Solar irradiance has been declining for 35 years. Which is one way we know it isn't the sun.
Also the troposphere is warming rapidly while the stratosphere is cooling. Which is only something you expect from greenhouse gas related warming.
Also night time temps are increasing faster than daytime temps. Another fingerprint of greenhouse gas induced warming.
Also the earth is hotter than it's been in 100,000 years and scientists predicted that greenhouse gasses would cause exactly this much warming with this level of greenhouse gasses 50 years ago well before it was obvious what was going to happen.
Also the troposphere is warming rapidly while the stratosphere is cooling. Which is only something you expect from greenhouse gas related warming.
Also night time temps are increasing faster than daytime temps. Another fingerprint of greenhouse gas induced warming.
Also the earth is hotter than it's been in 100,000 years and scientists predicted that greenhouse gasses would cause exactly this much warming with this level of greenhouse gasses 50 years ago well before it was obvious what was going to happen.
So yeah. Not the sun. Good question though.