ASPEN — A panel of experts at the Aspen Environment Forum concluded Thursday that there is no choice for humanity but to try out as many types of new technology as possible in an effort to reduce greenhouse gas emissions and slow down global warming.

But there also is no way to avoid the potential for unintended consequences that can arise from a willingness to try new things, and can create problems as serious as the ones they solve, the experts told an audience.

Nevertheless, David Keith, a presenter at this week’s forum, said: “We’re going to have to fundamentally change the way we make energy, so we can make it without carbon.”

The panel discussion, “Energy and the Law of Unintended Consequences,” was part of the ongoing forum at The Aspen Institute, which has drawn hundreds of scientists, policymakers, wonks and visionaries. The forum participants are discussing the world’s energy future in relation to global warming and resource depletion, among other topics.

The forum continues Friday at the Institute campus and concludes Saturday.

Keith, a one-time academic and current director of the Energy and Environmental Systems Group at the Institute for Sustainable Energy, Environment and Economy, said there have been innumerable examples through history of cases in which new technology led to unintended consequences.

For example, he said, “We used to have refrigerators that worked on ammonia, and they killed people, lots of people.”

When an American engineer came up with chlorofluorocarbons (CFC) in the late 1920s, and CFC replaced ammonia as a refrigerant, people were enthusiastic, Keith said. That lasted until the late 1980s and early 1990s, when scientists linked CFC with the depletion of the ozone layer that rings Earth, and the compound was banned.

Keith said there are certain questions that must be asked whenever a new technology is unveiled: Where does the resource underlying this product come from, such as the metals used to make solar cells? Where does it go once the technology is worn out or superseded? And there are other, more technical considerations.

One question, said Barbara Bramble of the National Wildlife Federation, is whether the conversion of land, once used for traditional agriculture, to new uses such as biofuels production or the placement of solar arrays, is truly sustainable.

For instance, she said, in 2007, when Congress passed legislation to vastly increase the output of produce for biofuels, they weren’t thinking about the consequences.

These consequences, she said, included the question of where to grow the foods that were displaced by the biofuel crops, which in many cases were crops high in sugar (sugar cane, sugar beet, and sweet sorghum) or starch (corn).

Instead, she said, the legislators were thinking solely about such issues as reducing U.S. dependence on foreign oil and the generation of jobs in the agriculture industry.

She said policymakers looking for options must consider such issues, particularly in a world where “the population is moving toward 9 billion people” who will need to be fed.

One idea that is gaining ground, she said, is the use of waste products to make energy, perhaps through the use of movable biomass power plants that could consume, say, the rubbish left behind by Hurricane Katrina or the vast numbers of dead trees killed by the pine bark beetle infestation of the Rocky Mountain region.

Martin Hoffert, professor emeritus of physics at New York University, told the audience on Thursday, “We need to be building demonstration plants” to test out all these new theories and ideas, such as creating nuclear power plants that recycle their own nuclear waste.

And doing so, he said, will require considerable federal support for research and development of technologies “that will get us to a carbon neutral state by the middle of the century.”

Because if the global society cannot turn itself around by the middle of the 21st century, he intoned, “It’s game over” for the world as it has been.

jcolson@aspentimes.com