August 2nd, 2017
There is only a five per cent chance of meeting the Paris Agreement target of limiting the increase in global temperature to below 2 degrees Celsius, a new US-based study has found.
The Paris Agreement set two major temperature goals: a long-term goal of keeping the increase in global average temperature to “well below” 2°C above pre-industrial levels, and a second goal to limit the increase to 1.5°C.
However, the new study, published in Nature Climate Change this week, found that it is highly likely that the planet will warm by over 2°C during this century.
The study led by researchers from the University of Washington outlined three major factors affecting future emissions – population, economic growth and carbon use.
The new research found that expected high population growth this century will have a relatively small effect on temperatures because most of the growth will occur in Africa “which uses few fossil fuels”.
A more important factor influencing future warming is carbon intensity or the level of carbon emissions produced for each dollar of economic activity.
Carbon intensity has dropped in recent decades as countries have increased efficiency and introduced standards to reduce carbon emissions.
The study concluded that the speed at which carbon intensity falls in coming decades will be key in determining future temperature rises.
This will depend on a variety of factors, including technological developments and national and international commitment.
Using projections based on 50 years of global data, the researchers concluded that we can expect an increase in global temperature of 3.2°C by 2100.
They also concluded that there is a 90 per cent likelihood that warming this century will increase between 2.0°C and 4.9°C.
The study found only a one percent chance that warming could be maintained at or below the more ambitious Paris Agreement target of 1.5°C.
“Our analysis shows that the goal of 2 degrees is very much a best-case scenario,” said Professor Adrian Raftery, lead author of the study.
“It is achievable, but only with major, sustained effort on all fronts over the next 80 years”, added the Dublin-born statistician.
According to Prof Raftery, while new findings are “compatible with previous estimates”, the “most optimistic projections” are now unlikely to occur.
“We’re closer to the margin than we think,” he said.
Speaking to The Guardian this week, Raftery added that “action is very important” even if the Paris climate target is not met.
“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”, he said.
“On the contrary, avoiding the higher temperature increases that our model envisages is even more important”.
Dargan Frierson, a co-author of the study, said that countries supported the 1.5°C target at the Paris Agreement because of “the severe impacts on their livelihoods that would result from exceeding that threshold”.
He warned, however, that damage caused by extreme heat, drought, and rising sea levels will be much more severe with a temperature increase of 2°C or higher.
Another study, also published in Nature Climate Change this week, found that air pollution caused by climate change, if unaddressed, could lead to roughly 60,000 deaths globally in 2030 and 260,000 deaths in 2100.