气候风险与适应：高地厂址、湿热升温的气候与受侵蚀的港口海岸

7.1 The site and its climate

The Kribi coast has an equatorial climate with two wet seasons and no truly dry month: even the driest months receive about 90 mm of rain [S60]. The homogenised record of Kribi station gives a mean annual rainfall of about 2,836 mm for 1937 to 1976, with the main wet season in September and October at about 500 mm a month and a relatively drier spell in July [S60]. Other sources give similar means, between about 2,800 and 2,900 mm [S60][S64]. On the ERA5 reanalysis for the Kribi grid cell, mean daily maximum temperatures range from about 26 °C in August to about 30 °C in March, and minimum temperatures from about 23 to 25 °C (1991 to 2020) [S64]; reanalysis tends to understate coastal maxima, which site measurements will confirm (Chapter 11); relative humidity ranges from about 70% to 78% in the afternoon to 92% to 96% at night [S60]. Squall lines bring short, violent gusts of up to about 20 m/s [S60][S62]. The US Geological Survey catalogue records no earthquake of magnitude 4.6 or more within about 170 km of Kribi since 1900 [S97]; a site-specific seismic hazard assessment is part of the geotechnical studies.

Source: Olivry, Monographie du Nyong et des fleuves côtiers, ORSTOM (1979), homogenised Kribi station record, 1937 to 1976 [S60].

The RC-1 site lies on the coastal plateau; satellite surface models give roughly 50 to 120 m across the wider area, and allowing for the forest canopy they include puts the ground at about 40 to 100 m above sea level (rounded; to be confirmed by survey) [S106]. The site is about 3 to 4 km from the coastline at the port frontage, measured from the centre of the indicative area (White paper 07, Table D.1). No river or marine flooding can reach the plant platforms at that elevation. The flood question on site is therefore one of stormwater: how much rain falls on the roofs, roads and stockyards of a large works, and where it goes.

7.2 Extreme rainfall is the main physical design load

The station record gives one-day rainfall totals of about 144 mm with a two-year return period, 193 mm at ten years, 243 mm at fifty years and 264 mm at one hundred years, from a Pearson type III fit to 33 years of data; the largest observed one-day total was 205.3 mm [S60]. Reanalysis datasets such as ERA5 smooth these extremes heavily (their mean annual maximum is about 76 mm [S64]) and should not be used for drainage design.

A warming climate intensifies heavy rainfall. The IPCC’s Sixth Assessment Report concludes that extreme daily precipitation events intensify by about 7% for each additional 1 °C of global warming [S59]. Applying that rate to the station values gives an illustrative allowance: about 283 mm for the 100-year day with one more degree of warming and about 302 mm with two (Figure 7.2). The station fit itself rests on mid-twentieth-century data, so part of that uplift may already have occurred.

Source: Kribi station Pearson III fit [S60]; IPCC AR6 WGI, scaling of extreme daily precipitation with warming [S59]. Uplift applied by Cameroon Steel.

For a steelworks, the consequences of under-designed drainage are not only nuisance flooding. Water entering a melt shop can cause steam explosions on contact with liquid steel or slag; flooded cable trenches and substations stop production; wet scrap raises furnace energy use and, if it carries trapped water into the furnace, is a safety hazard; and runoff from stockyards and slag areas must be collected and treated before discharge. Short-duration intensity-duration-frequency curves for Kribi, which govern the sizing of roof drainage and channels, are not available in the public record and are an evidence gap (Chapter 11).

7.3 Heat and humidity: a worker-safety issue first

Steelworks expose workers to radiant heat from liquid steel, slag and hot product, in addition to the ambient climate. In Kribi’s hot, humid conditions the body’s ability to cool by sweating is limited, so the combination is more demanding than either alone. The International Labour Organization estimated in 2019 that heat stress would cost 2.2% of total working hours worldwide by 2030, about 5% in western Africa, with central Africa among the most affected regions [S65]. Heat-stress management for RC-1 should be based on the wet-bulb globe temperature index defined in ISO 7243 [S66], with work-rest regimes, cooled refuges and pulpits, hydration, acclimatisation and monitoring, and with equipment specified for ambient conditions that include margins for warming.

Heat also affects equipment. Transformer, motor and drive ratings, the capacity of cooling towers (which depends on the wet-bulb temperature), and the performance of air-conditioned control rooms and electrical rooms should all be specified for hotter and more humid conditions than today’s averages.

7.4 Sea-level rise and shoreline retreat at the port interface

Globally, the IPCC projects sea-level rise by 2100, relative to 1995 to 2014, of about 0.44 to 0.76 m under an intermediate emissions scenario (SSP2-4.5) and 0.63 to 1.01 m under a very high one (SSP5-8.5), with a low-likelihood, high-impact outcome of up to about 2 m that cannot be ruled out [S59]. Kribi-specific projections were not obtained for this paper.

On the Kribi coast, sea-level rise adds to a more immediate process. Shoreline studies show that the coast was accreting by about 0.4 m a year on average between 1973 and 2000, retreated by about 0.9 m a year between 2000 and 2015 and by about 2 m a year between 2015 and 2020, with local rates far higher: about 32 m a year at the Lobé falls in 2015 to 2020 and 45 to 70 m a year near Lolabé in 2013 to 2017, while more than 15 m a year accumulated updrift of the port breakwater [S62]. A 2025 assessment rated 68.3% of the 31.5 km Kribi coast as highly vulnerable and linked part of the change to sediment trapping by the breakwater [S63].

