Alien Plants in Antarctica

This article is about how scientists think that aliens or tiny animals would be likely to spread as the climate warms that what researchers says." The Environmental Protection Agency says its will delay controversial water pollution standards for Florida lakes, river and streams to the state more time to draft its own rules".  The main point to this article is that it show the way the the pollution affect the climate. I think is article show us and help us understand how and what is affecting the climate. I wonder why do they think that alien and tiny animals would spread as the climate warms? why so they think the climate is changing? whats making it change?