Ahead of the meeting in Turin of the G7 environment and energy ministers, experts say the group's climate protection policy is inadequate and set to fall far short of targets.
According to a report released on Tuesday by the think tank Climate Analytics, members of the Group of Seven (G7) economically strong democracies may achieve just half of the greenhouse gas reduction needed to comply with the 1.5-degree Celsius limit by 2030.
None are on track to meet their existing emission reduction targets for 2030, which are not yet collectively aligned with 1.5 degrees, the authors said.
At the 2015 climate conference in Paris, the global community set itself the goal of limiting global warming to 1.5 degrees compared with pre-industrial times.
The background to the decision is the severe effects of global warming, such as increasingly frequent heavy storms, droughts, floods and forest fires.
The authors called on the G7 countries to review their respective targets for 2030 in order to harmonise them with the 1.5-degree limit.
With targets due to be set for 2035, now is the ideal time to make changes, they noted.
"Such a shortfall in ambition does not provide the leadership signal needed from the world's richest countries, making up around 38% of the global economy, and responsible for 21% of total [greehouse gas] emissions in 2021," the report said.
The G7 is an informal forum of the heads of state and government of Canada, France, Germany, Italy, Japan, the United Kingdom and the United States.
The European Union is also represented at the meetings, while Italy currently holds the G7 presidency.
The G7 ministers are scheduled to gather in Turin in northern Italy from Sunday to Tuesday.