Impact of Climate Change on Agricultural Production and Food Security: A Case Study in the Mekong River Delta of Vietnam

Abstract

Vietnam is a country highly vulnerable to climate change. Specifically, climate change has seriously impacted all aspects of Vietnam’s economic and social life, especially agricultural production. In this article, we focus on analyzing the current situation and the impacts of climate change on agricultural production and food security in Vietnam, especially in the Mekong River Delta (MRD) region. Vietnam’s climate change scenarios (RCP4.5 and RCP 8.5) have warned of serious increases in temperature, rainfall, and sea level rises for the MRD in coming times. This will lead to a risk of flooding in nearly 50% of the region’s area and will seriously affect agricultural production in many aspects such as soil quality degradation, scarcity of water resources, increased droughts and floods, reduced crop productivity, and so on. These impacts will reduce Vietnam’s food supply capacity, but do not compromise national food security from a short-term perspective. Faced with this situation, the Government of Vietnam has implemented many comprehensive measures to transform agriculture towards ecology, sustainability, and low carbon emissions, with the goal of green growth and neutral carbon emissions by 2050. In particular, the focus is on combining nature-based solutions with the application of modern science and technology in agricultural production, raising awareness and the response capacity of domestic people, with international cooperation in addressing climate change issues.

1. Introduction

Climate change is a change over a long period of time that is due to the combined impact of changing natural conditions and human activities, manifested by global warming, rising sea levels, and increased extreme hydrometeorological phenomena (Bibi, F. and Rahman, A., 2023) [1]. Climate change is evolving complexly on a global scale, seriously affecting all aspects of human life and the socio-economy, of which agricultural production is one of the most heavily affected sectors (Vien, 2011) [2]. Climate change can affect agricultural production directly and indirectly (Hatfield et al., 2020) [3]. Changes in the climate system increase extreme weather patterns such as heat, drought, heavy rain, storms, floods, etc., directly reducing crop productivity and output (Qiu et al., 2023 [4]; Neupane et al., 2022 [5]). In addition, climate change also indirectly affects agricultural production through processes that degrade soil quality (salinization, nutrient depletion); loss of agricultural land due to rising sea levels; shortages of irrigation water; disruption of production, storage, and transportation processes during and in the aftermath of extreme events; and increased pests and diseases in crops (Yang et al., 2020 [6]). Research on the impact of climate change on agricultural production and food security can be carried out using many different methods, but can be summarized into four basic groups [7]:

(i)

empirical research methods;

(ii)

extrapolation of historical factors method;

(iii)

analogy case study method;

(iv)

expert method.

Empirical research is used to determine the impact of climate and environmental factors (temperature, rainfall, salinity, and flooding due to rising sea levels, etc.) on research subjects such as: crop and livestock productivity; pest development; and changes in soil and water quality. The extrapolation of historical factors method is the use of simulation models to predict the future impacts of climate change based on worldwide observational data. This method is performed in four steps, including selecting the appropriate model; checking data needs; developing the model; and running the model to analyze the results. The analogy case study method is the use of data from similar cases in another area to assess the impact of climate change on the subject under consideration. Finally, the expert method is the collection of opinions and assessments of research experts on the impact of climate change on the subject under consideration. Expert opinions can be consulted directly or referred to from research documents and published scientific works. In fact, due to the complexity of climate change, the above research methods are often used in combination to achieve higher efficiency in analysis, assessment, and forecasting.

There have been many in-depth studies pointing out the specific impacts of climate change on agricultural production. For example, in China, unusually heavy rains reduced rice production by 8% over the two decades from 2000 to 2020 (Fu, Jin et al., 2023) [8]. In Africa, the El Niño phenomenon that lasted from 2014 to 2016 directly reduced millet productivity by 10–20% and sorghum productivity by 5–15%, causing food prices in the region to increase dramatically (Bezner Kerr et al., 2022) [9]. Climate change hurts agricultural production, thereby seriously threatening the world’s food security. According to the IPCC (2019) [10], the number of people at risk of food shortage in all climate change scenarios by 2050 is predicted to range from 8 to 80 million people, mainly concentrated in regions such as Africa, South Asia, and Central America. In fact, as of 2017, there were 821 million people in the world suffering from poverty (accounting for 11% of the world’s total population). By 2021, an estimated 720–811 million people will be undernourished. Of these, about 200,000 will be classified as critically food insecure, 32.3 million as acutely food insecure, and 112.3 million as critically food insecure (FAO, IFAD, UNICEF, and the WHO, 2021 [11]). This situation could get worse as greenhouse gas emission scenarios predict a decline in world food production, leading to a volatile increase in food prices (Hasegawa et al., 2021 [12]; Kummu et al., 2021 [13]). However, there are also many optimistic views that climate change will have little impact on the world’s food security shortly due to human progress in implementing measures to mitigate global warming and solutions to adapt to climate change in agricultural production (van Dijk et al., 2021 [14]; Janssens et al., 2020 [15]). Thus, whether viewed from a pessimistic or optimistic perspective, one can see the close relationship between climate change and food security. The negative impacts of climate change on agricultural production are the main cause threatening human food security. The severity of this problem depends largely on the actual effectiveness of climate change mitigation and the adaptation solutions implemented by countries around the world.

