Rising Seas May Be Costlier Than Anticipated

By Christina Phillis

Although sea level rise primarily affects coastal towns and cities, overall annual costs for the consequences could be as much as four percent of the global economy by 2100. According to a new study published in Environmental Research Communications, immediate action to reduce climate change and better prepare for sea level changes requires our immediate action.

In the study’s worst-case scenario, it could cost the world trillions of dollars if large amounts of polar ice melts. This figure is higher than previous estimates. Although not a very realistic scenario, it shows policy makers what could happen if they don’t act soon, says Thomas Schinko, climate economist and deputy director of the Risk and Resilience program at the International Institute for Applied Systems Analysis in Vienna. Schinko was quoted in a ScienceNews article by Megan Sever titled “Economic costs of rising seas will be steeper than we thought, unless we prepare.” But if countries can reduce greenhouse gas emissions enough to prevent global temperatures from rising more than two degrees Celsius above preindustrial levels and make preparations for sea level rise, the cost would be limited to less than half a percent of global GDP.

Predicting the Cost of Sea Level Rise 

Unlike previous studies based on a single economic model, the new study used three types of macroeconomic models to test the global economic effects of different energy policies and emissions scenarios during the next eight decades. These models included the economic impact of building dikes or sea walls to prepare coastal towns for sea level rise.

Simulations were adjusted for time passage, local sea level rise changes, and estimated future costs based on actions taken in earlier years. Both direct losses, such as destroyed infrastructure, and indirect costs, such as job losses, were calculated.

According to the models, every scenario leads to low global GDP losses through 2050. After that, costs would increase more or less depending on efforts to control climate change and prepare for rising waters.

Fine-Tuning the Models

Even the models used in this comprehensive study don’t provide a complete picture of the true costs of rising oceans. Certain climate events, such as flooding from hurricanes and typhoons, are not well represented, study coauthor Daniel Lincke, computer scientist and researcher at the Global Climate Forum in Berlin, told ScienceNews.

The study models also do not include the effects of compound flooding, the combination of high tides and heavy rainfall that can worsen outcomes. Sea level rise projections themselves are not exact. Depending on future greenhouse gas emissions, these vary from 25 centimeters to nearly a meter by 2100.

However, the data used for modeling continues to improve over time. Better elevation data has tripled the projected number of people who will be living in areas that are likely to be inundated by floods during the next century. Population maps, infrastructure and asset value estimates, and ocean circulation patterns continue to be updated and used to build better models.

As we improve our predictions of climate change, we will be better equipped to handle what comes next.