We are learning that a warming world means a wetter world. On a planet that is three-quarters covered with liquid water, this should come as no surprise. Call it the Bathtub Effect. Warm up the bathwater and more moisture condenses on the cool walls of the bathroom: drip, drip, drip. Warm up the world's oceans and more moisture enters the atmosphere: rain, snow, rain, snow. Heating of the global atmosphere and oceans by the increased insulative effect of CO2 emissions has increased atmospheric humidity by 4% on average since 1980. That may not sound like much, but it translates into many more rainstorms, snowstorms, hurricanes, tornados, and El Ninos. This is set to continue for a long time, as the amount of heat that has been trapped by the earth's atmosphere”that is, absorbed from the sun, but not re-radiated into space”is about twice the amount that has shown up as measurable effects. The rest is a staggering amount of latent heat in the atmosphere, oceans, and icecaps. It is estimated that feedback loops from the melting of icecaps (reducing albedo or reflectivity) and permafrost (releasing long trapped methane) will double the heating effects of the energy already received. This means that four times the amount of energy already showing itself will ultimately be registered as effects on the world's weather and environment. And that is if carbon levels in the atmosphere were to be stabilized today. Since we are still riding the CO2 roller coaster up, 392 ppm and counting, the downside is going to be even bigger.
Let us try to bring this Bathtub Effect into a little clearer focus. The monsoon which waters the Indian subcontinent operates in much the same way as global heating and storming. Warm, moist air rising from the Indian Ocean is drawn inland and northward over peninsular India by the rapid heating of the Eurasian land mass during the Northern Hemisphere summer. Land both heats and cools more rapidly than water, which is why there is as much change in temperature from day to night in Santa Fe, New Mexico, high in the desert, as there is from summer to winter in San Francisco, a city at sea level and surrounded on three sides by water. Tropical island dwellers know this too, because daytime heating pulls a breeze off the ocean which reverses in the early evening as cooler air over the land is drawn offshore by the warmer sea. Warmer land temperatures caused by increased CO, levels in the atmosphere will draw more moisture inland from warmer oceans, and rain and snowfall will increase, at least in areas near coasts or affected by oceanic wind patterns.
Flooded streets are increasingly familiar around the globe. Photo Keith Johnson.
This past summer, temperatures soared, not only in North America, but over large parts of Asia. Fires burnt across much of the Russian Federation as Moscow blasted through its previous record high temperature of 99°F / 37°C to hit 111°F / 44°C. Pakistan set an all Asia, all-time record of 129°F / 54°C. The seasonal melting of snow from the Himalayas and the Hindu Kush, combined with the apocalyptic melting of glaciers already underway for several decades, all compounded by an extra strong monsoon, or "chimney" effect drawing moisture from the ocean, led to catastrophic flooding in Pakistan for months. A fifth of the country was underwater for many weeks. Eleven million people were displaced from their homes, infrastructure was devastated, and cholera broke out in a number of areas.
In the same way, global storming is going to bring deluges to many areas around the world, but leave others high and dry. Remember that Russia is in the rain shadow of high mountains across virtually its whole southern border: the Caucasus, the Erebrus Mountains in Iran, the Hindu Kush, the Himalayas, the Pamirs, and others farther north. Because of the collision of plates and folding of the earth that is occurring in this region, almost all of its mountain ranges run east and west, intercepting the southerly, moisture-laden rains from the tropical Indian Ocean. Russian weather generated much of the heat that drew in the rains over Pakistan, but Russia didn't benefit from the moisture. So it will be with many mid-continental areas: engines of greater rainfall and storming, they will see less moisture themselves.
The increased risk of flooding is not just from more rainfall and glacial melt, but also from storm-related tidal surges and more. This spring, the world was transfixed as an unprecedented earthquake of magnitude 9.0 off the northeast coast of Japan launched a deadly tsunami, killing more than 20,000 people within minutes, and setting off a cascade of disastrous events at a nuclear plant on the coast of Fukushima prefecture. As the third magnitude 9 quake in seven years and the second in 12 months, the Japan earthquake has heightened speculation that increasing sea levels, also brought about by global heating, are ramping up seismic activity. (The Indian Ocean tsunami of December 2004 was driven by a massive quake off the coast of Sumatra; the 2010 quake along the Chilean coast was of comparable magnitude.) With justifiable fears for their densely developed coastline and the real risks of tsunami all along the seismically active island chain, the Japanese built what has become perhaps the world's most deadly gold brick in the form of their vast array of concrete sea walls, none of which protected anyone when "the big one" struck. Of particular relevance though, is the illusion of safety that the walls created, which seems to have induced the Tokyo Electric Power Company, operator of the Fukushima reactors, to place its diesel back-up generators and their fuel supplies”utterly critical to the continued safe operation of the plant in the event of massive grid failure”at ground level. They went underwater. The fires, explosions, and radiation releases, and the open-ended drama of regaining or losing control of the nuclear genie were all set in place by this and compounding acts of hubris: the seawalls won't be breached; the back-up systems can cool the reactors and the fuel rods, the containment vessels will hold; the containment vessels were 'perfectly adequate' and 'cheaper to build'; putting the spent fuel rods in pools on top of the reactors saves space, and we can always spray them with water...and anyway, nothing bad can happen to us. . .can it?
