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Brian Lehrer: It's The Brian Lehrer Show on WNYC. Good morning again, everyone. Happy New Year, again, everyone. Again in 2024, we will do our climate story of the week. Again in '24, we will do it on Tuesdays. This is Tuesday, not Monday, remember. Now our first climate story of the week for 2024. Now, while the problem remains overwhelming and anxiety-inducing, it might be helpful to break down the issue of climate change into its most basic building blocks to start the year.

Let's say the five elements of hydrogen, oxygen, carbon, nitrogen, and phosphorus, which make up the delicate balance needed to sustain life on Earth in the first place. In the current climate crisis, we have focused, of course, a lot on the impact that carbon dioxide has had on warming the planet, but we can look to the past as well to see what happens when one element or another is altered.

Joining us now is our first climate story of the week guest for 2024 to explain how five essential elements have changed the climate and the Earth and how we might learn from them to prevent more destructive climate change this year and in the future is Stephen Porder, associate provost for sustainability and professor of ecology, evolution, and organismal biology, I think I said that word right, at Brown University, co-founder of the radio show, Possibly, and author of the new book called Elemental: How Five Elements Changed Earth’s Past and Will Shape Our Future. Professor Porder, welcome to WNYC. Happy New Year. Thank you for coming on with us.

Stephen Porder: Thanks so much for having me, and happy New Year. It's great to be here.

Brian Lehrer: We'll get into some specific climate changing events as we go, of course. Can you tell us about why you chose these five elements, what you refer to as life's formula, as a focus for your book?

Stephen Porder: Yes. I think we are living through a really existential crisis of sustainability and worry. It's helpful to think broadly about the links we have to other organisms that have changed the world in the past and how that might lead us to a more sustainable future. These five elements, that are the centerpiece of the book and that you mentioned, make up over 99% of the atoms in every single living cell and every single organism on the entire Earth.

In addition, they play a fundamental role in shaping the climate and other ecological conditions on the planet. The link between what we're made of and the state of the planet is fundamental and comes through these elements. By understanding how organisms can change the flows of these elements around the planet, we can learn a little bit about how to live more sustainability.

Brian Lehrer: For example, listeners, put on your old science 101 student hats, and listen as I ask this question about how Stephen Porder writes about how twice in the past 4 billion years of life on Earth organisms changed the elements of life's formula, as you call it. The first time is when cyanobacteria evolved new ways of processing elements in a way that dumped oxygen into the atmosphere. Take us way, way, way, way, way back, and tell us more about how cyanobacteria created what you actually refer to as oxygen pollution.

Stephen Porder: Let me start by saying that the planet that we live on today is wildly different than the planet upon which life evolved. The oxygen that we breathe at 20% or so of the air that's made of oxygen, for the first 2 billion years of life on Earth, there was no free oxygen, no breathable oxygen in the atmosphere, no oxygen dissolved in the ocean, and all of life on Earth was a bunch of single-celled organisms floating in the ocean, but with no oxygen.

Cyanobacteria "figured out", and I put that figured out in quotes, how to capture a lot of sunlight by incorporating a new way of doing photosynthesis, which is the same process that plants do today, and also a way to capture nitrogen, another key element from the air as well. This nitrogen allowed them to build the machinery of photosynthesis. Together in a single cell, they had the capacity to build machinery, to get the food, to build up the machinery, to capture energy.

This combination of nitrogen and carbon capture through photosynthesis allowed them to proliferate wildly, to spread across the oceans as no organisms had before. Unfortunately, for the organisms at the time, the by-product of those chemical reactions was that they began to dump oxygen into the atmosphere. Now, of course, you and I are very grateful for that because we couldn't live without it, but imagine an Earth on which for 2 billion years there had been no oxygen, and now all of a sudden, this new free element, this free oxygen is being poured into the ocean and bubbling into the atmosphere.

In fact, it reacts with the gases in the atmosphere and changes the global greenhouse. The blanket of gases that was keeping the planet warm was profoundly changed by this oxygen, and it took the Earth from quite a warm place to a frozen place. For 2 billion years, you had an anoxic, no oxygen environment, where evolution was playing out in all sorts of complicated ways, and then you have this profound shift, a shift that has been in place or to a new state that's been in place for the last 2.5 billion years where there's oxygen in the air.

