What are some natural influences of the tundra ?

Human influences in the Arctic are both seen and unseen.  Human activity has seen a dramatic change in the arctic due to climate change.  This is, by far the worse impact human activity has had on the globe, but in particular, the Arctic is fragile.  Other human influences are the vast and untapped oil reserves in the Arctic have made it a target for oil companies.  Oil and gas pipelines are a huge human influence in the Arctic.  Garbage and other waste not to mention the impact of the oil and gas industry have left some parts of the Arctic polluted.