Climate Detectives Projects 2018-2019

Project topic: Cities

Project title: Geodiscovery

Team: GeoDiscovery

2018-2019   CED Nossa Senhora da Conceição – Casa Pia de Lisboa, I. P.   Lisboa   Portugal   26 Student’s age: 12-13

Summary of the project

Climate change and global warming start in local problems related with human activities: this was the statement that launched our project as climate detectives! The aim of our project was to investigate land surface temperature variations in Largo do Rato and surroundings (known as a heat island in Lisbon area). We wanted to study a possible correlation between temperature and land use, as well as analyse other meteorological items (relative humidity and wind speed) related with the existence of vegetation or with other urban characteristics, focusing on street patterns and building materials in urban areas. After defining our study goals, we thought it important to do some field measurements to collect data, using weather instruments such as thermometers, humidity sensors and anemometers. We also thought of measuring the temperature of common urban materials (concrete, asphalt, metal) and of local vegetation coverage, so we could compare temperature variations according to reflectance or to the amount of absorption or reflection of solar radiation. To accomplish this goal, we used infrared thermometers. We used Geographic Information Systems to show the collected data, spatial analyses, and, later, we compared the field collected data with land surface temperature and Normalized Difference Vegetation Indexes obtained from satellite imagery (from Sentinel 3). We were also curious about data in Portugal, so we decided to investigate a bit forward, and analysed data from other regions (Pedrógão Grande), in order to find similar correlations between temperature and land use and land cover (Corine Land Cover geoinformation), therefore establishing a comparison between urban and rural areas.

Main results

The temperature data collected in the field allowed us to map land surface temperature for the study area, differentiating sites with moderate values of temperature (with vegetation coverage) from sites with higher land surface temperature (with asphalt coverage, for example). We also mapped wind velocity, an important factor that interferes with land surface temperature. The obtained maps revealed the windiest sites had the lowest land surface temperature. The use of satellite imagery allowed us to calculate Normalized Difference Vegetation Indexes and land surface temperature for the study area. Such results were compared with land surface temperature obtained from the measurements carried out in our fieldwork. We found significant correlation between them. The results led us to conclude that the use of satellite imagery is an important resource to study land surface temperature, as well as to obtain information about the Earth’s land coverage. Satellite imagery provide diverse information, with the advantages of studying broader areas (without the need of fieldwork) and of obtaining land surface temperature variations between short temporal intervals (depending on the available satellite images). When comparing Lisbon (urban area) and Pedrógão Grande (rural area), the results showed significant changes in land occupation. In Lisbon, we found evident urban expansion, with predominance of waterproofed soils. On the other hand, in Pedrógão the loss of almost the entire forest emerges, due to forest fires in 2017. Those fires left the soils fully exposed to the erosive agents. These findings exemplify the factors that contribute to climate change; for that reason we thought it was important to propose the reforestation of the area affected by the fires, as well as the increment of green areas within the urban areas, which are important for the maintenance of lower land surface temperature, preventing the formation of urban heat islands.

Actions to help lessen the problem

As far as climate change is concerned, we need to act local to go global. We think that providing information is the greatest action we can take for now; therefore, it is important to take part in informative sessions, to increase people’s awareness about climate changes and about preventive individual actions everyone should assume. We participated in a workshop provided by the Associação Portuguesa de Educação Ambiental (a non-profit association that promotes the development of environmental education). This workshop taught us that we all need resources, but we all can use them conscientiously, respecting the environment and contributing to reduce greenhouse gas emissions throughout simple changes in our daily routines. The workshop also allowed us to learn that planning a city is very important; for instance, green areas are crucial to reduce land surface temperature and to increase humidity. We think that we should replicate this workshop in different classes, and also prepare sessions for our teachers and parents, creating an information about climate change net. We could make a difference if each and every one of us could act within inner communities, start acting locally with a butterfly effect purpose. Finally, we would like to talk to local governments about the importance of planning a city accordingly to sustainable purposes. Planners should be able to increase green areas, or to enlarge streets to allow the air to circulate, and, consequently, the cooling of the city.

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