Most of the planet’s coastal communities will suffer every year flood An event that has only ever occurred once every 100 years. This is what will happen by the end of the century, even in a moderate scenario in which carbon dioxide emissions peak in 2040, according to a scientific study. However As early as 2050, regions around the world could experience such major floods every nine to fifteen years.
The ‘flood of the century’ is an extreme water level that has only a 1% chance of being exceeded in a given year and is based on historical data. Despite the name, these megafloods can affect the same area for several years in a row or may not occur at all in a century, as they are an average number. However, a recently published study reveals that this historical average will no longer be the same from now on.
On the coast, water pushed inland by storms, tides and waves can cause extreme flooding; however, this study focuses on one component that contributes to flooding on a much longer time scale: Rising sea levels. As it rises, coastal infrastructure will be closer to the water, making storms, tides, and storms more likely to impact population centers.
Researchers used data from more than 300 tide gauges around the world to conduct trend analysis and predict future extreme sea levels. two carbon emission scenarios It was announced by the International Panel on Climate Change (IPCC). One of these is based on carbon dioxide emissions, which continue to rise until the end of the century. In the other scenario, emissions are predicted to peak in 2040 and then decline. In both scenarios, scientists observed that rising sea levels would lead to an increase in major floods. in most of the places they studied.
Hamed Moftakhari added that a better strategy in terms of spatial planning, urban development and coastal protection measures could help communities reduce the effects of such floods and prevent disasters.
Building a safer future
Engineers who design structures such as seawalls, seawalls, and breakwaters to protect communities from these extreme floods They rely on a concept known as ‘stationarity’ to predict future water levels.
“In ‘stationarity’ we assume that the patterns we observed in the past will remain unchanged in the future, but there are many factors resulting from climate change that change these patterns,” Moftakhari said. said. “We can no longer assume the stability of coastal floods.”
Previous studies relied on fixed estimates of extreme sea levels to predict 100-year floods, but this study used nonstationary methods and found: Change in extreme sea levels will not be uniform in many places.
As the climate changes, rising ocean temperatures and melting glacier waters are causing sea levels to rise, increasing the frequency and severity of coastal flooding. As a result, engineers need accurate estimates of future flood risk that do not assume that our changing future will reflect historical coastal patterns.
The situation is no longer stable
“What makes this so unclear is that most tools, design guidelines, application guides, etc. It is based on the assumption of stationarity“But these need to be updated so that we can see the pace of change,” Moftakhari said.
According to another study, more than 600 million people live in low-lying coastal areas and this number is expected to increase. well-designed coastal defense structures They play an important role in the ability of coastal communities to withstand major floods.
But sea level rise will not be the same everywhere. At higher latitudes, a drop in sea level may occur as heavy ice sheets melt and underlying land rises. But instead, areas such as the Gulf of Mexico are experiencing a faster rise in sea level than the global average due to gradual sinking of land. According to Moftakhari, coastal communities will need different solutions depending on the situation in each region.
“We know the average sea level is rising, the question is: How do we deal with it?” Moftakhari said. “As we have seen many parts of the coast permanently submerged and losing land, with many cities and coastal islands being flooded much more frequently than in the past, it is time to learn how to deal with non-state problems.
Reference work: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023EF003649
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