How green is space travel?

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Hi, hello, lovely people, and welcome to BBC Inside Science.

I'm Victoria Gill.

Today, we're taking an unexpected journey into a warming world that will take us from prehistoric forests into orbit via one of the coldest places on Earth.

When we told the story of the first ever civilian spacewalk a couple of weeks ago, it piqued the interest of a particularly curious-minded Inside Science listener who emailed to ask, why do we so often hear about the carbon footprint of Earth-bound vehicles, but nothing about pollution from extra-planetary transportation?

So today, we're putting the climate costs of the growing space industry under the microscope.

And to help with that, I'm joined by Hélise Murray, who leads the Atmospheric Composition and Air Quality Research Group at University College London, and by Richard Lowe, who is Chief Technology Officer at Satellite Applications Catapult.

That's an organisation that was set up to help boost the growth of the UK space industry.

Can I start with you, Eloise?

Can you just paint a picture for us in terms of emissions?

When a rocket launches, what's burned and emitted and where in the atmosphere?

The key aspect that really determines what's emitted is the kind of fuel that's burnt by the rocket and really the rockets that are launched currently predominantly use four kinds of fuel and all of these fuel types are producing some mix of chemicals or pollutants that are being released into just about all the layers of our atmosphere, all the way from the surface of the earth to 80, 100 kilometers and beyond.

Right.

So can you kind of take us through really

simply kind of what the what emissions are happening from when a rocket blasts off?

If it's okay for me to elaborate with chemical names we love a chemical name on inside science, absolutely.

Oh great.

Yeah there's sort of a handful of chemicals that we know of quite well that are predominantly produced by these rockets, something called nitrogen oxides or NOx,

black carbon or soot particles, alumina particles, chlorine, gas, water vapor, and all of these kinds of chemicals have different impacts on the atmosphere depending depending on where they're released.

So unfortunately, none of them are good for the atmosphere, they all have a bad impact.

Right.

So Richard, the space industry is growing.

There was a record number of launches last year, more than 200.

And as part of an organisation that wants to kind of see that industry grow, how much of a concern are those emissions?

I think we are very conscious, I think, in the space industry of the effect that it has on the environment.

That includes both the environment in orbit and the the atmosphere that we launch through.

I think one of the important elements to consider is the the scale of activity here.

So as you say, there are about 200 launches thereabouts over the last year.

That number has been increasing, but it it remains a relatively very small scale of activity.

In comparison to what?

So the small scale say compared to the aviation industry?

But yes, that's right.

So if we consider that we're talking about a total around 200 flights a year globally for the launch industry, that's versus

many tens of millions of flights in the aviation industry per year.

Now, clearly,

each launch has perhaps more impact than a given individual flight, but not many orders of magnitude greater.

So we're talking about a small amount of activity here and one that delivers a tremendously important payback in terms of why it's being done.

So Eloise, we we talked there about the comparison between the the scale and emissions of the aviation industry compared to rocket launches.

Is that a fair comparison to make?

It's it's somewhat of an erroneous comparison because our aircraft only rarely release chemicals up until about ten to twelve kilometres, whereas these rockets are going all the way to eighty hundred kilometres and so putting these chemicals into multiple layers in the atmosphere.

One of these layers is a layer layer of ozone that is crucial for protecting us from harmful UV radiation.

And so, you know, in the past,

we've tried to address this by controlling industrial sources that are close to the Earth, where the chemicals have to work a lot harder to get to that layer.

But now with rockets, we can just put them.

directly into that layer.

Interesting.

So we thought we'd kind of fix the problem with the ozone layer with the Montreal Protocol banning the main cause of that ozone depletion back in the 80s.

But is this something how much of a significant effect is that having on ozone depletion rocket launches currently it it's quite small but it depends on this the sort of big growth question we don't know how big space activity is going to be in 10 20 30 years time and so certainly as scientists and regulators we're certainly cognizant of this and keeping tabs on the potential impact this might have on the ozone layer and richard can we can we talk about growth then how much do we expect launches, or you know, we were looking a couple of weeks ago at the first civilian spacewalk, so we're looking at sort of more commercial and tourist trips.

How much do we expect that to increase over the coming years?

So a lot of the recent increase in launch numbers has been the result of, well, one company in particular, I think, which is SpaceX in the United States, who've brought in some new technology using that to launch one of the new mega constellations of spacecraft.

