“...lower the Earth’s surface temperature by 4.5 watts...”
A watt is not a unit of temperature.
Sorry I presumed ...
“The Sun releases an estimated 384.6 yotta watts (3.846×1026 watts) of energy in the form of light and other forms of radiation. We are able to survive on Earth because the energy is spread over the area of a sphere with a radius of approximately 93,000,000 miles.
“At the upper reaches of our atmosphere, the energy density of solar radiation is approximately 1,368 W/m2 (watts per square meter). At the Earth’s surface, the energy density is reduced to approximately 1,000 W/m2 for a surface perpendicular to the Sun’s rays at sea level on a clear day”
Amount of watts reaching the Earth’s surface and the Earth’s tilt and distance from the Sun determine the temperature; Earth’s gases have a magnifying or minimizing effect on the overall temperature (depending on the mix and percentages). The Sun also tilts and wobbles.
The surface wattage will be reduced by 4.5 to 6 watts while the Earth moves about 2 million miles (95-96,000,000) further from the Sun due to wobble and eccentricity of orbits. These two effects will make the Earth much cooler, perhaps approaching the Younger Dryas Period (the coldest recent period which followed the Ice Age. This situation will persist for about 350-400 years ...
Adding carbon to the atmosphere is useless and could cause more harm ... so a useless remedy.
Watts cause heating which is temperature much the same as a 100 watt light bulb heats a room ... the closer you are to the bulb the hotted it feels, because you are receiving more watts so the temperature rises.
Saying “A watt is not a unit of temperature” is just an argumentive misdirection on the subject at hand.