What is the ideal level of carbon dioxide in the atmosphere for human life?

LHF: [00:00:00] Welcome to TILclimate, the show where you learn about climate change from real scientists and experts. I’m your host Laur Hesse Fisher at the MIT Environmental Solutions Initiative.

We’re bringing you this episode in October 2020, just days before the U.S. election. An election that could shape American and even global action on climate change. So today, we’re asking a big question that’s on a lot of people’s minds:

Is it too late? Is it too late to prevent climate change? Will we be able to act fast enough to avoid the scary predictions that we hear about… or are they inevitable?

To get our heads around these huge questions, we brought in an MIT professor who studies how science, technology, and policy come together.

NS: [00:01:00] I'm Noelle Selin. I'm an associate professor in the Institute for data systems and society, and also in the department of earth, atmospheric and planetary sciences. I also serve as director of the technology and policy program.

LHF: [00:01:13] First, the not-so-good news. Human activity -- mainly burning fossil fuels -- has already added a lot of CO2 and other greenhouse gases to the atmosphere.

NS: [00:01:24] The CO2 concentrations in the atmosphere are some of the highest they've ever been. They’re well above what they've been in anyone's lifetime, that's on earth and several generations beforehand. This is unprecedented really in human existence. 

LHF: [00:01:41] Yeah, and that build-up of CO2 has already warmed our planet. And what happens on a warmer Earth? Well, we’re experiencing it now.

NS: [00:01:53] We're already seeing impacts with the climate change we have today. We've seen some extreme storms, extreme weather events, flooding beyond what infrastructure were designed to accommodate.

LHF: [00:02:07] Yeah, I mean, it seems like we keep seeing vivid reminders that climate change is already here. As we’re producing this episode, we’re hearing about Hurricane Delta hitting the Gulf Coast. The average Atlantic hurricane season sees only 12 named storms -- Hurricane Delta is our 25th. And California recorded its first ever wildfire to consume more than a million acres.

And… we’ll likely keep seeing this kind of activity for a while because a lot of the CO2 we’re emitting now will linger in the atmosphere for hundreds of years. In our first episode, we put it this way: think about fighter planes circling Europe in World War One. The CO2 from those flights is still in the atmosphere, warming our planet.

So how much has the Earth warmed because of human activity? 

Well, since humans started burning large amounts of fossil fuels, the Earth has warmed about one degree Celsius. That’s about 1.8 degrees Fahrenheit, but we’re going to use Celsius because that’s how scientists and policymakers talk about climate change.

The one degree Celsius of warming we’ve caused so far is pretty serious.

NS: [00:03:25] So in terms of thinking about the implication of a global average temperature rise, it's widely agreed that at about one and a half to two degrees, the impacts of climate change go from bad to decidedly worse. For example, increased fires, increased extreme events, strengthened hurricanes that all gets dramatically worse at one and a half to two degrees.

These are levels that the world ought to try to avoid to mitigate some of the very worst effects of climate change.

LHF: [00:03:59] This is where the Paris Agreement comes into the conversation. In 2015, representatives from nearly every country in the world met in Paris to agree on a shared goal for dealing with climate change. And, given what the science said, that goal became to hold global warming under 2 degrees Celsius, and to strive to go no higher than 1.5 degrees.

NS: [00:04:27] I view the Paris Agreement as the only real mechanism by which everyone that lives on Earth can get together and agree to do something in a coordinated way about climate change. And it sets out a global agreement that countries have signed on to, to really start that process of reducing their emissions within a framework in which all countries are participating, or at least right now. 

LHF: [00:05:00] The Paris Agreement is actually at stake in this presidential election. In 2017, President Trump started the process of taking the United States out of the Paris Agreement, and that process wraps up November 4th of this year, 2020. That would make the United States the only significant greenhouse gas emitter in the world not participating in this shared effort to fight climate change. Former Vice President Joe Biden has promised to rejoin the agreement if he’s elected.

But let’s get back to the question we started with: is it too late? It is too late to avoid climate change completely — we’re already seeing it. But is it too late to meet the goals of the Paris Agreement?

NS: [00:05:45] To have a decent chance at keeping within the 1.5 degree target emissions, we have to go to net zero by 2050. With the two degree target that is 2070.

LHF: [00:05:58] “Net zero” is short-hand for “net zero carbon emissions”. Basically it means that human activity isn’t increasing the amount of CO2 in our atmosphere. Said another way, when we’re at “net zero,” the levels of CO2 in the atmosphere stay constant, they don’t go up.

So let’s repeat what Prof. Selin’s said:

NS: [00:06:23] To have a decent chance at keeping within the 1.5 degree target emissions, we have to go to net zero by 2050. With the two degree target that is 2070.

LHF: [00:06:36] That means, to meet the 1.5 degree goal, humans need to stop adding more CO2 to the atmosphere by 2050. Like, zero. No more, by 2050.

NS: [00:06:52] How do you get all of the functions that fossil fuels have and all of the processes and industries that lead to fossil fuel emissions, how do you get that to net zero. And also get that to net zero in a 20 to 30 year timeframe. 

