Climate Interactive

Eric Roston of Bloomberg Green Explores En-ROADS Scenarios – How to Recreate His Experiments & More

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On March 23, 2021, Eric Roston of Bloomberg Green published a newsletter piece exploring the impact of different climate solutions using the En-ROADS simulator from Climate Interactive and MIT Sloan’s Sustainability Initiative – “What if the Perfect Climate Fix Can’t Arrive in Time?” For those with a Bloomberg subscription, the full article is here. Below you will find a video with detailed explanations of the settings used in the article and the model dynamics at play. 

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The meaning and math behind the “7.5%” number quoted in the newsletter is here: our modeling suggests that immediate discovery and commercialization of a new, zero-carbon electricity source could avoid the emission of 68 gigatons of CO2 by 2050 (notice the gap in Net Cumulative CO2 Emissions in 2050). A scenario that achieves net-zero emissions by 2050 such as this will avoid 908 gigatons of CO2 by 2050 (the best graph to view the value is here – observe the gap in 2050, when 3617 – 2709 = 908). And then 68/908 = 7.5%.

For additional information, please explore these resources: 

What role can afforestation play in addressing climate change?

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Note the authors of the paper discussed below have issued an erratum retracting some of their claims that we had pointed out initially. Additionally, En-ROADS has been updated since this post and so some scenarios may appear differently. (June 11, 2020)

Analysis of Recent Afforestation Reporting Based on Bastin et al. (2019) with the En-ROADS Simulator

By Andrew P. Jones, Dr. Lori Siegel, and Dr. Florian Kapmeier

New study on afforestation

Research published recently in Science by Jean-Francois Bastin et al. (2019) entitled “The global tree restoration potential” received high media attention all around the world. The authors found that “ecosystem restoration [is] the most effective solution at our disposal to mitigate climate change” (p. 78). Newspapers and journals reported with great excitement about this study, including leading outlets such as The New York Times and The Guardian, with eye-catching headlines like “The trees might save us yet” or “Tree planting has mind-blowing potential to tackle climate crisis”.

Planting trees sounded like THE silver-bullet solution to meet the Paris goals – obvious, cheap, effective, and apparently easy and fast to implement. Our team at Climate Interactive has assessed what is behind Bastin et al.’s findings.

Analysis of the analysis

In their research, Bastinet al. analyzed “how much tree cover might be possible under current or future climate conditions” (p. 76). The resulting tree carrying capacity map shows both the presence of forest in all existing forested land and the tree cover that could exist beyond already existing forested land. The authors estimate the total potential land area to be about 4.4 billion hectares (under current climate conditions). 

The study goes on to state that these newly planted trees could remove an additional 205 Gigatons of carbon. In the official ETH press release, the authors stress the following two insights:

  1. “Once mature, these new forests could store 205 billion tonnes of carbon: about two thirds of the 300 billion tonnes of carbon that has been released into the atmosphere as a result of human activity since the Industrial Revolution.“
  2. “[T]his would be the most effective method to combat climate change” (similarly stated in the paper: “This places ecosystem restoration as the most effective solution at our disposal to mitigate climate change” (p. 78)).

Analysis with En-ROADS

Our team at Climate Interactive has analyzed these two statements below with our En-ROADS climate and policy simulation model. We first reflect on the assumptions themselves, and then test the policies’ impact  on global temperature by 2100 – will it really have “mind-blowing potential”?

1)Assessing this first statement: “Once mature, these new forests could store 205 billion tonnes of carbon: about two thirds of the 300 billion tonnes of carbon that has been released into the atmosphere as a result of human activity since the Industrial Revolution.” 

