Transitioning to a non-polluting energy menu and safe climate in a world of growing energy needs and persistently abundant fossil fuels is a tough task, whatever path you favor. And realistically, there will be no single path, as the flexible architecture of the Paris climate agreement reflects.

In the United States, for example, there are places where new nuclear plants have a chance, and places where solar and wind power can have a greatly increased role. In every country, in fact, with its own unique energy mix, the challenge posed by simple inertia in physical systems and in social, financial and legal structures, may be a bigger impediment to energy transformation than coal, oil and gas lobbyists and campaign contributors.

And the overriding issue is the challenging scale of limiting global warming as humanity’s growth spurt – in both population and resource appetites – plays out. The Paris agreement contains a huge “reality gap,” as I called it – its commitments apply only through 2030, but avoiding dangerous warming by 2100 will require mass deployment of “negative emissions” technologies (like burning biomass and storing the emitted CO2) at a scale far beyond what experts see as plausible.

I discussed these issues in a recent conversation on next steps on climate change and energy with Bill Gates, which you can read and watch at and, in more detail, on my Times blog, Dot Earth. He laid out why he focuses, as he did in Paris with the rollout of the “Breakthrough Energy Coalition” investment initiative, on filling public and private investment gaps in pursuit of “energy miracles.”

Gates is concerned that today’s technologies will not solve the “reality gap” in the Paris agreements. Worse, the focus on ramping up deployment of those technologies diverts attention from the critical need to greatly intensify spending on basic research and large-scale development of new energy technologies. That is the only way to create the breakthroughs required to cut emissions of greenhouse gases to near zero later in the century – or suck the gas out of the atmosphere at gigatons-a-year scale if emissions efforts falter.

“A little bit of the trap people get into is they think, okay if we’re meeting some 2030 goal, we must be on the way, because we just do more of what we did,” Gates said. “So you thought, oh what a great thing we just did. But in fact it doesn’t scale to the sort of near-zero that we need to achieve.”

Summary of Discussion Here