Now, we are going to see more of those mega constellations being launched.

Right.

And what about regulation then?

Is there regulation on emissions from those launches now?

The emissions themselves aren't directly regulated.

I think that the space industry is broadly subject to the same types of regulations as any other industry on the ground.

So the process of producing and then launching rockets is is subject to normal industry regulation.

There are more specific space regulations which come into effect in terms of activities in space, but that's not directly relevant to the atmospheric question.

And Eloise, the regulatory sort of atmosphere of this industry is quite confusing.

Is there any limitation on those different pollutants that you were talking about?

How much of a concern is that?

Yeah, currently there really isn't regulation targeting the emissions that come from rockets.

And so one of the concerns that we have is the potential climate impact of black carbon or soot particles.

This black carbon is very, very good at warming the atmosphere.

Oh so it's not just the ozone impacts and it's not necessarily just those carbon emissions that we would think about on Earth as being the planet warming gases.

It's also those particles that are planet warming as well.

Yeah in the research that we do where we model this, so we run a model that simulates the atmosphere and we put emissions from rockets into that model, we're calculating an outsized climate effect of these black carbon particles.

An individual black carbon particle from rockets has about a 400 to 500 times greater climate effect than a black carbon particle released by anything on the ground, ships, cars.

Why is that?

On Earth we have weather, rain and all these kinds of events that clean up the atmosphere so they only stay aloft aloft for a few days whereas the stuff we release higher up into the atmosphere the only loss process is really slow gravitational settling and so they spend two and a half three years years there the bigger the effect yeah wow and richard what can we talk about technology are there are there solutions being developed to mitigate some of those emissions or kind of clean up some of those launches as as the industry grows absolutely yeah there are quite a few angles that are being addressed here so So, part of it is about the fuels that are used, as we've mentioned earlier.

So, a number of launchers being developed which use some of those sort of cleaner types of fuels.

And the sources of those fuels as well, the way in which those fuels are created, are being worked on as well, so that we can create the fuels in a clean way, so that we're not adding carbon in the production process.

There are also approaches being taken to make the spacecraft in space more reusable, which actually reduces the need to go up and

put new launches up.

So if you can repair a satellite or

you can repurpose it or use it, refuel it, then that starts to

bring down the requirement for undertaking launches.

Right.

And Eloise, we've heard about the pollutants that are associated with each launch.

Is there evidence right now sufficiently to make good predictions about the effect that this is going to have on our climate and on ozone depletion, some of those issues you you mentioned?

There's some certainty and some uncertainty.

We have evidence from past studies of the amount of these pollutants that come from the four main kinds of fuel that are used currently, but there's new fuel, and as there's new fuel, we now move into an area of uncertainty where we don't know the quantity of pollutants produced by that fuel.

And the growth of the space sector represents a large source of uncertainty.

So we are in a situation where we can predict some aspects.

Are we already talking about this too late when it comes to regulation in the space industry?

No, I don't think so.

No, I think we're at the start of a journey here that the space industry remains young, even though we began 50, 60 years ago.

So there's ample opportunity to make a difference here, I think.

It's very much about international agreements and trying to find norms of standards to work to.

Everybody, I think, accepts that the work that the space industry does, particularly in monitoring climate change, the very problem we're we're talking about here, is incredibly important.

So these launches need to happen.

We just need to get all the space-faring nations on the same page here.

And Eloise,

has the damage already been done?

No, I agree that this is the right time to start thinking about sustainability measures, policies, innovations in terms of technology to try and make sure that we don't make the mess that we've made in the past with so many other industrial sectors.

That is all we have time for, but thank you both very much, Eloise Murray and Richard Lowe.

And thank you to our listener who emailed in.

I hope we went some way to answering your question.

It's a complicated but fascinating one.

If you have any thoughts or questions, you can email us at insidescience at bbc.co.uk.

Now, this month, five seabirds were added to the UK's red list of threatened species, meaning they're in danger of disappearing completely from our shores.

It's a growing list, and two of these species, the Arctic tern and the great black-backed gull, can be found on a small rocky haven five miles off the Scottish coast.

My name's David Steele, and I'm the manager of a National Nature Reserve called the Isle of May.

It's a rugged, rocky island on the east coast of Scotland that lies at the mouth of the Firth of Forth.

It's about one mile long, half a mile wide.

Not particularly big,

but it's big on its wildlife.

