Asking for guidance on environment

Having spent my time telling readers what I think I know I am prepared to ask for guidance from the Green Party and others with knowledge of AGW (human caused global warming) to answer questions that continue to puzzle me, these are:-

What is the difference between global warming and the current term climate change?

What are the latest anticipated catastrophic effects of an average global temperature rise of 2C ?

With north pole seasonal temperatures ranging from –30C to –50C and south pole from –50C to –90C how can an average global rise of 2C cause melting of the ice?

From 1950 to 1998 the temperate rose 0.39C since then there has been no increase and the Met Office has now said that their revised computer model forecasts no increase up to 2017 a period of 19 years. This despite CO2 levels increasing. What is the explanation for this?

Here is the big puzzle. How is the average global temperature calculated. I have checked where the recording stations, 3,846 in number are, of these 3,436 are in northern latitudes and only 410 in southern latitudes.

I would be grateful for someone to enlighten me.

Brian Beck