Global warming due to carbon dioxide-based radiative forcing did not resist to a critical analysis largely based on fundamentals of chemistry, physics and thermodynamics. This finding led to giving water an essential role in an alternative mechanism in which heat and not CO2 is climate determinant. This mechanism is based on ice ↔ liquid water and liquid water ↔ vapor interphase equilibria combined with the physics of infrared waves when they pass through the atmosphere. Accordingly, future global average temperature and ocean level rises should be smaller than predicted in the case of radiative forcing. Climatic events depending on chaotic perturbations, increases in strength and frequency are expected if anthropogenic heat releases become significant relative to solar heat supplies. Applied to distant past climate fluctuations, the water-based heat-management mechanism showed that ice melting, evaporation and humidity also determined the ups and downs of temperature and ocean level during glaciation-deglaciation alternating periods. The present times are part of the last post-deglaciation pseudo plateau in which variations of global temperature are limited to ± 2°C, a range respected during the last 8,000 years, including the recent industrial era, and comparable to plateau periods in distant past. It is in this plateau period that anthropogenic heat releases are presently complementing historical heat supplies from the Sun. Heat being a physical phenomenon independent of the sources, global temperature and level of oceans should continue to vary within the rather narrow ranges typical of past plateau periods provided anthropogenic heat releases remain negligible relative to solar supplies. If it is not the case, ice melting and evaporation may become unable to compensate anthropogenic heat supplies. The + 2°C limit would then be exceeded with progressively more evaporation, more winds, more hurricanes, more tornadoes, more clouds, more rains, more floodings and droughts, and at the end shortening of the time to next glaciation. Trend may seem already manifest on the basis of local recent climatic events felt unusual. However, the stock of ices is such that the evolution should extend over several centuries, may be more if evaporation acts in complement.