sea levels

Sinking Cities | Earth Wise

October 24, 2022 By EarthWise Leave a Comment

Sea levels across the globe are rising as a result of the changing climate. Two factors are largely responsible: the melting of ice sheets in the polar regions and the fact that as the oceans get warmer, the water in them expands.

Estimates are that by 2050, there will be over 800 million people living in 570 cities that will be at risk from rising sea levels. The rising waters can drown neighborhoods, put people’s lives at risk, and wreck entire economies. Unless global emissions can be reduced sufficiently, sea levels will continue to rise.

A new study, published in the journal Nature Sustainability by Nanyang Technical University in Singapore in collaboration with the University of New Mexico, ETH Zurich, and NASA’s Jet Propulsion Lab, has focused on yet another aspect of the threat to coastal cities. They have found that many densely populated coastal cities worldwide are even more vulnerable to sea level rise because much of their land is sinking.

The researchers processed satellite images of 48 cities from 2014 to 2020 using a system called Interferometric Synthetic Aperture Radar. They found that land subsidence varied on a neighborhood and even individual block level but across all the cities studied, there was a median sinking speed of 6/10” a year. Some places had land that is sinking at 1.7” per year. Meanwhile, the global mean sea-level rise is about .15” per year.

The increasing prevalence of industrial processes such as the extraction of groundwater, and oil and gas, along with the rapid construction of buildings and other urban infrastructure are leading to the sinking of the urban areas.

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Rapid land sinking leaves global cities vulnerable to rising seas

Photo, posted October 24, 2015, courtesy of Jeffrey via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Scourge Of Salt | Earth Wise

June 10, 2022 By EarthWise Leave a Comment

Rising seas are increasing saltwater intrusion on land and rising temperatures are causing greater evaporation. The result is mounting levels of salt in waters and in soils.

Rising sea levels cause salty ocean water to push further into river deltas. There is already a surge in saltiness across all inhabited continents. Seawater works its way further upstream when dams hold back water. Pumps that remove fresh water from underground sources for irrigation and drinking supplies add to the problem. In dry regions, irrigation systems delivering water to crops increasingly bring salt onto fields.

People add to the problem by pouring saline drainage water from mines into rivers and by using salt to de-ice roads in the winter.

A modeling study pinpointed hotspots for climate change-induced salinization in numerous locations including the U.S. Southwest, wide areas of Australia, Mexico, South Africa, Brazil, central India, northern China, and more.

Some ecosystems are adapted to saline environments but major alterations in the balance between saline and fresh water is creating growing problems for ecosystems, lake fisheries, crop growing, and even human health.

The damage caused by salt is likely to be so severe that salinization will become a major cause of environmental refugees when the land they live on can no longer sustain them.

Salt will be a growing threat to the world’s food supplies, especially where farmers depend on artificial irrigation. About a third of the world’s food is grown in irrigated fields, and a fifth of those fields are deemed to already be salt-contaminated. Ultimately, only a halt to climate change will be capable of combatting the scourge of salt.

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Salt Scourge: The Dual Threat of Warming and Rising Salinity

Photo, posted June 3, 2017, courtesy of Jason Jacobs via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Antarctic Ice Collapse | Earth Wise

March 2, 2022 By EarthWise Leave a Comment

In Antarctica, a huge chunk of the Larsen B Ice Shelf collapsed suddenly and spectacularly in January.

The Larsen Ice Shelf is located on the northeastern side of the Antarctic Peninsula on the Weddell Sea. It was formed over the course of more than 12,000 years. The Weddell Sea used to be a completely frozen body of water. The famous Ernest Shackleton expedition in 1915 was trapped in its ice. But the Antarctic Peninsula has been steadily warming in recent decades.

The Larsen A Ice shelf collapsed in 1995 and the 1,250-square-mile Larsen B Ice Shelf collapsed in 2002. After that event, a portion of the detached ice shelf refroze in 2011 and was attached to the Scar Inlet Ice Shelf. The refrozen ice was called the Larsen B embayment.

In January, the embayment broke apart, taking with it a portion of the Scar Inlet Ice Shelf. It disintegrated within a matter of days. The combined Larsen Ice Shelves – called A, B, C, and D – once extended along a 1000-mile stretch of the eastern Antarctic Peninsula. Since 1995, it has shrunk from 33,000 square miles to 26,000 square miles.