Source: IPCC AR6 WGI Summary for Policymakers [S59]; Fendoung, Tchindjang and Hubert-Ferrari (2022) [S62].

RC-1 depends on the port in both directions. In Phase 1 the works would bring in about 351,000 t a year of imported metallics and consumables and ship up to 300,000 t of products, rising to about 1.24 Mt and 1 Mt at full build-out [S90]. Port infrastructure is the port authority’s responsibility. A mineral terminal at Kribi was the subject of a memorandum of understanding signed on 4 November 2025, and the port’s Director General said in March 2026 that it should be completed within five to six years [S87][S61][S74]; until then, iron units would pass through the existing terminals (White paper 02). Cameroon Steel’s own exposure lies in any jetty, conveyor or pipeline landfall it might build, in access roads near the coast and in the storage of imported iron units.

DRI deserves particular care. Freshly made DRI reacts with water and air, releasing heat and hydrogen; it is regulated as a hazardous bulk cargo under the International Maritime Solid Bulk Cargoes Code, which sets strict conditions for its carriage [S99]. HBI, compacted while hot, is more stable but must still be kept dry. In a climate with about 2,836 mm of rain a year, covered storage for DRI and HBI, both at the port and on site, is a safety requirement as well as a quality one. The RC-1 layout reserves a covered DRI/HBI store in the metallics yard [S90].

7.5 Climate risk to the power supply is also a carbon risk

Physical climate risk reaches the works through its power supply. Cameroon’s southern grid is about 90% hydro, and hydro output varies with rainfall: Nachtigal delivered about 28% less than planned in 2025 because of hydrology [S50]. Drier years, or longer dry seasons, would push more thermal generation onto the margin, raising both the cost and the carbon content of electricity at the time the works needs it (Chapter 3). Conversely, wetter extremes raise flood and sediment risks at hydro plants and along transmission corridors. For an electric-arc works, the climate resilience of the power system is therefore part of its own adaptation case, and a reason to contract for firmness rather than for energy alone.

7.6 Transition risks: the other half of a climate risk assessment

A climate change risk assessment under the Equator Principles covers transition risks as well as physical ones: the policy, legal, technology, market and reputational changes that a shift to a low-carbon economy brings [S22]. For an electric-arc works on a hydro-dominated grid, most of these are smaller than for a conventional steel plant, and several are opportunities. They are not negligible, however, and they belong in the same register as the physical hazards.

The policy channel runs mainly through export markets. Carbon border measures in the EU and the United Kingdom already price embedded emissions (Chapter 5), and buyers’ procurement rules increasingly do the same through product declarations. At home, Cameroon’s updated nationally determined contribution and its Plan National Climat set the direction of national policy [S80][S81]; a future domestic reporting obligation or carbon price cannot be excluded over a forty-year asset life. The technology channel concerns iron units: if ironmaking moves towards hydrogen and DR-grade ore stays scarce, the price and availability of the DRI and HBI that RC-1 buys could change materially [S11]. The market channel cuts both ways: low-carbon steel may earn a premium in some markets, but competing imports will also advertise low-carbon credentials, and unverifiable claims will not survive scrutiny.

Table 7.1 Transition risk screening for the RC-1 works

Source: Cameroon Steel screening; requirement from Equator Principles EP4 [S22].

7.7 A hazard screening for the Mboro works

Table 7.2 summarises the hazards, their relevance to the plant platform and the port interface, and the design responses that follow. It is a screening, not the full climate change risk assessment required by the Equator Principles for a project of this size [S22], which will be completed within the environmental and social impact assessment with site-specific data.

Table 7.2 Physical climate hazard screening (desk level)

Source: Kribi station data [S60]; IPCC AR6 [S59]; shoreline studies [S62][S63]; USGS catalogue [S97]; ILO [S65]; ISO 7243 [S66]; IEC 62305 [S98]. Screening by Cameroon Steel.

7.8 Adaptation is cheapest at the design stage

Most adaptation measures for a new works cost little if they are built into the design and a great deal if they are retrofitted. The main principles for RC-1 are:

• Design to the future climate, not the record. Use the station extremes with an explicit warming allowance for drainage, retention and roof design, and specify cooling systems and electrical equipment for hotter and more humid conditions.
• Keep water away from liquid metal. Melt-shop floors, pits and slag areas need positive drainage, raised thresholds and dry storage of charge materials.
• Separate clean and contaminated runoff. Roof water can be harvested for cooling-water make-up; runoff from scrap, slag and stockyards must be collected and treated.
• Protect people first. Heat-stress management, lightning protection and emergency plans for extreme weather should be in place before the first heat.
• Contract for firm power. The climate resilience of the grid is part of the plant’s own.
• Monitor and revise. A weather station on site from the start of construction, and a review of design assumptions at each phase, will keep the adaptation case current.

Physical risk and decarbonisation meet at one more point: the materials the works consumes and produces. The next chapter turns to circularity.