UN chief Antonio Guterres on Monday called for vast investment to help Pakistan recover from what he called a "climate disaster of monumental scale".
International donors rallied to provide the South Asian nation with more than $8 billion in support.
"Pakistan is doubly victimised by climate chaos and a morally bankrupt global financial system," the Secretary General said at a UN conference in Geneva to gather international donations for Pakistan as it responds to last year's catastrophic floods.
Officials from 40 countries, as well as private donors and international financial institutions, met to help Islamabad reach its goal of securing funding for about half its recovery bill of $16.3 billion.
Pakistan's Information Minister, Marriyum Aurangzeb, said pledges had reached $8.57 billion.
The biggest tranche of funding came from the Islamic Development Bank, which pledged $4.2 billion for reconstruction in flood-hit areas across Pakistan.
Mr Guterres said the world must face up to the "brutal injustice" of harm suffered by developing countries because of climate change.
“If there is any doubt about loss and damage — go to Pakistan," he said. "There is loss. There is damage. The devastation of climate change is real."
Pakistan is responsible for less than 1 per cent of global greenhouse gas emissions, he said, and is therefore not culpable for the climate crisis.
“No country deserves to endure what happened to Pakistan,” Mr Guterres said.
“But it was especially bitter to watch that country’s generous spirit being repaid with a climate disaster of monumental scale.”
People in South Asia are 15 times more likely to die from the effects of climate change than elsewhere, the UN chief said, repeating his call for "massive support" to countries on the front lines of the climate crisis.
Pakistani Prime Minister, Shehbaz Sharif, called for a sustained international support plan to meet "this daunting challenge".
"I am asking for a new lifeline for people who need to power our economy and re-enter the 21st century with a future that is protected from such extreme risks to human security," Mr Sharif said.
The 2022 flooding, caused by record-breaking monsoon rainfall, was Pakistan’s worst disaster in decades, leaving one third of the country submerged, affecting 33 million people, killing at least 1,700 and displacing 8 million.
The ensuing floods rendered more than 2 million people homeless, wiped out crops and destroyed or damaged vital infrastructure, including thousands of kilometres of roads and railway.
“And it pushed some 9 million people to the brink of poverty,” said Mr Guterres.
At a joint press event with Mr Sharif, he told reporters he was deeply frustrated that global leaders were not giving “this life-or-death emergency the action and investment it requires”.
Monday's one-day conference aimed to secure commitments of support towards the country's $16-billion recovery and reconstruction plan.
Pakistan's government plans to cover half that amount with "domestic resources", including through public-private partnerships, but is looking to the international community to cover the rest.