Re the sea ice - all science is based on 'best guesses', and then scrabbling around (while the know all ignorant fools laugh at them) trying to find out what they didn't know and what assumptions were wrong. It now appears that the gadgets used to make measurements of sea ice didn't exactly work the way they thought they did - this is scientific progress, and why it is best not to go rushing headlong down paths that may kill us long term, eg why some scientists were highly antagonistic re nuclear things that go bang, and things that just sizzled...