This is the 17649th most frequent Polish word.
ziemską
"Ziemską" means "earthly" or "terrestrial" in English.
Here, 'ziemską' (Earth's) is an adjective describing the noun 'atmosferę' (atmosphere), specifying it as the atmosphere of the Earth.
Obserwujemy ziemską atmosferę przez teleskop.
We observe the Earth's atmosphere through the telescope.
In this case, 'ziemską' is an adjective modifying 'ekosystemu' (ecosystem), indicating an association with the planet Earth.
Woda jest zasadniczą częścią ziemską ekosystemu.
Water is an essential part of the Earth's ecosystem.
Here, 'ziemską' modifies 'różnorodność' (diversity), identifying it as pertaining to Earth.