Secretary-General Antonio Guterres said experts who surveyed the state of the world in 2023 set the Doomsday Clock at 90 seconds to midnight, the closest ever to "total global catastrophe.''

He pointed to the war in Ukraine, "runaway climate catastrophe, rising nuclear threats,'' the widening gulf between the world's haves and have-nots, and the "epic geopolitical divisions'' undermining "global solidarity and trust.''

In a wide-ranging address Guterres urged the General Assembly's 193 member nations to change their mindset on decision-making from near-term thinking, which he called "irresponsible'' and "immoral,'' to looking "at what will happen to all of us tomorrow, and act.''

He said this year's 75th anniversary of the Universal Declaration of Human Rights should serve as a reminder that the foundation of the inalienable rights of all people is "freedom, justice and peace.''

Guterres said the transformation needed today must start with peace, beginning in Ukraine, where unfortunately, he said, peace prospects "keep diminishing'' and "the chances of further escalation and bloodshed keep growing.''

"I fear the world is not sleepwalking into a wider war. It is doing so with its eyes wide open,'' he said.

The world must work harder for peace, Guterres said, not only in Ukraine but in the decades-old Israeli-Palestinian conflict "where the two-state solution is growing more distant by the day,'' in Afghanistan where the rights of women and girls "are being trampled and deadly terrorist attacks continue'' and in Africa's Sahel region where security is deteriorating "at an alarming rate.''

He also called for stepped up peace efforts in military-ruled Myanmar which is facing new violence and repression, in Haiti where gangs are holding the country hostage, "and elsewhere around the world for the two billion people who live in countries affected by conflict and humanitarian crises.''

The secretary-general said it is time for all countries to recommit to the U.N. Charter, which calls for peaceful settlement of disputes, and for a new focus on conflict prevention and reconciliation.

The proposed new U.N. Agenda for Peace, he said, calls for "a new generation of peace enforcement missions and counter-terrorist operations, led by regional forces,'' with a U.N. Security Council mandate that can be enforced militarily and guaranteed funding. "The African Union is an obvious partner in this regard,'' he added.

Guterres also said it is time for nuclear-armed countries to renounce the first use of all nuclear weapons, including tactical nuclear weapons, a possible use that Russia has raised in Ukraine.

"The so-called `tactical' use of nuclear weapons is absurd,'' he said. "We are at the highest risk in decades of a nuclear war that could start by accident or design. We need to end the threat posed by 13,000 nuclear weapons held in arsenals around the world.''

As for the global financial system, Guterres called for "radical transformation'' to put the needs of developing countries at the center of every decision.

He pointed to rising poverty and hunger around the world, developing countries forced to pay five times more to borrow money than advanced economies, vulnerable middle-income countries denied concessional funding and debt relief, and the richest 1% of the world's people capturing "almost half of all new wealth over the past decade.''

Multilateral development banks must change their business model, Guterres said.

Guterres told diplomats that 2023 must also be "a year of game-changing climate action,'' not of excuses or baby steps, and there must be "no more bottomless greed of the fossil fuel industry and its enablers.''

The world must focus on cutting global-warming greenhouse gas emissions by half this decade, which means far more ambitious action to cut carbon pollution by speeding the transition from fossil fuels to renewable energy, especially in the world's 20 richest global economies, he said.

It also means cutting emissions from the highest emitting industrial sectors, steel, cement, shipping and aviation, he said.

Guterres had a special message for fossil fuel producers who he said are scrambling to expand production "and raking in monster profits.''

"If you cannot set a credible course for net-zero, with 2025 and 2040 targets covering all your operations, you should not be in business,'' he said.

The secretary-general invited any leader in government, business or civil society to the Climate Ambition Summit he is convening in September, with a condition.

"Show us accelerated action in this decade and renewed ambitious net zero plans, or please don't show up,'' Guterres said.