Vietnam is a country with a long history of agricultural production. In the current period, Vietnam is promoting the process of industrialization and the modernization of the country, with a shift in its economic structure from the agricultural sector to service and industry. However, agricultural production has always played an important role in Vietnam’s economy. The Vietnamese Government identifies agriculture as a pillar of the economy, contributing to ensuring national food security, and stabilizing the macro economy (MARD of Vietnam, 2023) [16]. Agriculture is the most important economic sector of Vietnam, both in the past and present. It has the most direct and powerful influence on the stability and development of the country, bringing in large foreign currency revenues and contributing to enhancing Vietnam’s position and prestige in the international arena (Vien, T.D., 2023) [17]. In 2023, the average growth of Vietnam’s agricultural sector reached 3.83%, contributing greatly to the 5.05% growth in the national economy. The agricultural sector also attracts 13.8 million workers, accounting for 26.9% of Vietnam’s labor force (GSO of Vietnam, 2023) [18]. Besides this, agriculture gives an important contribution to Vietnam’s export turnover; in 2023, the total agricultural export turnover reached over 53 billion USD, achieving the highest trade surplus ever at 12.07 billion USD, up 43.7% compared to 2022. This result has helped Vietnam become the world’s leading agricultural exporter. As the world’s leading agricultural exporter, especially of rice, Vietnam’s agricultural production makes an important contribution towards ensuring food security globally. However, agricultural production in Vietnam is facing many difficulties and challenges. Among them, the impacts of climate change are considered the most important challenge (MARD of Vietnam, 2023) [16].

Vietnam is a country with a vulnerability to climate change and natural disaster risks, being in the top 10 most at risk countries in the world (ranked 6th) according to Germanwatch’s rankings. Climate change has a strong impact on all the economic and social sectors of Vietnam (Germanwatch, 2020) [19]. Specifically, if sea levels rise by 1 m, Vietnam is at risk of losing 5% of its land area (mainly agricultural land), causing 7% damage to agricultural production, affecting 11% of the population, and reducing the national GDP by up to 10% (World Bank, 2007) [20].

Climate change directly leads to increased atmospheric temperature, erratic changes in rainfall, increased sea levels, and higher risks of natural disasters such as droughts, heat waves, floods, and tropical storms, etc. (Vien, 2011) [2]—not to mention the secondary impacts and systemic effects that climate change combined with other economic, political, and social factors causes. Climate change affects most aspects of economic and social life but has the most serious and strongest impact on agricultural production, affecting the lives of millions of farmers and directly threatening national food security (FAO & UNDP, 2020) [21]. In Vietnam, over recent years, the climate change trend has been relatively complex, and the country’s temperature and rainfall have changed significantly over the past 60 years (from 1958 to 2018). Specifically, temperature and precipitation have tended to increase; maximum temperatures and the average number of hot days have increased in all regions of the country, especially in recent years, while the average number of cold days per year has tended to decrease. However, there are now more severe and damaging cold spells, along with ice and snow that have never happened before in Vietnam (snow and ice in some northern mountainous provinces in the winter years of 2008, 2015, and 2016). Heavy rain has increased in both quantity and intensity, with unpredictable developments in recent years (MONRE, 2021) [22]. Complex changes in the climate system have changed natural farming conditions, cropping calendars, and seasons; increased epidemics; and induced other unfavorable factors for Vietnam’s entire agricultural production system, causing the agricultural sector to suffer heavy losses and possibly become unsustainable shortly.

Vietnam is a leading food-producing country in the world; however, the impacts of climate change may become the main cause threatening Vietnam’s food security due to its direct impact on natural and essential elements of the agro-food system. Vietnam’s main food crop is rice, which accounts for 94% of the cultivated land area. It is mainly distributed in the Mekong Delta and the Red River Delta, accounting for 54.47% and 24.08% of the country’s cultivated land area, respectively. Both regions are suffering severe impacts from climate change, especially the Mekong Delta (FAO & UNDP, 2020) [21]. In recent times, climate change has caused great damage to rice production and other major food crops in Vietnam (Phuong et al., 2022) [23]. Changes in temperature and precipitation lead to weather disturbances such as an increased number of extreme hot and cold days, heavy rains, floods, water scarcity and droughts, landslides, rising sea levels, and other extreme weather events (Woillez et al., 2021) [24]. This is a great danger to Vietnam’s food security if there are no timely interventions. Within the framework of this paper, we focus on analyzing the impacts of climate change on agricultural production and food security in the Mekong Delta of Vietnam, one of the world’s hot spots for the impacts of climate change.

2. Study Area and Methodology

2.1. Study Area

The Mekong Delta is the largest in the South of Vietnam, adjacent to the Southeast region (Vietnam), bordering Cambodia to the North, the Gulf of Thailand to the Southwest, and the East Sea to the East. This area includes 1 city (Can Tho City) and 12 provinces: Long An, Tien Giang, Ben Tre, Vinh Long, Tra Vinh, Hau Giang, Soc Trang, Dong Thap, An Giang, Kien Giang, Bac Lieu, and, Ca Mau. The Mekong Delta can be divided into three main sub-regions: (i) The highland area in the West (including Dong Thap, the An Giang provinces, and Can Tho city) is the upstream area of the Mekong River; (ii) The western region is often flooded during the rainy season due to the rising water levels of the Mekong River (including the provinces of Long An, Tien Giang, Vinh Long, Hau Giangm and part of the east of Kien Giang); (iii) The eastern coastal area is often affected by saltwater intrusion in the dry season (including the eastern part of Long An, Tien Giang, Vinh Long and, Hau Giang provinces; the coastal area of Kien Giang province; and the entire provinces of Ben Tre, Tra Vinh, Bac Lieu, and Ca Mau) (Figure 1). The climate of the Mekong Delta is equatorial (hot and rainy), which is favorable for agricultural development. The region has two basic seasons: the rain season from May to October and the dry season from November to April of the following year. The average annual rainfall ranges from 1600–1800 mm/year, mainly concentrated in the rain season.

