HONR 229L: Climate Change: Science, Economics, and Governance

HONR 229L: Climate Change: Science, Economics, and Governance Implementation Your name here 13 November 2018

As always, I suggest working the admission ticket questions into the presentation. While this not essential, it does provide a common point of reference for everyone. Actually, for this lecture more than most, the AT questions are an integral part of the entire reading, so would be good to use most (if not all) in the discussion I’d be delighted if, after the 45 min discussion you lead, the class comes away knowing: • The upper limit of the Paris Climate Agreement, limiting warming to 2°C relative to pre-industrial, could possibly be achieved if society can prevent atmospheric CO2 from rising above 560 ppm, which is 2pre-industrial level • An analysis of the world energy consumption projections shows that, to keep C emissions on the path to keep CO2 below 540 ppm, half of all global energy must be supplied by renewables by year 2060 • The world must figure out how to electrify the ~300 million homes in India that lack electricity, and most of Africa, without using fossil fuels • Methane is a “wildcard”, especially given fracking in the US You have free reign as to how to accomplish this!

You might want to lead with this well worn chart, to remind folks that for the RCP 4.5 scenario, which by now everyone in the class should know is what your instructors think could limit global warming to 2°C, the future abundance of CO2 will have to peak at less than 2 the pre-industrial level and CH4 will have to level off and then decline. Figure 2.1 GHG abundance, 19502100

You might want to lead with this well worn chart, to remind folks that for the RCP 4.5 scenario, which by now everyone in the class should know is what your instructors think could limit global warming to 2°C, the future abundance of CO2 will have to peak at less than 2 the pre-industrial level and CH4 will have to level off and then decline. You could ask the class “What was the pre-industrial value of CO2?” Hopefully students will remember that it was 260 to 280 ppm Can also ask “What is today’s value of CO2?” Hopefully students will know that today, CO2 is a little over 400 ppm. Can show https://www.co2.earth/daily-co2 should you so desire. This is all vitally important to the metrics needed to achieve the Paris Climate Agreement, because if we started at 280 ppm, we are now just above 400 ppm, and we need to stop CO2 from rising above 540 ppm, then clearly we are at about the half way point in terms of total C emissions. You are welcome to incorporate Table 4.1 (included at back of this PPT) should you so desire

If the EIA projections of energy demand prove true, then how much of the world’s energy needs must be met by sources that do not emit GHGs in year 2060, in order for emissions of atmospheric CO2 to achieve RCP 4.5? This is Q1 of the AT. I think it is important to walk through the charts of the book that support the view that half of the energy needs must be met by renewables, by year 2060, to achieve this goal: i.e., Figures 4.2, 4.3, and 4.5 I placed these figures in successive slides at the back: they are placed on the page such that the transition is seamless. If you move or re-size the figures, you can preserve seamless transitions by using the same numerical values for the size and position of each figure, on your slide It is worth showing Fig 4.5, because most of the climate modeling community thinks RCP 2.6 is the 2 °C pathway. It is important to communicate how severe the reductions in GHG emissions will need to be in order to achieve RCP 2.6

What is: a) one important similarity b) one important difference between the projections in Chap. 4 & those in the RCP 4.5 paper of Thomson et al. (2011). Note: there is no need to consult the Thomson et al. paper; this information is stated in the reading. Q2 of the AT. I would appreciate if this is discussed and if you can try to get the students to answer. The similarity, in case you did not pick this up, is the assumption for future energy demand of the RCP 4.5 paper (black circles, Fig 4.3) are nearly identical to the energy demand we use. The difference is the role of nuclear energy. Feel free to have a short discussion about nuclear energy, should you so desire.

What is the importance of Fig 4.4 (i.e., why did the authors include this figure in the chapter)? Q3 of the AT. Totally your call if you’d like to use this AT question! You could, should you want to use, remind students that the size of the green curve for the use of renewables in Figs 4.2, 4.3, and 4.5, for times prior to present, is a bit misleading since the dominant form of energy from biomass used globally is from use of wood, and in some cases cow dung, to provide fire for cooking. If you use this figure, again, try to draw the answer from the students and feel free to have a short discussion about the danger, to the health of woman and children, that is posed by the use of wood fueled fires to cook, particularly in poorly ventilated homes. Can easily find material on this. I covered this super fast on slide 72 of Discussion 13; you’re welcome to grab content off of this slide: http://www.atmos.umd.edu/~rjs/class/honr229L/lectures/HONR_229L_2018_discussion13.pdf

Summarize how NASA measurements of night lights are used in the reading. Q4 of the AT Our research group made Fig 4.6, 4.7, 4.8, and 4.9. The first three of these are self explanatory. Fig 4.9 is our attempt to show the various regions of the world on the same coordinate system. Would be great if you could included at least Fig 4.6, 4.7, and 4.8 into your discussion, then lead a significant discussion about the Green Climate Fund of the Paris Climate Agreement, whether folks thought this would be sufficient, etc. Feel free to either use, or omit, Fig 4.9

Is the future trajectory of atmospheric methane important for achieving the goal of the Paris Climate Agreement? Q5 of the AT Since this was the last AT question of the semester, would be great if you could include. If you need any help understanding Fig 4.12, send Ross and Laura an email. Here, you might want to remind folks that for RCP 4.5, CH4 is supposed to level off and decline by end of century (bottom trace of Fig 4.12a). Great if you are prepared to describe Fig 4.12 and lead a discussion about whether it is realistic to assume CH4 will truly level off. Can do your best to goad students memory of what we wrote on pages 169 to 171 about CPP, about diet, about the RCPs, etc. Should you so desire, you are welcome to include Table 4.4 (last slide) and lead a discussion about: a) why CH4 leakage matters (i.e., on a per molecule basis, CH4 is about 10 worse than CO2 for global warming; some people throw around 28 worse, but this is on a per mass basis) b) seeming preponderance of CH4 leakage during extraction (can discuss why some studies might differ) c) sensitivity of “break even point” to which time horizon is used for the Global Warming Potential of CH4 (i.e., footnote 35)

Completely your call whether to have any discussion of Section 4.4.1 Students were asked to read the entire chapter, but clearly this was de-emphasized since no AT question was written for this section. Totally your call. We’re fine, either way. Might want to conclude by leading a discussion of the content of the last paragraph on page 173 (need to think out to 2060) and the first paragraph of page 174 (how can “we” embrace this challenge) Figures and tables to follow

Figure 4.1 Sources of atmospheric CO2

Figure 4.2 World energy consumption and CO2 emissions

Figure 4.3 World energy consumption and CO2 emissions, modified to meet RCP 4.5

Figure 4.5 World energy consumption and CO2 emissions, modified to meet RCP 2.6

Figure 4.4 World energy consumption, renewables

Figure 4.6 Population and night lights, global

Figure 4.7 Population and night lights, North America and Africa

Figure 4.8 Population and night lights, Europe and India

Figure 4.9 Scatter plots of night lights versus population

Figure 4.10 Transient climate response to cumulative CO2 emissions, in units of Gt C

Figure 4.11 Transient climate response to cumulative CO2 emissions, RCP 8.5

Figure 4.12 Impact of CH4 on EM-GC projections using RCP 4.5

Table 4.1 Atmospheric CO2 and CH4 mixing ratios, in parts per million (ppm)

Table 4.2 Total cumulative carbon emission that will lead to cross Paris ΔT thresholds

Table 4.3 Future cumulative carbon emission that will lead to cross Paris ΔT thresholds

Table 4.4 Estimates of % of CH4 leakage from fracking, relative to production in the US, selected studies

HONR 229L: Climate Change: Science, Economics, and Governance