The primary productivity of an ecosystem is limited by a single nutrient. what do we call this nutrient

Analogy- 1 is to arete as 5 is to cirque horn glacial valley hanging valley

When fossil fuels are burned, carbon dioxide is released. how does this gas impact the environment?

If people from georgia have just experienced an extremely cold winter the last couple of months, what would the climate most likely be classified as? polar temperate maritime tropical