Satellite data and climate change

Expansion of irrigated agriculture in Wadi As-Sirhan Basin, Saudi Arabia, from 1987 before irrigated agriculture was present in the region, until 2012 when irrigation was widely used. ©NASA

This year is critical for climate action; it is the official launch of the global climate action under the Paris Climate Agreement, and the deadline for the global call for more ambitious climate action plans, the Nationally Determined Contributions (NDCs). Satellite data and geospatial analysis can offer invaluable guidance.

Satellite imagery offers a birds-eye view to efficiently assess conditions on the Earth’s surface and data gathered from satellites is increasingly used to track progress. It can collect information and track trends both at a local, zoomed-in scale, highlighting individual cities or buildings, and across much larger regions. The range of environmental and socio-anthropological trends that can be studied using geospatial data make it extremely valuable for climate action planning. Soil erosion, shrinking glaciers, urban expansion, development of electrical grids, changes in irrigation infrastructure and agriculture, sea level rise and coral reef damage can all be captured from satellite data.

Satellite images play a key role in helping policymakers monitor changes in forests. In Cabo Verde we can use satellite imagery to set objectives and monitor progress on its NDC targets to increase its forest cover. As demonstrated in Image 1 (below), from 2002 and 2014, the progress made from previous afforestation programmes on arid lands in Santiago, Cabo Verde is evident and new trees can easily be traced. This information enables policy planners to track the success of NDCs and to advise on reforestation and livelihood strategies.

Working with satellite images, policymakers can quantify changes in forest cover over time, by calculating the rate of forest loss and growth. These metrics are highly valuable for NDC goal setting, enabling a more precise understanding of what policies have been effective, and where resources should be directed.

Image 1. Afforestation in Santiago Island, Cabo Verde; images show the natural environment before the project in 2002 (left), and change resulting from the project in 2014 (right). Images from: https://eros.usgs.gov/westafrica/case-study/successful-large-scale-afforestation-santo-antao-and-santiago-islands

Satellite imagery is also commonly used to record dramatic landscape changes such as those accompanying the construction of hydropower plants and reservoirs since it is a reliable method to track progress on hydropower investments (Image 2). In addition to Paraguay, Ecuador aims to significantly increase hydro power and Equatorial Guinea plans to develop hydroelectric potential on the Wele River. The progress of construction can be monitored through geospatial data, and other analytical assessments done to evaluate the impact on neighbouring communities.

Image 2. The Paraná River in Paraguay, in 1985 (left) before the Yacyretá Dam project and in 2010 (right) when the dam’s reservoir had reached its final extent. Image from: https://www.vox.com/2015/4/7/8352381/anthropocene-NASA-images

Investment in other renewable energy sources, such as solar power, are also easy to detect — solar photovoltaic cells are generally large enough to be visible from satellites. Vanuatu has made solar power an important piece of its NDC with its aim to transition to 100 percent renewable energy by 2030.

Image 3. Farmland in California, USA in 2011 (left) was converted to a large, industrial solar farm by 2015. Image from: https://www.vox.com/2015/4/7/8352381/anthropocene-NASA-images

Image 4. Undine Bay in North Efate, Vanuatu in 2014 (left) before and then after a grid-connected, 1 MW solar power project was installed in 2017. Images from: Google Earth Pro (17°32'47.10"S, 168°20'4.70"E)

Several countries propose changes to their agricultural sector as a part of their NDCs. Satellite imagery can be used to track and quantify changes, as demonstrated in Image 5 showing agricultural expansion in Wadi As-Sirhan Basin, Saudi Arabia.

Image 5. Expansion of irrigated agriculture in Wadi As-Sirhan Basin, Saudi Arabia, from 1987 before irrigated agriculture was present in the region, until 2012 when irrigation was widely used. Image from: https://www.nasa.gov/topics/earth/features/saudi-green.html

A more advanced application of satellite data for agriculture is to extract information contained in the images to gain insight on irrigation practices and crop health (Image 6). With some additional processing, satellite imagery can be combined with climate information to assess how climate change is affecting agricultural, such as determining whether recent climate events correspond to changes in crop productivity.

Image 6. Satellite image showing vegetation health (a soil adjusted vegetation index) of agriculture near Alexandria, Egypt in 2016. Colours represent a false scale to code for vegetation health. Red represents the least healthy, green the healthiest. Image from: https://www.satimagingcorp.com/applications/natural-resources/agriculture/

As governments around the world refine their first-round climate action plans, establishing evidence-based approaches to reduce emissions and build resilience becomes a priority. Satellite images are an accurate, cost-effective, and timely source of data that will be highly useful in efforts to track progress mitigating and adapting to the effects of climate change.

By Sydney Neeley, GIS/Satellite Imagery Specialist, James Vener, Technical Specialist — Climate Change and Frieda Fein, GIS Specialist

UNDP’s GIS and Satellite Imagery Team is working with countries to provide free analysis and interpretation of the data.

Contact gis.support@undp.org or ndcs@undp.org with any questions and check out www.ndcs.undp.org for updates on UNDP support on NDCs. All information on NDCs from: https://cait.wri.org/indc.