DISCLAMER
Owning fossil fuel stock as part of a broad index fund isn't an "endorsement". Not owning fossil fuel stocks does nothing to hurt fossil companies. They made their money from the stock in the IPO. Any trading afterwards doesn't effect their bottom line at all.
Even if they have similar performance, the eco-friendly funds charge you much more every year. The article mentions VTSAX (Vanguards total stock market index) fund. It has an expense ratio of 0.04%. That's how much they charge you each year to own it. AMAGX (Amana Growth Investor) fund on the other hand has an expense ratio of 0.87%. They charge you more than 20x as much; Which more than erases the slightly better performance they've had.
If it helps you sleep at night, that's fine. That's great! It's well worth it for that alone. But don't for a moment think this is helping the environment at all. The only functional outcome it will have is putting a 0.5% or more drag on your portfolio.