Sidestep: Climate windows for Polynesian voyages

The Polynesians did a lot of voyaging within a specific window and not much before or after. This is mainly due to natural climate change, wind and current shifts. And currents and winds do change patterns. Too many assume that all that is now, was always this same.

The Polynesian colonization occurred mainly between the years 800−1400. They were always assumed to be upwind, when based on an understanding of modern climate patterns. It is the understanding of some that that migration routes lay downwind from East Polynesia during known times of initial colonization of New Zealand and Easter Island. Scientific debate about migration across the huge area of East Polynesia has been on seafaring technology, both of navigation and canoe capabilities, with some variation in sailing conditions through natural climatic changes and sea level pressures receives less attention.

Winds change with El Niño or La Niña conditions and sometimes these interchangeable conditions can last many years. Poleward expansion of the tropics results in more or less frequent, quasi-stationary anticyclones in the subtropics, and more or less north–south / west–east winds in the southwest Pacific.

During A.D. 800–900 and A.D. 1000–1100, the climate pattern resembles a shift to the Central Pacific El Niño pattern, with southwesterly wind fields over New Zealand, and anomalous westerly wind fields (trade wind reversals) over the Central Pacific. The A.D. 900–1000 period was dominated by the El Niño pattern. During A.D. 1140–1260, the Pacific was dominated by a La Niña pattern, together with an intensification of the subtropical anticyclone. This allowed a climate window for off-wind sailing routes to the southwest Pacific, primarily New Zealand.

After that date sailing would have to be upwind, but by then the location of NZ was already known to Polynesians.

Potential Polynesian voyaging routes to the CEP and extratropical southwest Pacifc post-A.D. 800 are shown. The RED route was open between A.D. 940–970 and between A.D. 1170–1210. The GREEN route was open A.D. 940–960, A.D. 1140–1160, A.D. 1210–1230, and A.D. 1240–1260. The black route was open A.D. 910–960, A.D. 1140–1170, and A.D. 1200–1240. The YELLOW routes were open from A.D. 800–910, A.D. 1010–1030, A.D. 1040–1060, A.D. 1080–1100, and A.D. 1250–1280. The more southern route from the Austral islands was open from A.D. 1290 to A.D. 1440, A.D. 1500–1540, A.D. 1550–1570, and A.D. 1590–1610. The BLUE route was open from A.D. 910–950, 1140–1170, and A.D. 1230–1250. Return voyaging along the green and black routes was open in A.D. 960–990, and mainly open from A.D. 1260 to A.D. 1550.

However, well before the Polynesians explored in their 500 year window the Melanesian's had already done so. NZ, Rapanui and Hawaii already had unique races living there before the Polynesian migrations. Ancient weather patterns would mean they could keep travelling eats. It is simply no one has found any evidence yet...yet! Go back longer and the Zealandia land mass would have enabled ancient people do travel huge distances without as much ocean travel. Of course rising sea waters (yes, they have been rising for thousands of years already) would have covered many ancient coastal sites but as the seas slowly rose so the populations would move with it, just as we do now. Sea currents, land masses, older islands, wind shifts and climate change would all allow what we cannot see now for we only seem to judge the past based on the present, as seen by the models that show that downwind migration from Polynesia was possible while academia still insist it was all upwind voyaging.