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Date: July 12, 2023 12:20AM
>That would be to somehow make the earth a perfect sphere,
Not possible. Because the Earth is not completely rigid, and because it rotates, centrifugal force is always going to cause an equatorial bulge. As it turns out, the difference between the equatorial diameter and the polar diameter is only 26-27 miles which is ~0.2%, so the Earth is almost spherical anyway.
>That way, when it was noon in one location, it would be midnight in another. When one location in the Northern Hemisphere experienced its normal July highs, another in the Southern Hemisphere would experience its normal July lows.
This is already the case. It is currently summer in the northern hemisphere and winter in the southern hemisphere. Where the sun is directly overhead (see here
https://rl.se/subsolarpoint) it will be noon, but 180 degrees of longitude away it will be midnight.
That doesn't mean that the temperatures will average out. Because water has a much higher specific heat than land, the same amount of sunlight over a large land mass will have more effect on temperature than the same amount of sunlight over a large body of water. The distribution of land and water on Earth is not uniform so parts of Earth will warm more on summer days than other parts (the Eurasian land mass will heat more quickly than the South Pacific Ocean for example). Local weather will also be a factor.
>The average global temperature would vary only slightly over the course of a year.
The problem with climate change is not directly due to the distribution of temperature from place to place. It is due to the overall heat balance of the planet. Earth gets heat from solar radiation ( and a little from internal radioactive decay) and it loses heat from radiation back into space. That loss from radiation is proportional to the temperature of Earth - the hotter the planet, the more radiation goes into space. When the two are balanced, the temperature will remain stable. If incoming solar radiation exceeds outgoing radiation, then the temperature will rise; if outgoing radiation loss exceeds incoming solar radiation, then the temperature will go down.
The problem now is that they are not in balance. Incoming radiation (while it has short term fluctuations) has on average stayed the same. Because of increased quantities of greenhouse gasses - CO2, methane, and several others - outgoing radiation has decreased because said gasses absorb the radiation and reradiate it back to Earth. As a result, the global heat balance is positive, and the global temperature is rising.