Renewable energy sources, such as solar, wind, hydropower and bioenergy, need to form a far bigger share in the rebound in energy investment after the coronavirus pandemic, the Paris-based agency said.
"We are not investing enough to meet for future energy needs, and the uncertainties are setting the stage for a volatile period ahead," said IEA chief Fatih Birol.
The IEA noted that demand for renewables continues to grow. However, "this clean energy progress is still far too slow to put global emissions into sustained decline towards net zero" by 2050, which the IEA believes will help limit the increase in global temperatures to 1.5 degrees Celsius (2.7 degrees Fahrenheit).
The IEA also said that the extra investment might not be as difficult as it sounds.
"More than 40% of the required emissions reductions would come from measures that pay for themselves, such as improving efficiency, limiting gas leakage, or installing wind or solar in places where they are now the most competitive electricity generation technologies," it said.
Under this scenario, temperatures in the year 2100 would be 2.6 C higher than preindustrial levels.
The second scenario looks at governments' pledges to achieve net-zero emissions, potentially doubling clean energy investment over the next decade.
If countries manage to implement these pledges in time, the global average temperature increase would be around 2.1 C by the year 2100 — an improvement, but still well above the 1.5 Celsius agreed under the Paris accord, the IEA concluded.
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Mans Nilsson, executive director of the environmental group Stockholm Environment Institute, told DW that the IEA has gradually moved toward a "more distinct tone urging decision makers to mitigate climate change."
"Traditionally, [the] IEA has been rather 'soft' on fossil energy and bearish on the potential of renewables. Their overly pessimistic forecasts of the development of installation costs for solar and wind have been infamous," he added.
"This has now been rectified," he said, adding that he believes the IEA seems "still too positive on oil and gas."
"In a way, it is a shift to a more rational and realistic view on the energy transition. It is also a shift to a more activist approach, which is a trend in many multilateral [organizations]," Nilsson said.
"Many governments have relied on the WEO in the past to justify their support for fossil fuels," said David Tong of the Price of Oil nongovernmental organization, which advocates transitioning to clean energy.
"At COP26, [governments] will compromise their credibility if they ignore the IEA's guidance now, when it's finally consistent with the 1.5-degree limit they agreed to in Paris," he told DW.
"We need our leaders to stop listening to fossil fuel CEOs and instead follow the science. Will they back up net zero and 1.5 degree commitments with immediate action to stop new oil, gas and coal extraction, and surge money into clean energy and efficiency solutions?"