Calculation of CO2Removals

We confirm the underlying calculation:

205 tons C/300 tons C = 68% (1)

For our analysis with En-ROADS, we translate carbon emissions into CO2emissions, representing roughly 750 Gtons of CO2removal and 1100 Gtons CO2for the total emissions (a CO2 molecule is 3.7 times heavier than only the C atom (Le Quéré et al., 2018)), thus 

750 Gtons CO2/1100 Gtons CO2= 68%  (2)

But the 1,100 Gtons CO2emissions in the denominator is misleading. Humans have emitted much more than this since the beginning of the industrial revolution. Bastin et al. removed, we assume,  the natural carbon uptake by the world’s ecosystems, subtracting 1,000 Gtons CO2that oceans and biomass (plants and soils) had already absorbed since the beginning of the industrial revolution. As these emissions polluted the environment, e.g., by acidifying the oceans, a more reasonable number to use is all cumulative anthropogenic carbon emissions to date without subtracting absorption by oceans and biomass. These are about 2,100 Gtons CO2: 

750 Gtons CO2/2100 Gtons CO2= 36% (3)

Hence, the maximum of the removals from afforestation are about 36% of total anthropogenic CO2emissions from 1870 until 2018, equaling closer to one-third as opposed to two-thirds. 

But still, this is not the full picture. The authors report (p. 78) that the uptake will not happen instantaneously, as it would take several decades for forests to grow. We agree. There are considerable time delays involved, including the acquisition of land and the growing of the trees (see also Sterman et al., 2018a and 2018b, two papers by three of our team members on bioenergy dynamics). We therefore consider the total amount of CO2emissions from the beginning of the industrial revolution until the future when the trees have all grown – let’s assume until 2100. 

Under the BAU scenario in En-ROADS, human activity will emit another 5,700 Gtons CO2. When adding past and future anthropogenic CO2emissions, total cumulative CO2emissions will be around 7,800 Gtons, thus: 

750 Gtons CO2/7800 Gtons CO2= 10% (4)

The carbon removal from the newly planted trees represents, at the very high end, approximately 10% of total cumulative human emissions.

To summarize: The absorption potential is not 2/3, but more likely, at the high end, 10% of total cumulative anthropogenic emissions through 2100.

While this does not sound as promising as formulated in the original paper, we strongly emphasize that this is still significant and should be enough to justify investment in this climate policy.

Assumptions on available land

Bastin et al. made another strong assumption in their analysis, when assuming that “there is room for an extra 0.9 billion hectares” (p. 76) of land available. The authors state that “they span the entire range of environmental conditions, from the lowest to the highest possible tree cover” (p. 76).

Considering the entire range of possibilities and thus a more conservative perspective, the Royal Society Report (2018) has issued possible ranges of global CO2removal potential. The upper limit for afforestation is at an annual uptake of 20 GTCO2, roughly in line with Bastin et al.’s findings of 900 million hectares of land. The lower end of the Royal Society Report lies, however, at an uptake of 3 GtCO2 annually. Considering this lower end, we arrive at only 1%:

70 Gtons CO2/7800 Gtons CO2= 1% (5)

To summarize again: The absorption potential is not 2/3, but more likely 1-10% of total cumulative anthropogenic emissions through 2100.

While afforestation plays a significant role in mitigating climate change, it seems as if the numbers used by Bastin et al. are somewhat misleading. The range of anthropogenic CO2 emissions removal from afforestation varies from 10% at the high-end to 1% at the low-end. Now, even if all the available land that could be afforested will actually be afforested, growth of trees is not certain. Trees in new (and existing) forests can be cut (legally or illegally), burned in wildfires, and/or die from diseases and insects. All this is more likely in a warming world with growing population in which climate zones are moving.

We also need to keep in mind that relatively lower atmospheric CO2 also means less flux of carbon into other biomass stocks and into ocean (Jones et al., 2016). Therefore, atmospheric CO2 will not fall by the cumulative amount of carbon held in new forests, but less, reducing the impact on warming and climate change even more.

Assessment of statement that afforestation is a “mind-blowing potential”

Now, let’s test whether afforestation really has the “mind-blowing potential,” as stated by The Guardian. To test the high-end scenario in En-ROADS, maximum available land for afforestation is increased to 900 Mha and a rapid afforestation planting time of 12 years is assumed, starting in 2020.

This scenario leads to a warming of 3.9 °C instead of 4.1 °C above preindustrial levels by 2100 (Figure 1 below).

En-ROADS afforestation potential
Figure 1: High-end afforestation scenario leads to a temperature decrease of 0.2 °C.

