Fossil fuel carbon dioxide (CO2) emissions are the main cause of global warming. From around the 1990s, analyses of fossil emissions and Integrated Assessment Models (IAMs) have focused on a handful of industrialized economies where emissions have been high (US, EU) along with rapidly-industrializing countries such as China and India1–4. To the extent that other countries have been included, they are typically aggregated into large and undifferentiated groups, such as “other developing countries”5 or “Rest Of World (ROW).” Yet since 2010 most of the growth in global emissions has been among these “ROW” countries. For example, all of the 59 countries whose annual emissions grew faster than the global nations’ average 2010-2018 (hereinafter “emerging emitters”) were developing economies, including many low-income countries6,7. Although none of these emerging emitters are individually large sources of emissions today, their combined emissions are greater than any single country except China and the U.S., and amount to 65% more than India’s annual emissions in 2018 (the world’s third largest emitter). Thus, the success of international mitigation efforts may depend on these emerging emitters—specifically whether their goals of economic growth and human development are achieved using fossil energy.
In addition to the normal (i.e. large) uncertainties of socioeconomic and energy system trajectories, the SARS‑CoV‑2 (COVID) pandemic has dramatically affected human activities throughout the world, including economic activity, energy consumption and CO2 emissions8–10. For example, global CO2 emissions declined by nearly 5.8% in 2020 relative to that in 201911. Yet there have been substantial differences among countries, including developing economies. For example, between January and October of 2020 per-thousand-people confirmed COVID cases and deaths in Peru were 27.3 and 1.04, respectively, while per capita cases over the same period in Vietnam were just 0.012112. Future impacts of the disease and public health responses are unclear: vaccines are beginning to be distributed in some wealthy countries, but outbreaks and related economic impacts may yet persist for years among poorer countries13, in turn affecting longer-term patterns of energy use and emissions there. It may therefore be particularly important in the context of low income countries, to understand the current public health situation and the policy, behavioral, and emissions responses during the pandemic period, i.e., 2020-2024.
Here, therefore, we systematically assess recent trends of emissions and their drivers among the 59 emerging emitters (defined as countries whose annual emissions 2010-2018 grew faster than (or similarly to) the average of all nations’ 2%, but excluding China and India), and then project future emissions from these countries under scenarios that span a range of near-term COVID impacts as well as longer-term socioeconomic and energy system trajectories. We separate the 59 countries from regional aggregations in major Intergrated Assessment Models (IAM) and update the Shared Socioeconomic Pathways (SSPs) based on recent emission pattern changes, in order to construct a country-specific future energy and emission dataset. Full descriptions of the datasets are available in Supplymentary Information. Details of our analytical approach are provided in the Methods. In summary, we first use index decomposition to analyze fossil fuel CO2 emissions data from the International Energy Agency (IEA) and characterize the drivers of each country’s emissions. We then develop country-specific emissions scenarios using a Disaster Footprint Accounting Model14 based on the Adaptive Regional Input-Output (ARIO) Analysis10,15 (to capture changes in the pattern of countries’ emissions due to COVID impacts on economic activities) for the period of 2020-2024. We then disaggregate each of the 59 countries from regional groupings of major IAMs and update the Shared Socioeconomic Pathways (SSPs) based on trends and drivers of these countries’ recent emissions, to construct country-specific projections of their energy systems and emissions for the period 2025-2040. Full descriptions and details of these projections are available in Supplementary Information. Finally, we compare the limits of carbon space set by international climate targets with the magnitude of emissions from those emerging emitters and discuss the roles of other countries in cooperative emission mitigation.
Emerging emitters
Figure 1 compares the percent changes 2010-2018 in annual CO2 emissions and GDP (Gross Domestic Production) among the 59 emerging emitters (listed in Supplementary Data 1). The average annual growth rate of emissions of the 59 countries 2010-2018 was 6.2%—much higher than the 2.0% average of all nations worldwide, and also higher than the 4.6% annual growth rate of these same countries’ GDP, reflecting rising carbonization of their economies. Located in Asia, Africa, and Latin America, individually these countries emitted between 0.7 and 542.9 Mt (million tons) CO2 in 2018 (bounded by Eritrea and Indonesia, respectively; Fig. 1). However, together the countries’ emissions grew by 40.7% over the period, from 2.7 Gt (gigatons) to 3.8 Gt CO2. In comparison, emissions in China, the U.S., and India were 9.6, 4.9, and 2.3 Gt CO2 in 2018. Moreover, the 1.1 Gt increase in emissions accounts for 38.9% of the global increase in emissions over the period.
