6.1.8 (HL)—Global warming and geological cycles

The Quaternary period began about 2.5 million years ago and contains repeated glacial–interglacial cycles; current global warming is moving Earth away from that recent pattern toward hotter conditions.

Climate has changed naturally over geological time, but current anthropogenic change is unusually rapid. Human greenhouse-gas emissions add positive forcing that the current orbital pattern does not explain; the syllabus places this human-dominated change in the Anthropocene.

Evidence of past natural cycles shows that climate can change without people, but it does not explain the rapid modern rise in greenhouse gases and temperature.

Attribution compares timescale, forcing and observed rate: long natural variability is a baseline, not an alternative explanation automatically.

‘Natural’ and ‘human’ are not mutually exclusive causes; quantify which forcing explains the observed change.