On the left hand graph, we observe that net CO2removals from afforestation first increase very quickly at an exponential rate, then reach an inflection point to increase at a decreasing rate until reaching a peak of about 10.7 Gtons in 2080. The graph in the upper-right hand shows greenhouse gas emissions by gas. An afforestation policy does not affect the other greenhouse gases, thus they are the same as in the BAU scenario. But, CO2emissions from land use & forestry start to decline slowly after 2020 and become negative after the 2040s: the forests take-up more CO2 than they emit and the forests become “negative emissions” (The Royal Society, 2018). CO2 removals from afforestation do not stay on this high level (left graph) but decrease because of natural processes of stored carbon after sequestration (typical biomass and soil release rates, through bacterial respiration (decay) and wildfire), which is why land-use CO2 slightly increases towards the end of the century.

The scenario settings used in En-ROADS to test the impacts of this policy are: 

  • Assumptions
    • Max available land for afforestation = 900 Mha 
  • Afforestation
    • Percent available land for afforestation = 100 %
    • Afforestation planting time = 12 years

The key insight here is that while afforestation does remove a critical mass of CO2and reduces temperature and afforestation efforts are a very crucial contribution to climate change mitigation, it is not a silver-bullet. It does not have “mind-blowing potential”, the trees do not “save us”, and they do not “save the climate”. Afforestation helps, and it is an important part of a silver-buckshot suite of policies and behavior change.

2)Now, assessing this second statement: “[T]his would be the most effective method to combat climate change”, which is similarly formulated in their paper: “This places ecosystem restoration as the most effective solution at our disposal to mitigate climate change” (p. 78).

Which other policies and behavior changes lead to avoiding 750 Gtons of CO2 emissions?

Bastin et al. find that extremely high levels of afforestation could remove 750 Gtons CO2(or, 205 Gtons of carbon). We use En-ROADS to assess what other actions, policies, or behavior changes are required to remove about 750 Gtons CO2 by 2100. We find that this uptake is similar to:

  • Introducing a Carbon Price: Setting a global carbon price of $24 per ton, starting in 2020 and phased in over 10 years. 
  • Reducing Deforestation: Reducing deforestation at a rate of 5% per year starting in 2020. 
  • Increasing Transportation Efficiency: Increasing the improvement rate of the energy intensity of new transportation capital, from 0.5% per year, to 5% per year (vehicles, shipping, and air travel). 
  • No New Coal: Ending global investments in new coal infrastructure, such as extraction and coal-fired power plants by 2050. 
  • Increasing Buildings & Industry Efficiency: Increasing the improvement rate of the energy intensity of new infrastructure, from 1.2% per year, to 2.6% per year (buildings, industry and commerce). 
  • Subsidizing Renewables: Subsidize renewables to reduce price by $0.03 per kilowatt hour, starting in 2020 and phased in over 10 years. 
  • Taxing Coal: Tax coal to increase price by $79 per ton, starting in 2020 and phased in over 10 years. 
  • Carrying out some Direct Air Capture, Carbon Dioxide Removal: Maximum removal of 2.75 Gtons CO2 per year beginning in 2030, achieved in 10 years. Drawn from Royal Society Report, Greenhouse Gas Removal. 
  • Empowering women to slow down Population Growth: Drawn from the UN population projection. Growth is 30% between the low and medium estimates, 8.4 billion people in 2100. 

We conclude that afforestation “would be the most effective method to combat climate change” is likely not true. There are many approaches that all accomplish mitigating climate change of which afforestation is a very important way to tackle the climate crisis. 

Role of afforestation under a mitigation scenario 

Using the same scenario settings as outlined for Figure 1 above, we take a look at CO2emissions by source (Figure 2 below). The green area below the “0” line represents the cumulative uptake of CO2 from forests (750 Gtons). The area above it represents the 7,800 Gtons that we will emit in the BAU scenario through burning coal, oil, and gas (grey area), CH4(blue), N2O (pink), and F-Gases (yellow).

ghg net emissions by gas
Figure 2: CO2 emissions by source in a high-end afforestation scenario.

We see that afforestation has a modest effect. However, when we apply other policies as well (Figure 3 below), the green area (carbon dioxide removal) becomes larger in comparison to the other areas (carbon dioxide emissions). In this scenario, fossil fuels are kept in the ground; coal peaks around 2022, gas around 2030, and oil around 2035.

