Vietnam Climate Scenarios Warn of Rice Losses, Dangerous Heat and Rising Coastal Risks

Rice losses and stronger storms sharpen the case for adaptation

Vietnam's updated 2025 climate scenarios project rice yield losses exceeding 10% in some Mekong Delta growing seasons if global warming reaches 4°C, alongside a roughly threefold increase in the annual probability of storms with winds comparable to Typhoon Yagi. The same assessment points to more dangerous heat in Hanoi and Ho Chi Minh City and growing pressure on transport, buildings and water systems.

The Ministry of Agriculture and Environment's update sets out three possible emissions pathways, rather than a single forecast. Under its high emissions scenario, average sea level across the East Sea, also known as the South China Sea, could rise 63.7 centimetres by 2100. The upper uncertainty bound reaches 84.2 centimetres. The Mekong Delta has the highest projected inundation risk.

The government's climate scenario announcement also translates the findings into investment guidance: projects lasting 10 to 20 years can use low or medium scenarios, while critical infrastructure intended to last more than 50 years should use the high scenario to prepare for adverse conditions.

That distinction matters because roads, ports, sea dykes and power networks built today may still be operating when the emissions pathways diverge more sharply later this century. The update connects those planning choices with detailed assessments of heat, rainfall, storms, sea level and several vulnerable sectors.

The stakes extend beyond physical damage. The World Bank Group estimated Vietnam's climate losses in 2020 at about $10 billion, equivalent to 3.2% of gross domestic product. Its development assessment identifies approximately $300 billion in commercial and industrial assets as vulnerable to climate disasters.

What the three pathways actually mean

The scenarios are SSP1-2.6, SSP2-4.5 and SSP3-7.0. SSP stands for Shared Socioeconomic Pathway, a framework combining assumptions about population, economic development, energy, technology and climate policy with different emissions trajectories.

• SSP1-2.6 is the low emissions pathway, associated with sustainable development and strong reductions in greenhouse gases.
• SSP2-4.5 is the medium pathway, reflecting moderate progress in development and emissions reduction policies.
• SSP3-7.0 is the high pathway, reflecting high emissions without sufficiently strong additional climate policies.

The update moves from the earlier RCP framework to SSPs and uses the CMIP6 generation of global climate models. RCPs primarily describe greenhouse gas concentration pathways; SSPs add explicit assumptions about how societies and economies develop.

Pham Thi Thanh Nga, director of the Institute of Meteorology, Hydrology, Environment and Marine Sciences, identified the institute as the lead developer. She described an update comprising eight chapters and specialized appendices, with new urban climate scenarios, assessments organized by global warming level, inundation risk analysis and guidance for users.

Global warming levels provide a second way to read the findings. A projection at 2°C or 4°C describes conditions if the global average temperature reaches that increase relative to the period before industrialization. It does not assign that threshold to a particular year. This helps planners compare risks without assuming that one emissions pathway will unfold exactly as modeled.

A warming country, with different regional risks

Vietnam's average annual temperature increased by approximately 0.2°C per decade between 1961 and 2023. The new scenarios project further increases in maximum temperatures across the country, generally by 1°C to 1.5°C at a global warming level of 1.5°C and by 3°C to 4°C at a global warming level of 4°C.

Minimum temperatures rise more sharply, especially in the North. In northern mountainous provinces, their increase could exceed 5°C at global warming levels of 3°C to 4°C. This means warming affects the cooler end of the temperature range as well as the hottest conditions.

The number of days above 35°C is projected to increase by 10 to 30 at 1.5°C of global warming and by 30 to 50 at levels of 3°C to 4°C. The government announcement says the increase itself could exceed 50 days annually in many parts of Central and Southern Vietnam. Other descriptions refer to more than 50 hot days a year without making that distinction, so the two formulations should not be treated as identical.

Severe cold days in the North are projected to fall by 20 to 30 at 3°C of global warming and by 30 to 40 at 4°C. Drought frequency and intensity increase in the North, while the South shows a slight decline. A single national average would conceal these differences.

Heavier downpours can accompany drier seasons

Rainfall projections show why more rain does not necessarily mean more reliable water supplies. Spring rainfall declines across much of Vietnam, including reductions of around 20% to 30% in the South Central Coast and Central Highlands. Winter rainfall increases across most of the country, typically by 20% to 60%, except in the Northwest.

Summer and autumn rainfall rise more strongly in the North. Maximum rainfall accumulated over one day and five days could increase by around 30% to 40% in the North and South. Under the high scenario, the number of days receiving more than 100 millimetres could increase by 80% to 100% in some northern areas, the Central Highlands and the South.

