U.N. Secretary-General Antonio Guterres has a message for leaders of the 20 major economic powers ahead of this week's summit: Take stronger leadership and bolder action to tackle critical problems from climate change to inequality at a time the world is facing "a crisis of confidence."

Before flying to Buenos Aires, Argentina, for the Group of 20 meeting, the U.N. chief told reporters Wednesday it is imperative that countries work together to create a fairer world.

"Those left behind by globalization are losing trust in governments and institutions," he warned.

He said inequality is "pervasive and increasing," trade disputes are escalating, and geopolitical tensions "are adding further pressure to the global economy."

In addition, Guterres said, "We are headed for a world of cataclysm and uncertainty due to climate disruption."

The Intergovernmental Panel on Climate Change recently said time is running out if the world wants to achieve the most ambitious target in the 2015 landmark Paris climate agreement — keeping global warming at 1.5 degrees Celsius (2.7 degrees Fahrenheit). The planet has already warmed about 1 degree Celsius since pre-industrial times and is on course for another 2 to 3 degrees of warming by the end of the century unless drastic action is taken, its report said.

"The social, economic and environmental costs of climate change dwarf the costs of acting now," Guterres said.

"Failure to act means more disasters and emergencies and air pollution that could cost the global economy as much as $21 trillion by 2050," he said. "On the other hand, ambitious climate action will not only slow temperature rise, it will be good for economies, for the environment and for public health."

Guterres said the G-20 members are responsible for more than three-quarters of greenhouse gas emissions that cause global warming, and they have the money and power to tackle the climate issue.

The secretary-general said he has the same message for the G-20 and for the leaders who will be meeting in Poland beginning Sunday to try to agree on the fine print of the Paris agreement: "At a time of declining global trust, our world needs stepped-up global leadership."

"Strong economic growth, reduced inequality, and limiting carbon emissions are possible and compatible," he said. "But we need greater ambition. We are in a race for our future. It's a race we can and simply must win."

Guterres, who will also attend the climate meeting in Katowice, said national leaders need to make their countries more ambitious in tackling problems like climate change but they also must be open to compromise because agreement "is the most important objective."

The secretary-general also is urging the G-20 leaders to help equip people with the skills to work amid technological progress and digitalization. Noting that the number of hungry people around the globe has risen to 821 million, he welcomed G-20 efforts to ensure "a sustainable food future" and improved food and nutrition.

He also called on G-20 leaders to move beyond pledges on gender equality and act against the discrimination, violence and unequal access to resources faced by "an overwhelming majority of women across the globe."

On the issue of migration, Guterres said that in many cases it "continues to be unsafe, disorderly and unregulated." He urged G-20 leaders "to support a global migration system that can accommodate the demand for mobility that exists in our increasingly dynamic populations."