Project description

For our project Rising Seas, we analyzed data about sea levels recorded over decades in hundreds of coastal regions worldwide. Our research started with a simple question: Has climate change already impacted the world’s coastlines?

We found the answer to our question in sea level data from a global network of tide gauges that have been used to measure mean sea levels for decades. Originally, the measurements were taken using level plates fixed to the walls of ports worldwide, and were used to navigate ships safely into ports. Today, sensors such as pressure probes or ultrasound equipment record the data.

Based on this historical data, we can see how the sea level has changed over the decades on a world map. It’s clear: The sea level is rising worldwide. Climate change is in full swing. Our data analysis shows how a rise in temperatures by only one degree celsius has already changed coasts around the world.

This investigation was a long term project, in which CORRECTIV cooperated with scientists and journalists around the world. Contributors included staff and students from Columbia University in NYC, as well as journalists in Iceland, Switzerland, France, and the Philippines. The resulting stories have been published in South Korea, the USA, France, Switzerland, and Germany.

Based on initial results from our data analysis, we gathered individual stories, researched by us and by our partners around the world. In addition to these stories, we made the data available online in a data explorer app that allows users to find the information we have for each country and to see the data – both visualized on a map and in charts. We also added more information for context, such as carbon dioxide emissions and data on the risks for the coastal population.

What makes this project innovative?

Other data investigations into rising sea levels are based on data from satellite measurements which have been around since the 1990s. Our analysis is based on publicly available data from the British Permanent Service of Mean Sea Level (PSMSL). Its scientists have been gathering data on sea levels from around the world for more than 80 years and provide data that sometimes reaches back even to the beginning of the 19th century. Therefore, we can see a much longer timeframe than is possible with more recent monitoring methods like satellite measurements. The data is unquestionable; sea levels have been changing around the world and climate change is a key driver in this trend.

Based on this data, we built a news app that lets users browse the data themselves and provides context for them to understand how the issue of rising seas relates to them.

This a collaborative project. Not only have we worked with partners in different countries, other journalists can download the cleaned-up data from the news app to do their own analyses or use the source code for this project, which is published publicly on GitHub.

What was the impact of your project? How did you measure it?

CORRECTIV is a small investigative newsroom that works with publishing partners to reach a bigger audience. Therefore, a key measure for us is the number and the reach of the publications that pick up our stories. This story has been published more than 35 times from news outlets world wide. Amongst others, it was featured in Mediapart in France, TagesWoche in Switzerland, Taz in Germany, Slate in the US, and by NPR’s Latin America program Radio Ambulante.

Source and methodology

We used publicly available data from the UK’s Permanent Service for Mean Sea Level (PSMSL). Their database includes recordings from more than 2,000 measuring stations around the world. Our analysis quickly found that some stations had only operated for a few years, or had incomplete measurements. Different measuring stations also began and finished recording at different times.

We had to set rules to get a consistent record. After many discussions with scientists, we arrived at the following criteria: data from a measuring station was only used if at least 70 percent of measurements between 1985 and 2015 were available. Stations with flawed measurements were removed from the dataset. The final dataset includes 513 stations and some 34,000 measurement points.

One problem with the data is that there are only a few measuring stations in the southern hemisphere. That means that there is very little data in our news app for Africa, South America and parts of Asia. There are fewer measurements in these regions because measurements are usually done in commercial ports. For regions without global trade traffic there is no data.

Technologies Used

For our data analysis, we used Python and Pandas in Jupyter Notebooks. From the notebooks, we exported CSVs that we used as a data source for a news app that provides a “scrollytelling” introduction into the topic and a data explorer app that allows users to browse the data. The news app was built using JavaScript and the riot.js framework. Within the news app, we used D3 for rendering data visualizations and Mapbox for maps based on vector tiles with custom data layers.

Project members

Felix Michel, Annika Joeres, Nadine Stammen, Jacque Manabat, Jòn Bjarki Magnússon


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