These ice shelves float on the ocean, so their loss does not actually increase global sea levels. However, the shelves act as dams that hold back glaciers located on the land behind them. The loss of Antarctic ice shelves dramatically increases the rate at which glaciers flow into the sea, and that does increase global sea levels.

Now that the sea ice from the Larsen B embayment is gone, it is likely that there will be additional inland ice losses from the newly exposed glaciers.

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Remnant of Antarctica’s Larsen B Ice Shelf Disintegrates

Photo, posted February 13, 2018, courtesy of NASA/Nathan Kurtz via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Threat From Thwaites | Earth Wise

January 20, 2022 By EarthWise Leave a Comment

The Thwaites Glacier in Antarctica is the widest glacier in the world. It is about 80 miles across and in places extends to a depth of about 2,600 to 3,900 feet. The glacier is roughly the size of Florida, and it currently contributes 4% of annual global sea level rise as it continues to retreat from a warming ocean.

The International Thwaites Glacier Collaboration is a team of nearly 100 scientists dedicated to studying the glacier. According to the scientists, Thwaites has doubled its outflow speed within the last 30 years. The glacier in its entirety holds enough water to raise global sea levels by over two feet, which would be catastrophic.

A third of the glacier flows more slowly than the rest because it is braced by a floating ice shelf that is held in place by an underwater mountain. The concern is that the brace of ice slowing the glacier may not last for long.

Beneath the surface, warmer ocean water is attacking the glacier from all angles. The water is melting the ice directly beneath the glacier causing it to lose its grip on the underwater mountain. Massive fractures have formed and are growing.

Warm water is also a threat for what is called the grounding zone, which is the area where the glacier lifts off the seabed. There are many possible scenarios under which there could be a major ice loss from the glacier. It is unclear how quickly it could occur. It might take decades, or it could be centuries. The threat is large enough and real enough that continued observation and research is essential.

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The Threat from Thwaites: The Retreat of Antarctica’s Riskiest Glacier

Photo, posted October 16, 2012, courtesy of J. Yungel / NASA Ice via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Global Flood Risk From Melting Ice | Earth Wise

December 13, 2021 By EarthWise Leave a Comment

Approximately 10% of the land area on Earth is covered by ice. This includes glaciers, ice caps, and the ice sheets of Antarctica and Greenland. Nearly 70% of all fresh water on earth is locked away in ice. If all this land ice were to melt, global sea levels would rise by more than 200 feet.

According to new research led by researchers at the University of Leeds in the U.K., global warming is causing extreme ice melting events in Greenland to become more frequent and more intense over the past 40 years, leading to an increased risk of flooding worldwide.

According to the findings, which were recently published in the journal Nature Communications, approximately 3.85 trillion tons of ice has melted from the surface of Greenland and into the ocean during the past decade alone. That’s enough melted ice to cover all of New York City with nearly 15,000 feet of water.

Rising sea levels threaten the lives and livelihoods of those living in coastal communities around the world. Beyond the obvious risk of flooding in low-lying areas, rising seas also disrupt marine ecosystems that many coastal communities rely on for food and work.

Rising sea levels can also alter patterns of ocean and atmospheric circulation, which in turn affect weather conditions around the planet.

Estimates from models suggest that melting ice from Greenland will contribute between 1 inch and 9 inches to global sea level rise by 2100.

These findings are just another reminder of how we need to act urgently to mitigate climate change if we want to prevent the worst-case scenarios from becoming reality.

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Increased frequency of extreme ice melting in Greenland raises global flood risk

Photo, posted April 21, 2017, courtesy of Markus Trienke via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

People And The Earth’s Increasing Heat | Earth Wise

September 23, 2021 By EarthWise Leave a Comment

A new study by Princeton University and the National Oceanic and Atmospheric Administration had found clear evidence that human activity is the primary cause of the significant increase in heat stored in our planet. In fact, the study found that there is less than a 1% chance that natural variability is the sole cause of the increase.

The researchers looked at data from satellite observations to determine the amount of energy received by the earth and the amount reflected and emitted by the Earth. In a balanced physical system, the amount of incoming energy should equal the amount of outgoing energy. But the earth’s system is not balanced at this point. More energy is coming in than going out, which is driving changes in the climate system. There have been other studies looking at the human influence on the climate, but this new study is the first to examine a 20-year continuous satellite energy balance record to see if natural fluctuations in the climate system or human activities is the primary driver for the significant change in the planet’s energy balance.