The total natural area of the Mekong Delta is 40,694.53 km², with a population of more than 17.7 million people (2022), accounting for 12.8% of the area and 17.9% of the population of Vietnam, respectively. The livelihood of people in the area is mainly based on agricultural production. This is the leading region in Vietnam in terms of food, fruit, and aquatic product output; specifically, the rice accounts for 54% of the country’s rice growing area and 58% of its output, and rice exports in the whole region account for 93% of rice exports for the whole country; aquatic products represent 77% of the country’s aquatic product area, 40% of its output, and 60% of the export output of Vietnam (GSO of Vietnam, 2023) [25]. Therefore, the Mekong Delta has an important contribution to ensuring Vietnam’s national food security. However, due to the flat and low terrain, the common altitude of the area is not more than 1 m above sea level, so the Mekong Delta is the area most heavily affected by climate change, especially by the impact of rising sea levels (Le S, 2016 [26]). During the dry season, a lack of rainfall combined with high tides leads to serious saltwater intrusion, reducing cultivated areas and yields and causing great economic losses (MRC, 2024 [27]). In addition to climate change factors, other factors from socio-economic activities within the region and from outside, especially the activities of water exploitation projects (hydroelectric dams, irrigation projects) of countries upstream of the Mekong River, have seriously impacted the natural ecosystem and agricultural cultivation capacity of the Mekong Delta region. For the above reasons, the Mekong Delta region is becoming a hot spot for the impacts of climate change on Vietnam and the world.

2.2. Methodology

In this study, the 2020 climate change scenario of Vietnam (Historical factors extrapolation method) is used to analyze the current and future trends and forecasts of climate change (Scenarios on temperature, rainfall, and sea level rises) (MONRE, 2021) [22]. In addition, actual data on agricultural production and the comments and assessments of experts on the impact of climate change on agricultural production and food security is gathered. The research approach diagram is illustrated in Figure 2.

2.2.1. Vietnam’s Method of Building Climate Change Scenarios

Data used to build Vietnam’s climate change scenario

-

Meteorological data: Temperature and rainfall observation data were collected from 150 out of 187 ground-based meteorological observation stations in Vietnam. The selected stations must meet two requirements: They must have started meteorological observations by 1986 and must have observation data from over 30 years.

-

Oceanographic data: Oceanographic data is collected from two sources: oceanographic observation stations and satellites, of which, Vietnam’s oceanographic observation stations include 17 stations located along the coast and islands of Vietnam. In addition, satellite monitoring of sea levels has been carried out since 1993 and ocean wave monitoring since 2009. The AVISO (Archiving, Validation, and Interpretation of the Satellite Oceanographic) sea level and wave data set is a combination of the ERS–1/2, Topex/Poseidon (T/P), ENVISAT, and Jason–1/2 satellites. The data have a temporal resolution of 7 days and a spatial resolution of 0.25 × 0.25 degrees latitude and longitude.

-

Digital elevation model data: Used to build flood risk maps, the data used includes a geographic information platform, digital elevation model, and a digital terrain map at the best available scale that was updated up to 2020, provided by the Department of Surveying, Mapping, and Geographic Information of Vietnam.

-

Method of building and updating climate change scenarios of Vietnam

-

The dynamic detailing method was the main method chosen to build and update climate change scenarios in Vietnam. Six regional climate models (RCMs) have been applied to calculate and develop climate change scenarios for Vietnam, including the (i) clWRF model; (ii) PRECIS model; (iii) Australian CCAM model, (iv) Italian RegCM model, (v) Japanese AGCM/MRI model, and (vi) Swedish RCA3 model. The input for these computational models includes 26 scenarios from global models (part of CMIP5).

-

Climate change results update: The calculated results of future climate variables are compared with the baseline period (1986–2005), which is also used by the IPCC as the baseline period for comparison in AR5. Variables related to temperature and rainfall are corrected before calculating changes. Variable calibration is based on actual measurements at meteorological stations to reflect specific local conditions and also to reduce systematic errors.

-

Method of building sea level rise scenarios due to climate change in Vietnam

Method for calculating sea level rise scenarios for Vietnam: built according to the method in AR5 of the IPCC. The results of sea level rise calculations for the East Sea area according to the IPCC are compared with actual measurements in coastal and island areas of Vietnam and satellite monitoring data. The calculation results for the East Sea area from the models are quite consistent with the water level data observed at hydrographic stations as well as satellite data. During the period 1986–2005, the rate of sea level changes calculated according to observational data was about 2.8 mm/year, slightly higher than the calculation results of the IPCC (about 2.4 mm/year). The standard error values of average water levels at monitoring stations, as well as from satellite data, are mostly within 5% ÷ 95% of the calculated results from the IPCC.

