Nigel Leck was sick of all the people on Twitter arguing that global warming isn't real. So, he made a program that would scan Twitter every five minutes for a phrases that argue against climate change. When it finds one, it pulls from its set of phrases and appropriate response.
Tweets about how Neptune is warming just like the earth, for example, are met with the appropriate links to scientific sources explaining why that hardly constitutes evidence that the source of global warming on earth is a warming sun.
Some people who receive tweets from this chatbot really get into it, and arguments can last for days. The bot, however, has not ear for sarcasm and sometimes goes after people who aren't really arguing against climate change.