The study examined 50 different climate models to look at this energy balance under scenarios where there was no human influence. These include changes in the sun’s output, volcanic eruptions, variations in pollution aerosols, and more.

The results, to no great surprise, are that increasing greenhouse gases over the last twenty years is by far the most important driver for the energy imbalance. This imbalance is what is driving rising temperatures, increasing sea levels, and causing other climate changes.

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Human activities responsible for rapid increase in Earth’s heat

Photo, posted May 6, 2021, courtesy of Marlis Borger via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Hudson River Tidal Marshes And Sea Level Rise | Earth Wise

January 29, 2021 By EarthWise Leave a Comment

A new study at the University of Massachusetts Amherst looked at the resilience of Hudson River Estuary marshes to rising sea levels. They observed that these marshes are growing upward at a rate two or three times faster than sea level rise, suggesting that they should be resilient to accelerated sea level rise in the future.

The study documented the fact that more than half of Hudson River tidal marshes actually formed since 1850. In that year, the river channel was straightened, and a riverside railroad, berms, jetties and human-made islands of dredged soil were built. All of these human-made features trapped sediment and created backwaters that often turned into marshes.

The research centered on seven sites spanning more than 100 miles of the Hudson Estuary from Wall Street up to Albany. Although these marshes were an unintended result of early industrial development, they serve to protect the shoreline and provide rich ecosystems in terms of direct ecological and human benefits. Marshes are a first line of defense against coastal flooding, provide an essential habitat for juvenile commercial fish species, store huge amounts of carbon that mitigates climate change, provide habitat for migratory birds, and filter nutrients coming off the land.

The study determined that such marches form relatively quickly. When sediment is readily available, freshwater tidal wetlands can develop rapidly in sheltered settings. There is concern that marshes globally will be drowned by rising sea levels, but this Hudson River case study shows how marshes may be able to resist the rising seas. The research will help guide future land acquisition and land conservation strategies for areas adjacent to the river.

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New Study Finds More than Half of Hudson River Tidal Marshes were Created Accidentally by Humans; Resilient Against Sea Level Rise

Photo, posted December 4, 2008, courtesy of Daina Dajevskis via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Caspian Sea And Climate Change | Earth Wise

January 22, 2021 By EarthWise Leave a Comment

According to the National Oceanic and Atmospheric Administration, global sea levels have been rising over the past century, and the rate has increased in recent decades. Sea levels are currently rising about one-eighth of an inch every year.

Sea level rise is caused primarily by two factors related to climate change: the added water from melting glaciers and ice sheets, and the expansion of seawater as it warms. While climate change is causing global sea levels to rise, higher temperatures in other regions are having exactly the opposite effect. The water levels are falling.

According to researchers from the University of Bremen in Germany, the Caspian Sea is a perfect example of how a body of water will change. While it is named a sea due to its size and high salinity, the Caspian Sea is actually a lake. In fact, it’s the largest lake in the world. Its largest inflow is the Volga River and it has no natural connection to the ocean. Its water level is determined by the proportional influences of inflow, precipitation, and evaporation. Climate change is causing increased evaporation, which leads to a declining water level.

According to the research team, the water level of the Caspian Sea could fall by 29 to 59 feet during this century.

The Caspian Sea is surrounded by Kazakhstan, Turkmenistan, Iran, Azerbaijan and Russia. It’s an important regional water reservoir, and a biological and commercial center.

The researchers hope the Caspian Sea will be used as an example in scientific research to assess the vulnerability of other regions to falling water levels.

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Climate crisis is causing lakes to shrink

Photo, posted October 31, 2016, courtesy of Amanderson2 via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Record Siberian Heat | Earth Wise

July 24, 2020 By EarthWise Leave a Comment

Siberia has been experiencing unprecedented high temperatures in recent months. May was the hottest May on record and temperatures in Siberia have stayed well above average for the past year.

On June 20, temperatures in the small Siberian town of Verkhoyansk hit 100.4 degrees Fahrenheit, which is a record-high temperature in one of the fastest-warming places in the world. Average high temperatures in June reach 68 degrees. Verkhoyansk sits on the Yana River in the Arctic Circle and, during the winter, is one of the world’s coldest towns. In 1892, its temperature dropped to -90 degrees Fahrenheit. And now there is hundred-degree heat above the Arctic Circle.