2.2.2. Empirical Research Method

In this study, we used some experimental data on the impact of climate change on the productivity of some crops in Vietnam. Specifically, a study on the impact of temperature on rice and corn productivity was conducted by the Vietnam Institute of Agricultural Environment; MARD and MONRE of Vietnam. In addition, data on agricultural production in the Mekong Delta region were used for checking and evaluation in combination with forecasts made in the climate change scenario of the Ministry of Natural Resources and Environment of Vietnam.

2.2.3. Expert Method

We have additionally consulted and compiled assessments, expert comments, and forecasts on the impact of climate change on agricultural production and food security in the Mekong Delta region in order to validate and complement the empirical research component.

3. Results

3.1. Current Status of Climate Change in the Mekong Delta Region

According to monitoring data from 1958 to 2018 (MONRE, 2021) [22], climate change trends in Vietnam’s Mekong Delta can be summarized as follows:

-

The average temperature of the entire region increased by 0.89 °C in the period 1958–2018 (60 years), in which the average temperature increased by 0.74 °C (32 years) in the period from 1986 to 2018. Thus, it can be seen that the increasing trend in temperature is becoming faster than before. Worryingly, the maximum temperature and number of hot days (>35 °C) has tended to increase, and many temperature records have been set and recorded in recent years.

-

Average annual rainfall increased by about 2.1% in the period 1958–2018. The trend of increasing rainfall in the Mekong Delta region is opposite to the northern regions of Vietnam (declining rainfall trend). Extreme rainfall (R × 1 day and R × 5 day) increased in the southern region of Vietnam, including the Mekong Delta.

-

Extreme weather phenomena: the number of hot days tended to increase. The trend of strong storms has increased in recent years.

-

Rising water levels: According to satellite monitoring data, the average sea level of the East Sea increased by 4.1 mm/year, of which, the sea level of Vietnam’s coastal strip increased by 3.6 mm/year.

In general, climate change has had quite serious effects on the Mekong Delta region in recent times, causing prominent impacts such as sea level rises, flooding in the rainy season, saltwater intrusion, an increased frequency of storms, and a lack of fresh water in the dry season.

3.2. Climate Change Forecast in the Mekong River Delta Region

According to the report of MONRE (2021) [22], the climate change scenario of the MRD region by the end of the 21st century is specifically as follows:

-

Temperature change scenario: According to estimates of the low emission scenario (RCP4.5) and high emission scenario (RCP8.5), the average temperature of the entire MRD region will continue to increase from now to the late 21st century (

Table 1. Average annual temperature change in the MRD according to the two scenarios of RCP4.5 and RCP 8.5.

No	Province	RCP4.5		RCP8.5
		2046–2065	2080–2099	2046–2065	2080–2099
1	Long An	1.3 (0.9–2.0)	1.8 (1.2–2.6)	1.9 (1.4–2.6)	3.4 (2.6–4.6)
2	Tien Giang	1.3 (0.9–2.0)	1.8 (1.2–2.6)	1.9 (1.4–2.7)	3.4 (2.7–4.6)
3	Dong Thap	1.3 (0.9–2.0)	1.7 (1.1–2.5)	1.9 (1.3–2.6)	3.3 (2.6–4.5)
4	Vinh Long	1.3 (0.9–1.9)	1.7 (1.2–2.6)	1.8 (1.3–2.6)	3.4 (2.6–6.5)
5	Tra Vinh	1.3 (0.9–2.0)	1.7 (1.2–2.5)	1.8 (1.3–2.6)	3.3 (2.6–4.5)
6	Can Tho	1.3 (0.9–1.9)	1.7 (1.2–2.6)	1.8 (1.3–2.6)	3.4 (2.6–4.5)
7	Hau Giang	1.3 (0.9–2.0)	1.7 (1.2–2.5)	1.8 (1.3–2.5)	3.2 (2.6–4.2)
8	Soc Trang	1.3 (0.9–1.9)	1.7 (1.1–2.5)	1.8 (1.3–2.5)	3.3 (2.5–4.3)
9	Ben Tre	1.3 (0.9–1.9)	1.7 (1.1–2.4)	1.8 (1.3–2.5)	3.2 (2.6–4.2)
10	An Giang	1.3 (0.9–2.0)	1.8 (1.1–2.6)	1.9 (1.3–2.6)	3.4 (2.5–4.6)
11	Kien Giang	1.3 (0.9–2.0)	1.7 (1.2–2.5)	1.8 (1.3–2.5)	3.2 (2.6–4.2)
12	Bac Liêu	1.3 (0.9–1.9)	1.7 (1.1–2.4)	1.7 (1.3–2.4)	3.2 (2.5–4.2)
13	Ca Mau	1.3 (0.9–1.9)	1.7 (1.1–2.4)	1.8 (1.3–2.5)	3.2 (2.5–4.3)
14	Mekong Delta	1.3 (0.9–1.95)	1.7 (1.15–2.5)	1.8 (1.3–2.55)	3.3 (2.5–6.5)

Note: Data in ( ) are the range of variation.

).

-

Rainfall change scenarios: According to forecasts, the average annual rainfall in the MRD region will continue to increase in the middle and late 20th century under both low (RCP4.5) and high (RCP 8.8) emission scenarios. Specifically, according to the RCP4.5 scenario, the average rainfall of the region increased from 8.3–17.9 mm by the mid-century and from 12.5–19.2 mm/year by the end of the century. Meanwhile, these figures were 18.3–21.6 mm by the mid-century and 19.9–26.3 mm by the end-century for the RCP8.5 scenario (

Table 2. Forecast of annual average rainfall changes in the MRD region according to the two scenarios RCP4.5 and RCP8.5.

