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Preparing for a radically changed planet
Preparing for a radically changed planet
POSTED APRIL 21, 2021
The coming decades will see our planet affected more and more by global warming. Severe weather events will increase in frequency and intensity. Droughts will last longer, and coastal flooding will force permanent evacuations. Climate refugees will be added to today's war and hunger refugees.
Steps we take now to reduce greenhouse gas emissions will mitigate the effects of global warming, but the climate change flywheel is a slow one. Whatever changes we make today will take decades, perhaps centuries, to have an effect. Atmospheric CO2 is now 50% higher than in pre-industrial times and could hit 500 ppm in 30 years. Planet Earth has not seen that level in at least 3,000,000 years. As atmospheric CO2 rises, so does the average global temperature. The polar regions are especially hard hit and melting snow from glaciers increases the sea level.
If the CO2 remains at 500 ppm for many decades, our coastlines, indeed our world, would be unrecognizable. In the March Atlantic, Peter Brannen compares the today's southeastern United States to what was there 3 million years ago:
Our modern coastlines would have been so far underwater that you'd have to take great pains to avoid getting the bends if you tried scuba diving down to them. Today traveling east through Virginia, or North or South Carolina, or Georgia, midway through your drive you'll pass over a gentle 100 foot drop. This is the Orangeburg Scarp, a bluff - hundreds of miles long - that divides the broad flat coastal plain of the American Southeast...Here, waves of the Pliocene high seas chewed away at the middle of the Carolinas - an East Coast Big Sur.
Further in the past, 16 million years ago, with CO2 in the same 500 ppm range, Brannen writes:
...the planet appears truly exotic. The Amazon is running backwards, and gathers in great pools in the Andes. A seaway stretches from Western Europe to Kazakhstan and spills into the Indian Ocean. California's Central Valley is open ocean.
Computer models of the sea level in 2100 predict a rise between 1 and 8 feet above where it is today. Increasingly severe weather events and their associated storm surges will exacerbate the problem, and inland areas will be subjected to destruction previously seen only along the immediate coast.
We can prepare now for this radically changed planet. Engineering solutions and science-based actions are some of the best investments we can make as we adapt. Protecting infrastructure located near coastal areas from critical damage and protecting coastal communities from flooding are two high priority goals.
Infrastructure
Since the beginning of civilization, humans have built important infrastructure next to the sea, taking advantage of the access to ocean-going transportation. Many of the world’s largest cities are near the ocean, more than 600 million people live within 10 meters of sea level [1 and link right], and forty percent of the world's population - some 3 billion people - live within 100 kilometers (60 miles) of a coastline.
Protecting the coasts and the areas immediately inland is an obvious priority. Of particular concern is the infrastructure that is located near the coastlines - some examples:
Docks and ports, major components of international trade, are obviously at risk. One early forewarning of what might be expected are near Bothnian Bay in northern Finland, where one-time piers and boathouses lie stranded. Another is the ruins of the ancient Egyptian port of Heracleion, which can only be visited today by scuba divers. [1]
The Turkey Point Nuclear Generating Station near Miami is in danger of being permanently flooded. Built pretty much right at sea level circa 1972, by mid-century the Turkey Point site will be below the high tide line. [1] Power plants, particularly nuclear power plants, located on or near the coast are at risk. Sea level rise, combined with more intense hurricanes, increases this risk. "Flooding can disable the backup power supplies and other safety equipment needed to keep the hot and highly radioactive reactor cores and spent nuclear fuel pools from overheating and melting down...It can also disable the electrical distribution systems needed to deliver electricity through the plant. If flooding disables backup power supplies, then some equipment needed to cool the reactor and spent fuel, such as electrically powered pumps, would not be available.” [1]
Super Storm Sandy was one of the most damaging weather events in U.S. history. A 14-foot storm surge drowned parts of New York City’s subway system. Financial damages amounted to $71.4 billion, including power outages for 8.5 million people and 20,000 canceled airline flights. [2]
One surprising bit of infrastructure that’s vulnerable to sea level rise is the internet. Large parts of the worldwide communications system are located underwater—in the form of ocean-spanning submarine cables. Yet, those cables connect to stations on shore and those nodes, and the fiber-optic cables radiating from them are not so robust. Researchers looking at the combination of internet infrastructure density and vulnerability to sea level rise and found that the New York, Miami, and Seattle metropolitan areas were at risk not just of limited outages, but of losing internet connectivity altogether. [1]
The solutions for existing infrastructure come down to:
"Hardening" their defense - for example, by building higher seawalls and raising pier height
Shutting down particularly vulnerable sites
Whenever possible, relocating the infrastructure to a safe location.
Coastal Communities
Global warming and rising sea levels put communities near coastlines and those in flood zones along rivers at greater risk. In the United States alone, hundreds of coastal communities will soon face chronic, disruptive flooding that directly affects people's homes, lives, and properties, according to an analysis by the Union of Concerned Scientists. ""More than 300,000 of today's coastal homes, with a collective market value of about $117.5 billion today, are at risk of chronic inundation in 2045...By the end of the century, homes and commercial properties currently worth more than $1 trillion could be at risk." [3]
Seawalls have long been the "go-to" answer for protecting against the sea surge from storms, but there are other, better options. Environmental scientists and engineers have devised ways to prevent coastal flooding by sopping up water and limiting erosion and wave energy - including "living shorelines" and permeable pavement, which allows floodwaters to seep into the ground below rather than pool on the surface. [4 and right]
Creating a living shoreline might be as straightforward as restoring what once existed at the site — whether it’s oyster reefs, coral reefs, or other living breakwaters that dissipate wave energy. The newly protected shorelines become more stable over time as plants, roots, and reefs grow. Salt marshes and mangroves trap sediment and organic matter, allowing them to grow in elevation. That affords rising protection against inundation. Similarly, the growth in height of oyster reefs can outpace sea level rise, allowing them to continue protecting shorelines as sea levels continue to rise. [4]
As sea levels rise, the frequency and intensity of flooding along rivers will also increase. Preservation and restoration of wetlands can prevent flooding - not only near the coast but near rivers. Wetlands - swamps, marshes, fens and bogs - are natural water-storage features on the landscape. They provide essential wildlife habitat and act as massive natural water filters, and "natural sponges" that hold water when it rains, then release it slowly. Wetlands play a crucial role in preventing floods not only where rivers discharge into the ocean (such as the Mississippi Delta) but also in the headwaters and watershed, where they store water during heavy rains, slowing runoff into streams and reducing flood peaks. [5]
St. Stanislaus was a boy’s Catholic Boarding School over a hundred years old in Bay St. Louis, MS. Located on the beach overlooking the Gulf, it was destroyed by Hurricane Katrina. The picture below was taken before the building disintegrated. (EPA website)
Wetland remediation projects often require substantial restoration work. When removing impacted sediments, it is often necessary to remove the surrounding flora and vegetation. When the excavation is completed, the area must be restored so that it can once again become a vibrant habitat for native plants and animals. Carrying out this restoration requires treatment of invasive species, placement of clean sand and sediment, seeding and planting, and, when complete, continued maintenance and monitoring. [6]
The world is changing and we need to adapt. The projects to preserve infrastructure and reduce the destruction from flooding will require much capital and many years, but delaying them will lead to immensely greater costs in the future.
References: [1] American Society of Mechanical Engineers (ASME) [2] Scientific American [3] Union of Concerned Scientists [4] NBC News [5] The Why Files [6] JFBrennan.com
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