What the big ocean changes mean for your region

Atlantic circulation weakening or collapse

If the AMOC collapsed, annual rainfall in the West African monsoon would fall by about 29% on average across four climate models, with shorter wet seasons and longer dry seasons.

Model experiment Ben-Yami et al. 2024. Medium: all four models agree on the direction; the amount varies widely between models (Jongman & Hall, forthcoming, Table 1)

Atlantic circulation weakening or collapse

Evidence from past climates and models links a slower Atlantic circulation to higher risk of severe drought across West Africa, Mesoamerica and the Amazon, even short of collapse.

Model experiment DiNezio et al. 2025. Medium (Jongman & Hall, forthcoming, Table 1)

Atlantic circulation weakening or collapse

In one model study, rapid Greenland melting weakened the West African monsoon enough to change farming practices; without adaptation, tens to hundreds of millions of people could be forced to leave the Sahel by 2100.

Model experiment Defrance et al. 2017. Low: one model, an extreme melt scenario (0.5–3 m of extra sea-level rise) and assumed population growth

Subpolar North Atlantic convection collapse

In the minority of climate models where convection in the subpolar North Atlantic collapses (4 of 35 CMIP6 models), tropical rainfall changes, notably in the Sahel. This is a second route by which North Atlantic change could reach the region.

Model experiment Swingedouw et al. 2021. Low to medium: a minority of models; crop and food losses not quantified

Fish on the move

Fish and other aquatic foods supply about 19% of the animal protein eaten in Africa.

Observed FAO 2026, The State of World Fisheries and Aquaculture. FAO statistics, 2023

El Niño now, and stronger extremes in future

FEWS NET rates food-security concern from the 2026–27 El Niño as moderate for West Africa. Parts of the Sahel had rainfall more than 40% below average in June–September 2026.

Observed FEWS NET 2026, El Niño special report (6 Oct 2026). Agency assessment, October 2026

Fish on the moveAll regions

Under very high emissions, almost 90% of about 25,000 marine species are at high or critical risk; cutting emissions lowers risk for almost all of them and benefits food-insecure people in low-income countries most.

Projection Boyce et al. 2022. Climate risk index

Atlantic circulation weakening or collapse

In the same experiments, June–August rainfall falls by about 37% at Niamey (range 9–61% across models), 36% at Kano and 32% at Bamako. All four models agree that these places get drier.

Model experiment NAHosMIP data (Jackson, Bellomo et al.), processed by Ocean Turning Points after Ben-Yami et al. 2024. Conditional on a collapse, whose likelihood this century is disputed (IPCC: medium confidence it will not happen abruptly before 2100). Single model grid cells of 100–250 km from idealised experiments; read as direction and rough size, not a local forecast

Atlantic circulation weakening or collapse

Water storage sized for more variable rainfall may prove too small if wet seasons shorten for decades. Few crop, water or livelihood studies use AMOC scenarios yet.

Expert assessment Jongman & Hall (forthcoming), Table 1. Sparse downstream evidence (Jongman & Hall, forthcoming)

Sea-level rise (likely range)

At Lagos, sea level is projected to rise by 0.47 m by 2100 under low emissions and 0.84 m under very high emissions (median, relative to 1995–2014). Local subsidence would add to this.

Projection IPCC AR6 sea-level projections (Garner et al.), values extracted by Ocean Turning Points. Medium-confidence median; IPCC likely ranges are given on the site. Excludes local land subsidence from groundwater pumping. No tide gauge within 380 km; value from the nearest 1° grid cell

Sea-level rise (likely range)

Flooding, erosion and pollution already cost Benin, Côte d'Ivoire, Senegal and Togo about US$3.8 billion a year, 5.3% of their combined GDP in 2017. Flooding and erosion account for more than 60% of this.

Observed Croitoru, Miranda & Sarraf 2019 (World Bank). Economic estimate for one year (2017); covers all causes of coastal degradation

Ice-sheet loss and high-end sea-level rise

If poorly understood ice-sheet processes kick in under very high emissions, the projection for Lagos reaches 1.7 m by 2100 at the 83rd percentile. Ports and coastal roads built now will still be in use then.

Projection IPCC AR6 sea-level projections (Garner et al.), values extracted by Ocean Turning Points. Low confidence (IPCC): includes poorly understood ice-sheet processes; a low-likelihood, high-impact outcome

Sea-level rise (likely range)All regions

Global sea level will keep rising for centuries under every scenario. The IPCC likely range for 2100 is 0.28–0.55 m under very low emissions and 0.63–1.01 m under very high emissions (relative to 1995–2014).

Projection IPCC 2021. Medium confidence in the likely ranges (IPCC); virtually certain that rise continues

Ice-sheet loss and high-end sea-level riseAll regions

Under very high emissions, a rise approaching 2 m by 2100 cannot be ruled out because of deep uncertainty about ice sheets.

Projection IPCC 2021. Low confidence (IPCC): includes poorly understood ice-sheet processes; a low-likelihood, high-impact outcome

Sea-level rise (likely range)All regions

Over the past two decades the average coastal resident experienced 7.8–9.9 mm a year of relative sea-level rise, about three times the global mean, because many live on sinking land.

Observed Nicholls et al. 2021. Global analysis of subsidence and tide-gauge data

Fish on the move

By the 2090s under very high emissions, the fish biomass national waters can hold falls by about 39% for Senegal, 30% for Côte d'Ivoire, 29% for Mauritania and Ghana and 21% for Nigeria. Under low emissions the losses are 2–9%.

Projection Blanchard & Novaglio (eds) 2024, FishMIP projections for FAO. Ensemble mean of FishMIP models; all models agree on a decline for the countries named

Ocean acidificationAll regions

The present effect of acidification on global fish and shellfish harvests cannot yet be assessed. Losses in North American Pacific shellfish farming in the 2000s remain the clearest example of harm.

Expert assessment Cooley et al. 2022 (IPCC AR6 WGII, Chapter 3). Limited evidence (IPCC)

Fish on the moveAll regions

Marine animal biomass falls by about 5% for every degree of warming, with larger losses for bigger animals higher in the food chain.

Projection Lotze et al. 2019. Multi-model ensemble; medium confidence (IPCC)

Atlantic circulation weakening or collapse

Hydropower that depends on monsoon-fed rivers could be affected, but no study has quantified this for an AMOC collapse.

Expert assessment Global Tipping Points Report 2025. Low: qualitative expert judgement

Atlantic circulation weakening or collapse

Natural disasters already push an estimated 26 million people a year into extreme poverty. A lasting fall in monsoon rain would add to these shocks in economies that depend on rain-fed farming.

Observed Hallegatte et al. 2016. Global estimate; no published estimate yet of the fiscal cost of an AMOC collapse for the region

Marine heatwavesAll regions

Marine heatwaves have roughly doubled in frequency since the 1980s. By 2081–2100 they are projected to be about 20 times more frequent than in 1850–1900 under low emissions and 50 times under high emissions.

Projection Cooley et al. 2022 (IPCC AR6 WGII, Chapter 3). Medium confidence for the multipliers (IPCC SROCC, quoted in AR6)

Ocean acidificationAll regions

Seawater pH has declined globally over the past 40 years, mainly because of human CO2 emissions, and acidification will keep increasing this century under all scenarios.

Observed IPCC 2021 (Technical Summary). Virtually certain (IPCC)