With the continued rise in global mean sea level, operational predictions of tidal height and total water levels have become crucial for accurate estimations and understanding of sea level processes. The Dutch Continental Shelf Model in Delft3D Flexible Mesh (DCSM-FM) is developed at Deltares to operationally estimate the total water levels to help trigger early warning systems to mitigate against these extreme events. In this study, a regional version of the Empirical Ocean Tide model for the Northwest European Continental Sea (EOT-NECS) is developed with the aim to apply better tidal forcing along the boundary of the regional DCSM-FM. EOT-NECS is developed at DGFI-TUM by using 30 years of multi-mission along-track satellite altimetry to derive tidal constituents which are estimated both empirically and semi-empirically. Compared to the global model, EOT20, EOT-NECS showed a reduction in the root-square-sum error for the eight major tidal constituents of 0.68 cm compared to in situ tide gauges. When applying constituents from EOT-NECS at the boundaries of DCSM-FM, an overall improvement of 0.29 cm was seen in the root-mean-square error of tidal height estimations made by DCSM-FM, with some regions exceeding a 1 cm improvement. Furthermore, of the fourteen constituents tested, eleven showed a reduction of RMS when included at the boundary of DCSM-FM from EOT-NECS. The results demonstrate the importance of using the appropriate tide model(s) as boundary forcings, and in this study, the use of EOT-NECS has a positive impact on the total water level estimations made in the northwest European continental seas.

In this Article, a processing error led to the wrong versions of Fig. 3 and Extended Data Fig. 4 being published. Figure 3e did not include the entirety of the eastern Africa soil carbonate δ13C database as compiled by ref. 13. Fig. 3 of the original Article has been corrected, and Fig. 1 of this Amendment shows the original and corrected Fig. 3 side by side, for transparency. In the Methods section of the original Article, there are further details about how this record has been produced. The last paragraph of the Methods has been corrected; the original text was: “On the basis of ref. 13, time series of δ13C values from soil carbonate were combined for the Omo-Turkana Basin and the southern Kenyan-Tanzanian sites using their medians, and interquartile ranges using six-data-point bins.” Furthermore, the original version of Extended Data Fig. 4 did not display data from eastern African hominin site Afar; the figure and caption have been updated accordingly, and the original and corrected versions are shown as Fig. 2 to this Amendment. These changes do not alter any inferences drawn from the data. These errors have been corrected in the online version of the Article.

Today, the eastern African hydroclimate is tightly linked to fluctuations in the zonal atmospheric Walker circulation^1,2. A growing body of evidence indicates that this circulation shaped hydroclimatic conditions in the Indian Ocean region also on much longer, glacial–interglacial timescales^3–5, following the development of Pacific Walker circulation around 2.2–2.0 million years ago (Ma)^6,7. However, continuous long-term records to determine the timing and mechanisms of Pacific-influenced climate transitions in the Indian Ocean have been unavailable. Here we present a seven-million-year-long record of wind-driven circulation of the tropical Indian Ocean, as recorded in Mozambique Channel Throughflow (MCT) flow-speed variations. We show that the MCT flow speed was relatively weak and steady until 2.1 ± 0.1 Ma, when it began to increase, coincident with the intensification of the Pacific Walker circulation^6,7. Strong increases during glacial periods, which reached maxima after the Mid-Pleistocene Transition (0.9–0.64 Ma; ref. ⁸), were punctuated by weak flow speeds during interglacial periods. We provide a mechanism explaining that increasing MCT flow speeds reflect synchronous development of the Indo-Pacific Walker cells that promote aridification in Africa. Our results suggest that after about 2.1 Ma, the increasing aridification is punctuated by pronounced humid interglacial periods. This record will facilitate testing of hypotheses of climate–environmental drivers for hominin evolution and dispersal.