That set the stage for the evolution of all multicellular life. It changed the planet forever. The key thing to learn from that lesson is that when an organism innovates new ways of getting energy and food, it can change the chemistry of Earth itself in a way that profoundly shapes the future, and that's the first world-changing organism that we know of.

Brian Lehrer: Listeners, sometimes we talk about events of the news cycle of the last 24 hours, sometimes we take just a teeny tiny step back and talk about the events of the last 2.5 billion years on Earth, as our guest Stephen Porder is doing right now. Climate change deniers will often say climate change is natural, maybe even normal, because the science tells us as you're telling us that it's happened at other points in history.

Since that is on one level true, how does the story you tell in your book support that human-made climate change is real and not just that we're going through another cycle of evolution of the elements or the mixture of the elements?

Stephen Porder: There are two pieces to that. It is true that the climate has changed in the past, but it is not true that it has changed this rapidly in the past, other than meteorite impacts. We really are, in some ways, unique in the pace of human-caused climate change. Now, it's chemically inevitable that if you pump enough CO2 into the atmosphere, you will change the climate. In fact, Svante Arrhenius in the late 1800s published a climate model that predicted almost precisely how much warmer it is today based on his extrapolation of, if you put this much CO2 in the air, how warm would it get? He did that with a paper and pencil, or maybe a pen and ink, I'm not sure.

The science of climate change is not in question. The more CO2 in the air, the warmer it will get. The problem with the pace of change is that we've set up a world, a global system with over 8 billion people, that depends on the climate as it is. There's nothing to say that humans couldn't live in a world that was tropical from pole to pole. After all, humans live in the tropics now, but living through the transition is going to be neither pleasant nor guaranteed for us or for other organisms.

It's wise and reasonable to try and slow the transition and try to make it as small as possible. If you're driving a car, and you're going to run into a tree, you'd rather run into it at 1 mile an hour than 100 miles an hour.

Brian Lehrer: Listeners, anybody have a science question? You can go back 2.5 billion years, you can go back 4 billion years, or you can go back to 12 minutes ago as we talk to Steven Porder, associate provost for sustainability and professor of ecology, evolution, and organismal biology at Brown University, co-founder of the radio show, Possibly, and author of the new book, Elemental: How Five Elements Changed Earth’s Past and Will Shape Our Future.

It's science history in this new book in the context of climate change for our first climate story of the week of 2024. 212-433-WNYC. 212-433-9692. None of it will be on the test. You can ask any question you want of Science Professor Stephen Porder. 212-433-9692, call or text. Let's actually continue to go back over some of this biochemical history of the planet Earth.

All that oxygen you were talking about before set the stage for multicellular organisms like plants, which leads us to the second environmental shakeup that you write about, when plants went from the sea to the land and evolved to take water up from the ground. You want to talk a little bit about that evolution and which of the elements were key to that?

Stephen Porder: Sure. If we go back to those five basic elements in life's formula, hydrogen, oxygen are the two most abundant, then carbon, nitrogen, and phosphorus. Imagine that you're living in the ocean as a single-celled organism. While water is easy to get, the ocean is made of water, so H and O are easy to get. I've talked about photosynthesis and nitrogen in the cyanobacteria. Phosphorus is a weird one. It comes only from the weathering of rocks.

Imagine a single-celled organism floating in the middle of the ocean at the ocean surface. Where's the nearest rock? There's nothing around. You can't get anything from rocks except for maybe some dust that blows off the continents or some rivers that are dumping sediment into the ocean. When land plants move to land, they have an incredibly big challenge. They have to figure out how to stay hydrated to get hydrogen and oxygen. They evolve roots and symbiosis with fungi and all sorts of complicated mechanisms for staying hydrated.

Once they do that, they're able to go straight to the source of phosphorus, this key element that is at the heart of the energy process in cells, it's at the backbone, it's part of the backbone of DNA. Plants go right onto the rocks, and they start dissolving them. They become the world's greatest miners. They dissolve rock and build the first soils, and that allows them to photosynthesize at a greater rate per acre than any organism in the ocean.

