Pope Francis, who reluctantly canceled his trip to the annual United Nations climate summit in Dubai, United Arab Emirates, because of a lung infection, sought on Saturday to lend his voice to the world’s destitute facing the brunt of climate disruption.

In an address written by the pope and delivered at the summit by the Vatican secretary of state, Cardinal Pietro Parolin, Francis assured the world, “I am with you, because time is short.” He wrote that the world, more than ever, faced environmental devastation that offended God and “greatly endangers all human beings, especially the most vulnerable in our midst, and threatens to unleash a conflict between generations.”

Francis, 86, in his decade-long pontificate, has elevated stewardship of the environment to a top priority of the church. In “Laudate Deum,” a letter on humanity’s obligations to the environment issued in October, Francis specifically called for tangible solutions at the Dubai meeting, which, at the time, he expected to attend.

But the pope’s health would not permit it. He was prevented not only from delivering the speech in person, but also from participating in many bilateral meetings, including with leaders of small and vulnerable nations whose plights he had hoped to amplify.

But the Vatican hoped his words would resonate, regardless. Cardinal Parolin read the pope’s speech in Italian-accented English, asking the assembled leaders whether the world worked “for a culture of life or a culture of death,” and again called for a multilateral new world order that, “whether we like it or not, will belong to everyone or else to no one.”

Cardinal Michael Czerny, who is one of Francis’ closest collaborators on climate issues, said that the pope was “very, very concerned” about the state of the environment and that he thought the lack of progress in recent years was “really alarming.”

“It’s a sad world that we are not able to generate self-government that can call us to what we need to do,” Cardinal Czerny said. “But anyway, that’s how it is.” He said that it was often the most vulnerable people who suffered climate change’s consequences, along with migration and hunger. “The touchstone is the suffering of the poor,” he said.

In the remarks read by Cardinal Parolin, Francis emphasized the human causes of global warming, but he added a moral critique of the consumerism, selfishness and capitalist profit motives that he views as the true root of the problem. “The drive to produce and possess has become an obsession, resulting in an inordinate greed that has made the environment the object of unbridled exploitation,” Francis wrote.

The pope urged leaders and those at the climate summit to “recognize our limits with humility and courage,” a message that is a hallmark of his pontificate. And he expressed indignation at what he saw as efforts to blame high birthrates among the poor for driving the environmental destruction.

The world’s impoverished communities account for a small share of greenhouse emissions, Francis wrote in his speech. “The poor are the real victims of what is happening: We need think only of the plight of Indigenous peoples, deforestation, the tragedies of hunger, water and food insecurity, and forced migration.”

The pope wrote that wealthy nations were incurring a “grave economic debt” for which they should be held accountable, and that those powerful nations should “find suitable means of remitting the financial debts” of vulnerable countries essentially colonized by economic interests.

Francis also called for concrete requirements for a transition away from fossil fuels that would be “obligatory and readily monitored.” And, he reiterated his call to fight world hunger and climate change with a fund replenished by the profits of the arms trade.

Tomás Insua, a co-founder of the Laudato Si’ Movement, a global network of Catholic organizations, said on a call from Dubai that Francis was using “much stronger language” than he had in earlier statements on the environment. But he lamented the fact that the pope was unable to attend the summit.

“His presence would have made a big difference,” Mr. Insua said.