Note that, in this two degree scenario, the afforestation proposed in Bastin et al. would remove approximately 18% of cumulative CO2 emissions from 1870-2100.

Fig3
Figure 3: A 2°C scenario with a high-end afforestation scenario along with other policies. Note that here, afforestation plays a bigger role because emissions (grey, blue, pink, yellow areas) are smaller relative to the removals (green area).

The scenario settings used in En-ROADS to test the impacts of this policy are:

  • Coal
    • Coal (tax/subsidy) = 56 $/tce
  • Renewables
    • Renewables (tax/subsidy) = -0.06 $/kWh
  • Carbon Price
    • Carbon price = 65 $/ton
  • Transport Energy Efficiency
    • Transport energy efficiency = 4.8 percent/year
  • Buildings and Industry Energy Efficiency
    • Buildings and industry energy efficiency = 5.6 percent/year
  • Deforestation
    • Deforestation (reduce/increase) = -5.6 percent/year
  • Methane & Other Gases
    • Methane and other gases (reduce/increase) = -63 %
  • Afforestation
    • Percent available land for afforestation = 100 %
    • Afforestation planting time = 12 years
  • Assumptions
    • Max available land for afforestation = 900 Mha

Furthermore, restoring forests is important for many reasons other than their (important) role in removing carbon from the atmosphere. First, they provide a natural habitat for many species that are currently under threat, thus ensuring biodiversity. Second, they stabilize soil and thus prevent land degradation. Finally, they absorb groundwater and provide important resilience against flooding as a result of extreme rainfall, which is more likely to occur in a warming world (our team at Climate Interactive calls these systemic solutions that protect the climate while also improving health, equity, and well-being “multi-solving”).

Summary

Our assessments show that afforestation efforts could remove likely only 1-10% of anthropogenic CO2emissions from the beginning of the industrial revolution until 2100, (up to 18% in a low emissions trajectory) in contrast with Bastin et al’s estimates of two-thirds. Additionally, the idea that planting trees will save us from climate change is incorrect. Afforestation is a big, important part of a broad suite of policies that address climate change, but it is not a silver bullet solution. If managed well or kept wild, trees (beyond removing carbon) can increase biodiversity, stabilize soil, retain groundwater, and increase resilience against flooding. 

Literature

Bastin, J.-F., Finegold, Y., Garcia, C., Mollicone, D., Rezende, M., Routh, D., . . . Crowther, T. W. (2019). The global tree restoration potential. Science, 365(6448), 76-79. doi:10.1126/science.aax0848

Jones, C. D., Ciais, P., Davis, S. J., Friedlingstein, P., Gasser, T., Peters, G. P., . . . Wiltshire, A. (2016). Simulating the Earth system response to negative emissions. Environmental Research Letters, 11(9), 095012. doi:10.1088/1748-9326/11/9/095012

Le Quéré, C., Andrew, R. M., Friedlingstein, P., Sitch, S., Hauck, J., Pongratz, J., . . . Zheng, B. (2018). Global Carbon Budget 2018. Earth Syst. Sci. Data, 10(4), 2141-2194. doi:10.5194/essd-10-2141-2018

Sterman, J. D., Siegel, L., & Rooney-Varga, J. N. (2018a). Does replacing coal with wood lower CO2 emissions? Dynamic lifecycle analysis of wood bioenergy. Environmental Research Letters, 13(1), 015007. doi:10.1088/1748-9326/aaa512

Sterman, J. D., Siegel, L., & Rooney-Varga, J. N. (2018b). Reply to comment on ‘Does replacing coal with wood lower CO2 emissions? Dynamic lifecycle analysis of wood bioenergy’. Environmental Research Letters, 13(12), 128003. doi:10.1088/1748-9326/aaf354

The Royal Society. (2018). Greenhouse gas removal. Retrieved from https://royalsociety.org/-/media/policy/projects/greenhouse-gas-removal/royal-society-greenhouse-gas-removal-report-2018.pdf:

New York Times Op-Ed: Climate Still Worth Fighting For

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Increased frequency and intensity of natural disasters around the world. Disappearing islands and coastlines. Mass species extinction and biodiversity loss. Powerful fossil fuel forces contributing to it all.

