Agriculture and related land use account for around 20 per cent of all human-caused greenhouses gasses. At the same time, agriculture is highly sensitive to climate change. The produced variations in the start and end date of seasons and in rainfall patterns, as well as direct impact of extreme weather events, negatively affect farming.
Space based technology and services can optimize the agriculture processes as well as help this sector to adapt to climate change. Remote sensing satellites equip farmers with information on pests and disease propagation, vegetation development, drought, rainfall, soil conditions, and others. For example, space-derived rainfall data helps to establish an optimal irrigation strategy.
Soil moisture data retrieved from satellite are not only useful for drought or flood monitoring, but are also used for agriculture, for instance to better manage water resources and more effectively model crop yields.
Soil moisture data is retrieved from active spaceborne microwave scatterometers. The measurement is based on the fact that the backscattered microwave signal returning to the sensor after reflexion on the detected ground varies strongly with the soil-moisture content.
More information on soil moisture measurements from space: https://www.un-spider.org/links-and-resources/data-sources/dsotm-soilmoisture
Another space-borne instrument useful for retrieving soil moisture is the gravimeter. This instrument measures gravitation field, providing insights, for example, on groundwater.
Gravitation is related to the mass, and as the mass of the Earth is not uniformly distributed (due to mountains, oceans, underground caverns at various locations) there are slight alterations in gravity across the surface of the planet.
To generate groundwater and soil moistures indicators using the Earth mass distribution, a system of a lead and trail satellite is used. Whenever the lead satellite passes over a region with stronger gravity it experiences a stronger gravitation pull and thus accelerates in comparison to the trail satellite that has not reached this region creating a stronger pull. In contrast, when the lead satellite flies over a slightly weaker gravitational field it slows down. The regular distance measurement between the two satellites allows to observe the change in speed, and therefore map the entire gravity field of the Earth, from which can be retrieved fluctuations in global soil moisture.
Soil moisture is an ECV defined by GCOS: https://gcos.wmo.int/en/essential-climate-variables/soil-moisture/
Global UN System agriculture monitoring systems
The Food and Agriculture Organization of the United Nations (FAO) developed the Agricultural Stress Index System (https://www.fao.org/giews/earthobservation/asis/index_1.jsp?lang=en) in support of states’ agricultural sectors adapting and being resilient to climate change. It uses spaceborne remote sensing data to assess regions on the probability of water stress.
Another monitoring system, PRISM (https://innovation.wfp.org/project/prism ) developed by World Food Programme, focuses on climate risk and impact analytics, and aims at mitigating the impact of climate related hazards. PRISM offers the visualization of Earth Observation data, including satellites and sensors on the ground, such as measurements of vegetation conditions, levels of precipitation, and temperatures, to enable decision-makers and actors in the agricultural sector to build greater resilience to climate change.
Precision agriculture is based on several space technologies such as satellite positioning (GNSS) and remote sensing, to better manage crops and reduce the environmental impact of agriculture by reducing the use of fertilizers, pesticides, and water. GNSS-enabled applications, like farm machinery guidance and automatic steering, are key to these climate mitigation efforts and help achieve substantial savings in the agriculture sector.
Also, integrating soil moisture monitoring as previously explained to optimize irrigation is another example of the climate adaptation trend in the agriculture sector.