The sea, lakes, and rivers act as a natural carbon dioxide filter, provides us food, water, recreation, rain, and a threshold between this world and the Other. But thanks to global warming, agricultural pesticides, urban pollution, oil spills, and plastic; the health of Earth's water is decreasing.
Sacred trees fallen for deforestation for the sake of lumber and livestock also affects us by raising global temperatures with more CO2, ruins habitats for other beings, alters the planet's water cycle, and can lead to soil erosion where nothing will grow.
Imagine how effective a Witch's craft is when they use genetically modified herbs that strip the soil's nutrients. Or a Faery Wiccan who tries to call the sidhe of a field sprayed with pesticides. Or a Heathen preparing a Yule feast of imported meat from a deforested livestock pen that releases large amounts of methane and carbon dioxide. Environmental degradation affects the spirit of the Earth and so, our spirit as well.