The emerging emitters include countries in development categories ranging from the least developed country (LDC) to economy in transition (EIT)7, but in most cases with levels of GDP per capita substantially less than the global average (53 countries with per capita GDP less than 11,000 in constant 2010 USD). 698 million people in these countries lived in absolute poverty (e.g. < 1.9 US$ per day in purchasing power parity value) in 2017, which accounts for 9.3% of global population16. Among the 59 countries, emissions grew faster than GDP in 34 (58%), and twice as fast as GDP in 12 of these (20%; Fig. 1). In 25 others (42%), economic growth outstripped emissions growth, corresponding to decreasing carbon intensity of those economies.
Drivers of recent emissions surge
Figure 2 shows the drivers of changes in emissions 2010-2018 for 20 emerging emitters in Africa, Latin America and Asia. Analogous plots for the other 39 countries are shown in Supplementary Section 2.2 (Figure S5-S8). In each case, we plot the 2 most influential drivers spurring emissions growth as well as emissions reductions. Across all 59 emerging emitters, population growth (red) is most important in 29% of the countries including Uganda (Fig. 2a) and Lebanon (Fig. 2d), though increases in GDP per capita (lavender) are the foremost driver of emissions increases in 44% including Ethiopia, Colombia and Vietnam (Figs. 2e, 2f and 2g). Following closely behind these socioeconomic factors are increases in use of a particular fossil fuel; increases in either oil (orange) or coal (light orange) are the most influential factor of emissions increases in 14% of the 59 countries, including Sudan, Haiti, Myanmar, Guatemala and Kyrgyzstan (Figs. 2i, 2j, 2k, 2b4, and 2n, respectively; for emissions by fuel type, see Fig. S3). Energy intensity (turquoise) increases drove 12% of the countries’ emissions growth as the top-two drivers, including Algeria and Laos (Figs. 2m and 2o). Less commonly, increases in share of industrial value added in GDP (dark blue) are the second-most important driver of emission increases (in 7% of the 59 countries) in Ethiopia (Fig. 2e), Haiti (Fig. 2j), etc. A rise in CO2 emissions intensity of energy use contributed most to 5% of the countries’ emissions growth, including Nicaragua, Botswana and Nepal (Figs. 2q, 2r, and 2s, respectively). In comparison, a decline in energy intensity is the most influential driver of emissions reduction in a third (32%) of the countries including Uganda, Mongolia, Ethiopia, and United Arab Emirates), followed by drops in CO2 emissions intensity of energy use (in 20% of the countries including Peru, Sudan and Haiti), a smaller share of industrial value added especially in Latin American and Other Asian countries in 15% (Fig.2f, 2n, 2h, and 2t), and declining share of oil use (in 15% of the countries, including Botswana and Nepal). We describe the drivers of case countries’ emissions in greater detail in Supplementary Section 2.3 and Fig. S9-14.
Projections of future emissions
In general, the 59 emerging emitters prioritize economic development to increase incomes and reduce poverty. In turn, GDP per capita is routinely a key driver of emissions increases (Fig. 2). Without offsetting decreases in the carbon intensity of these countries’ economies, such development will continue to spur growth of emissions in the future. The economic disruption of the COVID pandemic and recovery will strongly affect economic growth and energy use over the next several years, with longer-term trajectories determined by development and energy pathways. Figure 3 shows projected emissions for selected emerging emitters, as well as the sum of all emerging emitters (Fig. 3a; supporting data for all emerging emitters are included as Supplementary Section 3.2 and 3.3). In each case, these projections include: a “baseline” scenario (pale blue curves) that represents a counterfactual world in which the COVID pandemic had not occurred and countries developed according to their current policy ambitions thereafter (i.e. following the SSP2 “middle of the road” pathway17); a “default lockdown” scenario (dashed red curves, 2020-2024) that assumes two COVID-related lockdowns with more targeted restrictions in the second (see Methods for further description including of other “mild” and “severe” COVID scenarios not shown in Fig. 3 but included in Fig. 4; see also Supplementary Section 2.3); a “weak policy” scenario (dark red curves) in which post-2024 emissions reflect current policy ambitions (SSP2) but reflect a lower starting point due to COVID. Fossil fuel based electricity generation and transportations are the largest emission sectors for the emerging emitting countries. In 2018 they accounted for 64.2% of total emission in Vietnam and 52.5% of Ethiopia (see Supplementary Fig. S4). We design a low-carbon scenario (“LC”, dashed orange curves) that assumes new electricity-generating capacity installed after 2025 will increasingly be non-emitting and new vehicles after 2030 will increasingly be electric; and an extreme low-carbon scenario (“Extreme LC”, dashed green curves) that assumes all new electricity-generating capacity installed after 2025 will be non-emitting and all new vehicles after 2030 will be electric (for complete scenario settings, see Supplementary section 1.1, 1.2 and Fig. S1). These ambious low carbon scenarios sketch the best decarbonization effort can be made by emerging emitters (see Supplementary Fig. S2).
