The international community now views global warming as a major threat, with particularly dire implications for developing countries. A common view on the problem in the south (the developing nations, as opposed to the north, or developed countries) was expressed in an address by India’s ambassador to the United Nations, who reportedly told developed nations that the main responsibility to mitigate climate change “rests with them”, while efforts to impose greenhouse-gas commitments on developing countries would “simply adversely impact” their prospects of growth. Although this view commands near-universal support in the south, it remains largely an article of faith. If the south begins aggressive mitigation now, will it actually damage its own growth prospects? Or will such mitigation improve those prospects by significantly reducing the impact of global warming on the south itself?
A lot hinges on these questions, so an empirical test of the conventional wisdom seems warranted. Does the evidence support this view? If the answer is yes, then the south should indeed defer costly mitigation and a double burden should fall on the north: it should reduce emissions rapidly and compensate any mitigation undertaken by the south. If the answer is no, on the other hand, the converse is true: southern emissions are, by themselves, sufficient to damage southern growth prospects. In this case, the south’s interest dictates immediate action to reduce its own emissions, whatever the north has done or will choose to do in the future.
We will attempt to provide an unambiguous answer by isolating the southern experience, calculating historical and future emissions paths and atmospheric carbon dioxide concentrations for both north and south. We will also compare the southern path to the global path that has provoked alarm about global warming.
This experiment enables us to test the view, implicit in the Indian ambassador’s statement, that the isolated southern concentration path lags so far behind the global path that the south can defer worrying about its own emissions until it is much richer.
The atmospheric concentration of carbon dioxide (CO2) is determined by the pre-industrial concentration, plus cumulative emissions from human activity, minus terrestrial and marine re-absorption of emitted carbon. In our study, we combine a country-level emissions database and a land-use database to calculate cumulative anthropogenic CO2 in the atmosphere since 1850, using an approximation to the standard Bern carbon-cycle model that accounts for the intertemporal distribution of emissions among three reservoirs: the atmosphere, ocean and land biosphere. The model implies that for one tonne of carbon emitted in 1850, decay, or re-absorbtion of CO2, is relatively rapid during the first 40 years, with about 40% remaining in the atmosphere in 1890. However, rapid decline in the re-absorption rate leaves 25% of the original tonne in the atmosphere in 2010. We use this model to estimate contributions to atmospheric accumulation of CO2.
We then separate countries into the north and south. The north comprises Europe (including Turkey), the Former Soviet Union (FSU), North America, Japan, Australia and New Zealand. The south comprises Asia (excluding Japan and the FSU), Africa, the Middle East, Latin America, the Caribbean and the Pacific islands.
The north has dominated cumulative emissions from fossil-fuel combustion. In 2000, cumulative atmospheric CO2 measures from fossil-fuel emissions in the north and south were 372 and 115 gigatonnes (Gt), respectively. For land-use change, the converse has been true: Extensive deforestation in the south raised its cumulative CO2 contribution to 180 Gt by 2000, while reforestation in the north led to carbon re-absorption and a decline from a peak in the early 1960s to 58 Gt by 2000. For fossil fuels and land-use change combined, the cumulative CO2 from the south in 2000 -- 295 Gt -- was almost 70% of cumulative CO2 from the north -- 430 Gt.
To project conditions in the near future, we use a scenario that reflects the current aspirations of many developing countries: rapid economic growth in a globalising economy, low population growth, the rapid introduction of more efficient technologies, and an energy path -- unconstrained by carbon emissions reductions -- that is consistent with the current development strategies of countries with abundant domestic fossil-fuel resources.
In our projections, annual emissions for the south and north are already diverging toward southern dominance in 2007. By 2025, only 18 years from now, the south’s annual emissions are around 32 Gt -- 32% higher than emissions from the north (21 Gt). We use the Bern model to calculate cumulative atmospheric CO2 from the two regions. By 2025, the cumulative CO2 from the south -- 555 Gt -- is 91% of the north’s 609 Gt. The south takes the lead about five years later.
