Jianjun Yin
The U.S. East Coast has been hit with hurricanelike flooding in recent weeks, with South Carolina and Georgia getting the latest round. High tides are part of the problem, but there’s another risk that has been slowly creeping up: sea level rise.
Since 1880, average global sea levels have risen by more than 8 inches (23 centimeters), and the rate has been accelerating with climate change.
Depending on how well countries reduce their greenhouse gas emissions in the coming years, scientists estimate that global sea levels could rise by an additional 2 feet by the end of this century. The higher seas means when storms and high tides arrive, they add to an already higher water level. In some areas – including Charleston, South Carolina, where a storm and high tide on Nov. 5, 2021, sent water levels about 8 feet above normal – sinking land is making the impact even worse.
I’m a geoscientist who studies sea level rise and the effects of climate change. Here’s a quick explanation of two main ways climate change is affecting oceans levels and their threat to the world’s coasts.
Ocean thermal expansion
Climate change, fueled by fossil fuel use and other human activities, is causing average global surface temperatures to rise. This is leading the ocean to absorb more heat than it did before the industrial era began. That, in turn, is causing ocean thermal expansion.
Thermal expansion simply means that as the ocean heats up, sea water molecules move slightly farther apart. The farther apart the molecules are, the more space they take up.
That expansion leads to the ocean rising higher onto land.
During the past several decades, about 40% of global sea level rise was due to the effect of thermal expansion. The ocean, which covers just over two-thirds of the Earth’s surface, has been absorbing and storing more than 90% of the excess heat added to the climate system due to greenhouse gas emissions.
Melting land ice
The other major factor in rising sea levels is that the increase in average global temperatures is melting land ice – glaciers and polar ice sheets – at a faster rate than natural systems can replace it.
When land ice melts, that meltwater eventually flows into the ocean, adding new quantities of water to the ocean and increasing the total ocean mass.
During the past several decades, about 50% of global sea level rise was induced by land ice melt.
Currently, the polar ice sheets in Greenland and Antarctica hold enough frozen waters that if they melted completely, it would raise the global sea level by up to 200 feet, or 60-70 meters – about the height of the Statue of Liberty.
Climate change is melting sea ice as well. However, because this ice already floats at the ocean’s surface and displaces a certain amount of liquid water below, this melting does not contribute to sea level rise.
While the surface height of the ocean is rising globally, the impact is not the same for every coastal region on Earth. The rate of rise can be several times faster in some places than others. This difference is caused by an area’s unique local conditions – such as shifts in ocean circulation and the uplift or subsidence of the land.
The risks will keep rising long after emissions stabilize
Nearly 4 in 10 U.S. residents live near a coastline, and millions of people are already dealing with coastal flooding during hurricanes and high tides that can damage homes, buildings and other coastal infrastructure and ecosystems. The Chesapeake Bay area was hit with flooding during high tides in late October, and the Miami area now deals with high-tide flooding several times a year.
Worldwide, researchers have estimated that sea level rise this century could cause trillions of dollars in damage. In some low-lying island nations, including the Maldives in the Indian Ocean and Kiribati in the Pacific Ocean, rising seas are already forcing citizens to make stark choices about building costly ocean protections that will only last so long or plan to abandon their islands.
Officials from countries worldwide are meeting at the U.N. climate conference with a goal of agreeing to reduce global greenhouse gas emissions enough to keep global temperatures from rising too high.
Even when emissions come down, sea level will keep rising for centuries because the massive ice sheets in Greenland and Antarctica will continue to melt and take a very long time to reach a new equilibrium. The latest report from the Intergovernmental Panel on Climate Change shows the excess heat already in the climate system has locked in the current rates of thermal expansion and land ice melt for at least the next few decades.
Jianjun Yin is Associate Professor of Geoscience at the University of Arizona.
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Mark says
Driving electric cars will fix this problem.
beachlover says
Most electricity generation is produced from coal, so electricity use isn’t good for the environment.
FlaglerLive says
The commenter is not accurate. In the United States, less than 20 percent of electricity is still generated by coal, though 60 percent is generated by fossil fuels. https://www.eia.gov/tools/faqs/faq.php?id=427&t=3
Mike Cocchiola says
In 2020, about 477 million short tons (MMst) of coal were consumed in the United States. On an energy content basis, this amount was equal to about 9.2 quadrillion British thermal units (Btu) and to about 10% of total U.S. energy consumption
mark101 says
And where do you think the electricity comes from to charge those cars
Jimbo99 says
We’re getting a NorEaster, Not nearly a Tropical Storm or a Hurricane but a strong swell & surge just the same. Often times a NorEaster can significantly influence & alter the path of a Hurricane, just as cooler weather fronts of October & November can steer a Hurricane further off shore. We’re also getting heavier rains and longer duration and that may flood areas. Everytime we have some time of heavier rainfall, it’s always global warming. Any of these storms is relatively unpredictable, yet we have seen them pretty much every year. This NorEaster is also going to effect the Flagler Beach shoreline because the surf action is heavier, with bigger waves, even rip currents. This year we didn’t get the threat of a Tropical Storm/Hurricane formation in October and now thru the 1st week of November. Early July we had the same usual Hurricane threat in the Gulf that July has usually had. For storm names, we’re at Wanda, not a threat to FL’s coast lines. Anyway, this will clear by Sunday & bring sunny & cooler temps, dry out what rains of Friday & Saturday accumulate. Is it going to be soggier ? Nothing the swales can’t handle. Friday was the worst of it, Saturday should be similar. Winds are already shifting to N/NW, which should clean up the sloppier high surf.
