They found there's a 13 percent chance Earth is already committed to a climate that's 1.5 degrees Celsius warmer.
Earth's population is expected to reach 11 billion by the year 2100, according to the projections, an nearly 50 percent increase from the current world population.
"Our analysis shows that the goal of 2 degrees (Celsius) is very much a best-case scenario", Raftery said.
The research underscores the challenges nations face as climate projections become grimmer, and the odds of limiting global warming to an acceptable level shrink. Researchers estimated that ceasing all carbon emissions today would still result in a 1.3 degree rise by the end of the century.
On the basis of these data, "the increase of the temperature is probably 2°C to 4.9° C, with a median value of 3.2°C and a 5% chance that it is less than 2°C", the researchers write.
"Indeed, damages from heat extremes, drought, extreme weather and sea level rise will be much more severe if 2 C or higher temperature rise if allowed", says Dargan Frierson, co-author of the study and associate professor of atmospheric sciences at the University of Washington.
In the study, the researchers utilized statistical projections on world population, gross domestic product per person, and the amount of carbon emitted for each dollar of economic activity.
Raftery said that while their new analysis sits well with previous estimates, the most optimistic projections are not likely to occur, with the world being "closer to the margin" than believed.
Some uncertainty remains around how much Africa's emissions will grow over the coming century, he said, but relative to the United States, it's a question of whether Africa's per capita emissions will be "lower or much, much lower".
Thorsten Mauritsen from Max Planck Institute for Meteorology situated in Germany and Robert Pincus from the University of Colorado at Boulder have conducted this study and found out that global warming is inevitable and will come at a bit more degrees.
"This "committed warming" is critical to understand because it can tell us and policymakers how long we have, at current emission rates, before the planet will warm to certain thresholds". We already have gone through a 1.5 degrees Celsius warming out of the 2 ones earlier mentioned.
A USA -based expert team used projections for population growth to estimate future production, and related carbon emissions from burning fossil fuels.
"The consequences of not [acting] are even higher with these results than they were before, when we could think about 1.5 degrees as being in the realm of possibility - which I think, realistically, it's not", he said, urging more investments in research, a tax on carbon and other established paths to emissions reductions. "Future carbon dioxide emissions will then add extra warming on top of that commitment". There's a 99 per cent chance that climate change will break through that limit. And that number will climb over four-fold to 260,000 deaths globally by 2100.