In 30 years several areas of the planet would be submerged 4:06
(CNN) –– If the world does nothing to mitigate rising sea levels, coastal flooding will be so extreme and destructive that its damage would be worth up to 20% of global gross domestic product by 2100, according to new research.
The study, published this Thursday in the journal Science Reports , is the first to map the projected economic impact that sea level rise would have caused by the climate crisis.
The authors claim that rising sea levels could cost the global economy $ 14.2 trillion in lost or destroyed assets by the end of the century, as large areas of land, home to millions of people, become flooded.
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"This is on a 'normal' CO2 emissions scenario," said Ebru Kirezci of the University of Melbourne, who led the study. The “normal emissions” scenario assumes an increase in average global temperatures to the upper end of the predictions, if global emissions are allowed to continue on their current course.
As temperatures and sea levels rise, the research estimates that up to 287 million people could be exposed to episodic coastal flooding by the year 2100, well above the current peak of 171 million. More than a million square kilometers of coastline could also be compromised, an area that is almost twice the size of France.
Among the areas at greatest risk of extensive flooding are the northeast coast of the United States, northwest Europe, and large parts of Asia, including countries around the Bengal Gulf, Indonesia, China, and northern Australia, according to the authors.
Some of the most vulnerable areas are highly populated, low-lying, low-income regions that already face devastating floods each year.
Those most affected by rising sea levels 1:10The researchers detailed that their figures did not take into account coastal defenses or projected increases in the world economy or population by 2100. However, they noted that setting a dollar figure on the worst-case scenario could incentivize policy change sooner. it's too late
“If you want politicians to pay attention, you have to put it in terms that resonate with them. The terms that resonate with them are the economic impacts, ”said Ian Young, a Kernot professor of engineering at the University of Melbourne and co-author of the study.
This could change extreme sea levels by 2100. The map shows the world's highest sea levels modeled between 1974-2014, compared to the highest projected levels for 2100.
It's all about the extremes
Rather than focus on average sea level rise, the study looks at elevations during extreme storms over the past 30 years to model the maximum area that could be at risk of flooding.
They decided to go this route because flooding or beach erosion are more likely to occur during a storm, they said.
The researchers mapped all the flood events known as "100 years" (that is, they have a 1% probability of occurring) on the world's coasts, especially those related to storm surges and destructive floods that resulted from storms and intense cyclones . Combining these data with projections of sea level rises under different greenhouse gas emission scenarios, the authors were able to model the maximum sea level rises.
"We are seeing the extremes," Young said. "Being able to model the tide, the storm surge, the formation of waves, the rise in sea level, the extremes that this generates and doing it on a global scale, that is what makes this project unique," he added.
Sea levels are rising as greenhouse gas emissions heat the oceans and the planet, resulting in melting glaciers and ice sheets.
If nothing is done to reduce carbon emissions, by 2100 vulnerable areas at risk of a 100-year flood will experience this phenomenon once every decade, the authors found.
"We are already seeing a higher frequency in storm surges and in extreme sea levels," said Kirezci. "The risks are increasing and climate change exacerbates these impacts," he insisted.
To estimate the economic cost of more major floods, the researchers combined their model with topographic data to identify areas at risk of coastal flooding, as well as map them to population and GDP data in those affected regions.
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"Our main objective with the study was to inform decision makers and policies around the world so that we can identify the hot spots, the most vulnerable areas, on the world coast," said Kirezci.
What this means for vulnerable countries and populations
Severe flooding already costs billions of dollars each year in damage, destroying houses, buildings, farmland, and vital infrastructure such as highways, pipelines, and pylons.
In fact, flooding is currently the most common and costly natural disaster in the United States: it has caused property damage of around $ 155 billion in the last decade. Last year, many parts of the Midwest and South were inundated by waters that lasted for months and caused $ 6.2 billion in damage and at least four deaths, according to the National Oceanic and Atmospheric Administration (NOAA). ).
This year in Asia, millions of people in India, Bangladesh, Nepal, China and Japan are dealing with the worst floods in decades after relentless monsoon rains. In the states of Assam and Bihar, in eastern India, the advance of water flooded thousands of villages, with more than 100 people dead and almost 4 million affected.
In China, devastating floods have impacted at least 38 million people in 27 of the country's 31 provincial regions since June, and in some places water levels have reached dangerous levels not seen since 1998, when massive floods killed more than 3,000 people.
Kirezci's study suggests that those social and economic costs will only worsen if calls to build more flood defenses are ignored.
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"As with many environmental problems, it is the poor who are most affected," Young said. “The real humanitarian challenge will be what you do. Can you really afford to build coastal defenses? Do you have to relocate populations? How would you do that? ”, He completed.
Scientists say that even if we reduce greenhouse gas emissions now, a certain rise in sea level is inevitable.
"Regardless of what we do with climate change, those sea level rises are going to occur," Young warned.
In addition to reducing emissions, countries should invest in adaptation measures to protect themselves against future floods, according to the authors. These actions include the construction of natural defenses such as mangroves and seagrasses that absorb waves and tidal waves along the coasts, as well as the nutrition of the beach, where the sands move to reinforce the beaches and dunes.
As a last resort, the researchers said, entire populations may have to be pushed away from the coast, an expensive and highly disruptive decision that could cause major humanitarian problems.
Kirezci argued that people should be aware of the impact of the climate crisis on sea level. "We need to raise awareness about the coastal communities, which reside in the lowlands," he emphasized.
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