It has high cliffs on the west, which loom out the sea, 45 meters in height, and then slope down on the east side.

It's hugely important for seabirds.

We've got the third largest population of puffins in the United Kingdom nest on here.

52,000 pairs cram on this island.

We've got Arctic terns come and nest here on an annual basis.

It's a remarkable place to come and visit, to come and see, to come and smell.

It's a seabird colony, it's a seabird city, it is alive and it is brimming.

The UK is internationally important for seabirds.

We've got somewhere in the region of about 8 million seabirds in the United Kingdom, all making it their home.

The crags, the islands, the cliffs of the United Kingdom are so important to these birds.

But of course, like many birds, seabirds are in decline.

We've lost somewhere in the region of 62% of all seabirds.

It's staggering, really, when I think about it.

And I've seen it.

I've seen it on here on the Isle of May.

I've witnessed these declines.

Seabirds are.

Seabirds are struggling.

Seabirds have a lot thrown at them.

Obviously, there's things like you know, reduced prey availability.

We know that commercial fishing and incidental bycatch has had its impacts.

There's things like natives, predators, and non-native predators.

Things like rats.

Rats on islands, oh my goodness, it's the worst thing possible.

Of course, pollution, plastics being oil pollution.

But then there's a subtle

pollution-like plastics.

Believe it or not, the stat is that every fulmer in the world has a bit of plastic in its stomach.

Every fulmer, can you believe that?

And then there's unknowns, things like the offshore renewable energy developments.

I don't really know what the impact of those are, if any at all.

Of course, we've got the big one: the climate change, the one we talk about so much.

That is having a huge impact, as we know.

And then there's others, more modern.

In the last few years, H5N1

bird flu

it struck in 2021-2022, decimating some populations.

All these impacts, you can't just blame one of them, but all have

a threat and a meaning to these seabirds.

Of course, the million-dollar question is: what can we do about this?

Can we reverse the trends?

I'm always optimistic.

I always think that we can.

I wouldn't be doing what I do.

I've managed these reserves for 24 years and I feel we can make a difference, we can turn the corner.

Visiting the Isle of May, I mean, that's that's a good start.

You know, go and visit your local seabird colony.

It's easy to see from far on a television screen or on the internet, but actually come and immerse yourself in this glorious place and to actually appreciate what's actually happening on places like this.

We can educate, we can talk, we can listen.

That's what we've got to believe, that's what we've got to hope that we can do for these seabirds, making things better for the future.

A glorious place indeed.

Thank you to David Steele for that glimpse of seabird life on the Isle of May.

I have caught a glimpse of that island from the Fife Coast quite a few times.

Now I definitely feel the need to visit.

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Now, from an island haven to an icy expanse that's melting rapidly, the Arctic.

As our planet warms up, scientists predict the first ice-free summer in the region by 2060.

But the alarming pace of climate change has inspired some innovative solutions.

How about re-freezing the Arctic ice sheet?

This might sound far-fetched, but warming times call for desperate measures, and this one looks like it might actually work.

A team has been trying it out in a small-scale experiment in the Canadian Arctic and I spoke to Sean Fitzgerald, director of the Centre of Climate Repair at the University of Cambridge who is involved in the project.

It involves pumping of water to get the freezing process to occur on top of the sea ice rather than under the sea ice and the reason for that is that ice is quite a good insulator so if you want to go and use the cold Arctic sky to freeze ice, go and get that in the presence of the Arctic sky rather than underneath an ever-thickening ice layer.

The second twist on that is that in fact there's another process which involves pumping water from under the sea ice onto the top, but only so much as to consolidate any snow that might have fallen.

And the reason is that snow is an even better insulator than ice itself.

How far have you got with it and how do you tell whether it's working?

How do you measure that?

Last winter there was a period of about 10 days where some pumping was undertaken over an area of 4,000 square meters and when the team went back what they observed was first of all an increase in thickness of the ice of 25 centimeters on top of the original sea ice but the really exciting addition was that there was a further 25 centimeters growth on the underside as well as a result of turning that insulating snow into less insulating ice So that was extremely exciting.

Is this about sort of recreating an icy ecosystem, or what could this potentially do if it was possible on a larger scale to fight climate change?

Well, there are multiple reasons for having a go at this.

