One of the consensus ideas that has been popular for a long period of time is the belief that early Earth, over 3 billion years ago, was much warmer than it is today. In fact, some people have gone so far as to suggest that life could only have started to flourish in high temperatures, much warmer than in the modern world. Walls, it is said, are built to be knocked down – and it seems new research may be about to knock down this particular wall of the consensus. Research in South Africa, targeting some of the oldest rocks in the world, indicate global temperatures 3.5 billion years ago were not a lot different than they are nowadays – go to http://phys.org/print375950784.html
If the researchers are right global temperatures were far from overheated and we might be excused in thinking that some kind of equilibrium as far as temperature is concerned had been reached and planet's system has remained more or less intact ever since. This implies a few unwelcome thoughts might be worth considering (as far as mainstream is concerned) and the leading one might be that co2 was incapable of causing global temperature to rise as in alarmist global warming theories as the earth system is basically stable with excess heat released into space. Secondly, life on earth could have been kick started on many occasions and not just in a primordial soup. Thirdly, a re-evaluation of the Jurassic dinosaur age may be necessary as geologists are fond of telling us global temperatures at that time were much warmer than they are today – and even the poles were sub tropical (or bordering on that condition).