Siberia tends to experience large temperature swings month-to-month and year-to year. But it is very unusual for temperatures to stay well over average over an extended period of time as they have for the past year. According to climate scientists, the kind of temperature swings seen recently would only happen once in 100,000 years if it were not for climate change.

Siberia has seen raging wildfires and structural damage from thawing permafrost as its temperatures have stayed warmer than normal. The prolonged Siberian heatwave is an alarming situation.

The Arctic is warming twice as fast as the rest of the Earth because of a process known as Arctic amplification. The acceleration of the Arctic ice melt leads to a seasonal snow cover that isn’t as white. It therefore absorbs more sunlight, which then leads to more warming.

The amplified warming of the Arctic with its increased melting of ice leads to higher sea levels, and not just in the Arctic Ocean. With less Arctic ice to reflect sunlight, the world’s oceans continue to warm.

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Temperatures in an Arctic Siberian town hit 100 degrees, a new high

Photo, posted December 7, 2014, courtesy of Olga Dudenko via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The State Of The Climate

September 19, 2019 By EarthWise Leave a Comment

The federal government has issued the annual State of the Climate report and it is a sobering one. The report states that carbon dioxide in the atmosphere rose to levels the world has not seen in at least 800,000 years. Global carbon dioxide concentrations reached a record 407.4 parts per million during 2018. That is 2.4 ppm more than 2017.

Other greenhouse gases like methane and nitrous oxide also continued their rapid increase. Taken together, the global warming power of greenhouse gases was 43% stronger than it was in 1990.

Along with greenhouse gases, global sea levels also reached their highest levels on record for the seventh consecutive year. Ocean levels are rising about an inch per decade, but that number may rise if ice melt at the poles continues to accelerate.

Global temperatures had their fourth highest level on record in 2018, slightly lagging 2016, 2015, and 2017 for the highest ever. A La Niña over the Pacific cooled ocean waters for part of 2018, keeping temperatures a bit lower. So far, 2019 is on track to be the warmest year in recorded history.

Global sea temperatures also set a record level in 2018. And glaciers continued to melt at an alarming rate for the 30th consecutive year.

The State of the Climate report is yet another in a series of expert, science-based reports that continue to sound the alarm about the climate crisis. Climate change is affecting our weather, agricultural productivity, water supply, public health and national security. Unfortunately, the facts continue to be drowned out for many people by blogs, pundits, and posts on social media.

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Greenhouse Gases Reach Unprecedented Level

Photo, posted January 13, 2014, courtesy of Ronnie Robertson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

High-Tide Flooding And Pollution

April 30, 2019 By EarthWise Leave a Comment

Global sea levels are steadily rising. They are up 8 inches in the past century and now increasing at an average of 1.3 inches per decade. As a result, the incidence of high-tide “sunny day” flooding is on the rise, especially along the U.S. East Coast.

Norfolk Virginia experienced fewer than 2 days of high-tide flooding a year in the 1960s; it had 14 in 2017. Up and down the East Coast, flood days have increased by factors of 5 and more.

This has led to a form of pollution that hasn’t gathered much attention in the past: when these floodwaters recede, they can carry debris, toxic pollutants and excess nutrients into rivers, bays, and oceans.

In the aftermath of high-tide flooding in Norfolk, Chesapeake Bay was littered with tipped-over garbage cans, tossed-away hamburgers, oil, dirty diapers, pet waste and all manner of other things. Water that comes up on the landscape takes everything back into the river or ocean with it.

Analysis of tidal flooding along the Lafayette River in Norfolk indicated that just one morning of tidal flooding poured nearly the entire EPA annual allocation of nitrogen runoff for the river – nearly 2,000 pounds – into Chesapeake Bay. The effects of excess nitrogen in the water are well-known and responsible for the toxic algal blooms that endanger aquatic life as well as human health.

According to the National Oceanic and Atmospheric Administration, high-tide flooding frequency along the southeastern coast of the U.S. rose 160% since 2000. With the expected continuing rises in sea level, NOAA projects that as many as 85 days of high-tide flooding will occur along the coast by the year 2050. It’s a big problem.

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As High-Tide Flooding Worsens, More Pollution Is Washing to the Sea

Photo, posted September 20, 2018, courtesy of SC National Guard via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

More Antarctic Warming

April 23, 2019 By EarthWise Leave a Comment

East Antarctica is the coldest place on Earth. It makes up two-thirds of the continent, is home to the South Pole, and has vast ice sheets that have been around for tens of millions of years and are nearly three miles thick in places. Temperatures there hover around 67 degrees below zero. In 2010, a few spots on East Antarctica’s polar plateau reached a record-breaking 144 degrees below zero.

