NEW YORK –

Legions of diplomats are huddled right now in Paris trying to hash out a historic climate accord. Legions of entrepreneurs and investors aren't waiting on a treaty.

Bill Gates and other wealthy benefactors this week pledged $2 billion for investments in clean-technology research. Twenty of the world's biggest economies moved to double their R&D spending on new energy. There has been a remarkable six-year rise in the number of U.S. clean-energy patents. Maybe the world should engineer a fake volcano to counter the effects of climate change?

This attention on climate-saving technology has re-opened a rift between two rival approaches: Should we invent big new things or deploy effective ideas that already exist? The conflict was neatly summarized by clean energy entrepreneur Jigar Shah, in a message meant to push back against the announcement from Gates and his billionaire friends.

Those who favor Shah's view tend to believe the technological solutions to climate change are already here, toiling in semi-obscurity in the space where software, resource efficiency, and infrastructure all meet. Just how big is this burgeoning field? A new analysis published today by Pure Energy Partners, business-strategy advisers based in New York, counts at least 500 young companies focused on clean-tech infrastructure. These startups have attracted 800 deals over the last six years, totaling $8 billion in investment, by deploying resource-slashing technologies that are already available today. It is a sleeper tech market in the making, just when investors are looking for opportunities not already frothing over. And just when nations are looking for an economy that cuts carbon.

Nicholas Eisenberger, a managing partner at Pure Energy, said the attempt to study clean-energy startups started with the question: "Can software save the world?" His definition of who belongs in the nascent "clean web" sector extends to familiar sharing-economy stalwarts as Uber or Airbnb. But there are also novel startups such as Pips, which rewards users for replacing bad habits with good, or Tzoa, which makes wearable environmental sensors that report data about your personal air quality to a smartphone app. Some of these startups are even active on the sidelines in Paris. Hub Culture, for instance, is running "collaborative lounges" that it hopes in the long run will help it launch — long story — a digital currency tied in part to carbon reductions.

Pure Energy published the report as a way to draw attention to a trend still under radar—a fact Eisenberger finds surprising. There's an "unloved, unnoticed tech center that's up-and-coming and that can do a big part of the job, too," he says. "Why isn't there more attention to this?"