my introduction to looking for technical options for reducing emissions from air travel itself. We're going to spend some time looking at alternatives to air travel, so that's shipping and high speed rail and so on, that topic of fairness again just like we did for road surface transport yesterday is going to be covered, and then we'll end, just as we did yesterday, with two different views about how emissions from air travel might be reduced from two different speakers. OK, I'll leave it there. Thank you.