Exceptionally high tides are common when the moon is closest to Earth, known as perigee, and when it's either full or new. In the case of what's informally known as a super full moon, it's both full and at perigee.
But something else is going on with the way the moon orbits Earth that people should be aware of. It's called the lunar nodal cycle, and it's presently hiding a looming risk that can't be ignored.
Right now, we're in the phase of an 18.6-year lunar cycle that lessens the moon's influence on the oceans. The result can make it seem like the coastal flooding risk has leveled off, and that can make sea level rise less obvious.
This simplified chart illustrates how the lunar nodal cycle suppresses and enhances the effects of sea level rise in Miami. The basic model assumes a constant linear increase of sea level, so it doesn't capture the expected acceleration of sea level rise. Brian McNoldy / CC BY-ND
But communities shouldn't get complacent. Global sea level is still rising with the warming planet, and that 18.6-year cycle will soon be working against us.
I am an atmospheric scientist at the University of Miami's Rosenstiel School of Marine and Atmospheric Science who keeps a close eye on sea level rise in Miami. Here's what you need to know.
What the Moon Has to Do With Coastal Flooding
The moon's gravitational pull is the dominant reason we have tides on Earth. More specifically, Earth rotating beneath the moon once per day and the moon orbiting around Earth once per month are the big reasons that the ocean is constantly sloshing around.
In the simplest terms, the moon's gravitational pull creates a bulge in the ocean water that is closest to it. There's a similar bulge on the opposite side of the planet due to inertia of the water. As Earth rotates through these bulges, high tides appear in each coastal area every 12 hours and 25 minutes. Some tides are higher than others, depending on geography.
The sun plays a role too: Earth's rotation, as well as its elliptic orbit around the sun, generates tides that vary throughout the day and the year. But that impact is less than half of what the moon contributes.
How tides work! Earth merely rotates through the tides: in 24hr 50min there are 2 high & 2 low tides, with the extr… https://t.co/6cMHB4R5oc— Dr. James O'Donoghue (@Dr. James O'Donoghue) 1589627917.0
This gravitational tug-of-war on our water was discovered nearly 450 years ago, though it's been happening for nearly four billion years. In short, the moon has very strong control over how we experience sea level. It doesn't affect sea level rise, but it can hide or exaggerate it.
So, What Is the Lunar Nodal Cycle?
To begin, we need to think about orbits.
Earth orbits the sun in a certain plane – it's called the ecliptic plane. Let's imagine that plane being level for simplicity. Now picture the moon orbiting Earth. That orbit also lies on a plane, but it's slightly tilted, about 5 degrees relative to the ecliptic plane.
That means that the moon's orbital plane intersects Earth's orbital plane at two points, called nodes.
The lunar nodes are the points where the moon's path crosses the ecliptic, the plane of Earth's orbit shown as the view of the sun from Earth over the span of a year. Wikimedia
The Moon's orbital plane precesses, or wobbles, to a maximum and minimum of +/- 5 degrees over a period of about 18.6 years. This natural cycle of orbits is called the Lunar Nodal Cycle. When the lunar plane is more closely aligned with the plane of Earth's equator, tides on Earth are exaggerated. Conversely, when the lunar plane tilts further away from the equatorial plane, tides on Earth are muted, relatively.
The lunar nodal cycle was first formally documented in 1728 but has been known to keen astronomical observers for thousands of years.
Earth's ecliptic and equatorial planes. NASA
What Effect Does That Have on Sea Level?
The effect of the nodal cycle is gradual – it's not anything that people would notice unless they pay ridiculously close attention to the precise movement of the moon and the tides for decades.
But when it comes to predictions of tides, dozens of astronomical factors are accounted for, including the lunar nodal cycle.
It's worth being aware of this influence, and even taking advantage of it. During the most rapid downward phase of the lunar nodal cycle – like we're in right now – we have a bit of a reprieve in the observed rate of sea level rise, all other things being equal.
These are the years to implement infrastructure plans to protect coastal areas against sea level rise.
Once we reach the bottom of the cycle around 2025 and start the upward phase, the lunar nodal cycle begins to contribute more and more to the perceived rate of sea level rise. During those years, the rate of sea level rise is effectively doubled in places like Miami. The impact varies from place to place since the rate of sea level rise and the details of the lunar nodal cycle's contribution vary.
Another "super full moon" will be coming up on May 26, so like the one in April, it's a perigean full moon. Even with the lunar nodal cycle in its current phase, cities like Miami should expect some coastal flooding.
Brian McNoldy is a senior research associate at the University of Miami.
Disclosure statement: Brian McNoldy serves as a volunteer science advisor for Coastal Risk Consulting.
Reposted with permission from The Conversation.
