This lesson explores greenhouse gas mitigation — actions that prevent, limit, delay or slow the rate of climate change.
By the end of this lesson, you should be able to:
This lesson will take us one week to complete. Please refer to the corresponding module in Canvas for specific assignments, deliverables, and due dates.
If you have questions, please feel free to post them to the "Have a question about the lesson?" discussion forum in Canvas. While you are there, feel free to post your own responses if you, too, are able to help a classmate.
This week, we're looking at mitigation and next week we'll turn our attention to adaptation. It's important to understand the difference between these two ways we respond to climate change because they:
In other words, these terms are not interchangeable, nor do they happen in isolation.
The simplest way to understand it is:
Another way to think about this is mitigation is getting your flu shot to avoid illness while adaptation is taking medicine after you've gotten sick to alleviate your symptoms.
We can't focus our efforts on simply one or the other. At this point, we can't mitigate our way out of the problem entirely. Our centuries of fossil fuel combustion have already committed us to a certain amount of warming, even if we shut every emissions source down right now. Conversely, if we throw up our hands and decide that it's too hard to find lower-carbon solutions and instead we'll focus our efforts on adapting to the new normal, we likely won't be able to keep up with the pace and severity of change. We need to work on both parts of the problem: adapt to the warming and impacts we're already likely to face and reduce emissions now to prevent worsening impacts in the future.
Ultimately, the path we take to address climate change will be characterized as emphasizing one of three frameworks for response:
It's up to us to define our path (and be thinking about the path you want to take; you'll need that for Exam 3!!!). And if we're being honest, neither mitigation nor adaptation alone will save us. We need to emphasize both. If we shut down all of the power plants and took all the internal combustion engine cars off the roads today, we're still committed to a certain level of impacts from our historical emissions (see If We Stopped Emitting Greenhouse Gases Right Now Would We Stop Climate Change? [4] over on The Conversation for a nice discussion of this by Richard Rood, 2017).
The emphasis we choose leads to different costs and consequences. As a society, we need to identify the tradeoffs we're willing to accept and the ones we are not. This values-based introspective will guide the path we take. Do we want to spend aggressively on mitigation so that adaptation costs down the road are less? Or should we turn our attention to adapting to the likely future a not-so-very-well-mitigated scenario leads us to? And if we choose not to mitigate or adapt aggressively, are we willing to accept the costs of that inaction? These are the questions you'll need to help craft answers to as you venture off into the world to solve this global challenge.
We've spent the entire semester working under the premise that we need to reduce emissions and we need to do so quickly. The global carbon budget concept helps us understand not only why emissions reductions are important, but more specifically, why they are urgently important.
In 2013, the IPCC released the fifth assessment report - IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [5] which included an overall cap on the cumulative anthropogenic emissions of greenhouse gases possible since industrialization before we hit 2 degrees of warming and the catastrophic impacts it brings along with it. That number? A trillion metric tons. That number is arguably too big for most of us to comprehend, especially as we're thinking about it over a several centuries-long time frame. (If you're curious you can watch this real-time tracker at www.trillionthtonne.org [6] to see where we currently stand.) At the time the report was released in 2013, based on the previous several decades of emissions, they estimated we'd hit that trillionth tonne of emissions somewhere in late November 2040.
This short video (2:21) offers a concise explanation of the carbon budget. Take a look.The carbon budget helps us understand how much carbon we have left to 'spend' before we commit ourselves to various levels of warning. But what does that look like? Let's try to interpret these results. At current (2014 when this graphic was created) emissions levels, we had just 6 years before we reached that budget if we want to confidently contain warming to 1.5 degrees. If we decide we're ok with just shooting for 2 degrees, that stretches our budget out to about 20 years.
If you want to know more about carbon budgets, see WRI's According to New IPCC Report, the World is on Track to Exceed its Carbon Budget in 12 Years [9] (Levin, 2018).
An important consideration of the carbon budget is understanding that it is effectively a shared account.
Imagine that you and your friends (or roommates, siblings, family, whomever) share a single bank account and must each use it to pay your bills, buy the things you need, and maybe even have some leftover for fun once in a while. But what if you've got that one friend that's always taking more? There's only so much money you can then withdraw before you'll start incurring overdraft fees. Think of the United States as that spend-happy roommate you're sharing your bank account with. Take a look.
This animated graphic (no audio) from Carbon Brief demonstrates the cumulative CO2 emissions since 1750 for countries around the world. As you watch it, take note of the scale of emissions across the top (eventually, the top country's bar almost appears to be standing still, but that's just because they're running out of room and running the scale to the left).