The plants start their journey across the continents. In so doing, they too begin to change the chemistry of the atmosphere. They pull carbon dioxide out of the air and store it in their tissues. Plants are about 50% carbon in their wood, but they also accelerate the weathering of rocks. That actually, through a rather complicated chemistry, consumes CO2 from the air as well.

Over time, they gradually pull enough CO2 out of the air to cool the planet. When they emerged from the ocean somewhere around 400 million years ago, the world was tropical from pole to pole, but by the time about 300 million years ago, so 100 million years later, they've cooled the planet sufficiently that you start to see evidence of ice ages, and you actually get one of the five great mass extinction events at the end of a period we call the carboniferous.

What's really interesting about that is that the remnants of those plants from that time period are what we humans found and began to burn as coal as we started to industrialize our economies. Our society is founded on the bodies of our world-changing predecessors.

Brian Lehrer: The population, see if I have this right, of land plants exploded, and that created a certain kind of environmental catastrophe because plants pulled so much CO2 out of the air that the planet cooled and fell into a near-global ice age, and the mass extinction of plants, therefore, set the stage for the fossil fuels that we use today in the way you were just describing. Correct?

Stephen Porder: Not the mass extinction of plants, but the mass extinction actually of animals as a result of the climate change. The plants themselves have continued, although the tropical forest that once spread from equator to pole almost vanished, and some of those plants, yes, they formed the coal that we burn today.

I want to just come back to something you said a little bit earlier about, well, climate change has happened before and all that. It's important to wrap your head as best as possible around the timescale we're just talking about. That took over 100 million years. Modern climate change is taking place in 100 years. The timescale is so different. Even at that 100 million-year timescale, those changes were profoundly difficult for organisms to deal with.

Now we're talking about change at an incredibly accelerated pace, but I don't want to leave our listeners with a gloom and doom story because the key point I think that I'd like to highlight about this book is that is not that it's all gloom and doom, but rather that by understanding how organisms have changed the world in the past and understanding our links to those organisms and the elements underlying those changes, we can actually craft a more sustainable future around the wise management of life's formula. It really does provide us with a roadmap of how to build a more sustainable society.

Brian Lehrer: Well, I only got a B minus in high school chemistry, and I guess I'm not doing any better today. Jacob in Hempstead who says he is a public school science teacher, you're on WNYC. Hi.

Jacob: Hi. Thank you so much for taking my call. If you're asking why I'm not at school today because I actually have COVID, but that's why I'm not in school today. Here's my question. One of the things that I quite often get from my students is how do we know what it was like a million, 10 million, 50 gazillion years ago, how do we know what the climate was like?

Then you try to explain, well, there were ice cores, and you could dig down on the ice cores and figure out the amount of gas and the atmosphere and extrapolate the CO2 levels, but in 30 seconds or less, if you have to explain to someone in an elevator pitch of how do we know the temperature on the planet 10 million years ago, what would you say? I'll take my answer off the air. Thank you very much.

Brian Lehrer: Great question from a public school science teacher.

Stephen Porder: That's a great question. You're right. We have about 120 years, maybe a little bit more, of thermometer data. Back before that, we need to use what we call proxies, and there are many, many, many different proxies. What we mean by that is things that in the modern-day correlate with the temperature.

It might be the isotopes in water. We know in the modern day those correlate with the temperature. Then we can drill into ice cores, as you mentioned. We can measure the isotopes in the water, in the ice, and we can extrapolate what we think the temperature was based on the relationships we built in the lab and in the modern observations back through time.

We don't just use one because, of course, that would be uncertain. We use many, many, many proxies. One key point I want to make that I think is important vis-à-vis the question you asked about folks who don't think that climate change is real or human-caused, Jacob is absolutely right. Our uncertainty gets much bigger as you go back into the past.

Of course, 2.5 billion years ago, we have much less idea of what the climate was like than we have for 10,000 years ago, when we have ice cores, or for the modern where we have thermometers. Understanding of the modern is much better than the past. We always have to be humble and acknowledge that as you go further and further back in time, we get less and less certain.

