What are the possible consequences of a warmer Earth?
Three big ones are: Rising sea levels, more extreme weather events, and acidification of the oceans.
As the Earth continues to warm, this is increasingly melting ice from Greenland and Antartica which is feeding more freshwater into the oceans. Warming is also causing the oceans to rise from thermal expansion. Millions of people in coastal communities would be displaced and face starvation from rising sea levels.
More extreme weather events are projected to happen as the atmosphere contains more energy. More frequent heat events and more intense storms are two examples that are well documented.
As the atmosphere warms, some CO2 goes into solution in the oceans which lowers the ph in a towards a more acidic condition. This impacts many ecosystems and food webs in the ocean, especially shellfish which might not be able to precipitate their calcium carbonate shells anymore. Acidification could also impact commercial fisheries in the oceans too.