Those are different measures of risk. Seasonal totals help assess water availability, while intense rainfall over hours or days tests drainage, river channels and flood defenses. More concentrated rainfall can coexist with a drier spring, leaving communities exposed to both water shortages and flooding at different times.

At 4°C of global warming, the annual probability of a storm with winds around 58 metres per second, comparable to Yagi, rises from 2.6% to 7.7% in the North, from 2.0% to 6.3% in Central Vietnam and from 0.25% to 0.75% in the South.

These figures represent approximately threefold increases, not predictions of storms arriving on a fixed schedule. The modeled average recurrence interval shortens from about 38 years to 13 years in the North and from 50 years to 16 years in Central Vietnam. During 1991 to 2025, the South China Sea averaged about 12.7 typhoons and tropical depressions annually, including about 3.4 storms reaching intensity level 12 or higher, with substantial variation between years.

Sea level projections require careful comparison

By 2100, average sea level rise across the East Sea is projected at 46.1 centimetres under the low scenario and 63.7 centimetres under the high scenario, a difference of 17.6 centimetres. The high scenario's upper uncertainty bound of 84.2 centimetres is not the central estimate.

For Vietnam's coastal strip, the high scenario gives an average rise of about 61.9 centimetres and an upper bound of 82 centimetres. These figures differ from the East Sea estimates because they describe a different geographic area.

The government announcement also lists local median estimates from the draft: 60.2 centimetres for Quang Ninh, 64.3 centimetres for Ca Mau, 63.7 centimetres for the Hoang Sa archipelago and 67.4 centimetres for the Truong Sa archipelago. It does not explicitly identify the emissions pathway for those local figures in the passage presenting them.

Observed sea level trends also depend on measurement method. During 1993 to 2023, monitoring stations recorded an average rise of about 3.4 millimetres annually, while satellite measurements indicated 4.3 to 4.5 millimetres. These are separate observational estimates, not interchangeable readings.

The danger to the Mekong Delta is compounded by sinking ground. Earlier coverage of rising seas and subsidence described average sinking of about 1.1 centimetres annually, linked to groundwater extraction and reduced sediment supply. Sea level projections alone therefore do not describe the full change in water height relative to the land.

Rice risks reach far beyond individual farms

The new case studies project declining rice yields in both the Red River and Mekong deltas as warming increases. Effects become clearer from 2°C of global warming, with the Mekong Delta more vulnerable. At 4°C, reductions could exceed 10% in some growing seasons. That is a seasonal result, not a forecast that every harvest or national rice production will fall by the same percentage.

The World Bank Group's Climate and Development Report explains why these local losses matter nationally. The Mekong Delta accounts for about 50% of Vietnam's rice production and 95% of rice exports, alongside 65% of aquaculture production and one third of agricultural GDP.

The report also identifies saltwater intrusion, erosion and land subsidence as pressures on delta production. Its older assessment projects that, without adaptation, salinity could affect around 45% of the delta by 2030, at an economic cost of about $17 billion. That estimate should not be confused with the new assessment's rice yield projections, which measure a different outcome under different assumptions.

Its recommended regional measures include reducing groundwater extraction and sand mining, changing farming practices, improving freshwater flows and aquifer recharge, and restoring mangroves. Together, these address both climate hazards and local activities that make the delta more exposed.

Urban heat threatens health and household budgets

The 2025 scenarios project a sharp increase in dangerous combinations of heat and humidity in Hanoi and Ho Chi Minh City, especially in inner urban areas. The assessment uses a wet bulb globe temperature, or WBGT, above 32°C as its dangerous heat threshold.

WBGT is a heat stress measure that accounts for humidity, radiant heat and air movement as well as temperature. A WBGT reading of 32°C is therefore not equivalent to an ordinary weather forecast temperature of 32°C. Humidity can reduce the body's ability to cool through sweating, making conditions hazardous even when air temperature alone does not capture the risk.

Dengue risk also increases as warmer temperatures and other climate conditions become more favorable to mosquitoes that transmit the disease. The scenarios do not provide a specific future case count, and climatic suitability is not the same as a guaranteed outbreak.

The World Bank Group report connects rising heat with lower labor productivity, higher cooling costs and increased electricity demand. It also cites a modeling exercise in which a day during a heatwave could increase mortality by 0.7%. That is a separate research estimate, not a death toll calculated by the 2025 scenarios.

