We have the tech to fix these problems if we try. WWII could have been avoided as well, had there only been rescource issues. Petroleum is already on its way out. Solar is here to stay. Aquaponics are beginning to become a viable food source. Space is finally opening up. Windturbines are getting cheaper and better. Geothermal heating and cooling have been available for 90+ yrs. We can still save the Earth. We can't bring back what we lost, but we can't bring back the dinos either. We can still save ourselves and many of our fellow organisms on this planet.
It's like a Disney fairy tale one day a prince is going to save you and you'll live happily ever after. One day their might be technology that could get more power from a solar panel, but it's so far out it's ridiculous. If it was viable we wouldnt skip a beat. Why do you think everything fell apart? You cut off your main energy source along with everything attached to it and didn't have anything to replace it.
This is older but not a lot had changed.
http://blog.heartland.org/2012/01/why-solar-power-is-permanently-inefficient/
Same with wind.
https://www.masterresource.org/grassroots-opposition/20-bad-things-wind-3-reasons-why/
Look at electrical engineering/physics forums search for these topics