GOTHENBURG, SWEDEN—We know the future of energy usage that we want: a rapidly decreasing reliance on fossil fuels with a greater share of global energy use going to people in the developing world. We also know the current state of technology and the rate at which things are changing. Is it possible to get these two horizons to meet? And, perhaps more importantly, will we need to?

There was a definite tension among the panelists at the Nobel Week dialog about what the future of energy might hold and how well we could predict that future based on current trends. For example, Carl Henric Svanberg (of BP and Volvo) noted that, while renewables are the fastest growing portion of the energy market, if you extrapolate out current trends, non-hydro renewables will only cover six percent of the world's energy needs by 2030.

And that's not good enough, Svenberg said: "We need to move fast, because time is not on our side." He was one of a number of speakers who called for a carbon tax to tilt the economic scales. In his case, Svenberg said, "I cannot understand how those who burn carbon get to do that without charge." It was put another way by Johan Rockström, who referenced the increases in various extreme weather events by saying, "The atmosphere was not sending invoices back to the economy. That has changed." Carbon taxes would be one way to forward those invoices on to the parties responsible.

Although there was widespread agreement that a carbon tax would be a positive step, there seemed to be less unanimity as to whether it was absolutely necessary, since some aspects of the energy economy were already pushing us toward conservation and efficiency. Even without a carbon tax, the International Energy Agency's Fatih Birol noted that oil prices have hovered near or above $100 a barrel for about five years, something he called "without precedent in market history."

But will this trend continue? Birol thought it would, but both he and others also shared stories about how their market predictions for oil ended up being badly wrong. And the Chief Economist of BP, Christof Rühl, noted that oil's share of the global energy market has been dropping since the oil crises of the 1970s—events that were driven by political considerations. Technology can also change things rapidly as well. The IPCC's Rajendra Pachauri pointed out that, as recently as five years ago, some projections were still completely ignoring the impact that shale gas would have on the energy economy.

Another speaker, Nebojsa Nakicenovic, emphasized the degree to which technology could alter how we use energy. He showed a slide with 50-year snapshots of various technologies, ranging from a primitive steam engine of the late 1800s to a bullet train, from a hot air balloon to a 747, from a horse to a Prius. At the time, many of the steps undoubtedly seemed evolutionary, but the cumulative impact has been radical.

If "revolutions are a constant," as he put it, they're not necessarily distributed in the ways we might like. We can make heavy investments in the sorts of technology we need—and Nakicenovic definitely felt we should do so, calling for a doubling in our investments—but that won't guarantee we'll get everything we need. For example, he pointed out that continued emissions have ensured that most of the options for limiting climate change to two degrees Celsius by the end of the century will now require some form of large-scale carbon capture and storage. But research in the area is still stuck at the stage of small test projects.

All of this back and forth left a lot of ambiguity in its wake. Should we expect a revolution? Can we specifically fund the ones we need? Based on past experience, chances seem good that something will change. But, given we don't know what that will be, it may be that extrapolating current trends is the best we can do.

This post is part of Ars' coverage of the 2013 Nobel Week Dialogue. It first appeared on the Dialogue's website.