With separate cumulative emissions series for the north and south, we can compute the atmospheric CO2 concentrations that are attributable to each region. This provides an illuminating comparison between the historical global CO2 concentration and the projected concentration attributable to the south alone. The south’s isolated concentration in 2025 matches the measured global concentration in 1986 -- 350 parts per million (ppm) (see figure 1). And by 1986, serious scientific concern about the greenhouse effect had already generated the crisis atmosphere that catalyzed the UN Conference on Environment and Development in 1992.
Projecting the consequences of southern development alone, with no historical or future contribution from the north, by 2040 the south surpasses the current global concentration; by 2060, it surpasses the 450 ppm threshold that the IPCC associates with large, irreversible impacts on developing countries. By the end of the century, the atmospheric concentration is nearing 600 ppm and the south has long since passed the extreme-danger threshold. It is important to bear in mind that these figures are, if anything, conservative. They do not include possible carbon cycle feedback effects -- such as increased soil carbon respiration or diminished ocean absorption -- as the Earth warms and the oceans acidify. Such processes would result in concentrations of atmospheric CO2 even higher than reported here. The clear implication is that emissions from the South alone are more than enough to catalyse a climate crisis for the south.
Our results reveal the dangerous fallacy in the notion that the south can utilise carbon-intensive growth to dramatically increase incomes -- a kind of last-minute, fossil-fueled development push -- before the onset of catastrophic climate change. In this scenario the south achieves rapid short-run development, but on a carbon-intensive path that virtually assures the crossing of critical climate thresholds, even if there had never been any emissions from the north. To reinforce the implication, it’s worthwhile to pursue the counterfactual a bit further. By the 2030s, the scientists in an isolated south would observe unequivocal global warming, widespread glacial and polar melting, and a rising sea level. Out of necessity and self-interest, the south’s governments would then replicate the recent global experience by convening to plan for a carbon-free future.
Unfortunately, things are even more precarious for the south in the real world, which also confronts the north’s legacy of fossil-fueled growth. If global emissions continue unabated, the resulting increases in temperatures and sea level, greater storm intensity, reduced agricultural productivity and dwindling freshwater supplies will likely undermine the south’s development long before it arrives at northern income levels. But from the perspective of the south’s own self-interest, focusing exclusively on the northern sources of this problem is a dangerous distraction. As our results indicate, the south’s own emissions have already moved it near the brink of rapid global warming. Cumulative emissions from the north have primarily served to shift fundamental and unavoidable southern decisions about mitigation a few years closer to the present.
This conclusion is sufficiently startling that the mind gropes for an alternative to such injustice. Why should the south have fallen into this trap, when the north has somehow managed to avoid it? On reflection, the answer is obvious. The south’s population is over four times greater than the north’s, so it has been trapped by the sheer scale of its emissions at a much earlier stage of development. The south finds itself weighed down by a mass of humanity, as well as the energy technologies and fuels of an earlier age. The question is not if the south will commit to emissions reductions -- under any scenario it eventually must for its own sake -- but whether it will do so in time, and how the costs of the transition are to be shared.
We conclude that the conventional wisdom is dangerously misguided. The south cannot relegate mitigation to the north until it achieves prosperity. In fact, cumulative emissions from a carbon-intensive south have already reached levels that are dangerous for the south itself. They are more than sufficient to create a global climate crisis, even if the north eliminates all of its emissions immediately. So we face another inconvenient truth: a carbon-intensive South faces environmental disaster, no matter what the north does. For its own sake, the south must recognize this hard truth, accept the necessity of serious, costly mitigation, and immediately embark on a low-carbon development path. The north must clearly do the same, while recognising that its own survival requires an immediate, large-scale commitment to assisting emissions reductions in the south.
David Wheeler is a senior fellow at the Washington-based not-for-profit think-tank, the Center for Global Development
Kevin Ummel and Robin Kraft are both research assistants at the Center for Global Development