How is nature represented in Beowulf and in Sir Gawain and the Green Knight? What is the relationship between nature and humanity?

Some of the differences in the portrayals of nature between these two works have to do with a change in time, culture, and religion. Beowulf is an Old English poem, composed some time between the eighth and eleventh centuries, and rooted in the pagan culture of the Norse saga with a thin Christian overlay, while Sir Gawain and the Green Knight is a courtly romance, grounded in a Christian and aristocratic rather than heroic ethos.

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Some of the differences in the portrayals of nature between these two works have to do with a change in time, culture, and religion. Beowulf is an Old English poem, composed some time between the eighth and eleventh centuries, and rooted in the pagan culture of the Norse saga with a thin Christian overlay, while Sir Gawain and the Green Knight is a courtly romance, grounded in a Christian and aristocratic rather than heroic ethos.

Nature in Beowulf is to a large degree a hostile force against which a hero strives. The earliest heroic deed of Beowulf (though recounted only retrospectively) is a swimming contest that resulted in a struggle against a sea monster. Although humans strive against other humans, competing for wealth and honor, they share a common enemy in the harsher elements of nature. The true antagonists of the epic are "natural": Grendel, his mother, the sea monster, and the dragon. Nature itself provides a harsh and unforgiving backdrop to these contests. While humans cannot completely match the brute force of nature, they must in their contest against it win by a combination of strength, intelligence, and courage. 

The portrait of nature is Sir Gawain and the Green Knight is more grounded in Christian notions of nature as both representing God's creation and also representing the wild and uncivilized forces that exist before and outside Christian civilization. The Green Knight, in both his choice of color and the location of his castle, represents nature. Although Gawain engages in a contest with the Green Knight, and one that appears initially to be of the same type as the physical contests found in Beowulf, in reality what is being tested is his moral character. The contest reveals both his strengths and weaknesses as a moral agent and serves to instruct him in ethics.