https://weather.com/weather/tenday/l/Flagler+Beach+FL
https://www.nhc.noaa.gov/
Anna Mac says
Exactly. The misinformation, misinterpretation and outright corruption surrounding climate change is a tragedy. How can the government make intelligent decisions if the data has been corrupted and academics are using weather as a grant generating mechanism? The rest of the world, particularly the EU, wants to hamstring U.S. business and join other corrupt globalist organizations at the trough fed by U.S. taxpayers. Honest reporting has to start somewhere. Why not at FlaglerLive?
Bartholomew says
How do you know this is misinformation?
Jimbo99 says
Well, the weekend came & went. At some points later Saturday afternoon, I was cleaning debris in the yard from the gustier winds and saw holes in the sky for blue skies & white clouds. Sunday came and it was a calm day, the rain threat was totally gone, the ground had even dried out and the swale never really had standing water for very long. Just as I predicted it would, Mother Nature took care of dead palm tree branches like she usually does for trimming. That debris will be removed county wide in the next trash pick up cycle(s). Hopefully something will come along and give the kids something to surf on next weekend for the Tommy Tant Surf Contest at Flagler Beach on Saturday & Sunday. Low 50’s to 70’s all week long with sunnier days ahead. The weather is going to be beautiful, enough in November to see lower power bills. Heater will take the place of AC Cooling. So basically no Covid 5th wave or whatever the pandemic doom & gloom is, no end of the world flood or storm in Flagler county. Carry on with living your best lives.
Land of no turn signals says says
Hey let’s blame everything on global warming but nobody wants to admit that taking huge wooded areas around the world can mitigate this.Let’s start here in Flagler county where it seems to be against the law to leave a friggin tree standing.
The Great Escape says
Its this very reason I’m looking at property up in the Mountains of Tennessee and North Carolina. Preferring some acres with springs and underground caverns for future living. Selling my house this year. Its been a great 31 years of enjoying Florida. But as an avid outdoorsman, fisherman, and general all-around Beach Bum, I have been keeping records of water levels, water pollution, marine life changes, and increasing HEAT during the spring, summer, and fall months. Changes are happening with increasing persistence . I have to make sure I leave my grandchildren a place to escape to when the SHTF.
Ld says
Sounds nice, where are you looking in particular?
Bartholomew says
Tennessee area is great for outdoor adventures, but it does get cold there
capt says
We are doing the same thing, after 64 years living in Fla, We are done. I’ve lived all over this state inland, beachside but its just getting so darn crowded. When I was born here in Fl in 1957 there was 4.3 million, now there is 21 million., Let the “up northers”and midwesterners come to Fla and turn it into little NY or little PA or little NY, or not Fla anymore. PS some of my best golfing and fishing buds are from up north :)
Charlie Ericksen Jr says
Let’s not forget, what are called “KING TIDES”…These occur , when NEW and FULL moons occur. during the year and based upon the , locations of the sun, moon, they can then cause high tides to be much HIGHER ….Any College professor should know that
Don't Cull Me says
No swales in my neighborhood. Just the Intracoastal covering half my backyard today. It is what it is but I sure wish the idiots racing down the Intracoastal when there is obvious flooding (you couldn’t miss seeing it) would slow the hell down!! We had waves crashing over our dock most of today from the boaters. Lost another foot or two of the yard too. Be considerate!!
water bloot says
By warming; We’re changing how much water vapor is in the atmosphere, we are physically altering the water cycle, too…. and by then how much falls .. Yea sea levels, that’s a part, but it’s so much more complex than that.
A.j says
Climate change, is happening. We have always had tropical systems in this part of the country. This storm was non tropical. Did climate cause this I dont think so. Coastal storms are quite common here on the east coast, they produce a lot of rain and can cause floods on low lying areas. This isn’t new. We will have coastle storms in the future, will they be caused by climate change? Biblical Paul experienced a hurricane in the book of Acts was that climate? Some of Job,s family were killed by tornadoes in the Bible. was that climate change? Biblical events droughts, floods, earthquakes, climate change?
Chris says
Any normal storm, snow, cold, heat wave, now is all classified as global change!!! What a load of crap!! And yes the biggest problem is destruction of the forest!! That is what controls the weather more than anything! Take away the trees and natural forest, the planet will burn up to a cider
mark101 says
Its Fla people its flat and living near water comes with risk, just like living on a cliff or in a earthquake zone or in an area that gets ice and snow that covers your home or gets these northeasters each year and or living in tornado alley, holly smokes having your home and town wiped out in mere minutes by a F4 or F5, well been there done that. Hell living anywhere these days comes with some risk. You get what you want and take your chances to find your little piece of happiness,
herewegoagain . says
BEST COMMENT HERE
Timothy Patrick Welch says
Yep a storm occurred during a big tidal change period. Stop the fear mongering!
Do you live in a flood zone?