You're completely right that yes, we want to try and preserve ecosystems, marine life, and the way of living for people in the Arctic, but on a global basis, what happens is that in the Arctic summer, the amount of heat being absorbed by a dark Arctic ocean compared with the amount of radiation being reflected off that sea ice is enormous.

So 90% of the radiation coming down from the Arctic summer sun can get reflected back out to space.

Whereas, well, up to 90% of it can potentially be absorbed by a dark ocean.

So in terms of a global heat balance, and that does matter for the overall world, sorting out what happens in the Arctic is really significant.

How scalable is this?

Because when you look at the Arctic sea ice loss, the numbers are just mind-boggling.

Well, you're completely right, but there's nothing that we can do in terms of affecting the global climate that involves small numbers.

So it's comparing some big numbers with other big numbers and finding out which of those are actually plausible that we could achieve.

There was initial estimates undertaken involving the first idea of just pumping seawater in order to actually get freezing from above.

And his estimate was around like 10 million pumps to go and tackle 10% of the Arctic.

The idea of snow flooding involves rather less pumping because once you've pumped enough just to flood the snow then you move on to another location so you can use these pumps in multiple locations and you're not pumping for very long periods.

So the idea there is that we're going to be able to use far fewer pumps but there will still be a large number of them but the engineering elements of this in terms of scalability are well within the grasp of humankind.

You've got to run pumps right so is there is there a cost and emissions and fueling associated with that?

Can you figure out whether that's offset by the benefits?

Well it's not just fuel and things like this.

There are lots of potential unintended negative consequences that we need to be concerned about and that we need to grapple with.

So for example marine life, the impact on ecosystems.

Are there things for example bringing organisms from the water on top of the sea ice?

What does that do these are all really really important questions and in terms of the energy costs in the Arctic winter it's pretty blowy and the sort of the end game would be to see whether there are opportunities to for example to use wind energy to then power the pumps in a fossil fuel free way in terms of the kind of slightly different chemistry you have seawater being used that has a different melting point.

What's the impact of that?

Have you seen any kind of unpredictable effects?

Oh, it's a really great question.

And it's something that I've wrestled with because you go and pump seawater on top of sea ice to go and create, let's say, a solid matrix, but the make-up of that is very different because you've now brought brine onto the top of the ice.

Whereas when ice forms naturally, the brine in large part gets rejected.

So the actual ice, sea ice, is nowhere near the same salinity as seawater.

But by pumping seawater up, you've brought that to the very surface.

So you may have made the ice thicker, but have you made it saltier?

In fact, have you made things worse?

Does the ice actually melt more quickly?

But when they did the measurements in May of 2024, they didn't just look at the thickness, they looked at the quality, the salinity makeup of the ice.

And rather pleasingly, encouragingly, the actual brine content of the ice was much lower than we had forecast.

And we think that's because it has then burrowed itself down and started draining through the existing sea ice.

That's incredibly encouraging.

That sounds extremely promising given the kind of bleak outlook for the Arctic.

It's a small-scale trial, lots of things to find out, lots of questions, but how much of a difference do you think this could make?

Well, it has the potential to be pretty significant in terms of helping address the issue of what we call Arctic amplification.

So, when we talk about the one and a half or two degrees C target, it's a global average.

What's happening in the Arctic is rather more than that.

So, this is a way of trying to address that, and it could be really quite significant, but we've got more work to do to verify this.

Thank you to Sean Fitzgerald there.

Now, picture the Falkland Islands and what springs to mind?

I think rugged maritime landscape and penguins, lots of penguins.

Something I don't picture is trees.

In fact, the islands have no native tree species at all, but our next guest has made quite a startling discovery about the island's ancient landscape.

Dr.

Zoe Thomas has found evidence that it was once covered with a lush rainforest.

Zoe, welcome to the programme.

Hi there, thanks for having me.

I have many questions, but to start, why on earth did you go to the Falklands to study trees?

Well, it's quite funny, actually, because the reason I went to the Falklands wasn't really because of these ancient trees at all.

I was really there looking at how the climate and environment had changed over the last 20,000 years, so since the last ice age.

But what I ended up discovering was something far, far older than I had anticipated.

You have ended up doing a study of ancient trees, so how did you find them?

What we were really looking for for was some of the peat deposits on the surface.

But as word got around, we ended up talking to someone at the South Atlantic Environmental Research Institute who had a friend who had a partner that worked on the building site for Tussock House, which is an assisted living facility.