Having said that, we know that over the last 2 million years, there have been several ice ages and deglaciations. We understand why those have happened, and we also understand from records in ice cores that CO2 levels in the atmosphere, which we know control the climate, are at a high of several million years now and are continuing to rise.

While there is uncertainty going back in the past, the basic answer to the question is we find lots of different things, from the chemistry of corals, to the chemistry of ice, to tree rings, to pollen records, to all sorts of things, we correlate those with the modern temperature, we see how they change with changes in modern temperature, and then we extrapolate those back through the past, and we use a multitude of those to try and get around the fact that they all have their own uncertainty.

Brian Lehrer: John, in South Orange, you're on WNYC with Stephen Porder from Brown University, author now of Elemental: How Five Elements Changed Earth’s Past and Will Shape Our Future. Hello, John.

John: Hey. This may sound like a silly question, but the fact that we have 8 billion people on the planet now versus God knows how many we had going back 10,000 years and beyond, humans just in their native state and the population growth obviously are themselves contributing to CO2 emissions. To what extent do any of these studies control for just the sheer impact of population growth over time?

Brian Lehrer: Great question. Professor Porder?

Stephen Porder: That's another great question. You're right. We have a lot more people. For example, the year I was born, 1971, there were I think 3 billion people on the planet. I'm not 100% sure of that. Fortunately for us, it's not our number that matters for our emissions of CO2. It's the energy we use outside our bodies. Now, I'll give you an example. The average American emits about 20 tons of carbon dioxide per year. The average Kenyan, less than two.

It's not the number of people, it's the amount of energy we use for things like cars and airplanes and heating and big houses and food production. The beauty of that is that we can divorce the number of people, to a certain extent, from the amount that we change the planet. It's not completely possible to divorce the number of people. If there was one person, it would obviously be a lower footprint than 8 billion.

Our major impact is not because there are a lot of us. Our major impact is because we use energy in a way that pollutes the atmosphere, and we can fix that. We produce food in a way that nitrogen and phosphorus are spilled into the environment with a lot of unfortunate side effects, and we can fix that too. Yes, the number of people matters, but actually not as much as one might think based on the explosive growth of the human population. It's really about the energy we use to power our society and decoupling that from the pollution that nobody wants.

Brian Lehrer: I want to take one more phone call for you before we run out of time. For people who are just joining in the middle of this conversation, I'll recall that you were describing how 4 billion years ago, something called cyanobacteria evolved new ways of processing elements in a way that dumped oxygen into the atmosphere. That changed the basic conditions of planet Earth, what you even called oxygen pollution of 4 billion years ago, created by cyanobacteria evolution. Mook, I should say, in Carrboro, North Carolina, I think, has a question that picks up on that. Hi, Mook.

Mook: Hi, Brian. Hi, Professor Porder. Thanks for this segment. I just wanted to make a connection to what you're talking about before, which Brian summarized, whether humans are the new cyanobacteria. Just the way that we produce our food and energy, like cyanobacteria, tends to lead to carbon dioxide pollution instead of oxygen pollution. Just wanted to draw that connection, and just thanks for the segment. Also, as a side note, what happened to cyanobacteria? What's the story there? Thank you so much.

Brian Lehrer: Mook, thank you very much. A question we've never before gotten on the show, Professor Porder, are humans the new cyanobacteria?

Stephen Porder: I love it. I would say that humans are world changers 3.0. If the cyanobacteria were 1.0, and plants were 2.0, I would say we're 3.0. We share a lot in common with them in that we are finding new ways of getting energy and new ways of getting nitrogen, phosphorus, and using water, but there are some profound differences. Those profound differences, as Mook pointed out, are that we're not producing oxygen, we're producing CO2.

CO2 is the single biggest product of humanity by mass, more than cement or steel or anything else. We produce CO2, but we are the third great world-changing organism. We can use that understanding, as I said, to craft a more sustainable future. I do want to point out one slight correction. Cyanobacteria, more like 2.4 billion years than 4 billion years. When you're talking about deep time, what's 1.6 billion between friends?

Brian Lehrer: That's a billion and a half year mistake. Now I get it. Go ahead.

