The International Energy Agency, in a report with the Organization for Economic Co-operation and Development, recommends governments make policy transformations like ending fuel subsidies and putting a price on CO2 emissions.
"As the energy sector is responsible for the majority of man-made CO2 emissions, reforming it is critical to solving the climate change dilemma," IEA Deputy Executive Director Richard Jones said in a statement.
Both agencies said that emerging economies are starting to develop modern energy technology, meaning demand is growing and so are the strains on the environment.
The report said $46 trillion is needed before 2050 to transform the economy to one based on low-carbon technology. If that investment is made, the agencies say, energy-related emissions of CO2 would drop by half by 2050.
"Rising global energy demand and the need to drastically cut CO2 emissions require a transformation in the way we produce, deliver and consume energy," said Jones.