LHF: [00:07:07] If you listened to the second season of this podcast, you’ll know that even the energy portion of that problem is really complicated with no one easy solution. 

NS: [00:07:19] The challenge is that it's really not one in particular innovation because it's such a systems problem. So you can think about energy innovation, but at the same time, you need transportation innovation happening, the food sector, agriculture, all of these are different problems with different solutions and they have to all innovate at the same time and all add up.

Because when you talk about zero, you need zero from everything. And the fact that societies have waited this long--it would have been easier if, for example, countries and organizations had started 20 years ago, because that would allow for a more gradual transition. Now, what we're looking at is in countries like the United States, a very rapid transition in order to meet some of those goals.

LHF: [00:08:09] So basically, it’s not too late; we just need to act fast.

NS: [00:08:15] One of the things that surprises me often though, is when change happens, the pace and the, yeah the pace of change once it happens can be really rapid. So, I’m very much open to surprise in this area. if change happens and if that change is rapid, I'm somewhat optimistic that societies can get this done.

You also have a lot of governments who are working really hard at implementing net zero goals and strategies.

LHF: [00:08:45] But then the question still remains… what if we don’t hit net zero? What if it’s 2050 and 2070 and we’re still adding CO2 to the atmosphere? At that point, is it truly too late?

NS: [00:09:00] It's not a bright line. So I think what's important to recognize is that two degrees is a nice round number, but there's no inherent. Distinction 2.1 versus 1.9.

LHF: [00:09:14] OK, climate change isn’t like trying to catch a plane, where if we miss our 2:00 departure, the whole trip is off. 

NS: [00:09:23] But the more that climate change can be mitigated, the better off most people who are living in the world are. So if you can cut expected warming from four degrees to three degrees: that's a benefit. If you can cut from three degrees to two degrees, that's, that's a benefit again.

So yeah, the more you can do the better. So that's a reason why it's never really too late.

LHF: [00:09:54] So specific numbers like 1.5 degrees or 2050 help us create a clear and common goal. But again we care about these numbers because of what they mean for people and the planet and our prosperity.

NS: [00:10:11] We care about climate change because we care about the impacts that the climate has on things that are affecting people in the near term and in the longer term. So we're worried about the climate because of food production. We're worried about the climate because of heat. And we're worried about the climate because, because of the impacts on infrastructure and human health.

That challenge does get harder the longer that you wait to act. 

LHF: [00:10:39] But it’s not all about the future. In fact, Prof. Selin focuses on how we can benefit now by taking action on climate change.

Noelle: [00:10:49] We've done a lot of research looking at the kinds of strategies that different countries or regions can use to reduce CO2 emissions. And then actually went ahead and quantified the benefits of those in the near term, looking specifically at air pollution and the impacts of air pollution.

So A lot of fossil fuel plants have real detrimental effects on populations nearby. That's because the impacts of fossil fuels on people's health. So particulate matter or fine particulate matter PM 2.5, that's small enough to be inhaled into the lungs, it's damaging to people's health and those are really major impacts on populations worldwide.

And the kinds of sources that are leading to these high levels of pollution that are seen across the world are the same sources that are emitting CO2 and other greenhouse gases. So any efforts that you can take to mitigate that impact have some near term benefits. And in a lot of cases, those benefits really are overwhelming. They are larger than the cost of mitigating climate change.

LHF: [00:12:04] In one of her recent studies, Prof. Selin found that China is spending more to deal with the health impacts of air pollution from fossil fuels than it would cost to switch those fossil fuels to clean energy -- at a fast enough rate to fully meet China’s pledges under the Paris Agreement.

NS: [00:12:24] That's really the point of climate action in my view, is to think about how the climate system is so connected to human wellbeing in so many different dimensions both today and in the future. Not only are you having benefits for the climate system, but this is something that has real impacts on you and things that you care about.

LHF: [00:12:51] A colleague and friend of mine, Raj Pandya of the American Geophysical Union’s Thriving Earth Exchange, once said, climate change is no one’s first priority. But climate change affects everyone’s first priority. We all want clear air. We all want to feel safe, and live somewhere where we can thrive and where our children can thrive. 

NS: [00:13:14] There are benefits that societies and individuals and communities can see from cutting greenhouse gases in the very near term. And that action is urgent and necessary. So it's never really too late to address these pressing needs.

LHF: [00:13:36] Have a question about something we covered today? Something still on your mind? You can reach out to us at @TILclimate on Twitter or email us: TILclimate@mit.edu. We also launched something new called Ask MIT Climate, where you can ask questions to MIT experts. Check out climate.mit.edu to get started.

Hey if you’re listening to this right around the time of election or soon after, there’s still time to fill out our survey. We’d love to hear if these episodes are making a difference for you. Please to tilclimate.mit.edu to fill out a 1 minute survey -- we will reach each one -- plus, two lucky people will win a $50 gift certificate to either Better World Books, which uses book sale profits to fund literacy programs. Again, to take the survey, go to tilclimate.mit.edu/survey.

Thank you to Prof. Noelle Selin for talking with us, and thank you for listening.