No	Province	RCP4.5		RCP8.5
		2046–2065	2080–2099	2046–2065	2080–2099
1	Long An	8.3 (0.7–32.0)	14.7 (3.2–26.6)	19.2 (7.8–30.2)	26.3 (15.5–42.1)
2	Tien Giang	16.8 (−1.8–37.1)	14 (−0.9–28.6)	18.9 (6.7–31.1)	23.7 (8.9–40.7)
3	Dong Thap	17.0 (−2.0–31.0)	14.9 (2.3–26.9)	18.3 (9.1–28.7)	24.6 (15.7–39.4)
4	Vinh Long	16.3 (0.8–28.5)	12.5 (1.4–22.0)	20.3 (12.4–31.2)	21.2 (13.0–35.3)
5	Tra Vinh	16.7 (−3.3–30.3)	13.2 (4.4–20.2)	20.6 (11.4–32.3)	24.3 (14.4–37.5)
6	Can Tho	16.3 (0.8–28.5)	12.5 (1.4–22.0)	20.3 (12.4–31.2)	21.2 (13.0–35.5)
7	Hau Giang	14.5 (4.2–25.5)	19.2 (3.8–33.8)	19.0 (7.8–30.1)	24.9 (12.1–42.8)
8	Soc Trang	15 (1.2–26.0)	14.1(4.0–23.1)	19.0 (11.4–26.9)	23.4 (12.3–39.8)
9	Ben Tre	17.9 (−2.8–33.3)	19.2 (4.9–33.4)	21.6 (10.4–33.8)	29.2 (12.6–47.9)
10	An Giang	16.9 (2.3–31.2)	15.0 (2.1–27.9)	18.3 (5.7–31.5)	20.4 (8.2–37.4)
11	Kien Giang	14.5 (4.2–25.5)	19.2 (3.8–33.8)	19.0 (7.8–30.1)	24.9 (12.1–42.8)
12	Bac Liêu	12.5 (1.3–21.8)	13.1 (5.0–19.8)	18.0 (11.3–24.7)	20.1 (11.4–33.0)
13	Ca Mau	13.9 (1.8–23.8)	13.9 (6.0–20.8)	15.4 (6.9–22.7)	19.9 (11.4–30.3)
14	Mekong Delta	8.3–17.9 (−3.3–37.1)	12.5–19.2 (−0.9–33.8)	18.3–21.6 (5.7–33.8)	19.9–26.3 (8.2–47.9)

Note: Data in ( ) are the range of variation.

). However, according to forecasts, average rainfall increases unevenly between regions and times of year, mainly concentrated in the rainy season. The number of heavy rains occurring during the rainy season tended to increase (R × 1 day and R × 5 day increase). This process increases the possibility of short-term local flooding and negatively impacts agricultural production.

-

Sea level rise scenario: According to calculations of the RCP4.5 low emission scenario, the average sea level in the MRD region will increase by 23 cm in 2050 and by 53 cm in 2100. Similarly, if calculated according to the RCP8.5 emission scenario, the average sea level of coastal areas in Vietnam will increase by 27 cm in 2050 and 73 cm in 2100, respectively. According to estimates, if the sea level rises by about 100 cm, the risk of flooding in the MRD will be about 47.3%. Of these, the two provinces of Kien Giang and Ca Mau will be the most flooded, by 79.6% and 75.7%, respectively. The flood risk of the MRD region corresponding to rising sea levels is shown in

Table 3. Forecasting the level of flooding in the MRD region corresponding to sea level rises.

Province	Areas (ha)	% Flooded Area Corresponding to Rising Sea Levels
		10 cm	20 cm	30 cm	40 cm	50 cm	60 cm	70 cm	80 cm	90 cm	100 cm
Long An	449,100	0	0	0.31	0.49	0.61	1.36	2.85	7.12	12.89	27.21
Tien Giang	251,061	0.13	0.71	1.43	2.57	3.79	6.71	12.58	24.06	37.69	47.8
Dong Thap	337,860	0	0	0.17	0.21	0.36	0.69	0.96	1.28	1.94	4.64
Vinh Long	152,573	0	0.34	0.61	0.91	1.31	2.02	3.66	8.28	18.34	32.03
Tra Vinh	235,826	0.5	0.61	0.89	1.28	2.29	4.95	11.51	22.22	32.79	43.88
Can Tho	143,896	0	0	0.03	0.05	0.99	2.88	9.97	26.69	44.89	55.82
Hau Giang	162,170	0	0.75	3.42	10.31	18.83	29.37	38.5	45.88	53.21	60.85
Soc Trang	331,188	1.78	2.91	5.13	8.32	11.32	14.97	20.25	26.91	33.13	55.41
Ben Tre	239,481	0.55	1.43	2.52	4.08	6.74	10.19	15.11	21.46	27.83	35.11
An Giang	342,400	0	0	0	0.03	0.08	0.16	0.29	0.49	0.9	1.82
Kien Giang	634,878	0.66	3.38	12.63	23.67	36.82	48.85	58.47	66.16	71.69	75.68
Bac Liêu	266,901	0.71	2.87	6.66	12.14	20.08	27.78	36.84	46.31	54.38	61.87
Ca Mau	522,119	7.21	14.06	20.17	28.73	40.31	48.05	56.81	64.42	73.58	79.62
Mekong Delta	4,069,453	1.29	2.97	5.92	9.86	14.86	19.69	27.94	31.94	38.8	47.29

.

