Improving estimates of sea level rising population: not as simple as it seems
Understanding the number and location of the population living near the low-elevation coast-the area is called the low-elevation coastal zone (LECZ)-for decision makers and communities to prepare and adapt from Sea-level rise Caused by climate change. As more and more satellites and other sensors are launched, more and more organizations develop capabilities that can be used to estimate the number of new data sets in these populations and risk areas-including elevation, population, and location of human settlement information And type-continue to grow to generate and disseminate data, more advanced methods allow rapid analysis of large amounts of data. Although new and more data sets are usually a positive development, they must be used critically in order to have a good understanding of new or different conclusions that may emerge. Climate scientists have long been aware of this and use a variety of models to understand the uncertainty of predicted phenomena—for example, in weather forecasts. When estimating the number, location, and type of settlements living in low-lying coastal areas, similar methods are needed.
To bridge this gap, a new Paper Published on Earth Science System Data Use new data inputs on coastal elevations, spatial population data, and spatial descriptions of urban areas to better estimate the population living at risk of rising sea levels. It uses sensitivity analysis to establish the importance of assessing LECZ data quality in research and policy development—building a comprehensive estimate of all data set combinations, revealing its strengths and weaknesses—and recommending “applicability” guidelines to apply these LECZ data set in exposure assessment.
A low-elevation coastal zone (LECZ) constructed by different digital elevation models (DEM) in Bangkok and surrounding areas. The deepest blue indicates the ocean, and the gray border indicates the state/province boundary.
LECZ was measured as a land area connected to the coast at an elevation of ≤ 10 meters or ≤ 5 meters, but each of the four data sets evaluated in the study showed slightly different risk areas, as shown in the figure above.
An analysis of 2015 data found that there are 750 million to more than 1 billion people living within 10 meters of LECZ globally, up from 521 million and 745 million in 1990.
The population density of cities, quasi-urban and rural areas is composed of urban proxy data sets (y-axis) and population data (x-axis).
In the comparison below, we see that one LECZ data set shows that more people live in LECZ ≤ 5 meters, while the other three data sets show that more than half of the LECZ population lives between 5 and 10 meters above sea level. This shows how important data selection is in accurately understanding the risks faced by LECZ residents. Importantly, no matter which data set combination is used, the study found that the data sets are consistent, that is, since 1990, the built-up area and population of LECZ have grown faster than those outside LECZ. These findings have important implications for coastal policy and management, and consider coastal disasters and sea level rise, their impacts and risks.
The percentage of the global population in the four altitude data sets and four population data sets in 2015 with ≤ 5 and 5-10 LECZs.
This article discusses the many challenges of using large-scale coastal data and provides practical suggestions for continuing this work. This is a collaboration between Kytt MacManus and Rya Inman of CIESIN; Deborah Balk of the Institute for Population Research (CIDR) of the City University of New York; Hasim Engin, formerly CIDR, now CIESIN; and Gordon McGraw of the Institute for Development of the University of Sussex Nahan.
The data includes the land area of cities, quasi-urban, rural and total population in 234 countries and other recognized territories in the LECZ in 1990, 2000 and 2015. It has been updated and expanded. First estimate The population and land area of LECZ, conduct More than ten years ago.
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Contributors to this blog post include Kytt MacManus and Hasim Engin, CIESIN; and Deborah Balk of the Institute for Population Research, City University of New York. The data and source code behind this new research are disseminated by NASA’s Center for Socio-Economic Data and Applications (SEDAC) in cooperation with the Institute for Population Research (CIDR) of the City University of New York (CUNY).
