Floods are increasing WAY faster than we expected

- Extreme rain events are

increasing

at an alarming rate in the US and around the world, but the problem is not how much rain falls in a given location, but how long it takes to fall. And fascinating new research sheds light on exactly how that is changing. Over the last century, global precipitation has only increased 0.04 inches per decade. But if we look at individual regions of the US, we can see that some places have experienced 30% more rain during the same period. However, more rain is not the whole story. That's why the First Street organization created an innovative risk map that shows a big change in what NOAA calls 100-year

floods

.

These are events so extreme that the odds of them occurring in a given year are about one in 100. - A 100-year precipitation event occurs most frequently about once every seven or eight years in the most extreme cases. - And that's important because infrastructure like sewage systems are built with this metric in mind. But why the change? This is because a warmer atmosphere is a thirstier atmosphere, meaning it can retain more moisture... for each additional increase in temperature. For one degree Celsius. Air can contain 7% more water - Vapor. And that is fundamentally changing the hydrological cycle. Dry times get drier and wet times get wetter at an exponential rate, and not just on an annual scale, but also in hours and minutes.

So First Street reanalyzed U.S. rainfall data until its analysis uncovered a major trend and led to a new flood risk map of the United States. It turns out that some places that currently experience less annual rainfall and more droughts should also expect more flooding. In this episode we'll look at this map to see which regions are most at risk and how we can adapt with all this extra water. - This is not something anyone should go through when dealing with a disaster, especially a hurricane. - We can learn a lot from New York City when it comes to extreme rainfall because they are getting a lot of it.

Just last September, the city saw nearly eight inches of rain in a single day. - A place like New York City used to be very, very green and covered in lakes and streams. And over time it has been completed. The same thing happens in almost all cities. We have replaced natural permeable surfaces with concrete and asphalt. Nearly 72% of New York City is now covered by impervious surfaces. So instead of a natural water system, runoff must be managed by a sewage system designed for a climate that no longer exists. - The original designers who built our sewer system didn't know we were going to have 3, 4, 5, 8 inches of rain. - A one-in-a-hundred-year event in New York City actually occurs about once every 35 years. - This is a new problem, so they can only handle about one to two inches of rain per hour. - Our infrastructure simply cannot withstand all the rain we are receiving.

And the NOAA maps, which we refer to as Atlas 14 and Atlas 2 that we use to project flood risk and determine where to improve our infrastructure in the event of flooding, the events also do not keep pace with the rainfall. - They use traditional historical methods to measure precipitation risk. And for a long time it was perfectly fine. The problem is that if there is an

increasing

trend in precipitation, suddenly the average no longer captures what the current events are. It actually dates them back to a climate that could date back 20 or 30 years. - In other words, NOAA maps look backward and not forward.

So First Street decided to take a different approach to NOAA data. - Our report really focused on extreme precipitation events as opposed to average precipitation levels across the country. And it's not necessarily that we're seeing more of these events, but when we do see them, they're more severe, we're seeing more severity in the intensity of the rainfall over shorter periods of time, which is causing more flooding. Amit Shivprasad lives in Hollis, Queens. His neighborhood has been affected by flooding for a long time, but recently the situation has worsened. Looking around, the area has very little green space to absorb rainwater and Amit discovered that this area used to be a real lake. - So this is actually our house where you are right now.

So if you look, it's actually in the middle of a pond right now, and this is what the pond looked like in 1928. If you look at an old map of New York City and see where all the streams and the lakes are, They used to be, and then you look at today's flood map, you can see it's virtually identical. - FEMA's 100-year floodplain map derived from NOAA Atlas 14 directly impacts the cost and access of flood insurance. But because the map does not include storm flooding, many communities are left out. And as a result, overexposed: Flood insurance was never sold to anyone in this community because we don't live in a flood zone or on a century-old FEMA map.

But... The

floods

have devastated this community. In 2021, after Hurricane Ida made landfall as a category four, it traveled across the eastern US, dumping record rainfall in its wake in New York City alone. More than seven inches fell, peaking at three inches of rain per hour. Amit's neighborhood was not prepared. - It started like a normal day, I had dinner with my parents and all the warnings began to sound. I ran downstairs, grabbed my poncho, with me and my dad we took our shovels and the rake and went out to clean the basins like we do every time it rains.

But... The sewer basins on Amit's street were not working that day. - The city was doing works and practically all the roofs of the basins were covered. Notice how the rain was coming higher. So I ran and grabbed my keys, moved the truck up the block before returning to the end of the block, the entire street was flooded. - Floods killed 13 people in New York. - 11 of those people died in flooded basement apartments, most of them here in Queens, Phamatee Ramskriet, 43, and her 22-year-old son, Krishah, also known as Tara, and Nicholas could not survive the heavy flooding in last night.