According to the RCP4.5 scenario, the proportion of flooded areas in the MRD in 2050 will be over 2.93%, and in 2100 will be over 14.86%. Meanwhile, the numbers corresponding to the high emission scenario RCP8.5 will be nearly 5.92% in 2050 and over 27.94% in 2100, respectively. Thus, in both scenarios, a large area of land in the MRD region will be flooded, seriously threatening people’s production and living activities, especially agricultural production activities.

4. Discussion

4.1. Impacts of Climate Change on Agricultural Production

Climate change has a great impact on the input factors of agricultural production, of which land and water are the two most important factors.

4.1.1. Impact on Water Resources

The MRD is the region with the most abundant water resources in Vietnam; the amount of water in the MRD of Vietnam accounts for 60% of the total water volume of the whole country (MONRE, 2018) [28]. In theory, this amount of water will fully meet the country’s water needs for agricultural production and other water uses. However, like other regions of Vietnam, the water volume of the MRD depends heavily on exogenous water sources outside the territory (endogenous water volume only accounts for 30–40% of the total water volume). On the other hand, rainfall in the MRD region is concentrated in the rainy season (from May to September) (Son et al., 2020) [29], with low rainfall in the remaining months. Therefore, the source of irrigation water for agriculture depends heavily on the exploitation of water by upstream countries and seasonal climate factors. Without appropriate water regulation solutions, the MRD region will be at risk of water shortages for agricultural production, especially in the dry season.

Climate change has already reduced freshwater availability in the Mekong Delta by about 4.8%, and this figure is expected to be 14.5% by 2050 and about 33.7% by 2100 (MONRE, 2021) [22]. This puts the water security of the MRD in an alarming state. This shortage of water resources will directly affect crop production due to a lack of irrigation water, reductions in freshwater aquatic resources, increased droughts, and saltwater intrusion (Vien, 2011 [2]; Bibi, F. and Rahman, A., 2023 [1]). In particular, saline intrusion in recent years has had a very serious impact on agricultural production and the lives of people in the MRD. The 2015–2016 drought and salinity were considered the most severe in the past 100 years in this area. Salinity measured on two major tributaries of the Mekong River, the Tien River and the Hau River, were 4% and 4.5%, respectively, with salinity penetrating 70–90 km inland from the river mouth. Salinity in water penetrated deep into the inland areas of the MRD, forcing 11 out of 13 provinces and cities in the region to declare a state of natural disaster due to drought and saltwater intrusion (MARD, 2016) [30]. This drought and salinity affected 119,913 hectares of agricultural land (Figure 3), causing 400,000 hectares of summer–autumn and winter–spring rice to be unable to be cultivated in season, resulting in the loss of 160,000 hectares of rice and a shortage of fresh water for 155,000 households (800,000 people) (

Table 4. Summary of the effects of the drought and salinity in the MRD region in 2015–2016.

No	Impact	Unit	Value
1	Area of agricultural land affected by salinity	Ha	119,913
2	Lack of fresh water for daily life	Household	155,000
		Person	800,000
3	Affected rice area by salinity (Not cultivated in the right season)	Ha	400,000
4	Area of rice lost by salinity	Ha	160,000

Source: MARD, 2016 [30].

). The shortage of freshwater resources in the MRD region is warned to get worse due to the combined impact of climate change and the water exploitation activities of countries upstream of the Mekong River, especially China, Laos, and Cambodia, in the coming time.

4.1.2. Impact on Land Resources

Climate change directly and indirectly affects land resources such as losses in agricultural land due to flooding and the degradation of land quality due to drought, salinity intrusion, and fertility decline, etc. These processes all have negative impacts on agricultural production.

Based on the estimated results of sea level rises for the MRD region, we can calculate the flooded land area of the MRD, as shown in Figure 4. Accordingly, in the RCP4.5 scenario, the flooded land area is 52.5 thousand hectares (in 2050) and nearly 605 thousand hectares (in 2100), respectively. For the RCP8.5 scenario, the flooded land area will be nearly 241 thousand hectares and more than 1137 thousand hectares in 2050 and 2100, respectively. Most of this flooded land is agricultural land. Thus, without timely and appropriate response solutions, a large part of agricultural land in the MRD will be permanently lost due to rising sea levels over time.

Besides its direct impacts, climate change also causes prolonged heat and drought, increasing drought conditions during the dry season; increased rainfall with short, intense rain events increases the risk of flooding, erosion, and leaching of soil nutrients; and freshwater shortages during the dry season combined with rising sea levels exacerbate salinization of agricultural land. All these processes provide evidence of the impacts of climate change on the quality of agricultural land in the MRD region. According to the results of the national land assessment survey in Vietnam (MONRE, 2021) [31], the total area of degraded agricultural land in Vietnam is 11,838 thousand hectares, accounting for 40.64% of the total area of the assessment survey (29,132 thousand hectares). In terms of land degradation types, the three most common types of land degradation in Vietnam are fertility loss (degradation rate accounts for 46.06%); erosion (degradation rate reaches 45.58%); and drought, desertification, and desertification (degradation rate reaches 57.75%). Meanwhile, in the MRD region, the three most common types of soil degradation are acid sulfate soil at 67 thousand hectares, accounting for 53.6% of the total acid sulfate soil area of the country; salinization at 23 thousand hectares, accounting for 11.68%; and fertility loss in 833 thousand hectares, accounting for 6.21% over the whole country (

Table 5. Degraded land area of the MRD compared to the whole country.

