How would conditions on the surface of the earth be different without greenhouse gases?

The absence of greenhouse gases would allow all surface heat to freely escape into space, which would result in a significant decrease in temperature during periods when solar radiation was not reaching the Earth's surface. This would particularly affect nighttime lows and extreme temperatures at the poles.

Since there are very few examples of celestial bodies that have an atmosphere but no greenhouse gases, it is difficult to imagine how much colder it would get on the dark regions of the Earth.

Without greenhouse gases, the Earth's surface would be much cooler. Greenhouse gases, such as carbon dioxide, methane, and water vapor, trap heat in the Earth's atmosphere, creating a greenhouse effect that helps maintain temperatures suitable for life. Without these gases, more of the sun's heat would escape back into space, leading to significantly lower surface temperatures and potentially rendering the planet uninhabitable. Additionally, without greenhouse gases, the water cycle would be disrupted, resulting in less precipitation and altering global weather patterns. Overall, the absence of greenhouse gases would have profound consequences for the Earth's climate and ecosystems.