Former Democratic presidential candidate Sen. John Kerry and former Republican House Speaker Newt Gingrich may agree on little politically, but they agreed Tuesday on this: Global warming is no hoax.

Video: Kerry, Gingrich Debate

So instead of arguing about the merits of climate change science at a face-off sponsored by New York University's Robert Wagner School of Public Service, the Brookings Institution and the Cato Institute, the pair debated the right approach to tackling global warming.

They also promoted each other's books. Gingrich said Kerry's new book, "This Moment on Earth: Today's New Environmentalists and Their Vision for the Future," is "a very interesting read" and said he agrees with 60 percent of it. Kerry hasn't read Gingrich's new book on the environment, due out later this year, but said he has always enjoyed their exchanges.

Gingrich, who has said he'll decide on whether to run for the presidency by the fall, advocated a "green conservativism," market-based approach, including cash incentives and tax breaks to stimulate new technology.

"I want to suggest that we need a new science- and technology-based, entrepreneurial, market-oriented and locally led environmentalism," Gingrich said.

Kerry said legislation and regulation offer a faster route to heading off the "tipping point" level of greenhouse gases of 450 parts per million. That's the level of greenhouse gases in the atmosphere that scientists say would seriously hurt worldwide economies.

He said market solutions can't be solely relied on to respond to the situation fast enough. Asking industry to come up with solutions "is like saying, 'Barry Bonds, go investigate steroids.'"

Center stage at the debate was a just-released report from the Intergovernmental Panel on Climate Change that predicted increased hunger, species extinction, more severe weather and other major threats to the planet and humankind.

The report, the second of four due by the end of the year, represents the work of about 2,500 scientists examining 29,000 sets of data collected over the past five years. The first report in February laid out the scientific case for how global warming is happening.

Related: Download The IPCC Report

Despite accusations by scientists that the report has been watered down, it's the clearest and most comprehensive scientific statement to date on the impact of global warming mainly caused by human-induced carbon dioxide pollution, he said.

The United States, China and Saudi Arabia raised many of the objections to the phrasing, often seeking to tone down the certainty of some of the more dire projections.

Among the report's conclusions:

• Areas in drought will become even more dry, adding to the risks of hunger and disease.
• The world will face heightened threats of flooding, severe storms and the erosion of coastlines.
• North America will experience more severe weather and weather-related events -- hurricanes, floods, droughts, heat waves and wildfires -- with human and economic loss. Crop yields may increase by 5 percent to 20 percent from a longer growing season, but will plummet if temperatures rise by 7.2 degrees.
• By 2020, up to 250 million people in Africa are likely to be exposed to water shortages. Agricultural production, including access to food, in many African countries and regions is projected to be severely compromised by climate variability and change.
• Freshwater availability in Central, South, East and Southeast Asia, particularly in large river basins, is projected to decrease due to climate change which, along with population growth and increasing demand arising from higher standards of living, could adversely affect more than a billion people by the 2050s.

At one point, Kerry asked Gingrich to comment on climate change doubters such as Sen. James Inhofe, R-Okla., who has characterized climate change science as "greatest hoax ever perpetrated on the American people."

"What's your message to them here today?" Kerry asked.

"My message, I think, is that the evidence is sufficient that we should move towards the most effective possible steps to reduce carbon loading in the atmosphere," but regulation and litigation are the least effective approaches, Gingrich said.