So, they were excavating this site and dug a deep geotechnical borehole and found this peat deposit sort of six to seven meters deep.

And within this peat deposit, there were tree branches, tree stumps, clearly, something really quite different to what is there now.

Wow, so very clearly a tree.

Yes, absolutely.

You know, people thought, oh, you know, you're interested in peat, would you like to come and have a look?

And we thought, oh, yeah, absolutely.

So we headed down to the building site and we had a look at some of these tree deposits that had been sort of excavated out.

They were sort of just lying in the ditch and they were scrabbling around in the ditch, very glamorous as scientists are.

It really looked like these bits of tree could have been buried yesterday.

So we were just really quite amazed as to what we could possibly be handling.

How old were these trees?

And why haven't trees been there for so long?

As we know, the Falkland Islands are really windy, and so this can really inhibit the growth of early trees.

What we also think is probably an issue is because the Falklands are covered in these peat deposits, they're very acidic, and so that can make growing of trees quite difficult.

Did that acidity preserve your tree as well?

This is exactly what happened to this deposit.

But it was quite difficult to understand exactly how ancient it was with these organic materials.

There's not too many options for actually dating it.

So how did you do that?

So there's pollen that's preserved within this ancient peat sediments that the wood was kind of trapped in.

And pollen is well known for being well preserved.

And what this tells us was what was growing at the time.

And so essentially by piecing together sort of piece by piece, looking at this ancient pollen, we could understand at what time some of the species had sort of come in and what time they'd gone extinct.

And so from that, we could kind of narrow down the envelope of how old this deposit was.

How old were these trees?

And can you paint a picture of what the island would have looked like at that time?

We narrowed down the deposit to be somewhere between 15 and 30 million years old.

So really very ancient.

We know that the rainforest was quite diverse, so lots of different species living there, but probably dominated by nothophagus trees.

So these are southern beech trees.

They have their nearest living relatives in Patagonia, so probably would have looked not dissimilar to some of the rainforests we find in Tierra del Fuego.

These beech species would have been interspersed with ferns and other shrubs.

So in summer it would have been this vibrant green colour.

And then in autumn, we know that these nothophagus trees change colour and they turn this beautiful golden yellow.

So that would have been a really stunning vista in autumn as well.

Wow.

So, I mean, it would have looked dramatically different from what the Falklands looks like today.

What's been the reaction on the islands from people there about what you've discovered about this ancient landscape?

I think everyone thinks it's really cool.

And I think one of the things that I find really exciting is that it was really in the capital of the Falkland Islands, so Stanley, which is where most people live, and it's sort of six or seven meters underneath the feet of everyone who's living there.

And I think that is something that's quite special.

A lot of these discoveries are found on really remote places that you'd never really go to.

But I think the fact that this is just underneath everyone's feet is really something quite special.

It is very special.

Might we ever see trees of this like again on the Falkland Islands?

That's an interesting question.

I think probably the answer is no.

We know that the climate back then was much warmer and probably be a bit wetter than it is at the moment.

But we know that what's happening in the Falkland Islands is that it's actually getting warmer and drier.

So this isn't really the sort of conditions that is favourable for rainforest growth.

But the evidence of it

all those millions of years ago is right underneath people's feet, almost perfectly preserved.

And well, thank you.

Zoe Thomas, paleoclimatologist from the University of Southampton.

Thanks very much for being on the programme.

Thank you.

And that is all we have time for this week.

You've been listening to BBC Inside Science with me, Victoria Gill.

The producers were Ella Hubber and Gerry Holt.

Technical production was by Rhys Morris, and the show was made in Cardiff by BBC Wales and West in partnership with the Open University.

And if you want to test your climate change knowledge, head to bbc.co.uk and search for BBC Inside Science and follow the links to the Open University.

Next week, Marnie will be back in the seat, digging up some more.

Next week, Marnie will be back with you, digging up some more of the science that's shaping our rapidly changing world.

But for now, thank you very much for having me and bye-bye.

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Sucks!

The new musical has made Tony award-winning history on Broadway.

We demand to be home!

Winner, best score!

We demand to be seen!

Winner, best book!

We demand to be quality!

It's a theatrical masterpiece that's thrilling, inspiring, dazzlingly entertaining, and unquestionably the most emotionally stirring musical this season.

Suffs!

Playing the Orpheum Theater October 22nd through November 9th.

Tickets at BroadwaySF.com.