Mars also has a very thin atmosphere, so its surface temperature is much more directly related to sun irradiance and doesn't have any greenhouse effect (despite being mostly made up of carbon dioxide, btw). Its atmosphere is thin because it has a weak magnetic field, though, as the solar wind "blows" the atmosphere away. Venus' magnetic field is also very low, and it's much closer to the sun, but its atmosphere is very thick and has a continuous cloud cover. The correlation and causation is a bit more complicated.
If I understood it correctly, with a weak magnetic field cosmic radiation penetrates deeper into the atmosphere and creates aerosol-like seeds for clouds by ionizing the air. A stronger cloud cover increases albedo and reduces solar irradiation, lowering temperatures.
Given the increased urbanization and usage/drying of wetlands, heat islands would form more readily. Lower albedo, higher heat retention, decreased water vapourisation.
@Crni Vuk
Yeah nah, the solar industry wasn't axed here, it just became not profitable anymore. As I said, solar cells are easy to produce, but require a lot of power, don't automate well, and are dirty in production. All of which are ideal for production in China, but not in Germany. I don't really see how we could go full renewable. Their power density is extremely low, and I apparently need to remind you again and again that every single kWh of renewables needs to be backed up by stable power plants or storage. And the technology for storage might be there, but not at this scale. Not economically feasible.
Here's the thing: Yes, the recent heat waves are sensationalism. Not because they are not real, but the cause for them is quite likely misreported. Heat waves and droughts are used to sell increased taxes on everything because it's an effect everybody notices or can be convinced to notice, and everyone is scared. War is peace, after all.
And hey, how fitting. Politicians talking about increased VAT on meat, and just now the IPCC released a report stating that agriculture releases like 23%-30% of CO2. Right on cue. In lesser news, Germany started to have a budget deficit again, and there's a recession on the horizon. But let's not focus on that, let's increase the taxes to save the world instead!