Conceived and designed the experiments: LC DR JPK. Performed the experiments: DR. Analyzed the data: LC DR JPK. Wrote the paper: LC.
The authors have declared that no competing interests exist.
Although developing countries are called to participate in CO2 emission reduction efforts to avoid dangerous climate change, the implications of proposed reduction schemes in human development standards of developing countries remain a matter of debate. We show the existence of a positive and time-dependent correlation between the Human Development Index (HDI) and per capita CO2 emissions from fossil fuel combustion. Employing this empirical relation, extrapolating the HDI, and using three population scenarios, the cumulative CO2 emissions necessary for developing countries to achieve particular HDI thresholds are assessed following a Development As Usual approach (DAU). If current demographic and development trends are maintained, we estimate that by 2050 around 85% of the world’s population will live in countries with high HDI (above 0.8). In particular, 300 Gt of cumulative CO2 emissions between 2000 and 2050 are estimated to be necessary for the development of 104 developing countries in the year 2000. This value represents between 20 % to 30 % of previously calculated CO2 budgets limiting global warming to 2°C. These constraints and results are incorporated into a CO2 reduction framework involving four domains of climate action for individual countries. The framework reserves a fair emission path for developing countries to proceed with their development by indexing country-dependent reduction rates proportional to the HDI in order to preserve the 2°C target after a particular development threshold is reached. For example, in each time step of five years, countries with an HDI of 0.85 would need to reduce their per capita emissions by approx. 17% and countries with an HDI of 0.9 by 33 %. Under this approach, global cumulative emissions by 2050 are estimated to range from 850 up to 1100 Gt of CO2. These values are within the uncertainty range of emissions to limit global temperatures to 2°C.
Consensus emerging in favor of low CO2 stabilization targets requires the participation of developing countries in the efforts to reduce global green-house emissions
In order to tackle above mentioned challenges, the CO2 allocation and reduction approach here outlined contrasts from existing ones
In
The dashed line represents a least squares fit through all values. The coefficient of determination is
Our approach starts by investigating the evolution of future human development standards. We assume that the HDI,
HDI values are plotted for each country by using a transformed time
In the following section we provide the main assumptions used to extrapolate per capita emissions of CO2 from fossil fuel burning (see also section III.B in
The correlations between HDI and CO2 emissions per capita,
We take advantage of these correlations and assume that the system is ergodic, i.e. that the process over time and over the statistical ensemble is the same. In other words, we assume that these correlations also hold for each country individually and apply the exponential regression
For 52 countries out of 173 data was found to be insufficient to perform the regressions Eq. (1) or Eq. (3). This is, they comprise less than the minimum number of data points required to fit the HDI versus time or CO2 emissions per capita versus HDI. In the
In
Panels
Future country-based emissions estimates are obtained via multiplying the extrapolated CO2 per capita values by population numbers extracted from three scenarios published in the Millennium Ecosystem Assessment report
The statistical approach undertaken in this work can be named “Development As Usual” (DAU) in the sense that development and emission trends continue as in the past. Accordingly, we are not claiming that the calculated HDI and CO2 extrapolations are predictions, instead, they represent a plausible near-future world (by 2050) where CO2 emissions from fossil fuel combustion are still closely linked to human development. This assumption is supported by (i) the findings that no discernible decarbonizing trends of energy supply among world regions can be identified
Global emissions are split into two emission budgets: emissions necessary for development (until an HDI of 0.8 is reached) and emissions occurring after development (all developed countries in 2050). Population scenarios are extracted from the Millennium Ecosystem Assessment report
Of a total of 165 countries, 104 were found to be developing countries (HDI below 0.8) in the year 2000. By using the UNDP HDI threshold of 0.8 to differentiate countries with high human development from developing countries with medium to low human development
In a DAU future we estimate that between 200 and 300 Gt of cumulative CO2 emissions will be necessary for developing countries (104 in the year 2000) to proceed with their development. In the scope of our approach, 61 developing countries are expected to overcome the HDI of 0.8 by 2050 consuming roughly 98 % of the above-mentioned 200-300 Gt budget. The remaining 43 countries are likely to stay below the UNDP high human development threshold in the considered time frame. Total cumulative emissions occurring after development range from 1500 to 2000 Gt of CO2.