Air pollution adds another health burden. The report cites a World Health Organization estimate of about 60,000 deaths annually from severe urban air pollution. Those deaths should not be counted as heat deaths, although reducing fossil fuel emissions can also reduce some harmful air pollutants.

Infrastructure damage can spread through the economy

The updated scenarios identify extreme temperatures, prolonged heatwaves and changing extreme winds as threats to the durability and service life of transport infrastructure and urban structures. Flooding introduces another route to damage and disruption.

The World Bank Group report estimates that road failure caused by river flooding could increase by at least 40% by 2030. It also finds that losing a single link on National Highway 1A could cause $1.9 million in daily economic losses from rerouting freight alone, before accounting for physical repairs.

This distinction between damaged assets and interrupted services is central to investment decisions. A broken road or power line can halt production elsewhere, interrupt trade or isolate communities. Northern mountainous areas with few alternative routes are especially exposed to loss of connectivity.

The report's analysis of upgrades to 20 national highway sections estimated investment needs of about $153 million and benefits of $651 million to $3.66 billion over 35 years. Those figures imply benefits of roughly four to 24 times the investment, within that analysis's assumptions.

It also estimated that shifting 10% of road freight to other transport modes could reduce economic impacts from climate extremes by 20% to 25%. Strengthening individual assets and providing alternative routes are therefore distinct ways to reduce disruption.

How the scenarios should guide decisions

The government's guidance distinguishes project lifetimes. Low or medium scenarios can inform projects lasting 10 to 20 years. Regional planning, transport and energy investments lasting 30 to 50 years should compare medium and high scenarios. Critical structures lasting more than 50 years, including sea dykes and ports, should use the high scenario.

For plans tied to specific dates, the guidance recommends SSP information. For risk assessments and flexible adaptation strategies, global warming thresholds offer another useful basis. Neither approach turns the scenarios into a forecast.

The report's account of pathway divergence explains the timing: differences are smaller before 2050 and become more pronounced afterward as the effects of global development and emissions policies accumulate. Long asset lifetimes make those later differences relevant to decisions taken now.

The scenario data are described as detailed to commune level, provided at decadal intervals and integrated into a WebGIS system, an online platform for viewing geographic information. Authorities can use inundation maps and other projections in settlement planning, permits, infrastructure management and reviews of technical standards.

Deputy Minister of Agriculture and Environment Le Trong Yen called for ministries, local authorities and businesses to incorporate the information into development and investment plans. He also requested urgent preparation of a Climate Change Law for submission to the National Assembly. No submission deadline or legislative vote date is identified.

The timeline and the limits of the assessment

The edition year and the reported presentation date are different. The update is called the 2025 version, while the workshop announcing it is dated October 9, 2026. The chronology also includes earlier policy action and observational periods that underpin the risk assessment.

• 1961 to 2023: Vietnam's average annual temperature rose by approximately 0.2°C per decade.
• 1993 to 2023: Station and satellite measurements both recorded rising sea levels, with different average rates.
• 2017: Resolution No. 120/NQ-CP established a policy framework for sustainable development and climate resilience in the Mekong Delta.
• July 28, 2026: Conclusion No. 75-KL/TW of the Communist Party's 14th Central Committee identified proactive climate response and disaster risk reduction as key tasks.
• October 9, 2026: A workshop in Hanoi presented the scenarios bearing the 2025 edition label.

The older World Bank Group assessment provides useful measures of economic exposure, but many of its projections use RCP pathways rather than the SSP framework adopted in the new update. Its flood, agricultural and financial estimates cannot simply be combined with the new scenarios as though they came from one model.

The World Bank Group itself acknowledges gaps concerning health, education, water security and coastal infrastructure. It states:

The CCDR does not address all the key climate-related challenges faced by Vietnam.

The new sector case studies help narrow some gaps, but they do not establish precise future dengue case numbers, losses for every rice season or repair costs for individual structures. Those decisions require local exposure data, engineering assessments and adaptation choices alongside climate projections.

Key Points

• Vietnam's 2025 update uses three SSP emissions pathways and assessments organized by global warming level.
• Mekong Delta rice yields could fall more than 10% in some seasons at 4°C of global warming.
• At that warming level, annual probabilities of storms comparable to Yagi rise roughly threefold.
• Average East Sea level rise reaches 63.7 centimetres by 2100 under the high scenario, with an upper uncertainty bound of 84.2 centimetres.
• Dangerous heat and humidity become more frequent in Hanoi and Ho Chi Minh City.
• Critical infrastructure lasting more than 50 years should be planned using the high scenario.
• The scenarios support risk planning; they are not forecasts of one inevitable future.