Types of Soil Degradation	Vietnam (103 ha)	MRD
		Area (103 ha)	Compared to the Whole Country (%)
Fertility loss	13,417	833	6.21
Soil erosion	13,358	0	0.00
Drought, desertification, and desertification	16,823	29	0.17
Concretion, laterite	1156	0	0.00
Salinization	197	23	11.68
Acid sulfate soil	125	67	53.60

Source: MONRE, 2021 [31].

).

In general, the situation of agricultural land degradation is complex in Vietnam and the MRD. There are many different causes leading to land degradation, one of the most important causes being the impact of climate change. This process is forecast to continue to increase if Vietnam does not have appropriate response measures in coming times, due to the increasingly complex climate change situation.

4.1.3. Impact on Crop Yield

Climate change changes factors such as temperature, rainfall, and atmospheric humidity, thereby changing the living conditions of species. As a result, many species have disappeared because they could not adapt to new conditions, while on the contrary, some species have prospered (UNDP, 2015) [32]. In recent years, many pests that are well adapted to climate change have increased in number and have had negative impacts on crops. They cause a series of diseases such as brown planthopper, yellow dwarf, and twisted leaf dwarf in the Mekong Delta, which directly affects the ability to intensify and increase crops and reduces rice yields (UN, CRS and Save the Children, 2020) [33]. Climate change can impact crops through changes in crop calendars, seasonal structures, regional planning, irrigation techniques, pests and diseases, and degradation of soil and water resources, leading to reduced crop yields (FAO & UNDP, 2020 [21]; Phuong et al., 2023 [34]). In addition, climate change also contributes to reducing biodiversity and increasing the risk of extinction of many species, thereby losing rare genetic resources for agricultural production (Vien, 2011) [2].

Rising temperatures make droughts more common, directly affecting crop distribution and productivity. According to ADB’s assessment, if the temperature increases by 1 °C, rice productivity will decrease by 10%. This situation will seriously threaten national food security and affect tens of millions of Vietnamese people, especially in the MRD region (ADB, 2013) [35]. According to research results from the Institute of Agricultural Environment in Vietnam, climate change reduces the productivity of some main crops. Specifically, spring rice yields will decrease by 0.41 tons/ha in 2030 and 0.72 tons in 2050. Corn yields are at risk of decreasing by 0.44 tons/ha in 2030 and 0.78 tons in 2050 (MONRE, 2021) [22].

4.2. Impacts of Climate Change on Food Security

Vietnam is a leading food-producing country in the world, but climate change could become the main cause threatening national food security because of its direct impact on the natural and essential elements of the agricultural system. Vietnam’s main food crop is rice (which accounts for 94% of the cultivated land area), which is grown mainly in the Mekong Delta and Red River Delta, with 54.47% and 24.08% of the total cultivated land area, respectively. Both of these regions have been suffering severe impacts from climate change, especially the Mekong Delta region (FAO & UNDP, 2020) [21]. In recent times, climate change has caused great damage to rice production and other main food crops in Vietnam. The reason for this is that changes in temperature and rainfall lead to weather instability, such as an increase in the number of extremely hot and cold days, heavy rain, floods, water scarcity and drought, landslides, sea level rise, and other extreme weather phenomena (Woillez et al., 2021) [24].

With the current climate change situation, Vietnam will face the reality of losing about 40,000 km², equivalent to 12.1% of its total area and affecting 17.1 million people, accounting for 23.1% of the country’s total population. Rising sea levels make coastal erosion and saltwater intrusion more serious, especially in the MRD, the most important agricultural production area of Vietnam. In the MRD, rising sea levels combined with a shortage of fresh water from upstream lead to the risk of salinity for about 1.3–1.7 million hectares of arable land (World Bank, 2016) [36]. The main rice crops in this area will be seriously affected. This is a big danger for ensuring food security for the whole country if there are no timely interventions.

However, even in the worst scenario where Vietnam’s MDR is flooded by more than 50% and the productivity of major food crops declines by 10% due to climate change, Vietnam’s national food security is still guaranteed. Because Vietnam is a country with experience in agricultural production, technical advances in agricultural cultivation can increase crop yields to compensate for reductions in food intake due to climate change. In addition, although Vietnam’s rice production has decreased, it can still fully meet the food needs of the entire population of 100 million people. However, the decline in agricultural production in the MRD will certainly push a large number of farmers in this region into difficulties, as agriculture is the country’s main source of income. As a result, Vietnam’s economy will suffer many negative impacts. Globally, the decline in agricultural production in the MRD will have a strong impact on world food security, as the Mekong Delta accounts for 90% of the total rice exports of Vietnam—the world’s second-largest rice exporter. The supply shortage will push up world food prices, creating instability in the world food market.

