Crop water origins and hydroclimate vulnerability of global croplands – Nature

Report on Atmospheric Moisture Origins and Hydroclimate Vulnerability of Global Croplands

1.0 Introduction and Objectives

An analysis was conducted to determine the influence of water availability on global rain-fed agricultural productivity, with a focus on achieving Sustainable Development Goals (SDGs), particularly SDG 2 (Zero Hunger) and SDG 6 (Clean Water and Sanitation). The primary objective was to trace the atmospheric moisture origins for major global crops between 2003 and 2019, differentiating between oceanic and terrestrial sources to identify regions vulnerable to hydroclimate stress.

2.0 Methodology

The study utilized a combination of satellite-derived water isotope observations and physical models. This approach allowed for the quantification of the fraction of rainwater originating from terrestrial land sources (f) versus oceanic sources for major global rain-fed croplands over a 17-year period.

3.0 Key Findings

The analysis revealed significant geographical and seasonal variations in the sources of rainwater for agriculture. A critical threshold was identified, indicating heightened vulnerability in regions dependent on land-based moisture.

• The fraction of rainwater originating from land (f) varies significantly by region and season.
• A critical threshold was identified at approximately f = 36%.
• Regions with an f value exceeding 36% are demonstrably more susceptible to:
  1. Insufficient rainwater supply during the main growing season.
  2. Significant soil moisture deficits.
  3. A higher probability of drought conditions.
• Crops in these high-f regions exhibit greater sensitivity to hydroclimate variations, resulting in reduced productivity during years with lower rainfall.

4.0 Vulnerability of Staple Crops and Impact on SDG 2 (Zero Hunger)

The study highlights a significant threat to global food security by quantifying the vulnerability of key staple crops. This vulnerability directly challenges the objectives of SDG 2 (Zero Hunger) by placing a large portion of the global food supply at risk from hydroclimate stress.

• Over 40% of global maize is cultivated in regions where rainfall is heavily dependent on land-originating moisture (f ≥ 36%).
• More than 60% of global winter wheat is grown in these same high-vulnerability regions.

5.0 Implications for Sustainable Development Goals (SDGs)

The findings have direct implications for several SDGs, emphasizing the interconnectedness of water management, climate action, and food security.

• SDG 2 (Zero Hunger): The identified vulnerability of staple crops underscores the urgent need for resilient agricultural practices to ensure stable food production and global food security.
• SDG 6 (Clean Water and Sanitation): The results emphasize the critical importance of managing local and regional land moisture sources, aligning with targets for sustainable water management and protecting water-related ecosystems.
• SDG 13 (Climate Action): By identifying regions where agricultural productivity is highly sensitive to hydroclimate, this report provides a basis for developing targeted climate adaptation strategies to enhance agricultural resilience.
• SDG 15 (Life on Land): The report implicitly calls for sustainable land management practices that can help maintain the terrestrial water cycle, which is crucial for local and regional rainfall patterns.

6.0 Recommendations

To mitigate the identified risks and advance the SDGs, the report concludes that strategic interventions are necessary. The findings provide a clear evidence base for policymakers to enhance agricultural resilience through targeted water management.

1. Implement targeted water management strategies in agricultural regions where f ≥ 36%.
2. Prioritize the management and conservation of local land moisture sources to stabilize regional water cycles.
3. Develop policies that promote agricultural resilience as a key component of climate adaptation and food security strategies.

Analysis of Sustainable Development Goals in the Article

1. Which SDGs are addressed or connected to the issues highlighted in the article?

The article’s focus on water availability, agricultural productivity, and the vulnerability of staple crops connects to several Sustainable Development Goals (SDGs). The primary SDGs addressed are:

• SDG 2: Zero Hunger

  This goal is central to the article, which examines the “agricultural productivity” and “vulnerability of key staple crops” like maize and winter wheat. The study’s findings on how water availability affects crop yields directly relate to achieving food security and promoting sustainable agriculture.

• SDG 6: Clean Water and Sanitation

  The article’s core analysis revolves around “water availability” and tracing “atmospheric moisture origins.” By highlighting regions prone to “insufficient rainwater supply and soil moisture deficits,” it underscores the importance of sustainable water management, a key aspect of SDG 6.

• SDG 13: Climate Action

  The research discusses the sensitivity of crops to “hydroclimate stress” and a “higher likelihood of drought.” This directly links to the need for strengthening resilience and adaptive capacity to climate-related hazards, which is the main objective of SDG 13.

• SDG 15: Life on Land

  The article emphasizes the importance of “managing local land moisture sources” and distinguishes between oceanic and terrestrial water sources. This connects to the sustainable management of terrestrial ecosystems, as land use and health directly impact the water cycle and moisture recycling, which is relevant to protecting and restoring ecosystems on land.

2. What specific targets under those SDGs can be identified based on the article’s content?

Based on the issues discussed, the following specific SDG targets can be identified:

1. Under SDG 2 (Zero Hunger):

   • Target 2.1: End hunger and ensure access to sufficient food. The article’s focus on the productivity of “global maize and winter wheat” directly relates to ensuring a stable and sufficient supply of staple foods.
   • Target 2.4: Ensure sustainable food production systems and implement resilient agricultural practices. The article’s conclusion calls for “targeted water management strategies” to “enhance agricultural resilience,” which aligns perfectly with this target.

2. Under SDG 6 (Clean Water and Sanitation):

   • Target 6.4: Substantially increase water-use efficiency and address water scarcity. The study’s analysis of regions “prone to insufficient rainwater supply and soil moisture deficits” highlights the challenge of water scarcity in agriculture and the need for more efficient water management.

3. Under SDG 13 (Climate Action):

   • Target 13.1: Strengthen resilience and adaptive capacity to climate-related hazards. The article identifies crop vulnerability to “hydroclimate stress” and “drought,” pointing to the need for adaptive strategies to protect agriculture from climate impacts.

4. Under SDG 15 (Life on Land):

   • Target 15.3: Combat desertification and restore degraded land. The article’s discussion of “soil moisture deficits” and “drought” is directly related to the processes of land degradation and desertification. Managing land moisture sources is a key strategy in combating these issues.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

The article, being a scientific study, uses several metrics that can serve as or inform official SDG indicators:

• Indicators for Agricultural Productivity and Resilience (SDG 2):

  The article measures “agricultural productivity” and its reduction in “lower-rainfall years.” These can be used to track the resilience of food production systems (Target 2.4).

• Indicators for Water Stress (SDG 6):

  The article explicitly mentions “insufficient rainwater supply” and “soil moisture deficits” as key problems. These are direct measures of water stress, relevant to monitoring progress on Target 6.4.

• Indicators for Climate Vulnerability (SDG 13):

  The study identifies the “likelihood of drought” as a critical factor. Furthermore, it proposes a novel indicator: the “fraction of rainwater originating from land (f),” with a threshold of ~36% indicating higher vulnerability. This could be a powerful tool for measuring hydroclimate sensitivity and progress towards Target 13.1.

4. Table of SDGs, Targets, and Indicators

Source: nature.com