This amount is similarly divided among countries carrying out a development transition (700 to 1000 Gt) and those whose development occurred before the year 2000 (800 to 1000 Gt) as summarized in
Cumulative CO2 emissionsin Gt of CO2 by 2050 | |||
Necessary for development |
|
|
|
Emitted after development |
|
|
|
from countries crossing 0.8 HDI between 2000 and 2050 | 700 | - | 1000 |
from countries already developed in 2000 | 800 | - | 1000 |
Global | |||
Emissions under DAU |
|
- |
|
Emissions under the proposed framework |
|
- |
|
Allowable CO2 emissionsin Gt of CO2 | |
By 2050 | |
75% probability of not exceeding 2°C |
|
50% probability of not exceeding 2°C |
|
By 2075 | |
To limit CO2 concentrations at 450 ppm |
|
To limit CO2 concentrations at 560 ppm |
|
To limit CO2 concentrations at 560 ppm |
|
The table summarizes the emission values before and after countries reach the HDI of 0.8 according to a DAU approach and under the proposed reduction framework. A collection of previous calculated budgets for allowable CO2 emissions highlights the efforts necessary for emission reductions.
*Cumulative emissions necessary for development assuming an HDI threshold of 0.9 would range from 600 to 600 Gt CO2.
**Assuming the same uncertainty as in DAU.
Emissions for development where found to be very sensitive to the selected HDI score. Assuming that developing countries want to achieve western development styles would require to set the minimum development standards to values of 0.9. In such a case, emissions necessary for development by 2050 range from about 700 to 900 Gt of CO2. This range is higher by at least a factor of 3 than the values obtained for a HDI threshold of 0.8.
We further compare our estimates with previously calculated CO2 budgets for particular time frames, global warming targets and atmospheric CO2 concentrations. We find that the emissions necessary for development consume up to 30 % of the 1000 Gt CO2 limit for a 75 % probability of keeping global warming below 2°C, as calculated by Meinshausen
The question logically arising from the results is how to operate a fair transition of developing countries towards high development standards without compromising current climate targets. A fair approach implies that an hypothetical developing country should not be limited in its emissions of CO2 until it reaches a particular threshold of human development. In practice, the development path made by current developed countries in the past should be possible for developing countries in the future if they choose to do so. This key aspect of the proposed framework convenes in our opinion a better representation of fairness in CO2 emissions allocation as opposed to fixing a point in the past from where emissions are integrated.
The reduction framework proposes four domains of climate action that are both fair in an historical perspective and constrained by current technological developments. Reserving a fairness domain for developing countries implies that their participation in climate efforts can be operated in a voluntary basis. The development threshold of 0.8 HDI is taken from United Nations Development Report 2009
To formalize this, we propose that a developed country
The value of
Solid lines stand for the historical emission while the connected circles represent extrapolated emissions when countries follow the reduction scheme proposed.
The period in time when developing countries are expected to reach an HDI of 0.8 is represented by the colored hatches.
Previous reduction schemes of global CO2 emissions make use of population numbers
These approaches disregard to some extent the possible development set-backs caused by CO2 reductions in the socio-economic development of a country. We use the HDI in order to take development needs of developing countries into consideration. In a DAU world, we estimate that up to 300 Gt of CO2 represent a pre-condition for raising a considerable amount of developing countries (comprising HDI below 0.8 in the year 2000) to a minimum HDI of 0.8 in the year 2050. If development pathways proceed as in the past, resulting CO2 emissions will pose tighter constraints on the achievement of the previously mentioned climate targets. One can legitimately question the likelihood of such assumption. In a sense, our approach can only be regarded as an approximation since aspects like technological innovation and enhanced technology transfer between developed and developing countries cannot be anticipated. This is a recurrent problem when projecting trends of socio-economic systems into the future. The assumed ergodicity would benefit from further investigation.
Depending on mankind’s decision concerning acceptable levels of climate change and desirable human development goals, emissions necessary for development can represent substantial shares of the CO2 budgets here analyzed (see
We propose a differentiated and dynamic allocation scheme of CO2 emissions based on human development achievements. Developing countries are not obliged to reduce their emissions until a certain threshold of human development is achieved. From then on the country is no longer considered to be developing, and should therefore engage on the proposed emissions reduction path. It is worth to point out that the investigated population scenarios only show substantial divergence in values beyond 2050. Obtained differences in CO2 emissions between scenarios are therefore small during the time frame of analysis.
Within the scope of our approach the efforts for climate protection commitments from developing countries can be operated on a voluntary basis. With CO2 reduction rates linked to the evolution of HDI as proposed here, the 2°C target can be met even if emissions from developing countries evolve according to DAU during the early stages of development. Independent of the climate target, a fair allocation and reduction of emissions between developed and developing countries must consider the dependence between CO2 and human development here discussed.
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We thank M. Boettle, S. Havlin, A. Holsten, N. Kozhevnikova, D. Reusser, H.D. Rozenfeld, J. Sehring, and J. Werg for discussions and comments. Furthermore, we thank Alison Schlums for help with the manuscript. The main author further thanks N. Kozhevnikova for her refined sense of critique. All authors express their gratitude for the Editor comments that largely benefited the current manuscript.