New research, published in Nature Climate Change has projected only a 5 percent chance that the world will meet the 2 degrees Celsius warming target laid out in the Paris climate accord. The study says that trends in the economy, carbon emissions, and growth in population have nearly ruled out staying under the 2 degree threshold. The accord, which was signed by 195 nations, set out to keep temperature increases “well below 2C” from pre-industrial levels, with a more ideal target of 1.5 Celsius. The study found just a 1 percent chance of keeping temperatures below this aspirational threshold.
University of Washington Professor Adrian Raftery, who led the study, warned:
“We’re closer to the margin than we think. If we want to avoid 2C, we have very little time left. The public should be very concerned.”
The Paris agreement settled on the 2C target partially because scientists have warned the most drastic effects of climate change, such as sea-level rise, drought, and heatwaves would be much worse if temperatures rise beyond such a threshold. A separate study, released Monday, showed these effects, if unmitigated, could lead to 60,000 deaths by 2030 and 260,000 by 2100. It found that temperature increases could worsen air pollution.
The new study, from University of Washington, forecasts a 90 percent likelihood that temperatures will rise between 2 and 4.9 degrees Celsius by 2100. Such an outcome would avoid both the most optimistic and the worst possible outcomes projected by the UN Intergovernmental Panel on Climate Change.
Instead of focusing on the relationship between temperature and greenhouse gas emissions, the research looked at trends over the past 5 decades in global population, per capita GDP, and carbon intensity – which refers to carbon dioxide emissions per dollar of economic activity.
Using statistical modeling, the study found that carbon intensity will be a major factor in warming patterns. Advances in technology are projected to reduce carbon intensity 90 percent over the next century, especially in places such as India and China. Yet, the research found, this will not be enough to keep warming under the 2C threshold.
Although the world’s population is expected to reach 11 billion by the end of the century, the research projected only a minor impact on warming trends, since much of this growth will be in sub-Saharan Africa, where carbon emissions are low.
“We would warn against any tendency to use our results to say that we won’t avoid 2C, and so it’s too late to do anything. On the contrary, avoiding the higher temperature increases that our model envisages is even more important, and also requires urgent action.”