Impact on Life at the Coast and Inland
Researchers at ETH Zurich scoured satellite images from the last 20 years and recently reported the planet is losing 267 gigatonnes of ice each year from its glaciers. The rate of loss has accelerated from 227 gigatonnes per year in the early 2000s to 298 gigatonnes per year by 2019. Cynics point out we are simply gaining more freshwater as the ice melts. This statement only seems true when we fail to understand that freshwater rivers run to the sea where the water translates into higher sea levels — more saltwater, not more freshwater.
A recent Smithsonian report placed yearly ice loss at about a trillion tonnes (1000 gigatonnes). Remember, this number includes both the world’s glaciers and the ice caps of Antarctica and Greenland, where about 99 percent of all the earth’s ice is stored.
Questions about what this means are germane to understanding climate change, but first, let’s take a step backward and look at the numbers. Freshwater accounts for only 2.5% of the earth’s water supply. The rest is saltwater. If we further divide up the world’s freshwater, we find that 68.7% is frozen into glaciers and ice caps, 30.1% is groundwater, and the small remaining fraction of 1.2% is at or near the earth’s surface or in the atmosphere. Only 0.006% is in rivers and streams.
Another set of boring calculations reveals how every year we lose an amount of ice only slightly less than all the water in the planet’s rivers. It would take about 24,000 years to melt all of the world’s ice at the current melt rate. While this lengthy period may initially provide the reader with a sigh of relief, we haven’t actually accounted for acceleration. As the climate warms, the rate of ice melt increases. The Smithsonian report indicates that the rate of ice melt has increased by about 60 percent in the past 25 years. Add in this acceleration rate and the earth’s ice, all 24,064,000 gigatonnes, melts in about 270 years.
Yes, this number is just a raw calculation based on current acceleration rates, and it is at odds with other estimates that place the melt time closer to 5000 years (National Geographic). In between these two estimates, we have melt-rate evidence from the end of the last ice age when sea levels rose by about 25 meters in 500 years. So even without the assistance of humans stoking the warming cycle, full ice melt could occur in 1400 years. The real answer to this Anthropocene conundrum is, “We don’t know how long full ice melt will take.” What we do know is that melting ice is a two-edged sword, cutting those living at sea level and many of their fellow humans living far from the ocean.
On the Beach Front
The clear and most frequently mentioned losers from the coming years of massive ice melt are those who enjoy their ocean views at eye level and not from atop cliffs or hills. They reside at sea level or even below, living in farms, rural towns, and coastal metropolises. Of course, the vast majority of unfortunate souls in this category live in the world’s coastal metropolitan areas. Jakarta may be the poster child for early submergence below the sea.
Indonesia’s massive capital, Jakarta, is situated on the northwest end of the elongated island of Java. Its metro-area population includes 33 million people living at an average elevation of eight meters above sea level. But averages are deceiving since they simply even out the highs and lows. Currently, about 40 percent of Jakarta is below sea level.
Jakarta has the unwanted distinction of suffering from two anthropogenic effects — the ocean is rising, and the land is falling.
Climate change is driving a sea-level rise in two ways, both related to rising temperatures. We have already touched on the first of these, melting ice from glaciers and ice caps. The second is from thermal expansion. Seawater, like most materials, expands as it heats up. Since the ocean basins have fixed boundaries, the only way the water can expand is by rising higher. According to NASA, 38 percent of sea-level rise is from thermal expansion, and the remaining 62 percent is from meltwater.
However, human beings tend to exacerbate their problems through the unintended consequences of collective ignorance or indifference. The second of Jakarta’s problems is again man-made. Not only are its residents contributing to increasing ice melt, but they are also working hard to lower ground levels across the city. This self-induced ground subsidence allows them to sink beneath the sea at a much faster rate than the rest of the world. This feat is accomplished by pumping out groundwater.
Under normal conditions, rainwater sinks into the ground and replenishes underground aquifers, so water pumped out for human use is replaced by new rainwater sinking into the ground. This healthy balance is disrupted when we pump out more water than the rain can replace. Water residing in the rock and soil beneath our feet takes up space, and it also provides some structural support. Pressure from the water pushes against grains of rock and clay, keeping the pore spaces open. When the water is removed, the structural support is lost, and rock grains collapse into the empty pore spaces. The space a cube of land takes up is a combination of rock, soil, and water. When the water is removed, the land volume decreases. It accomplishes this by subsiding.
Over-pumping of groundwater is a common problem around the world. In the United States, over pumping of the Ogallala aquifer in the midwestern farmlands of the country has caused ground subsidence. This part of the world is relatively dry, and the problem there is not enough annual rainfall to replenish the amount of water being removed. But Jakarta gets rain for about 300 days each year, and their problem is not a lack of rain.
Jakarta suffers from a concrete problem — there is too much of it. Rampant development has paved over so much of the city that rainwater cannot replenish the aquifers. Instead, the water runs off into the sea, further assisting the meltwater in moving sea levels higher.
