Print Source 3

Global Warming - an Overviewby Helen Willetts
An article from BBC

Claim: Humans are directly contributing to global warming through greenhouse effect and as evidence for this mounts, so do the temperatures exceeding natural increase estimates.

Evidence:
1. "So far model simulations point to global temperature rises of approximately 3 degree C in the next 100 years...some 20,000 years ago is only around 6 to 8C."
2. "The best estimate is 50cm by 2100, [sea level measurements] but this will vary considerably with location."
3. "Sea level rises will be due to thermal expansion of the ocean along with the melting glaciers and mountain snow and ice."

Warrant for Claims:
1. This takes hard facts and history to make more of an effect. Yes, you cannot argue with the facts but the warrant to this claim is the fact that there has been such an increase already and now temperatures are predicted to rise 3 more degress in the next 100 years which backs up her overall claim that temperatures are continuing to rise.
2. Even though this is not proven fact, it is an estimate that not only seems pretty accurate, it also raises awareness that the sea levels will rise regardless. Also this claim introduces the idea of locations already located below sea level with the estimates.
3. This is a fact that warrants the claim above by giving factual reasons for sea elevation but also directly refers back to the effects of global warming.