Tuesday's one-day summit at the annual U.N. General Assembly gathering of more than 100 world leaders is a forum for non-binding pledges. It was designed to lay the groundwork for a new global treaty to tackle climate change in December 2015.

More than 150 countries set the first-ever deadline on Tuesday to end deforestation by 2030, but the feasibility of such a goal was eroded when a key player, Brazil, said it would not join. Forests are important because they absorb the main greenhouse gas, carbon dioxide. The United States, Canada and the entire European Union signed on to a declaration to have forest loss by 2020 and eliminate deforestation entirely by 2030.

"Today we must set the world on a new course," United Nations Secretary-General Ban Ki-Moon said in opening remarks. "Climate change is the defining issue of our age. It is defining our present. Our response will define our future."

And world leaders took over with the first of many of the non-binding pledges, promising by mid-morning a total of at least $5 billion to help the world become more sustainable. That often includes turning away from the burning of coal, oil and gas and away from the destruction of the world's carbon-absorbing forests.

The European Union offered one of the few proposals — specific targets beyond 2020 — saying its member nations would cut greenhouse gases so that by 2030 they would be 40 percent below the 1990 level. The vow also calls for using renewable energy for 27 percent of the bloc's power needs and to increase energy efficiency by 30 percent.

Jose Manuel Barroso, president of the European Commission, stressed it could be done without harming the economy in brief Tuesday speech. He said over the next seven years, the European Union would provide $3 billion euros (nearly $3.9 billion) to help developing countries become more sustainable.

"The European Union is on track to meet our targets and at same time we have seen our economy grow," Barroso. "We prove climate protection and a strong economy must go hand in hand."

France for its part promised $1 billion. Korea pledged $100 million. Others, like Chile, pledged cuts in greenhouse gas emissions by 2020.

When it comes to forests, if the goal is met, the U.N. says it would be the equivalent of taking every car off the road in the world. The group of companies, countries, and non-profits also pledged to restore more than one million square miles of forest worldwide by 2030. Norway vowed to spend $350 million to protect forests in Peru and another $100 million in Liberia.

Japan, which had relaxed earlier promised targets, vowed to issue new goals early next year and be a model for a low-carbon society. It also said it was launching a satellite to monitor and verify emissions. Canada pledged to make cars and trucks more fuel efficient.

Venezuelan president Nicolas Maduro used the opportunity to chastise "polluting powers" for causing an "evil of such planetary dimensions" and then wanting to barter their way out of their responsibilities.

Seychelles President James Michel called small island nations like his "victims of this pollution" and said it was up to the countries that burn the most coal, oil and gas to do the most.

"If they don't do something the Earth will not survive and that will be the end of us all," Michel said in an interview with The Associated Press before the start of the summit Tuesday.

Peru's environment minister, Manuel Pulgar-Vidal the chair of the treaty negotiations scheduled for Lima at the end of this year, said in an interview with the Associated Press that the "only way to succeed in this debate is to bring all the voices together."

But he said divisions remain in key areas.

Ban, actor Leonardo DiCaprio, former U.S. Vice President Al Gore and Rajendra K. Pachauri, who headed the Nobel Prize-winning panel of scientists who studied the issue, warned that time was short. By 2020, Ban said the world must reduce greenhouse gases to prevent an escalating level of warming that world leaders five years ago called dangerous. Leaders in 2009 pledged to keep world temperatures from increasing by another 2 degrees Fahrenheit (3.6 degrees Celsius.)

The actor turned UN ambassador on climate change echoed The World Bank in calling for nations to put a pricetag or tax on carbon to pressure people and countries to cut back.

Pachauri and Ban told world leaders the effects of global warming are already here, pointing to a U.N. building that flooded during the devastating Superstorm Sandy in 2012. Pachauri said it will get worse with droughts, storms, food and water shortages. He foresaw even more violent climate-driven conflicts.

And, Pachauri said, "a steady rise in our death toll, especially among the world's poorest. How on Earth can we leave our children with a world like this?"