ROME — Pope Francis upbraided political leaders for their half-hearted response to the climate crisis Wednesday, suggesting their weak resolve in cutting emissions reveals a lack of political will.

In his message to the participants in the COP25 United Nations convention on climate change, currently taking place in Madrid, the pope reiterated his conviction that climate change is “one of the main challenges for humanity” because it threatens the future of the human race.

The scientific data at our disposal call for a “strong sense of urgency for rapid action” to stop global warming, Francis said, but the window of opportunity to do so is closing fast.

The pontiff praised the swift passage of the COP 21 Paris Agreement in 2015, while lamenting the apparent cooling of interest on the part of the international community.

“Sadly, after four years, we must admit that this awareness is still rather weak,” he said, adding that recent studies “show that the current commitments made by States to mitigate and adapt to climate change are far from those actually needed to achieve the goals set by the Paris Agreement.”

“They demonstrate how far words are from concrete actions!” he said.

“From this perspective, we must seriously ask ourselves if there is the political will to allocate with honesty, responsibility and courage, more human, financial and technological resources to mitigate the negative effects of climate change, as well as to help the poorest and most vulnerable populations who suffer from them the most,” he declared.

Limiting global warming requires “a clear, far-sighted and strong political will, set on pursuing a new course that aims at refocusing financial and economic investments toward those areas that truly safeguard the conditions of a life worthy of humanity on a ‘healthy’ planet for today and tomorrow,” he said.

As he has done on other occasions, the pope pointed hopefully to young people as the vanguard of the battle against climate change, especially the celebrated 16-year-old activist Greta Thunberg.

“Young people today show a heightened sensitivity to the complex problems that arise from this ‘emergency,’” Francis said. “We must not place the burden on the next generations to take on the problems caused by the previous ones.”

Last August, the pope said he was greatly encouraged by the involvement of young people in the battle against climate change, which he called a “global emergency” that can lead to “the death of humanity.”

There are signs of hope for the environment “especially in the movements of young ecologists, such as the one led by Greta Thunberg, ‘Fridays for Future.’” Francis said.

“I saw one of their signs that struck me: ‘We are the future!’” he said.

The pope met the young Swedish activist in the Vatican last April and urged her to continue her crusade against climate change.

Just yesterday, Ms. Thunberg warned crowds in Lisbon that people are “underestimating the force of angry kids,” while assuring her hearers that in fact they are “angry and frustrated.”

Follow @tdwilliamsrome