Although the modeled effects of COVID may be substantial, our scenarios suggest emissions from emerging emitters will increase in the coming decades, and in all cases the combined total exceeds 5 Gt CO2 per year by 2040 (Fig. 3a). The combined annual emissions of the countries are between 5.4 and 6.6 Gt CO2 in 2040 (Fig.3a), bounded by the extreme low-carbon scenario at the lower end and weak policy scenario at the upper end. Where low-carbon technologies are phased in gradually after 2025 (LC scenario), the combined emissions of these countries are reduced by 698 Mt CO2 (-10.6%) relative to the 6.6 Gt CO2 in the weak policy scenario (Fig.3a). In the extreme low-carbon scenario, the reduction in emissions is 1.1 Gt (17.2%) relative to the weak policy scenario (Fig.3a). But even under this highly ambitious scenario, emissions continue to grow in 2040, calling into doubt that there are pathways for these countries to develop as also “climate friendly.”
However, despite the increase in their combined emissions, there are important country-level differences in the emerging emitters’ trajectories after the COVID shock. For example, in countries such as Peru and Vietnam, emissions continue to grow after ~2023 but slows markedly after 2030 in the low-carbon scenarios (Figs. 3b and 3c). By contrast, in countries like Myanmar, emissions grow steadily through 2040 regardless of scenario (Fig. 3d), and in others (Ethiopia and Uganda) emissions accelerate (Figs. 3e and 3f). These increases occur despite progressive decarbonization of transport and electricity, driven instead by increases in emissions from industry, and fuel consumption by the residential and commercial sectors. Across countries, emissions reductions under the extreme low-carbon scenario are 15%-23% relative to the baseline, mainly reflecting the share of current emissions that is from coal-fired electricity and transportation.
From 2020 to 2040, we project cumulative CO2 emissions from the 59 emerging emitters will exceed 100 Gt (see Fig. S16 for comparison between our projections and those for SS1-SSP5 produced by different IAMs), except in the most severe COVID scenario followed by the extreme low-carbon pathway (see Fig.4a). Between 2020 and 2024, lockdowns and gradual recovery in the default COVID scenario reduce cumulative emissions from the emerging emitters by 0.9 Gt CO2 compared to the 16.2 Gt emitted in the baseline no-COVID scenario. In comparison, the extreme low-carbon scenario results in an almost tenfold greater reduction in cumulative emissions among these countries 2024-2040, 8.5 Gt. Yet even under this most ambitious decarbonization, the magnitude of emissions we project from these emerging emitters will strain the limits of the remaining budget of emissions that would avoid 1.5℃ warming18, leaving very limited carbon space for other countries (Fig. S15). Fast carbonization of the 59 emerging emitters would require significant space by 2040 and leaves small room for other countries if we aim at achiving any climate target set in international agreements. This implies today’s largest emitters would have to achieve net-zero CO2 emissions by 204019. If the emerging emitters continue growing at the speed under the weak-policy scenario (+2.4% per year), achieving the global target of 1.5℃, will require the rest of the world to reduce their emissions at an annual rate of 14.1% over 2020-2040 (8.2% per year for limiting warming below 2℃, see Fig. 4b). Even if the emerging emitters are able to follow the Extreme LC pathway as we assumed (+1.2% per year) and global warming were to be limited below 1.5℃, the rest of the world will have to reduce emissions by 13% per year over 2020-2040 (7.6% per year for 2℃ limit).