As populations across the world grow, new research out of MIT shows the rising influence of large or developing countries in shaping our future global challenges.

MIT's Joint Program on the Science and Policy of Global Change's 2012 Energy and Climate Outlook report projects that energy use could double by 2050. China alone could go from having about 50 million cars and trucks on the road to having about 300 million in less than 40 years. Fast-growing G20 nations – including Russia, Brazil, Mexico, China, India and other developing Asian countries – could put four times more vehicles on the road by 2050 than they have today.

"While we have known for some time that large economies outside Europe, North America and Japan would have a growing influence on greenhouse gas emissions and the climate, the dramatic increase in their energy use and emissions [by 2050]," as projected in the new report, "is staggering," says John Reilly, the co-director of the Joint Program on Global Change and a lead author of the study.

Reilly, along with the other lead author Sergey Paltsev and nine others, based their projections on the United Nations' estimate that the world's population will grow to more than 10 billion by the end of the century. They then used a computer modeling system to project how this growth would affect our energy and climate — incorporating pledges to cap emissions by 2020, made by G20 nations at an international meeting in Copenhagen in 2009.

"The unrelenting increase in greenhouse gas (GHG) emissions, concentrations and changes in climate — even assuming success at capping emissions in Europe, North America and Japan — is especially troubling, and it points to the need to redouble efforts to reduce emissions," Reilly says.

BP's head of policy Paul Jefferiss and BP economist Paul Appleby agreed in an emailed statement: "Copenhagen is a small step in the right direction but leaves an awful lot still to be done."

The report projects that as Russia, Brazil, Mexico, China, India and developing countries grow and substantially increase their energy use, they would also likely become the largest sources of emissions — contributing to a doubling of global GHG emissions, and a tripling of global carbon emissions over the century.

William M. Colton, vice president of corporate strategic planning for ExxonMobil Corp., says these projections overall show the "growing role of developing nations in shaping long-term energy and environmental trends worldwide."

With rising emissions, temperatures would warm by as much as 6.7 degrees Celsius by the end of the century, the report shows — a projection slightly higher than that of the Intergovernmental Panel on Climate Change, which has said temperatures could warm by as much as 6.4 degrees Celsius.

While the researchers note in their study that the amount of temperature increase considered "dangerous" remains open to debate and uncertainty, they write, "few would argue that the increases projected in our study — ranging from 3.5 degrees to near 7 degrees Celsius or more by 2100 — constitute danger."

Greenhouse gases other than carbon dioxide will be significant as well, the report shows. While about two-thirds of GHG emissions will continue to come from carbon dioxide, the report shows other types of sources could increase — like nitrous oxide from fertilizer, and methane from livestock. Because these other types of emissions are expected to become more prevalent, the report notes that efforts should focus on reducing them as well. That's in line with a coalition of international leaders — including the United States — who recently agreed to cut emissions of soot, methane and hydrofluorocarbons.

In assessing where we will get energy in the future, the report shows that the Copenhagen emission-reduction targets may not be enough to divert people toward using cleaner energy. It projects that coal, oil and gas would continue to be the predominant forms of energy through the next half century.

"The momentum for rising greenhouse gas concentrations — and the relatively modest growth in the share of renewable energy" indicated by the report's projections "underscores the extreme challenges to containing long-run global warming to safe levels," says Ian Parry, an advisor on climate change policy for the International Monetary Fund. These projected trends "really emphasize the critical importance of using the most effective policies for addressing these problems."

Parry advocates broad-based carbon taxes as the best solution — a tactic the European Union has adopted for airline emissions, and received much backlash for. He also says the report strengthens the case for complementing mitigation policy with research into "last resort" technologies, like expensive technologies for directly sucking CO2 out of the atmosphere, which might be deployed in the event that catastrophic warming occurs.

The MIT report comes amidst similar efforts from the U.S. Department of Energy and some large energy companies, such as ExxonMobil and BP. Both companies say the projection that there will be a substantial increase in global energy consumption, led by developing countries, is very similar to their own projections out to 2030.

But Reilly says while their projections are similar, the MIT report has a wider scope. "The forecasts presented here are similar through that period [2030], but by including detailed projections through 2050, as well as the global climate and environmental implications of population and economic growth through to 2100, we begin to see much more clearly the environmental risks we are likely to face if we continue the path we are on."

By taking this "significant long-term view," Colton says, the report shows the "overall scale and nature of challenges facing individuals, businesses and nations at large."

The researchers warn that the report should be taken as a cautionary tale, as the study says: "These findings are a projection — not a prediction, as it is within our power as a society to change the current path if we do not like its implications."

[Disclaimer: BP and ExxonMobil were not associated with the research for this report, but are financial sponsors of the Joint Program on the Science and Policy of Global Change. The International Monetary Fund is not a program sponsor]