By Tatiana Schlossberg
Earlier this week, the UN reported that the restoration of the ozone layer was back on track after a worrying spike of CFC-11, a banned ozone-depleting compound, a few years ago in China.
But before I get to that, I have a favor to ask you. If you enjoy this newsletter, would you please consider forwarding it to a few people you think might also enjoy it, and tell them to subscribe? Let’s say 3-5, but even one person would be A+ work and very much appreciated!
Okay, back to business.
Scientists figured out that these kinds of compounds, chlorofluorocarbons, which were widely used in refrigerants and foam insulation, were destroying the ozone layer in the 1970s. In the 1980s, they discovered a hole in the ozone over Antarctica in the 1980s, and the global community came together to phase out the use of these compounds in 1986, part of the Montreal Protocol, which took effect in 1989.
This is an image of the hole in the ozone layer from before the science was known, and after the Montreal Protocol. The latest image is from 2011. Credit: NASA.
Now, the scientists say, the ozone layer is expected to return to pre-1980 levels by 2040, and the holes which appear over the North and South Poles with some regularity, will recover by 2045 and 2066, respectively.
This is great news, and something I’ve written about before. But it reminded me of an amazing quotation from one of the scientists who identified the problem: “What’s the use of having developed a science well enough to make predictions if, in the end, all we’re willing to do is stand around and wait for them to come true?”
Which brings me to the next piece of news that came out this week: in 2022, U.S. emissions rose by about 1.3 percent from the year before. A lot of this was a result of increased air travel “after” the COVID-19 pandemic; emissions are still lower than they were in 2019.
That’s not really a silver lining: we need emissions to fall. President Biden has pledged that the U.S. would reduce its emissions by 50 percent (compared to 2005 levels) by 2030, to stay in line with the world’s stated goal of staying within 1.5ºC of global average temperature increase compared to pre-industrial levels.
President Biden speaking at COP27. Credit: Doug Mills, New York Times
This news reminded me that some of you were interested in an explanation of what it actually means when people say we need to limit warming to 1.5ºC. On its face, it’s pretty simple: reduce our greenhouse gas emissions enough that the average surface temperature of the Earth only warms by 1.5ºC (2.7ºF) compared to the average temperatures before we started emitting tons of carbon dioxide (around the time of the Industrial Revolution).
But most summaries of the 1.5ºC goal leave out some important information, and that’s because usually governments and others decline to include certain details: WHEN will 1.5ºC be reached, WHAT happens after it is reached, and WHAT happens between now and then. Not to mention that the global average surface temperature has already increased by 1.1ºC.
Since we have pumped so much carbon dioxide into the atmosphere, a certain amount of warming and its effects are inevitable – there is already that much energy in our system. Even if we stopped emitting excess emissions tomorrow, some dire consequences will still happen. The sooner emissions reduce or stop or, ideally, go negative
(meaning that we manage to absorb more carbon than we emit) the better, because fewer of those warming compounds will accumulate and therefore the effects will be smaller.
Based on the models produced by scientists (of how quickly the world can switch over to clean energy and remove carbon dioxide from the atmosphere), there are about 1,200 different scenarios that ultimately result in temperatures reaching a maximum of 1.5ºC.
But there is a wide range within those scenarios and they contain bunch of different assumptions. Almost all of them assume that we will develop carbon sequestration technologies or strategies that significantly draw down carbon dioxide from the atmosphere. Some of them require that to happen within the next 10 years, and those scenarios produce the best result: that temperatures never pass 1.5ºC of warming, or they overshoot it slightly before coming back down.
Most of those scenarios are probably not possible, given the technological assumptions they make.
This is Climeworks’ “direct air capture” facility, which pulls carbon dioxide from the atmosphere and injects it into the ground where it reacts with basalt to become stone. Climeworks, a Swiss company, just delivered its first certified “carbon dioxide removal” services to its corporate clients on Thursday, Microsoft, Stripe, and Shopify. Credit: Climeworks.
Many scenarios that are more realistic (in some ways) hit the 1.5ºC target in the middle of the century and go past it – maxing out at somewhere around 1.6ºC to 1.8ºC – before coming back down by 2100. That would mean several decades of temperatures above 1.5ºC with catastrophic consequences. The assumption that temperatures would fall would also mean that the drawdown of carbon dioxide from the atmosphere would need to be even more significant and take place faster than those scenarios discussed above that have little to no overshoot. Again, this is possible, but it is not without its challenges: achieving such significant carbon sequestration will be difficult; humanity (and plants and animals) will suffer, with the suffering borne by those who are least responsible for causing the calamity.
The Washington Post has a great visual explainer on this issue, which was very clarifying to me and some of you, especially those who are visual thinkers, might also find it useful.
There are also big differences between warming by 1.5ºC and warming by 2ºC. This piece from the New York Times does a good job at explaining much of it.
I know that this kind of thing can be scary and dispiriting, but I do think it’s important to understand the carbon math. It can help us prioritize by showing us what is necessary, what is the most urgent, and that when we do these things really matters and does make a big difference.
That being said, the numbers aren’t everything. Like I wrote about last time, the measurement systems we use bias us. The obsession with measurement can lead to that feeling the scientist articulated above: what’s the point in figuring out how to measure anything if we don’t do anything with the measurements and the information they give us? Almost every day we see something that shows us that things are out of balance; that the measurements we’ve relied upon in the past and the averages they’ve helped us to define as “normal” no longer apply on a changing planet.
Tomorrow is Martin Luther King, Jr. Day. Climate change is a justice issue. While Dr. King died before the environmental movement really began, his message about segregation and inequality – that it harms us all – extends to the environment, and scientific research has proved him right. Here is an excellent piece about that by the always insightful Kendra Pierre-Louis from 2018 from the New York Times. I hope you find ways to observe the holiday that commemorates his life and work.
[Dr. King Said Segregation Harms Us All. Environmental Research Shows He Was Right.]
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