Global temperatures could rise by 1.4-3.0C (2.5-5.4F) above levels for late last century by 2050, a computer simulation has suggested.
Almost 10,000 climate simulations were run on volunteers' home computers.
The projections, published in Nature Geoscience, are somewhat higher than those from other models. The researchers aimed to explore a wider range of possible futures, which they say helps "get a handle" on the uncertainties of the climate system.
People planning for the impacts of climate change need to consider the possibility of warming of up to 3C by 2050, even on a mid-range emission scenario, the researchers say.
The study - run through climateprediction.net with the BBC Climate Change Experiment - ran simulations using a complex atmosphere-ocean climate model.
The representations of physical parameters were varied between runs of the model, reflecting uncertainties about precisely how the climate system works.