Five and a half years ago, the narrative was all about storm surge, faulty levees, and river flooding in New Orleans and along the Gulf Coast. In other recent years, the pictures from Bangladesh have shown a country under water. Quietly in the background of world events, the residents of the Chatham Islands in the south Pacific have negotiated a permanent retreat to New Zealand, as their former homeland slides under the waves. As the world heats up, rainfall increases, and sea levels continue to rise, we will see flooding more and more take center stage as society attempts to cope with the effects of technological overreach. Just because it is possible to boil water with the heat of a nuclear reaction does not mean we should do so. Just because it is possible to contain a nuclear reaction does not mean we will always be able to do so. Just because there's more oil underground doesn't mean we should pump it out and burn it.
My own foretaste of warmer-means-wetter came six years ago when I experienced first-hand the effect of three hurricanes in three weeks. Then living in western North Carolina in a rural ecovillage, I wrote about that local disaster in the pages of issue #54 of this magazine, contrasting rural and urban preparedness, and noting the distinctive patterns of the various storms, one generating enormous rainfall (Francis), another unexpected wind damage (Ivan). The city of Asheville, home to about 60,000 people, had no nuclear disaster then, but it saw its own ugly cascade of effects from intense and sudden flooding, as chemical dumps and oil tanks along the Swannanoa River ruptured and flowed into the Tennessee River watershed, source of drinking water for a million people. Electrical and public water systems failed as a result of the storms. Attempts to preserve the city's main reservoir led directly to destruction of the supply system itself. The Asheville flooding, from Hurricanes Francis, Ivan, and Jean, happened a year before Katrina struck the Gulf Coast, and it was really a minor footnote in the long march toward a brave new world, but the lessons that it delivered and that I attempted to summarize then, are no less relevant today.
More than cars are in the floodwaters. Photo: Keith Johnson
Why floods kill
Historically, floods have been the most devastating of natural disasters, killing more people and causing more damage than fire, earthquake, tornadoes, and volcanic eruptions combined. This comes about because of five interactive factors:
1. River valleys and seacoasts have been the site of civilizational growth since the end of the Neolithic era. Populations are dense along fertile alluvial floodplains and coasts. About 50% of humanity lives within 50 miles of the ocean. In many coastal regions there is little high ground, so that almost everything goes under water during floods. Almost by definition, the richest land is the flattest and, ironically, the most vulnerable to the deadliest of disasters. Two of the world's most densely settled regions” Holland and Bangladesh, both river deltas and each with over 1,000 persons per square mile, are located at or below sea level.
2. Agriculture and urbanization increase runoff dramatically compared to native (mostly forested) landscapes. The channelization of rivers for barge transport and dikes and levees built against flood both exacerbate flooding by reducing the stream's natural capacity to absorb the shock of high flows.
3. Key infrastructure, public buildings, ports and depots, road and rail lines, power plants, water and sewer systems, is located close to creeks, rivers, and seacoasts for reasons of enduring practicality. When floods hit, the loss of support systems creates chaos and throws people back on limited personal resources. Everything becomes much, much harder. Escape routes also become blocked, so that people fleeing the rising waters become trapped and sometimes drown.
4. Flood seizes everything loose and distributes it widely. In particular, water spreads disease organisms by moving manure, nightsoil, and sewage out of confined areas. In the modern era, the leakage of industrial pollutants can be added to this list. Rodent populations are disturbed and begin to proliferate among the rubble and debris. This creates conditions for the rapid spread of infectious diseases.
5. Drinking water supplies are disrupted or contaminated, while medical and emergency services are encumbered. In the 2008 flooding that inundated parts of central Indiana, among the first casualties in the city of Columbus, east of where I live, was the hospital, rendered inoperable by rising floodwaters that filled its basement and ground floors.