We've talked (briefly) about issues of equity, fairness, and climate justice - particularly as they relate to vulnerability to the impacts of climate change. While China is currently the largest annual emitter of greenhouse gases (having surpassed the US in 2017), the US is historically the biggest emitter. This means that during UN climate negotiations, many countries view the US as having a larger (or at least a large) responsibility to reducing emissions. In other words, we've enjoyed the largely unfettered economic growth and prosperity it has created since the Industrial Revolution with little in the way of climate considerations as limitations. Now, isn't it our responsibility to take an active role in addressing a problem we've had a large role in creating? Should we not use our relative economic strength, built on carbon-intensive activities, to reduce our own emissions and help ensure the most vulnerable among our global family are protected?
And then this happened while I was updating this lesson. To continue on with the shared bank account analogy, that roommate that drains your shared account regularly has announced they will no longer be making any deposits.
We need to think about mitigating greenhouse gases in 3 distinct phases:
Often, we talk generically about 'reducing emissions' and when we do, we're talking about reducing them from what they are right now. But in this context, we're talking about reducing them beyond the point of stabilization. We have a lot of work to do slowing emissions growth and stabilizing emissions before we can really dig into reducing them.
Each year, the UN puts out an Emissions Gap Report. Quite simply, the report shows us where we are vs. where we need to be (and how that has changed from year to year) and discusses ways to close that gap. Let's take a look.
Remember, the science tells us we want to contain warming to between 1.5-2 degrees Celsius. Those trajectories are shown in green and blue. What do you notice about how they align with projected emissions reductions under current Paris Agreement commitments (NDCs or nationally determined contributions)? The space between those scenarios is the emissions gap. Are you surprised or did you expect the gap to be this big (or this small depending on how you're looking at it)? Can we get there?
That gap looks a bit daunting, doesn't it? But how are we doing? Globally, we aren't on track to meet our 2030 goals [11] under the Paris Agreement, and in early November 2019, the Trump Administration submitted its formal request to pull the US out of the agreement altogether (this process takes a full year, though, so depending on this November's election, perhaps the US won't end up leaving the agreement).
This lesson was intended to be a broad overview of the concept of mitigation rather than a laundry list of types of mitigation across sectors. Rather than listing out those options, I thought it would be more useful to think about the totality of the problem as it relates to what the science is telling us needs to happen to these emissions trajectories. The SPM reading really reinforces the urgency of the problem - if we want to contain warming to 1.5C we need to halve emissions by 2030 and be net-zero by 2050. And 2030 somehow sounds really far away (in the same way that the year 2000 still feels 'recent' - to me, anyway), but it's 10 years from now. And as we are thinking about turning the cogs necessary for the large scale systemic change we need, a decade doesn't feel so long.
The Davis et al. piece is an update to a reading assignment I used to use for this class (Stabilization Wedges: Solving the Climate Problem for the Next 50 Years with Current Technologies [13] by Pacala and Socolow from 2004). I've tried to update that a bit since it was getting outdated and in the intervening years, we've just kept adding to our emissions, meaning we need more and more wedges. I like to think of these wedges as a precursor to the solutions we see in Project Drawdown [14]. The message is the same in both frameworks, and it's an important one to hear:
We already have everything we need to mitigate GHGs and avoid the most catastrophic impacts of climate change. Everything, except perhaps the political will to deploy the solutions. It's an important framework to explore - we often think that we need to find some magic technological fix, but in reality, we already have lot of tools in our toolbox to pull that emissions curve steeply down. Are they easy? Cheap? Popular? Maybe not. But do they exist? Absolutely.
You have reached the end of Lesson 10! Double-check the lesson assignments in the corresponding lesson module in Canvas to make sure you have completed all of the tasks listed there.
Links
[1] https://www.pexels.com/photo/alternative-energy-building-clouds-energy-356036/
[2] http://creativecommons.org/share-your-work/public-domain/cc0/
[3] https://www-jstor-org.ezaccess.libraries.psu.edu/stable/resrep01900
[4] https://theconversation.com/if-we-stopped-emitting-greenhouse-gases-right-now-would-we-stop-climate-change-78882
[5] https://www.ipcc.ch/report/ar5/wg1/
[6] http://www.trillionthtonne.org/
[7] https://www.carbonbrief.org/six-years-worth-of-current-emissions-would-blow-the-carbon-budget-for-1-5-degrees
[8] https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode
[9] https://www.wri.org/blog/2018/10/according-new-ipcc-report-world-track-exceed-its-carbon-budget-12-years
[10] https://www.unenvironment.org/resources/emissions-gap-report-2018
[11] https://www.nationalgeographic.com/science/2019/11/nations-miss-paris-targets-climate-driven-weather-events-cost-billions/
[12] https://www.wri.org/blog/2018/10/8-things-you-need-know-about-ipcc-15-c-report
[13] https://science.sciencemag.org/content/305/5686/968
[14] https://www.drawdown.org/