As Climate Interactive’s Andrew P. Jones and Auden Schendler, Vice President of Sustainability at Aspen Skiing Company, make clear in the title of their recent New York Times op-ed, “Stopping climate change is hopeless. Let’s do it.” At a challenging time for the future of the planet, Schendler and Jones offer readers an incredibly compelling reason to instead feel optimistic about our future: the present.

Equal parts soberiThe New York Timesng and inspiring, the article points out that our species has faced, and overcome, insurmountable challenges before, as the op-ed says: “Historically, we’ve tackled the biggest challenge — that of meaning, and the question of how to live a life — through the concept of “practice,” in the form of religion, cultural tradition or disciplines.”

Regardless of whether we limit warming to 1.5 degrees Celsius above pre-industrial levels, to give up the fight and succumb to hopelessness would be to violate our natural instinct to survive. Truly, to remain in the ring means to aspire to the very essence of what it means to be human, “The work would endow our lives with some of the oldest & most numinous aspirations of humankind: leading a good life; treating our neighbors well; imbuing our short existence with timeless ideas like grace, dignity, respect, tolerance & love.”

It won’t be easy. It will be hard as hell. Harder than anything we have ever done before. But the rewards are more than worth the fight. As the authors conclude, “Perhaps the rewards of solving climate change are so compelling, so nurturing and so natural a piece of the human soul that we can’t help but do it.”

It begins with how we live our lives every moment of every day.

For more information from Auden Schendler, read his excellent book “Getting Green Done”

“You Fix the Climate” – Behind the New York Times Opinion Piece

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The new interactive tool in the New York Times, “You Fix It: Can You Stay Within the World‘s Carbon Budget?” gives you the power to explore over 8,000 scenarios for addressing climate change.

For many, experimenting with the opinion piece can be a challenging experience. We recommend that you watch this video or read this post on ten reasons for climate hope and learn more about Multisolving, our community-level response to the climate and sustainability challenge.

Behind the Interactive

The model, framing, and data behind the NY Times interactive were created by the three authors — Andrew P. Jones, Stuart A. Thompson, and Jessia Ma, with the full Climate Interactive team: Shanna Edberg, Tom Fiddaman (Ventana Systems), Todd Fincannon, Travis Franck, Ellie Johnston, Andrew Jones, Skuk Jones, Stephanie McCauley, Grace Mwaura, Phil Rice, Juliette Rooney-Varga (Mass-Lowell Climate Change Initiative), Elizabeth Sawin, Lori Siegel, and John Sterman (MIT Sloan).

The scenarios behind this tool were created with C-ROADS, a scientifically reviewed climate simulator that is designed to aggregate the proposals of countries and country groups to calculate long-term global climate impacts such as carbon dioxide concentration and temperature. C-ROADS was built by Climate Interactive, Ventana Systems, and the MIT Sloan School of Management. Read more about C-ROADS in this System Dynamics Review article and the C-ROADS technical reference guide. You can also learn about how we have applied

 it to the UN negotiations, or try it out for yourself for free.

The carbon budget value in the interactive (2900 GtCO2 cumulative) comes from the IPCC AR5 report, table 2.2 (on page 64), shown below. It is noted as the total global carbon budget starting from the year 1870 needed to stay within 2°C. Note that the table acknowledges a broader uncertainty range — from 2900 to 3200.

This interactive focuses on CO2, the primary (but not the only) greenhouse gas. It does not explore possible changes in methane, N2O, and f-gas emissions that could also help limit warming. As a result, CO2 emission reduction rates are more severe than other scenarios that would still limit warming to within 2°C and also include reductions in other gases. However, even with reductions in other gases, the level of ambition illustrated in the interactive is representative of what is needed to keep global temperatures “well below” 2°C and aim for 1.5°C, as the Paris Climate Agreement calls for.

