Six years ago, the inconvenient truth surrounding human-caused climate change was edgy enough to earn a Nobel Prize for Al Gore and the Intergovernmental Panel on Climate Change — but the IPCC's upcoming re-assessment of our climatic future is far less likely to shake up the planet. Instead, the next chapter of the climate saga is shaping up as a long exposition, driven by economics rather than politics or science.

"The core scientific understanding has been in place for decades," says Roger Pielke Jr., a climate policy analyst and professor of environmental studies at the Center for Science and Technology Policy Research at the University of Colorado at Boulder.

The IPCC draft report due for release later this month reflects that core understanding: Earth's climate is changing, industrial activity is a factor in that change, and the effects of those changes will be increasingly felt in the decades ahead. Based on last month's leaks, the report may play up the potential effect on sea levels and play down the effect on surface temperatures — but Pielke says those projections amount to mere fine tuning.

Roger Pielke Jr. is associated with the University of Colorado's Center for Science and Technology Policy Research and other policy research centers. Courtesy of R. Pielke Jr.

There's a lot of fine tuning going on in climate science nowadays: For example, an increasing number of studies are setting out detailed forecasts for future weather patterns, or trying to explain why past predictions on rising seas or rising temperatures haven't come to pass. Pielke told NBC News that such studies are basically "watching the wiggles" in long-term trends.

"That's a little bit like watching the stock market from noon until 1 and trying to figure out what's going to happen to your retirement portfolio," the 44-year-old said.

What is to be done?

So if the core science is basically settled, how is that translating into government policies on climate change? "Not much has changed on the policy level, other than our awareness of how poorly the policies have been performing, " Pielke said. He doesn't expect the next IPCC report to remake the policy landscape, either.

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That's not to say there haven't been dramatic shifts. The economics of energy production have had a far greater effect on the climate outlook than the Kyoto Protocol. "It's hard to overstate how dramatically the energy landscape has changed over the past five years," Pielke said.

The rise of natural gas — thanks in part to hydraulic fracturing, or "fracking" — is the biggest factor behind that change. Pielke acknowledges that fracking has become an environmental flashpoint, due to concerns about pollution and the potential seismic effect at drilling sites. But as an energy source, natural gas outshines coal in terms of its climate impact, and in terms of its contribution to U.S. energy independence.

"It has made the U.S. more competitive in some respects, because of the cheaper cost of energy," Pielke said. "It has led to a significant decrease in emissions. ... The mathematics of natural gas are that it's about two-thirds or half as much carbon dioxide per unit of energy, compared to coal. Which is a good thing, if you're worried about carbon dioxide. But it's still two-thirds to a half."

The next inconvenient truth

When it comes to policy, the inconvenient truth — or, in Pielke's words, "the uncomfortable reality" — is that the range of possibilities for government action will have a marginal effect at best on global climate. If anything, the current trend is to fall back on fossil fuels to close any perceived energy gap.

Germany, for example, was once considered a leader in making the transition from fossil fuels to nuclear power and renewables. But in the wake of Japan's Fukushima nuclear crisis, the country is unplugging the nuclear reactors and shifting to gas- and coal-fired power generation in a big way.

Japan, too, is in a state of energy flux. Since Fukushima, the Asian country has increased its reliance on coal, oil and gas. That trend was starting to turn around over the past couple of months, but renewed concern about Fukushima has cast a pall over nuclear power once again.

Despite all the efforts to promote wind, solar and other renewable sources of power, the statistics are pretty much the same as they were 20 years ago: Eighty-seven percent of total power production continues to come from fossil fuels, due to the ever-increasing global demand for energy. "If people were under the impression that renewables were gaining share, they're not," Pielke said.

A painless carbon tax?

To make a dent in atmospheric carbon dioxide levels, Pielke said the world's economies would have to drive that 87 percent down to 10 percent, while at the same time doubling or tripling global energy production. Unless some sort of climate crisis radically changes public sentiment, the only way to do that is through fostering technological innovations on a scale comparable to the shale-gas revolution of the past 30 years, he said.

"We need to start thinking about energy like we think about national defense, or health R&D," Pielke said. He noted that federal support for energy research and development (including fossil fuels) amounts to $5 billion per year, compared with $150 billion for military R&D and $40 billion for health R&D, he noted.

To fund more research, Pielke suggests a tax on carbon dioxide production — say, $5 per ton of carbon. The tax should be small enough to avoid setting off political alarm bells, but large enough to lay the groundwork for America's carbon-free energy future. And the world's, for that matter.

What will that energy future look like? Pielke resists bringing out the crystal ball.

"We have a horrible track record of picking technological winners, because we don't know where breakthroughs are going to occur," he said. "Breakthroughs could come in solar, they could come in energy storage or transmission. It could be modular nuclear reactors. ... There are far-out ideas about capturing carbon dioxide. There's tidal power, there's fusion. The list goes on and on, but we need an energy R&D portfolio big enough so that some of these things may become possible."

Climate policy analyst Roger Pielke Jr., author of "The Climate Fix," joins NBC News Digital's Alan Boyle at 8 p.m. ET Wednesday on "Virtually Speaking Science," an hourlong talk show that airs on Blog Talk Radio as well as in the Second Life virtual world. Tune in, join the virtual audience in the Exploratorium's Second Life auditorium, or listen on demand via Blog Talk Radio or iTunes. To ask questions via Twitter, use the hashtag #AskVS. Here's a rundown of previous "Virtually Speaking Science" episodes:

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the NBC News Science Facebook page, following @b0yle on Twitter and adding +Alan Boyle to your Google+ circles. To keep up with NBCNews.com's stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.