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This is my first wildfire season — also known as summer — in my new home state of Oregon. I'm learning the geography by way of (potential) catastrophe.
After nearly two decades in San Francisco, my wife and I moved to central Oregon in May. We had been plotting our escape to a more rural location for years. While climate change wasn't our reason for leaving the Bay Area, it was a consideration in where to go next.
We first looked at towns along the east and west flanks of California's Sierra Nevada. But our searches mostly ended in frustration... and a bit of fear. We'd hear from locals about getting dropped from their fire insurance or the skyrocketing costs of keeping their policies. And then there were the actual wildfires — like the ones that reduced large swathes of Paradise, and now Greenville, to ash.
When we eventually settled on central Oregon as our next home, we were under no illusion that it would be free from wildfires: I'm an environmental journalist who covers fires and climate change as part of my beat. Wildfire risk, we knew, would come with our new territory.
And it has. As I write this, ash from multiple fires burning in the region dusts my patio furniture. Cascade peaks, usually visible on the horizon, have been smudged by smoke. The air quality has once again reached unhealthy levels.
Still, there are numerous reasons we're glad to be here, even if we do have occasional pangs of doubt and wonder why we didn't move out of the West entirely — out of the path of increasingly longer fire seasons.
Around the country, other families find themselves in similar situations, or may soon. As this summer so cruelly illuminates, climate change will present a barrage of challenges — including droughts, floods and hurricanes — no matter where you live.
Louisiana National Guard members in high-water vehicles work with St. John the Baptist Parish officials to rescue citizens stranded in their homes in the wake of Hurricane Ida. Louisiana National Guard / CC BY 2.0
Understanding the risks of different places isn't easy. As we contemplated our move, I dug through state climate assessments and read scientific reports. But it was hard to match general findings with specific places, even for someone like me who gets paid to do that kind of stuff. Most people don't have hours to read journal articles and try to decipher scientific lingo.
That got me thinking: Whether moving or staying put, how do we assess risk in a climate change world?
Where to?
Last summer the San Francisco Bay Area had a day when the sun never seemed to rise. The sky remained a darkened, calamitous gray-orange from morning till night as the August Complex fire burned, eventually scorching a record-breaking 1 million acres. I received more than a few texts from friends asking if it was time to move somewhere less "apocalyptic." Was there a safer place to live in the coming years and decades as the planet continues to heat up?
It's a question on a lot of people's minds. The real estate website Redfin reports that the increasing frequency and intensity of natural disasters and extreme heat are factors in plans for about half of people considering moves in the next year.
Where to go may be a popular question, but it's also a hard one to answer for a number of reasons, says Daniel Swain, a climate scientist at UCLA who gets asked that question multiple times a day.
"I don't know what people's motivations are, what their priorities are and what their lives are like," he says. "It's so personalized and individualized."
The scientific factors, he says, are equally complex. For example, the difference between living somewhere with an extreme fire risk and a place with very little could be just a few miles in places like Los Angeles, he says.
And this summer has already shown that climate change is going to bring surprises.
"Most folks would have thought that Seattle or Portland would have been great places to escape extreme heat waves," he says. "Well, clearly, that's not always going to be the case. Seeing Death Valley-like temperatures in British Columbia in June, I think, really gave people pause. Climate projections suggest that all of these things and more are possible in the future, but I think it's a particularly visceral recent example of how things are changing pretty fast."
Climate change is likely to throw us other curveballs, too.
While most people are concerned with drought and fire in California, Swain says he's more worried about how the state will handle the extreme flood risks that will also come with a warming climate.
"A lot of the risks, the physical hazards that are relevant in a changing climate, are not going to be obvious, and they're not often going to be the ones that people are really hyper-focused on in a particular region," he says. "What comes out of the woodwork in 10 or 20 years won't necessarily be the same problems in the same places that we're facing right now."
Understanding the Science
So given what we know — and don't — how do we go about figuring out where might be safe?
Historically, there haven't been a lot of great resources to tap. Most climate models aren't accessible to the general public. Or their raw data is taken out of context by others when trying to convey more localized impacts, which can be misleading, says Swain.
"I think a good example of this is California, where most of the state, according to climate models, is expected to see neither more nor less mean precipitation in the future with a few degrees of mean warming," he explains. "And if you look at all of these downscaled products, it'll say 'great news, your water availability isn't going to change,' which of course is completely wrong for a variety of reasons."
One reason is that rising temperatures will ensure that even if total precipitation doesn't change, there will still be less available water supply because there'll be more evaporation and thirstier soil, diminishing runoff.
But even a small change in annual average precipitation doesn't catch the variability that California's likely to experience with more extreme storm events and more droughts.
