Understanding Planet Earth is not the same as understanding the universe. We've been studying the oceans and atmosphere for centuries. We put measurement probes adrift in both media.
and we still know less about the sea bed than we do about the surface of the moon. Where is the data about the heat being added to the oceans by the undersea volcanoes and geysers? Our earth's crust is a series of unstable plates floating on molten rock - where are all the measurements about how the earth is heated from within?
The IPCC only allows science it approves of and is on message to be published - you can peer review as much as you like but if the data and studies you review are flawed or skewed then you won't get a true result.
The issue of past temperature variations is exactly the point - how can you claim to know what is happening now if you can't explain what happened in the past?