Firstly, your polar ice stat is actually quoting a DAILY MAIL article where they compared the ice levels in March (end of winter, when ice levels are highest), to the end of summer when they're lowest. Of course they were going to get those results. They were also comparing ice levels regardless of thickness of ice, the total volume is rapidly decreasing because thick ice is melting faster.
Global warming itself has only happened for around 25 years? Smooth the data by an 11 year rolling average and that isn't the case. Check this graph showing it's been around since at least the 1880s, when temperature recording started to become reliable:
What the graph also shows is the regular repeating pattern in rises/falls of temperature is probably caused by the 'solar cycle', the sun gives off different amounts of radiation in a repeating pattern.
Is global warming natural? Sure you could make the argument that the climate has changed before, so this is like all the other times. Or you could look at it a different way - the climate is extremely sensitive to occurrences on earth. Geological data shows large volcanoes caused significant global warming for example. Knowing that the climate is so sensitive to change only reinforces the idea that significantly increased CO2 levels cause an increase in the global temperature.