"So you get more really wet periods, but also more really dry periods," says Swain. "In practical terms, it's a really dramatic change. And so you might get a very inaccurate picture of what the future holds if you look at the wrong variables in the wrong context, even if the information is technically correct."
Emerging Tools
So how do we find the right information in the right context? There are some new efforts attempting just that.
Redfin, for example, recently partnered with ClimateCheck to add a feature to their listings that provides the future climate risk of a particular property. It assesses the change in the risk of heat, fire, drought and storms over the next 30 years.
First Street Foundation has been doing something similar focused on floods.
Getting down to the address level makes sense because risk itself can be hyper-local. Whether your house survives a disaster may depend not on what state or town you live in, but on what side of the street.
But can these tools really be precise at such a fine scale?
Swain, who has done some consulting for ClimateCheck, says it's possible to take regional climate data and combine that with very high-resolution spatial data at the parcel level. But he cautions, "I think it's more important to get it right than to be first to put something out there." After having seen it implemented poorly in the past, he says he now sees people today "who are trying to do a more thorough job of vetting and contextualizing everything."
Do Everything
Having better resources to find places that may have less risk is great... for the people who can afford to move there. Or move anywhere.
I'm among those lucky enough to get to pick a place on the map and point the moving truck in that direction. But that's not going to be a reality for a lot of other folks, as we saw last month before Hurricane Ida, when many people didn't even have enough cash on hand to temporarily flee the impending disaster, let alone permanently uproot their lives.
"It's a pretty extreme privilege in a global and even a national context to be able to choose where you want to live on the basis of your perceived comfort or safety from a climate perspective," says Swain. "That's not a choice the vast majority of people on Earth even get to make, even if there is good information to use for making that decision."
And while some places may seem like the proverbial higher ground, climate change is not a problem we can move away from — even for those with more resources. If it's not directly threatening our homes, it may endanger our food supply, water, jobs, health, neighbors, or the wildlife and wild places we hold dear.
That means making every place safer is a better bet — especially considering that the ground we're starting from isn't level. Many communities of color and low-income communities already face greater climate risks and climate-related health threats.
As far as I can tell, our best bet is to do everything — big and small. First and foremost, reduce greenhouse gas emissions and speed up the energy transition — equitably. At the same time, we'll need to protect and restore critical habitats, green urban areas and increase resilience wherever we are — including curbing new developments in areas we know will flood and burn.
When I started this article, I wanted to ask what resources people could use to pick new places to live. I also wanted to ask: Who has access to them? But maybe, instead of focusing on where we should go, it would be better to ask, "What more can we do to stay in the homes and communities we already love?"
Reposted with permission from The Revelator.
The rains caused floods and sent New York City into a state of emergency, as the storm carried into New England with threats of more tornadoes.
Police in New York City reported seven deaths, including a 50-year-old man, a 48-year-old woman and a 2-year-old boy who were found unconscious and unresponsive inside a home. They were pronounced dead at the scene, police said. One death was reported in New Jersey.
New York's FDR Drive, a major artery on the east side of Manhattan, along with the Bronx River Parkway, were underwater by late Wednesday evening.
Subway stations and tracks were inundated to the point where the Metropolitan Transportation Authority suspended all service, and videos posted online showed subway riders standing on seats in cars filled with water. Streets and apartments were under up to 1 meter (3 feet) of water in some places, and more than 5,000 homes were left without power.
The wrath of Hurricane Ida: New York announces its first-ever flash-flood emergency | DW News youtu.be
'Enduring Historic Weather Event'
"We're enduring an historic weather event tonight with record breaking rain across the city, brutal flooding and dangerous conditions on our roads," New York Mayor Bill de Blasio tweeted.
The alert marked the first-ever alert of flash-flood emergencies in the region, an alert level reserved for "exceedingly rare situations when a severe threat to human life and catastrophic damage from a flash flood is happening or will happen soon.''
Destructive Tornadoes
The city also implemented a temporary travel ban for all nonemergency vehicles. Earlier Wednesday, the storm hit states including New Jersey and Pennsylvania, with at least two tornadoes, heavy winds and rains. Photos showed homes reduced to rubble, while the roof of a U.S. Postal Service building collapsed in New Jersey.
Highway 440 flooded in Jersey City, New Jersey, on Sept. 2, 2021 with hundreds of cars stuck in water as Hurricane Ida left behind flash floods. Tayfun Coskun / Anadolu Agency via Getty Images
The National Weather Service had predicted flooding from what remained of Hurricane Ida, saying steep terrain and even city streets were particularly vulnerable to a band of severe weather that stretched to Massachusetts, where tornado warnings were issued early Thursday.
Tropical Storm Henri hit the region a little more than a week ago, causing flooding and making the cities more vulnerable to this week's set of weather events.
Reposted with permission from DW.
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