The Scenarios

The four scenarios shown for each country or country group are:

  1. No Change. This is the business as usual or reference scenario behind the Climate Scoreboard analysis, wherein countries do not take action on climate change and continue to increase their emissions. The scenario is calculated by Climate Interactive based on separate estimates of population, GDP per capita, and carbon intensity of the economies of fifteen regions, aggregated into six for this application. It was revised in 2017 to incorporate changes and policies from recent years.
  2. Flatten. Countries and country groups would achieve half of the emissions reductions included in their Paris Agreement pledges by 2025 or 2030 (see below for an example) and then, in 2030, flatten emissions through 2100.
  3. Reduce. Countries and country groups would achieve all of the emissions reductions included in their Paris pledges by 2025 or 2030 and then reduce emissions post-2030 at a fixed annual rate, so that emissions are halfway between the “Flatten” and “Eliminate” scenarios by 2100.
  4. Eliminate. Countries and country groups would achieve 50% more than the emissions reductions included in their Paris pledges by 2025 or 2030 and then, post-2030, reduce to near zero by mid-century. To reflect differentiated capacities and responsibilities, developing countries reach near zero emissions later than developed countries.

As noted above, three of the scenario choices above involve half, all, or 50% more than the Paris pledges. “Half” means that emissions would reduce 50% of the way between the Reference Scenario and the full pledge in the pledge year. For example, 2025 emissions for the US would be 5.45 Gtons/year in the Reference Scenario (selected with the “Grow” choice) and 4.25 when following all of the Paris pledge (26% below 2005 emissions, selected with the “Reduce” choice). Choosing “Flatten” would lead 2025 emissions to be 4.85, halfway between the two values. And choosing “Eliminate” would lead to 3.65, which is 50% beyond the Paris pledge.

In order to simulate futures that achieve some fraction of the Paris Pledges, the interactive includes the Nationally Determined Contributions (NDCs) submitted by nations to the UN Framework Convention on Climate Change.

The interactive was constructed with 8,192 unique scenarios developed in C-ROADS. Scenario output that was created but not shown in the interactive includes annual emissions for all six regions, annual CO2 concentrations in the atmosphere and annual temperature. Those data are available upon request via info [at] climateinteractive.org.

The interactive has the ability to include Carbon Dioxide Removal (CDR) approaches, which would pull CO2 out of the atmosphere and into soils and storage via a possible set of activities, including bioenergy with carbon capture and storage, agricultural soil carbon, biochar, mineralization, afforestation, and direct air capture. Selecting this action in the simulator removes 4 GtCO2/year by 2050 and 12 GtCO2/year by 2100. We chose the rate of CDR deployment based on a set of papers summarized in Table 1 in Tavoni, M. and R. Socolow. Climatic Change, 2013. 118: 1 – 14. Modeling meets science and technology: an introduction to a special issue on negative emissions. Several CDR techniques are still in development and not commercially available, while others would require large

scale policy intervention (and land) for them to be realized. The scientific literature on the potential for CDR to be successful is varied. Our numbers here are not predictive of what may happen in this uncertain domain — we consider this a helpful “what if” scenario, not a forecast.

Division of countries into “Other Developing” and “Other Developed” groups are explained in the C-ROADS technical reference guide.

More Resources

We provide other resources for deeper engagement with the simulation behind the interactive. They include:

Analysis: U.S. Role in the Paris Agreement

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By Ellie Johnston, Andrew Jones, Lori Siegel, and John Sterman

President Trump is about to decide whether to withdraw from the historic Paris climate agreement or even take the US out of the UN climate negotiation process (UNFCCC).  The implications of this decision will be momentous for the US and for the world.

To explore the possible consequences we have examined a variety of scenarios using the C-ROADS interactive climate policy simulation.


Highlights

  • The U.S. matters a great deal.  The US emissions reduction pledge under the agreement accounts for more than a fifth of all emissions avoided through 2030 (21% of the total of pledged by all nations).
  • The difference between the US pledge and the US following the business-as-usual scenario (an unlikely outcome, but illustrative of the scale of the US role in climate action in the Paris Agreement) is that US emissions are estimated to be 6.7 Gigatons of CO2 equivalents per year by 2025, compared to emissions of 5.3 GtCO2e/year if the US follows through on its commitments. Global annual emissions would be 57.3 gigatons per year instead of 55.8 gigatons per year, a difference of nearly 3%. US emissions in 2016 were 6.5 GtCO2e/year. If US emissions follow the business-as-usual scenario instead of meeting its Paris pledge, while all other countries fulfill their commitments (and no further action is taken), the world would warm an additional 0.3°C (about one-half a degree Fahrenheit) by 2100.
  • If states, cities, corporations or other subnational entities implement strong actions to reduce emissions independent of US federal action, then US emissions could fall below business-as-usual levels. There are many trends supporting this.
  • If, however, the US abandons its Paris pledge and this leads other nations to weaken their efforts, it could mean the difference between meeting the Paris limit of 2.0° (3.6 °F) and missing it.