But almost unbelievably, parts of the East Antarctic seem to be melting.

Scientists are seeing worrying signs of ice loss in the East Antarctic. Glaciers are starting to move more quickly and are dumping their ice into the Southern Ocean. Satellite images show the fast-moving ice. The biggest glacier – the Totten Glacier – alone contains enough ice to raise global sea levels by over 12 feet.

The Antarctic as a whole contains about 90% of the planet’s ice. In theory, if it all melted, it would raise global sea levels by an average of 200 feet.

The growing concerns about eastern Antarctica are not that its interior plateau will soon start to melt. It is still extremely cold there and should stay that way for a long time. But its edges, which are in contact with warming ocean waters, are the real worry. As the region’s ice shelves, which float atop the Southern Ocean, erode, the vast glaciers behind them could rapidly accelerate their slide into the sea.

Today, satellites show huge glaciers moving rapidly toward the coast, with wide rivers of ice sometimes moving several miles a year. In the face of rapid change and limited data, it is difficult to predict what the Antarctic will do in the future. But it doesn’t look good.

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Polar Warning: Even Antarctica’s Coldest Region Is Starting to Melt

Photo, posted January 3, 2013, courtesy of Christopher Michel via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Ice Melt In Greenland

March 12, 2019 By EarthWise 1 Comment

A new study published in the Proceedings of the National Academy of Sciences warns that Greenland’s ice Is melting much faster than previously thought. The ice loss rapidly accelerated around 2002-2003 and by 2012 the annual loss was nearly four times the rate in 2003.

Most of the new ice melt is in southwest Greenland, a part of the island that wasn’t known to be losing ice that rapidly and is not where most of the large glaciers are in Greenland. The loss is coming from the land-fast ice sheet itself.

Data from NASA satellites and GPS stations scattered around Greenland’s coast shows that between 2002 and 2016, Greenland lost approximately 280 billion tons of ice per year. That is enough melt to cover the entire states of Florida and New York hip deep in meltwater, as well as drowning Washington, D.C. and one or two other small states.

Global warming of just 1 degree Celsius is the main driver behind this massive meltdown of ice. The temperature rise coupled with a negative phase of the North Atlantic Oscillation causes rapid surface melt of the ice sheet during summers. The Oscillation is a natural, irregular change in atmospheric pressure that brings warm, sunny weather to the western side of Greenland during its negative phase.

The Greenland ice sheet is 2 miles thick in some places and contains enough ice to raise sea levels 23 feet if it all melted. The melting Greenland ice is already slowing the Gulf Stream, which is wreaking havoc with European weather. If we don’t get a handle on global temperature rise, things are only going to get worse.

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Greenland’s ice is melting four times faster than thought—what it means

Photo, posted April 21, 2017, courtesy of Markus Trienke via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Melting Ice In Greenland

January 18, 2019 By EarthWise Leave a Comment

The Greenland ice sheet is the second largest ice body in the world after the Antarctic ice sheet. It covers over 660,000 square miles, more than twice the size of the state of Texas. But it is melting.

According to a new study published in the journal Nature, the Greenland ice sheet is melting faster today than at any point in the last 350 years. A team of U.S. and European researchers analyzed more than three centuries of melt patterns in ice cores from western Greenland. They then linked this historical data to modern observations of melting and runoff across the entire ice sheet.

According to the researchers, from an historical perspective, today’smelt rates are off the charts. There is a 50% increase in total ice sheet melt water runoff since the start of the industrial era and a 30% increase since the 20th century alone.

Over the last 20 years, melt intensity has increased 250 to 575 percent compared to pre-industrial melt rates. The period from 2004-2013, the most recent decade analyzed, experienced a more sustained and greater magnitude of melt than in any previous 10-year period in the 350-year record.

The Greenland ice sheet is the largest single contributor to global sea level rise. It is adding 72 cubic miles of meltwater to the world’s oceans every year.

The melting of the Greenland ice sheet is accelerating which is a frightening prospect. If the sheet were to melt in its entirety, global sea levels would rise by 23 feet. The world needs to do whatever it can to keep that doomsday scenario from happening.

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