The economic damage caused by a ton of CO2 emissions, often thought of as the social cost of carbon, could be six times higher than that estimated by the United States.
It is the conclusion of a study carried out by scientists at Stanford University, in the United States. But according to the new study, published this week in the online edition of 'Nature Climate Change, the current cost could be much higher. "We estimate that the social cost of carbon is not $ 37, as previously estimated, but $ 220," says study co-author Frances Moore, a doctoral student in the School's Emmett Interdisciplinary Program in Environment and Resources. of Stanford Earth Sciences. Based on the results, countries may want to increase their efforts to reduce greenhouse gases, says another of the authors of the paper, Dr. Delavane Diaz, a doctoral student in the Department of Science and Engineering Management.
"If the social cost of carbon is higher, many more mitigation measures will have to undergo a cost-benefit analysis," says Diaz. Because carbon emissions are so harmful to society,… For their Study, Moore and Diaz modified a well-known model to calculate the economic impact of climate change, known as an Integrated Assessment Model, or IAM. Its alternative formulation incorporates recent empirical findings that suggest that climate change could substantially decrease the mass of economic growth, especially in poor countries. IAM is an important policy tool. As it includes the costs and benefits of reducing emissions, it can provide information on the optimal level of investment in reducing emissions. The United States Environmental Protection Agency, for For example, he used the median value of $ 37 from three AMIs to evaluate greenhouse gas regulations ero. Canada, Mexico, UK, France, Germany, and Norway have also used IAM to an… Although useful, IAMs have to make numerous simplifying assumptions. For example, one of the limitations is that it does not take into account how the damages associated with climate change might persist over time. "For 20 years, models have assumed that climate change cannot affect the basic growth rate of the economy," says Moore.
However, a number of new studies suggest that this may not be entirely true. If climate change doesn't just af… In the new study, Moore and Diaz used a widely used IAM, called the Dynamic Integrated Climate-Economy Model (DICE), and modified it in three ways: They allowed climate change to affect the growth rate of the economy; they took into account adaptation to climate change and divided the model into two regions representing high- and low-income countries. Every ton of CO2 emitted into the atmosphere causes $ 220 damage. "There have been many studies that suggest that rich and poor countries will fare very differently in terms of the future effects of climate change and we wanted to explore that," says Diaz.
One of the main conclusions of the new work is that the damages associated with reductions in the rates of economic growth justify a very rapid and early mitigation that is sufficient to limit the growth of global temperature 2ºC above pre-industrial levels. This ... "This effect is not included in the standard IAM - points out Moore -, so until now it is very difficult to justify aggressive and costly mitigation measures because the damages are not great enough".
Developing countries may suffer more from climate change.
"If poor countries become less vulnerable to climate change as they get richer, delaying some emission reductions until they are more fully developed to make better policies," explains Diaz. Our model shows that this is a great uncertainty in the mitigation policy that no one has explored in previous works. "
The DICE model indicates that the representation of mitigation is limited because it does not take into account, for example, the fact that low carbon technologies take time to develop and deploy. Additionally, while exploring the effects of temperature on economic growth, the model does not take into account the possibility that mitigation efforts will also impact growth.
"For these two reasons, the level of rapid, short-term mitigation detected in our study may not necessarily be economically optimal," Diaz acknowledges.
"But this does not change the overall result that if temperature affects economic growth rates, society could face much greater climate damage than previously thought and this would justify stricter mitigation policies," he concludes.