The waters broke through the wall and poured into his basement apartment. - Tara and Nicholas were tenants in Amit's family's basement. Before Ida, she raised the doors of her house three to four feet to prepare for the flood, but the storm brought in too much water. She no longer rents her basement and now uses the space for community events. - Unfortunately, the wall collapsed and that is the reason why all the destruction occurred. So I've done my part when it comes to repair. I just pray and ask God that it never floods again. That's all. - Ida caused $75 billion in damage across the United States.

More than 33,500 buildings in New York City were destroyed, and Amit's renovation alone cost more than $344,000. But not all areas were equally affected, across the Hudson Hoboken, New Jersey did not suffer the same flooding, and this is in part due to its efforts to adapt to this new climate reality. - Flooding has always been a problem in the city of Hoboken. Actually, we were originally a tidal marsh. The area where we were was a swamp. All of these low-lying areas that were swamps that were filled in for industrialization in the early 19th century are very subject to flooding today.

We also have a combined sewer system where our stormwater and wastewater flow through the same pipes. Now, with climate change, we are seeing more frequent and more severe storms. - To address flooding issues, Hoboken has been building resilience parks around the city. We took a tour of the larger park to understand how these green spaces work. - This is one of 19 rain gardens found in Resiliencity Park. And these rain gardens will manage water during a rain event. You will see that it almost looks like a pond. The entry of water into our stormwater system is slowly being delayed.

It filters through garden rain through all the plants and soil. That water then slowly drains into the underground tank beneath the park and then out into our sewer system. And that is all the water that is not in our streets. During a rain event, our million-gallon retention tank located under this grass can hold rainwater coming from the park site, as well as all of North Hoboken, and it is working. Hoboken has seen an 88% decrease in flooding since these mitigation measures were installed. And only time will tell if these measures resist future climate changes. But it is a strong proof of concept.

The comparison between Hoboken and Hollis also follows another trend. Recent studies find that race and wealth play an important role in where natural disaster recovery efforts take place, and this affects the safety and economic outcomes of residents. A 2018 study found that in areas with at least $10 billion in damages from a natural disaster, white families actually saw an increase in wealth of about $126,000 after recovery, while Black families saw a decrease in wealth. wealth of $27,000. This map shows the extent of this wealth gap in some major cities in the US. Hoboken is 64% white, while Amit's neighborhood in Queens is just 1.4% white, or 1.3 million.

New Yorkers live on or directly adjacent to a floodplain, and that number will rise to more than 2 million. By the turn of the century. Half of those people are considered low income by HUD, our federal government, and half of those people are communities of color. - Hollis, which is Amit's neighborhood in Queens and the adjacent Queens Village, underwent a $24 million sewer expansion from 2019 to 2021 to try to address the flooding issue. However, the Hollis community still experiences frequent flooding. -My neighbor across the street, every time it rains, she comes to our house because she is afraid that her wall will collapse again.

And you know, it's, it's, it's kind of sad. That everyone in the community feels the same: as the climate changes and the wet times get wetter. Intervention efforts are becoming increasingly complicated and challenging. - And this will probably be one of the biggest problems we will face in the next 20 years: where will we stay and where will we go? There is no single solution for each neighborhood or for each place. - But there is hope that efforts will be made to mitigate the flooding. Every dollar spent on flood mitigation generates a return of up to $8. - So we can manage that water with green infrastructure and turn New York City into a sponge in every neighborhood and every place where we can do it.

We would like to absorb water, so that it can be in our streets, on our green roofs or in our parks. - Now that we understand the challenges and opportunities for addressing urban flooding, let's return to First Street's new risk map, which focuses primarily on flooding caused by heavy rain. - There are currently about 8 million properties in the FEMA special flood hazard area compared to our about 17.7 million properties. Most of that, about 65% of that gap that we see, is actually due to precipitation risk. In fact, by FEMA's own estimate from 2015 to 2019, 40% of flood insurance claims came from outside the high-risk zones on the FEMA map.

But perhaps most surprising is the update to NOAA's flood maps. This shows the difference between NOAA maps and what First Street found, where 100-year floods now look more like 35-year floods, as in the case of New York City. Their study even found that in some areas, 100-year floods have now become just eight-year floods, making them 12 times more likely. - The Midwest in particular sees a large underrepresentation of those once-in-a-hundred-year events, places like southern Indiana and northern Kentucky around the Louisville, Kentucky metropolitan area. They're seeing that the depth of one every hundred years according to NOAA Atlas 14 records is as much as one every seven or one every eight years. - According to First Street, not only the Midwest, but the entire northeastern United States has a hidden risk of extreme precipitation.

And even in Northern California, which is seeing a decline in overall rainfall, the 100-year chance of a flood is now one in35. With climate change, we are seeing strange patterns and complex impacts on our climate systems. We may not know exactly what a warmer world will look like, but it is clear that changes are occurring. Therefore, it seems prudent that we adapt. In this episode. We learned what is at stake in flooding due to these extreme rainfall events and looked at places like the city of Hoboken, a place that is doing a great job of navigating these changes in our hydrological cycle.

But I'm curious, how is your community adapting to these changes? Let us know in the comments below.