It is naive to think that climate models will be 100% accurate. They used to be less accurate. Then we discovered CO2 going into the ocean and they became more accurate. At some point we accounted for the Earth's orbit around the sun (eliptical) and the models became more accurate. At some point we accounted for the (average length) sun cycle of 11 years and it's effect on Earth temperature and the models became more accurate. At some point we used new methods for measuring atmosphere history in the recent past, 700,000 years, or the more recent past, last 22,000 years and the models could be made more accurate. The fact has been (it may not be now) all(probably) records and research show that, historically, temperature rise has come before CO2 rise. So, unless we can show that the CO2 level rise precedes temperature rise (22,000 year reference) we are in completely uncharted territory.
The climate is changing, that has been shown. CO2 is playing a role that has been shown.
You ask one of two questions : What if we're wrong and the temperature doesn't rise and sea levels stay the same and it is ok to burn fossil fuels?
Remember, we've predicted many scenarios of how temperature will change based on how we control the carbon changes. The prediction is that sea levels will rise, people will be displaced, weather patterns will change, maybe deserts will become fertile land and maybe wetland will become deserts.
What if we're wrong the other way? What if the feedback is so strong that things change faster than we could have predicted (this situation has never been seen before, nothing to learn from)? What happens if all the Earth ice melts? It has been calculated that ice melt and expanding ocean water(higher temperature) can cause sea level rise of 120 feet.
Not declaring Armageddon. This is a call to caution. The prediction for change provides an extremely high probability. The predicted consequences (hundreds of years in the future) are cataclysmic. High probability times extreme damage means extreme danger/risk. This is a risk you mitigate. This is one we do as humanity, not states or nations.