Water, ocean currents, water vapour and clouds ultimately dominate the earth's dynamic biosphere and sustain all life within it.
Human civilisation emerged in the Late Cenozoic Ice Age (the past 34 million years) - and subsequent recurring glacial cycles and climate spikes over the last 2.58 million years of severe glaciation cycles.
CO₂ ultimately does not drive such massive shifts in the world's climate. CO₂ is still a single trace gas at 420 parts per million. Nor do its effects increase exponentially as volume increases, as the warming crisis narrative seems to imply.
The effects of CO₂ are logarithmic, as parts of its bandwidth become saturated or overloaded. Each additional unit has a diminishing impact.
There are endless examples of warming trends that were not caused by CO₂, such as the Roman and Mediaeval warm periods during the 11,700 years of the current Holocene interglacial warm period. This 'control knob' scenario cannot be compared with the massive, linear influence of a world dominated by the oceans and ocean currents.
The oceans are vast, covering 71% of the world's surface area to an average depth of 2.3 miles - holding 96.5% of all the planet's water. They also contain 91-93% of the world's retained heat energy, the great driver of ocean currents. Water is also 1,000 times denser and heavier than the air.
Water is the de facto lungs of the earth, containing 86% of the surface carbon reservoir (the atmosphere retains only 1-2%). Oceans are also the world's great air conditioning unit and the heartbeat of all life, through photosynthesis.
Ocean currents have warmed Northern Europe since the closure of the Isthmus of Panama around 2.8–3 million years ago. One round trip takes 1,000 years for a single parcel of water. The flow of warm waters to the north prevents much of northern Europe having a frigid climate like Greenland.
The effects on the climate we experience day-to-day are overwhelming. There's a hundred times more water vapour in the air than CO₂, a trace gas at 426 parts 'per million'. Water vapour dominates the world's atmosphere, reaching up to 4% in the humid tropics and warm oceanic regions and the mid latitudes. Water vapour is the primary source of clouds, storms, rainfall, humidity and snowfall.
Clouds permanently cover around 67% of the world's surface, reflecting incoming shortwave radiation from sunlight yet trapping outgoing longwave infrared radiation. They are a unique cooling parasol and warming blanket at the same time.
Solar radiation, orbital cycles, oceanic thermohaline circulation and water vapor dictate earth's endlessly changing climate - largely independent of CO₂.
Oceanic heat content is the primary driver that dictates how much water vapor is released, rather than the air temperature alone.