It’s easy to get lost in the stultifying language, but the message from the world’s top leaders on Monday deserves to be elevated: “Deep cuts in global greenhouse gas emissions are required,” leaders of the Group of Seven nations declared, “with a decarbonisation of the global economy over the course of this century.”

These words are a tad cumbersome and strategically vague — but nonetheless remarkable. They project a world that uses little or no coal, oil or natural gas by the end of the century, at least not without new anti-emissions technologies. They foresee few or no greenhouse-gas emissions from the activities that produce them — power generation, cement production, refrigeration, chemical manufacturing and air travel, to name just a few. If this vision is seen through, humans’ complex dependency on fossil fuels would be broken.

The ambition behind this goal is as profound as the time frame is long. The International Energy Agency has projected that world electricity demand will leap almost 80 percent between 2012 and 2040 as people in developing nations achieve higher living standards. Renewable energy will supply about half the electricity generation needed to meet that new demand. Even so, absent strong policies that go beyond what countries have already committed to doing, coal, oil and gas will still represent about 55 percent of power generation by then.

Simply inventing new, cheaper renewables technology would not be enough to decarbonize the world. The more renewables displace available fossil fuels, the cheaper those fuels will become. Even if renewables become very inexpensive, governments would almost certainly have to suppress the use of fossil fuels if they are to be wrung out of the economy. Try telling that to oil-producing Venezuela.

Things will change in large and unexpected ways over the course of this century, and the difficulty of decarbonizing could ease much more than expected. Nevertheless, these considerations suggest that the world may fall short of the G-7’s vision. Even the medium-term goal of a 40 percent to 70 percent cut in global emissions looks tough. And even if the world largely succeeds, there may well be some residual — though far less threatening — level of greenhouse-gas emission that lingers for some time.

But that doesn’t mean the declaration is useless. It encourages ambition among international negotiators meeting in Paris later this year to hammer out a major global warming pact. It also puts the various countries’ energy conditions into the right long-term perspective. The United States, for example, has seen a domestic energy renaissance over the past several years, producing and burning a lot more natural gas. Cheap gas, which is cleaner than coal, has driven U.S. emissions down, and that is a good thing. For now. The G-7 has made clear that this shift is far from good enough; it represents a way station in a much longer journey toward a transformed economy.

Editorial by The Washington Post