What a thought-provoking imaginative question! As much as people say they don’t like hypotheticals, they can provoke us to think differently. I have tried to answer this from the current paradigm of how things are presently on Earth.
All else being equal, we’d still face the same resource problem from an environmental point of view. With the same consumption habits and a consumption-based economy driven by fossil fuels (assuming they are available and accessible), I think we would still have to deal with the consequences of climate change – erratic weather events, reduced green cover, rising temperatures among many. Some of the greenhouse effects may be counteracted by the fact that a significantly smaller share of Earth’s surface area is covered by ocean water, which absorbs light and traps heat. So if my scientific understanding serves me right (I’m not an expert in this field; I know based on what I’ve read in the media), there will be less heat absorption from the Sun since about 2/3 rds of this hypothetical Earth is covered by land.
Interestingly, Antarctica and the Arctic Circle are left as is. So I guess we still need them to reflect off the light and serve as a protective cover for the planet from the Sun.. 🙂 But I fear the exploitation that will take place since these regions are accessible by land.
Geographically, I feel that in the set-up depicted in the picture, there will be large chunks of land (and by extension, people) that will be harder to reach by sea. The Pacific and Atlantic “continents” will be hard to reach without flying. I think the longest flight will be across the Eurasian “ocean” from the Atlantic “continent” bordering the “Spain sea” to the South China “region”.
I can’t comment on the weather differences between regions and continents. But they will exist as they do now in the real Earth.
As anyone who has studied history knows, societies and communities located next to the sea are ones that are most receptive to new ideas, cultures, and influences. There will be few such communities. In contrast, there will be more inward-looking albeit autonomous societies due to the large stretches of land. I believe these societies will have less trade and external contact with each other. This would especially be true in the Pacific “continent”.