Stephen Porder: No big deal. Then what happened to the cyanobacteria? They're still around. They made it through the transition, and they continue to contribute a huge amount to both the amount of photosynthesis in the ocean and the amount of nitrogen that comes into the ocean. They're here with us today, and will continue to be, I would imagine, long after we have left. They're doing just fine.

Brian Lehrer: By the way, we talk so much about carbon, and sometimes about methane. One of the five elements that you want us not to forget about when we talk about climate change is phosphorus. In brief, why phosphorus?

Stephen Porder: Phosphorus is a really interesting element. I think of fossil fuels as being finite and replaceable. We can replace them with solar and wind, other forms of energy. I think of nitrogen as infinite. The air is 80% nitrogen, and so the real problem is keeping it where we want it. Phosphorus is absolutely essential to all life on Earth. It is finite in that we mine it from deposits that will be gone when we use them up. It is completely irreplaceable, unlike fossil fuels.

The only answer to the phosphorus problem is to learn how to recycle it better. Again, there we are making really good progress. This is not a project for a year or even a decade, but a truly sustainable society over centuries, we'll need to manage phosphorus in a way that does not take it from concentrated deposits to spread out all over and dumped into the ocean. Fortunately, I think we have a little bit of time to solve that problem.

The climate problem is much more urgent, but it does need to stay in the back or even in the fronts of our minds as we think about how to move forward sustainably. The great thing about that is that there's also lots of progress to be made, and relatively simple solutions exist. On a personal level, a lot of the problem with nitrogen and phosphorus can be solved with reductions in red meat consumption, for example, as a simple change.

Brian Lehrer: Do you get political in this book, as well as giving us the science history foundation of today's climate change problem?

Stephen Porder: Actually, not so much. One thing I think is that nobody wakes up in the morning wanting to make the world a worse place. Everybody is trying to do their best. There are profound disagreements. I think that the people who argue, whatever side of the political spectrum they're on, argue that this is not a real problem, are really mistaken, and their mistake is dangerous. Nobody has all of the answers about how to fix this. We need everyone on deck and everyone on board. There's myriad ways to approach this problem.

I think anything that contributes to a wiser management of life's essential elements will help us build a more sustainable future. I have problems when people deny basic facts. Climate change is human-caused, and that's an undeniable fact. What we do about it is a really complicated question. I think we can learn how to do better. We need to learn to do better much more rapidly than we are.

I'm not really interested in talking only to part of the world. The whole world needs to help with this problem. It's something we collectively need to deal with because we all share the same small planet with the same constraints.

Brian Lehrer: I'm just curious, before you go, besides being a science professor at Brown, I see you also have the title of Associate Provost for Sustainability. Associate Provost for Sustainability. What does that mean that you do?

Stephen Porder: Thanks. Actually, Brown was the first university in the country that I'm aware of to create this position. By creating a provost for sustainability, it's essentially saying, sustainability has to be at the core of the university's mission, both its research and its teaching mission, but also how it operates its campus. For example, I'm helping to lead the transition off of fossil fuels for our campus. We'll be completely done with fossil combustion by 2040 at the latest.

We have to integrate that transition into our research and teaching mission so that we train the next generation of leaders how to transform the rest of society as we transform our own campus. It's an integrative role that tries to put this incredibly important issue of the transition to a more sustainable society front and center at the operations level of the university across all the pieces of the campus.

Since Brown created this role for me, several other universities have created similar roles. We have a little group of us that chat and try and figure out best practices since it is a relatively new thing. It's been incredibly rewarding to take the basic science that I've spent my career working on and try and work directly on solutions in real time. It's given me an appreciation for the challenges, but also the opportunities that we have right in front of us that we can really make progress on.

Brian Lehrer: Stephen Porder's new book is called Elemental: How Five Elements Changed Earth's Past and Will Shape Our Future. Thank you for sharing it with us and being our first guest on our climate story of the week, which will continue every Tuesday in 2024 here on the Brian Lehrer Show. Professor Porder, thanks a lot. Happy New Year.

Stephen Porder: Thank you so much for having me. Have a great New Year.

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