Use of remote sensing in climate change adaptation

Remote sensing is used to produce knowledge or even decision support systems for targeted users (e.g. practioners involved in disaster risk management, urban planners, land planners, farmers, etc.). The involvement of final users as stakeholders along the entire process of knowledge and products design and creation is essential to produce outputs which are really used and useful, according to the co-production paradigm.

Remote sensing techniques, and specifically satellite images, have been already successfully used in a wide range of climate change fields, such as for: (i) investigating global temperature trends, both at the ocean surface and in the atmosphere, (ii) detecting changes in solar radiation affecting global warming, (iii) monitoring aerosols, water vapour concentration, and changes in precipitation regime, (iv) studying the dynamics of snow extension and ice cover, (v) monitoring sea-level changes and coastal modifications, (vi) monitoring vegetation status and change, (vii) monitoring water resources and impact due to droughts and dry periods, (viii) monitoring fire events and fire emissions, (ix) predicting disaster risk, such as cyclone, floods, and drought, (x) guiding decision-making processes on climate change adaptation. The use of remote sensed data is quickly evolving, both in terms of available techniques and resolution, and other uses relevant for climate change adaption are expected to emerge in the next future.

Some concerns, however, have been posed on the use of remote sensing. Studying and monitoring climate change require long-term time series of observations, while satellite data are often available for short-term period. Furthermore, some uncertainties and distortions of received image frames due to vibrations and turbulence can derive by biases in sensors and retrieval algorithms, so the use of satellite observations in climate change studies requires a clear identification of such limitations. Other possible limitations include: (i) high cost for acquiring aircraft and drone high-resolution data; (ii) in some cases, limited access to needed technologies due to costs or skills constrains; (iii) temporal discontinuity of aircraft and satellite data; while the first can be particularly expensive and therefore available for a limited number of surveys, the second are collected at fixed intervals depending on the satellite return time.

Direct land observations are typically limited in spatial coverage, whereas remote sensing techniques allow for monitoring a greater scale. Satellite data have wide coverage, multi-temporal and multispectral capability, providing climate change related data and information for extensive areas. This allows improvements in understanding the climate system, studying and predicting climate change effect on ecosystems, and monitoring the effectiveness of implemented adaptation measures.

Remote sensing also allows data collection in dangerous or inaccessible areas, with no disturbance for the site, and provides frequent updates. Data acquisition is often less expensive and faster than direct collection of data from the ground. In addition, the use of drones adds flexibility in time and space monitoring and the advantage of no human risks.

Price of satellite imagery varies depending on spatial resolution. Low resolution (> 10m) archive images are usually free of charge, while price increases from 1 to 8 $ per km² passing from 5-10 m resolution to 0.3-1 m resolution (2019 prices; see for example Geocento). Costs are slightly higher for images taken by airplanes and drones; this latter can arrive at a resolution < 0.05 m. Of course, prices increase if customized images are required. Resources are also needed to process data and develop applications. Finally, enough skills and capacity are required for using remote sensing data.

The implementation time refers to data processing and delivering of final knowledge or products. It greatly depends on the specific scope and use of remote sensing techniques, the level of available skills, the availability of needed tools, and the collaboration between the different stakeholders involved.

The use of remote sensing techniques for studying climate change and supporting the definition of actions for mitigation and adaptation to climate change can be performed both at the short- and long-term period.