TOPSHOT – A picture taken on November 30, 2019 shows smoke and vapor rising from the cooling towers … [+]
With all the talk of apocalypse and catastrophe associated with climate change, it would be easy to miss out on an incredible change in expectations for future carbon dioxide emissions. Based on the projections just released by the International Energy Agency (IEA), it now appears that the world has a very good chance of seeing carbon dioxide from the burning of fossil fuels plateau over the next several decades. Peak carbon dioxide may be on the horizon.
The IEA, in its 2019 World Energy Outlook, is careful to observe that its scenarios are not forecasts. The scenarios are projections conditional upon certain assumptions. IEA explains, “a forecast would need to try to second-guess the future responses of policy makers. whether these are triggered by concerns about energy security or affordability, or by a reaction to rising emissions and their impacts. We do not give decision makers the benefit of the doubt on these future responses.”
One of the scenarios produced by IEA focuses on projections based on what policies governments’ have actually adopted by mid-2019, and is called the Current Policies Scenario (CPS). A second scenario focuses commitments and plans that governments’ have announced, but not yet enacted, and is called the Stated Policies Scenario (SPS). IEA projects the consequences of these scenarios to 2040.
Justin Richie, a researcher at the University of British Columbia, has identified a remarkable feature of the new IEA scenarios. Both the CPS and SPS have carbon dioxide emissions for 2040 that are lower than almost all of the scenarios reviewed in the most recent assessment (AR5) of the Intergovernmental Panel on Climate Change (IPCC). Richie identifies an important reason for the difference in how the IEA treats coal use to 2040 versus how coal is treated in the scenarios of the IPCC: Coal use in the CPS “is lower than 90% of all the IPCC scenarios, and the IEA SPS is lower than 95% of the IPCC scenarios.”
Less than a decade ago, conventional wisdom was that coal use would expand dramatically through the 21st century. But just last year IEA suggested that global coal use may have peaked in 2014. In an analysis published last week at Carbon Brief a team of energy analysts argue that, “Global electricity production from coal is on track to fall by around 3% in 2019, the largest drop on record.” Robbie Andrew, a scientist at the CICERO Center for International Climate Research in Oslo, Norway, has published data indicating that coal generation for electricity in India is down 2.5% in 2019 from the year before.
The new conventional wisdom is that for myriad reasons – climate, air pollution, economics among them — coal is on its way out. The end of coal won’t happen anytime soon, but it does appear that nightmare scenarios of unmitigated expansion of coal burning are far less likely that recently assumed.
It is hard to overstate the importance of the shift in expectations for future emissions that is represented by the difference in the new IEA scenarios versus those of the IPCC. One significant implication of the shift in perspective is that it renders much of the climate impacts literature of the past decade, and the media reporting that accompanied it, as obsolete. The reason for this obsolescence is that thousands of academic papers projecting future climate impacts have emphasized a very high-end emissions scenario focused on the burning of massive amounts of coal throughout the 21st century. While policy makers in coming decades may yet chose to return to coal, at present that seems far-fetched.
In technical terms, based on the CPS scenario, in 2040 the world would have emissions lower than RCP 4.5, and much less than RCP 6.0 and RCP 8.5 (RCP = representative concentration pathway, technically a “a scenario set containing emission, concentration and land-use trajectories” leading to “radiative forcing levels of 8.5, 6, 4.5 and 2.6 W/m2”). While many climate impact studies of the past decade also included projections focused on RCP 4.5 in addition to more extreme scenarios, often it was the more extreme results associated with higher forcing levels that were emphasized.
To avoid a lost decade of impacts research, it will be important to revisit the literature with a focus on RCP 4.5, rather than RCP 8.5. The unavoidable conclusion of such a second look is that climate change will appear much less scary, and political strategies that are consistent with updated understandings will have to adapt accordingly.
A second significant implication of the new perspective on emissions trajectories over the next several decades is that the IPCC is at risk of already being obsolete to the extent that its forthcoming 6th assessment report emphasizes high end emissions scenarios. Of course, carbon dioxide emissions are not the only factor that matters in projections of future climate. However, projected emissions play a role in not just climate and impact projections, but also in analyses of the cost effectiveness of various mitigation policies. Reliance on outdated scenarios that are out of sync with present understandings could badly bias the next IPCC assessment, potentially threatening its credibility or misleading policy makers.
A close look at the new IEA analysis suggests that while the world may not yet be at peak carbon dioxide, the world looks to be entering an extended plateauing of emissions. Consider that the IEA says that its emissions estimates are accurate to about 5% for major economies and to about 10% for many other countries. That means that the projected emissions in 2040 of the SPS has uncertainty ranges for carbon dioxide emissions that overlap with those of 2019. In other words, if policy makers follow through with current stated commitments, the global carbon dioxide emissions two decades from now will be similar to what they are today.
There is even greater reason for optimism that emissions have plateaued. The IEA projects that the global economy will grow at a rate of 3.4% annually to 2040, representing a per capita growth rate of about 2.5% per year. This rate of growth is higher than 95% of the projected GDP growth rates of the IPCC AR5 scenario database. As I have argued in this space recently, almost all of the IPCC scenarios overstated GDP growth over the past decade. The projected IEA global GDP growth rate also exceeds that recently projected by leading economists.
There is thus good reason to believe that the IEA projection of GDP growth to 2040 is too aggressive. While forecasting economic growth is fraught with challenges, it is clear that an error of just a few tenths of a percentage point in the IEA projection of yearly economic growth to 2040 would be enough to turn the CPS from showing a modest increase in carbon dioxide emissions to a plateau, and turn the SPS from a showing a plateau into a modest decline.
The final metric to look at is the implied rates of decarbonization in the IEA scenarios. Decarbonization refers to the rate of decline in the ratio of carbon dioxide emissions to GDP. For much of the past two decades, using IEA data, global decarbonization has typically been less than 2% per year, though from 2014 to 2016 it averaged about 3% annually, and from 2010 to 2018 it averaged 2.4%.
The CPS implies a global decarbonization rate of about 2.1% per year to 2040, while the SPS implies a rate of about 2.8% per year. Neither of these values seems unrealistic, based on recent experience, and may even be conservative depending upon the degree to which policy makers act more aggressively than the stated policies they have already committed to. But these numbers remain far off from what would be needed if the world is to achieve deep decarbonization of 80% reductions or more from present levels. Achieving such a goal would require annual rates of decarbonization of 7.5% per year to hit a 2 degree Celsius target and 11.3% per year to hit a 1.5 degree target. The emissions reduction challenge remains as daunting as ever.
But make no mistake, the change in perspective that is implied by current expectations for energy consumption and the mix of technologies that comprise it, along with expectations for economic growth, provide welcome good news on climate. The worst-case scenarios that have dominated discussions over the past decade or more are off the table, and will stay there unless we actively choose to follow them. That seems unlikely. Consequently, a new generation of climate impact studies is needed, along with new understandings of the costs and benefits of policy options to further accelerating decarbonization.
We’ve reached the plateau. Now it’s time to figure out how to start running downhill.
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