Jakarta is only one of many cities at risk. A two-meter rise in sea level will displace some 187 million people. Florida, and Miami in particular, will be feeling the pinch of rising seas. Miami is perched a mere 2 meters above sea level. The recent voter suppression legislation passed by the Florida legislature may be rendered irrelevant if there are no voters to suppress.
Worldwide, approximately 600 million people live within 10 meters of sea level. They are probably the largest group of losers as ice melt accelerates. Of course, these changes won’t happen overnight via a biblical-scale flood. But the gradual encroachment of the seas will steadily take its toll in the form of massive population displacement and relocation. Perhaps in Miami, the wealthy will turn South Beach into an elevated luxury retreat only accessible by boat or helicopter. Tough luck for those living in cinderblock ranch homes.
Inland Trials and Tribulations
Melting glaciers also have an impact far from the coastline. Glaciers form a vital part of the water cycle in many areas of the world. High mountain glaciers, also called water towers, serve as storage tanks — collecting water during the winters in the form of ice, and releasing that water in warmer months as the ice melts. Ice melt in the hot, dry months forms the base flow of many rivers.
As the climate warms, two changes will impact the water towers. The first is, warmer winters will reduce the amount of snowpack accumulating each year. The second blow will come as warmer summers melt what ice remains. Initially, downstream cities and farms will not feel the effect of this increased melting, and perhaps hot seasons will bring more water than usual as melting accelerates. However, when the glacial water supplies become depleted, the dry season base-flow will reduce to a trickle. The Indus river, cutting along the border between India and Pakistan, is a prime example of how glacial melt issues may affect us.
Meltwater from glaciers of the Karakoram, Hindu Kush, and Himalayan ranges feeds the Indus river. From the mountain headlands, the river flows across the dry Indus plains, where it provides life to over 120 million people.
The Indus valley has harbored civilizations for more than 4000 years from when the Harappa culture thrived along its banks. But about 2500 years ago, shifts in seasonal rainfall forced a northward migration of the Harappa people as rains from summer monsoons dried up, severely impacting agriculture and food supply.
Today summer monsoons and meltwater cause the river level to spike during July and August, but the critical growing period during spring and early summer depends almost solely on snowmelt and stored water, often leaving the land parched by June. Without water, there is no life, and just as climate change forced human migrations in the past, it will probably do so again in the future as glaciers disappear.
The Indus Valley is not alone in its climate-change plight, and communities worldwide feel the squeeze as glaciers melt, snowpacks disappear, and the ensuing droughts cause us to rethink a path to the future. Droughts and megadroughts will create water shortages in many areas, while at the same time, rising sea levels will push too much water into coastal cities.
“Change is the only constant,” and the future will bring massive changes, challenging us to adapt or perish. Fortunately, adaptation skills form one of the strengths of the human species. All we need to do is overcome our natural tendency to ignore facts and evidence and bury our heads in the sand until disaster wreaks havoc. Proactive adaptation now is preferable to reactive, knee-jerk, future solutions that treat the symptoms and don’t address the cause.
References from my previous articles:
The Ogallala Aquifer, Sustaining Life (By William House; Medium)
Water and Megadroughts (By William House; Medium)
Read more about art, science, and the environment on ArcheanWeb
See my medium publications:
Environmental Articles on EarthSphere
Stories, Life Observations and more on Dropstone
Read my recent fictional adventure on the origins of life
Other Sources:
Global glacier retreat has accelerated (Source: ETH Zurich; Science Daily)
Earth Loses 1.2 Trillion Tons of Ice Per Year, a Nearly 60% Increase From 1994 (By Alex Fox; Smithsonian)
Ice, Snow, and Glaciers and the Water Cycle (Source: USGS)
Quick Facts on Ice Sheets (Source: NSIDC)
What Would the World Look Like if All the Ice Melted (Source: National Geographic)
Antarctic Ocean Reveals New Signs of Rapid Melt of Ancient Ice, Clues About Future Sea Level Rise (By Bob Berwyn; Inside Climate News)
Coasts Should Plan for 6.5 Feet Sea Level Rise by 2100 as Precaution, Experts Say (By Sabrina Shankman, Inside Climate News)
Understanding Sea Level (Source: NASA)
A watery onslaught from sea, sky and land in the world’s fastest-sinking city (By Johan Augustin; Mongabay)
Factsheet: People and Oceans (Source: The Ocean Conference)
Climate Change Likely Caused Migration, Demise of Ancient Indus Valley Civilization (Source: Woods Hole Oceanographic Institution)
Feature Image: Perito Moreno Glacier, in Los Glaciares National Park, southern Argentina (Modified by ArcheanWeb); Original Credit: By I, Luca Galuzzi, CC BY-SA 2.5, Wikimedia Commons
