No-analog (variants may omit the hyphen and/or use the British English analogue), or alternately novel, climatic conditions ("no-analog climates") or biological communities ("no-analog communities") in paleoecology and ecological forecasting are those without current equivalents.
- An even more extreme case of no-analogue climate is the Palaeogene ‘greenhouse’ climate that extended to the shores of an ice-free Arctic Ocean. Canadian and Danish palaeobotanists describe fossil trees that grew within 10–20° of the North Pole, yet lack any indication of frost-damaged tree rings. Where is the modern analogue for a high-latitude coastal plain with rivers flowing throughout the year, abundant rainfall, and an open spruce–birch woodland, yet with 6 months of near-total darkness? Again, none exists, yet in such a climate the crystalline shields of Canada and Scandinavia developed a deep saprolitic weathered surface layer that was subsequently removed by glacial erosion.
- Projections of future no-analog communities based on two climate models and two species-distribution-model algorithms indicate that by 2070 over half of California could be occupied by novel assemblages of bird species, implying the potential for dramatic community reshuffling and altered patterns of species interactions.
- Axel Heiberg Island ~80°N is known for its large ~45-million-year-old 'fossil forests'.
- Effects of global warming
- Ellesmere Island ~80°N is known for its ~55-million-year-old 'fossil forest'.
- Extinction risk from global warming
- La Brea Tar Pits are well known for their fossils of extinct North American megafauna.
- Pleistocene rewilding