Approach

We examine four scenarios using the C-ROADS simulation:

  1. Business as usual: 

“Business as usual” is the C-ROADS Reference Scenario. The expected temperature increase in 2100 for this scenario is 4.2°C (7.6°F) with an uncertainty range of 2.5°C – 5.5°C (4.4°F – 9.9°F). The reference scenario accounts the UN’s medium fertility population projections, historical GDP per capita rates that converge over time to be consistent with other integrated assessment models, and GHG per capita projections for each gas that reflect trends over the last decade for CO2 and follow the IPCC’s RCP8.5 for the non-CO2 greenhouse gases. Consult the Climate Scoreboard “Science and Data” page for more details.

  1. Paris Pledges:

This scenario, highlighted in our Climate Scoreboard, adds up the contributions all countries have made to the UN climate negotiations. If all nations fully achieve their Paris pledges, and all submitted long-term strategies, average global surface temperature in 2100 is expected to be 3.3°C (6.0°F), with an uncertainty range of 1.9°C – 4.4°C (3.5°F – 7.9°F). The analysis includes Intended Nationally Determined Contributions (INDCs), Nationally Determined Contributions (NDCs), and long-term strategies submitted as of April 18, 2017 and does not include further action for countries beyond the country’s pledge. Consult the assumptions page in the Climate Scoreboard for more information.

  1. Paris Pledges without the US:

Here all countries fulfill their pledges as in scenario 2, except the US, which takes no action. This scenario is offered as a thought experiment to highlight the contribution that the United States is making with the Obama-era national pledge. Many feel confident that even if Trump withdraws from Paris some action will continue due to market trends in renewable energy along with state, local, and private sector action. Additionally, future US administrations could resume action to cut emissions to achieve the original US Paris pledge. This scenario achieves 2100 temperature of 3.6°C (6.4°F), with an uncertainty range of 2.1°C – 4.7°C (3.7°F – 8.4°F).

  1. Below 2°C:

The “Below 2°C” scenario is one of over 600 that would achieve the Paris temperature goal, limiting warming to 1.8°C (3.3°F) in 2100. In this scenario, all countries reach a peak in greenhouse gas emissions by 2030 and then steadily cut emissions, with reduction rates in the post-2030 period faster in the developed countries (5%/yr) than in the developing countries (3.5%/yr). It does not include “negative emissions” other than the afforestation pledges that are included in the Nationally Determined Contributions (e.g., in China’s pledge). Details are available here. Scenarios that achieve the Paris goal of limiting warming to 1.5°C (2.8°F) are shown here.

Will US withdrawal from Paris lead other nations to erode their goals?

So far, other key nations have stated that they will not let a possible US exit from Paris or UNFCCC, or the abandonment of climate-friendly policies in the US that have already been announced, affect their commitment. However, if the US pulls out other nations may weaken their commitments or their efforts to achieve them, possibly leading to a cascade of defections from Paris. Many developing nations faced with the prospect of diminished financial assistance, may not be able to meet their own emissions reductions efforts or make more ambitious pledges.

Furthermore, if the US loses its seat at the table, it would weaken US ability to shape international actions going forward, including actions on other issues. Other nations, such as China, the EU, etc. may seek policies that punish the US for stepping back from climate action, including the imposition of border adjustment tariffs on US exports and other policies that could harm the U.S. economy, such as freezing US firms out of contracts to supply renewable energy to other nations. Withdrawal cedes leadership in the emerging renewable energy industry to China and others.

Weakening action on climate change harms many of the Trump administration’s own goals:

  • It increases risks of conflict in many parts of the world at a time when the administration is seeking to avoid committing US military and troops.
  • It slows job creation in renewables and energy efficiency (industries that are now bigger than coal in terms of employment), jobs that would mostly benefit many working class people who supported President Trump.
  • It continues to harm the health of those same people through continued exposure to air pollution from burning fossil fuels at a time when health care may be cut back.