4.3. Response Solutions of the Vietnamese Government

Analysis of the impact of climate change on agricultural production inputs such as water, the climate, and soil quality shows that it will be difficult for Vietnam to promote the food supply capacity of the Mekong Delta region through expanding the area and increasing the land use turnover time, as at present (currently, the Mekong Delta has the ability to cultivate 3 rice crops/year). The limitation of irrigation water resources, declines in soil quality (increased salinity), and increases in weather and climate patterns require Vietnam to transform agricultural production towards increasing adaptation to actual conditions. On the other hand, scientific and technical advances in seed production and farming techniques need to be increasingly used to increase crop productivity, to compensate for food loss due to the impact of climate change. In fact, the Vietnamese Government has made many efforts in implementing response solutions, including some specific solutions such as:

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Implementing green transformation in agricultural production. Natural agricultural production models such as sustainable agriculture, circular agriculture, smart agriculture adapting to climate change, green agriculture, and ecological agriculture have been promoted in Vietnam in recent years. One of the typical programs that can be mentioned is the project “1 million hectares of high-quality and low-emission rice cultivation associated with green growth in the MRD by 2030”, approved by the Vietnamese Government in 2023 (Vietnam Government, 2023) [37]. In this program, Vietnam will invest in the development 1 million hectares of rice land in a new production direction, applying advanced and modern technology to create high-quality rice products while minimizing greenhouse gas emissions. Environmentally friendly farming techniques such as using high-quality seeds, applying biotechnology in disease and pest control, modern fertilization and irrigation techniques, minimizing the use of chemical pesticides, increasing the application of machinery, and automated equipment will be prioritized and encouraged for use. This represents a major change in Vietnam’s agricultural production orientation, from focusing on quantity to focusing on quality and from farming against the laws of nature to farming in harmony with nature.

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Promoting the application of modern science and technology in agricultural production in the MRD region to restore the natural ecosystem and minimize the negative impacts of climate change on agricultural production. The National Science and Technology Program “Climate change response for sustainable development of the Mekong Delta to 2030” (KC 15/21-30) has been deployed to realize this goal (MOSAT, 2023) [38]. This program focuses on promoting Vietnamese scientists to research and find specific policy, technical, and engineering solutions to help gradually restore the inherent natural ecosystem of the Mekong Delta, increase the adaptability of agricultural production in the Mekong Delta to climate change trends, and find solutions toward developing sustainable livelihoods for people in the Mekong Delta.

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Promoting communication and raise the awareness and responsibility of people, especially farmers, in protecting the natural environment, implementing green production, green consumption, and green lifestyles through the national green growth strategy (Vietnam Government, 2021) [39]. In this strategy, developing circular agriculture is considered an important key to help Vietnam’s agricultural production develop sustainably by both making good use of the country’s natural strengths and reducing the greenhouse gas emissions and waste that pollute the environment.

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Internationally, Vietnam demonstrating its responsibility in efforts to reduce greenhouse gases to achieve the goal of net zero emissions by 2050 as committed at the COP26 Conference. In addition, Vietnam should also strive to coordinate with countries in the Mekong River Basin to cooperate in exploiting and using water resources effectively and sustainably, minimizing negative impacts on the natural ecosystem and the lives of communities in the basin.

5. Conclusions

Climate change is evolving complexly in the Mekong Delta region of Vietnam, with the average atmospheric temperature increasing by 0.89 °C and rainfall increasing by 2.1% in the period 1958–2018 (60 years). In addition, the average sea level rose 3.6 mm/year during the same period. According to forecasts, the climate change trend in the Mekong Delta region will continue to increase, specifically: average temperatures may increase by 1.7 °C and 3.3 °C; rainfall will increase by 19.2% and 26.3%; sea level rise by 53 cm and 73 cm by 2100, according to the RCP4.2 and RCP6.5 scenarios, respectively. Climate change has seriously affected agricultural production in the Mekong Delta by reducing clean water by 4.8%, increasing salinity in irrigation water sources, and increasing flooding and soil salinity in coastal areas (67 thousand hectares of salinized land in the Mekong Delta accounts for 53.5% of the total salinized land area in Vietnam). Extreme weather phenomena such as heat, drought, heavy rain, flooding, and storms occur more commonly with higher intensity. As a result, the food supply capacity of the Mekong Delta region has decreased by 10%. This process does not threaten Vietnam’s food security at present or in the future, because Vietnam’s food supply needs exceed consumption needs many times. However, this decline will significantly impact the world’s food security as the Mekong Delta accounts for 90% of Vietnam’s rice exports—the second largest rice exporter in the world. Faced with the great impact of climate change on agricultural production in the Mekong Delta region, Vietnam has taken specific steps to convert agricultural production from traditional farming methods to natural farming methods, increasing the ability to adapt to climate change. This is the direction of the Vietnamese government. However, to achieve this shift, it is necessary to strongly promote research and the development of new agricultural models and apply advanced and modern scientific and technological achievements in seed production, farming techniques, and water resource management.

This study is only an initial study to outline the current status of climate change impacts on agricultural production and food security in the Mekong Delta region. Therefore, this research still has many limitations such as the lack of experimental studies on the impact of climatic factors (temperature, humidity, rainfall, ...) on the productivity of major crops in the Mekong Delta region, leading to limitations in assessing the decline in the region’s ability to supply food. This study also has not clearly separated the impacts of climate change and other factors (natural disasters, economic development, environmental pollution) on agricultural production in the Mekong Delta. In the coming time, there is a need for more in-depth studies on the specific impacts of climate change and the combined impacts of climate change and other factors on agricultural production in the Mekong Delta region.