Notes

Country Groupings. Most countries are included in either the other developed or other developing categories. The distribution of countries in those groups can be found in Table 3-10 of the C-ROADS Technical Reference Guide. India is included in the Other Developing grouping.

U.S. Pledge Post-2025. The U.S. pledge to the Paris Agreement only covers emissions through 2025. For the trend from 2025-2030 and beyond, we used the emissions trajectory outlined in the U.S. Mid-Century Strategy announced November 2017 in Marrakech at the UN Climate Talks, available here.

Engaging Others. Climate Interactive and MIT Sloan have developed an engaging role-play exercise used around the world that helps people explore the trends. The World Climate Simulation is freely available in multiple languages.

More Analysis. Climate Interactive has examined what the effect of rolling back the Obama-era climate policies would have here.

“Normandy 1944” Quote. The New York Times article by Justin Gillis and Nadja Popovich included a calculation about when the US used up its share of the Carbon budget (See image to the right). Some background on the calculation: Total global budget from 1850 to stay within 2°C is 2900 GtCO2 (Table 2.2 – AR5). US is 4% of population today so it gets 126 GtCO2. But the US went over-budget (used 126 cumulatively back in 1944 (Note – the US has pumped out 429 by here in 2017).

Media coverage of this work has appeared in New York Times, Washington Post, and Associated Press.

If you are interested in using data or the analysis, contact Ellie Johnston at: ejohnston@climateinteractive.org

What Slashing Climate Rules Means For the U.S. Pledge to Paris

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President Trump has issued an executive order to begin repealing the Clean Power Plan and other Obama-era climate policies. So what are the impacts on the U.S. pledge to the Paris climate agreement?

See the story in the New York Times for more.

The New York Times used our data and analysis to show the enormous effect in the graphic story “Trump’s Executive Order Pushes the U.S. Climate Pledge Further Out of Reach.” Others are welcome to use the data as well. Contact us: info-at-climateinteractive.org.

We explored what policy actions were intended to deliver upon the U.S. pledge to the Paris climate agreement, and which actions are now threatened due to the new administration’s slashing of climate rules.

Source: NY Times

 

Overall Approach

The data pull together analysis from Lawrence Berkeley National Laboratory (LBNL) and a report from the EPA and NHTSA, in addition to our own work (the C-ROADS simulation and Climate Scoreboard analysis). The New York Times used a version of this work previously in December 2015 for a similar story on what policies were under threat with Trump’s election.

Historical Data and Reference Scenario

Historical net emissions data for the U.S. came from Global Carbon Budget for 2010–2015 for energy CO2. Land use, land use change, and forestry (LULUCF) emissions data for 2010–2014 comes from FAO. Data for the other greenhouse gases for 2010–2012 comes from EDGAR (4.2). F-gas data is only for 2010. We used C-ROADS to simulate the business as usual trend for the United States from the end of the historical data through 2025.

Federal Government Actions to Deliver on the Pledge

We then employed analysis from “Assessment of the climate commitments and additional mitigation policies of the United States” in Nature Climate Change by Greenblatt and Wei (2016) of LBNL to calculate the impact of a wide range of federal and state actions on U.S. emissions. The paper outlines 18 different types of actions and estimated emissions reductions (see Greenblatt and Wei, Table 1) – these actions were aggregated into the two lines shown in the graphic.

greenblatt-table-1

The LBNL study included the Obama-era fuel efficiency standards for cars and other light-duty vehicles in their baseline. Unfortunately, these standards are now under attack, so we separated them out in this latest analysis using the EPA and NHTSA’s report on the impact of those standards. It is expected that the fuel standards if they continued to be fully implemented would reduce 140 mtCO2e in 2025. Since the business as usual scenario we use from C-ROADS did not account for the fuel standards, we were able to include them with the impact from the policies that were included in the LBNL study.

Other Notes

For other information on long-term U.S. emission scenarios, particularly those that are consistent with limiting global warming below 2.0°C please consult our analysis of mid-century strategies here.