Portent of things to come
To this list of five human-implicated factors in flood damage, we most assuredly can add a 21st-century sixth: global storming. Climate change brought about by the burning of fossil fuels and by deforestation has increased both the speed and volume of the hydrologic cycle worldwide. Warmer atmospheres and sea temperatures are resulting in more tropical storms, as evidenced by the increase in superstorms, the lengthening of the hurricane and typhoon seasons, and the spread of severe storms to new areas. Brazil recorded its first ever hurricane-force storm off the South Atlantic in 2004. Typhoon flooding racked Burma last year and tens of thousands may have died. Rainfall increases overall. Distribution becomes more erratic, bringing drought to many areas, but this results in more intense rain events, hence more flooding. This does not bode well for the global economy, already staggering under debt load and resource shortages. The year 2011, not half over, stands to present the insurance industry with its heaviest losses ever, and there is no end in sight to this trend. Annual loss payouts are up ten-fold in the past 25 years. Individuals and businesses ultimately pay these costs, which drag against other pressing needs.
Heavy weather poses unexpected problems beyond excessive rain. Wind directions can be very erratic. Ivan the Terrible, a category 5 hurricane that crossed northern Florida, Alabama, and Georgia in 2004 before it washed itself out over the Carolinas, showed sustained winds over 200 mph as it struck Cuba a glancing blow on the way north. Five hundred miles inland Ivan still had enough wind force to fell 100-year old trees, blocking roads and bringing down power lines over western North Carolina. In our small village, several people came within a few feet of being crushed in their sleep as giant trees fell. The weather service reported that storm was the sixth most powerful hurricane ever to originate in the Atlantic. Hurricane Mitch, which killed nearly 20,000 in Nicaragua and Honduras in 1998 (one of the hottest years on record) was of the same caliber. So was Hurricane Katrina in 2005 as it moved inland over the Louisiana marshes.
Ivan's effects were particularly destructive because it brought high winds unexpectedly out of the southeast. In the northern hemisphere hurricanes and typhoons circulate in a counter-clockwise direction. The opposite is true south of the Equator. That means that hurricanes hitting the southeast US coast lead with northeasterly winds, and storms crossing the Gulf Coast between East Texas and Florida (as Ivan did) can carry fierce southeasterlies. This is just the reverse of prevailing winter storms so it complicates the problem of design for wind protection.
What can we do about it?
Design for flood protection should focus on minimizing damage. The watchwords are knowledge and preparation. The first and most important defense is information. Maps of the floodplain are essential tools for cataloguing risk and avoiding Type I errors in building placement. When the North Carolina legislature authorized $41 million to update floodplain maps in the state following Hurricane Floyd in 1999, it neglected to ensure that this money was distributed statewide. None of it reached the mountain counties, which were imagined to be at little risk. In 2004, we learned that risk was everywhere.
Knowing what areas will flood when enough rain falls allows you not only to avoid placing buildings there, but tells you what should be removed. Chemicals, fuels, and biocides don't mix well with flood waters. Neither do nuclear fuel rods and reactors. Be sure to secure these substances out of harm's way. It may not be easy to relocate nuclear plants away from the seacoast, but we should make efforts to decommission and remove radioactive material from those that are already there, and avoid building any more.
Healthy streams have associated wetlands, meanders, and ample flood plains to help them absorb high water flows. We have to resist the development pressures to channelize streams or to usurp these areas for inappropriate purposes. Planting crops in a flood plain is a relatively harmless ephemeral activity (though lowland forests might be more ecologically sound). So too are parks and sports playing fields, but garbage dumps in flood-prone areas, for example, pose unnecessary risks to public health.
Know what lies upstream and uphill of you and what may be brought down by heavy runoff. If you live downstream from a large body of impounded water, it's in your interest to know whether that dam is sound and if there is a proper spillway to protect it. (see PCA #52, Max Lindegger on dams)
If you live in a flood-prone area, plan an evacuation route to higher ground, and be prepared to activate it early. Remember that crossing roads. or streams already in flood is a bad idea. You or your vehicle could easily be swept away. Even a foot of rapidly flowing water has enough force to knock you off your feet, especially if the surface below is irregular. If you are caught by floodwaters in a vehicle, get out of it as quickly as possible.
Inland areas subject to flooding face one set of risks, most of which can be foreseen (and thus planned for) because of the relatively predictable way high water will interact with landforms. The greatest impact of floods is typically first to property, and secondly to health due to loss of services and the spread of disease. Drowning is usually limited to cases of panic or poor judgment, except in the case of tsunami. Unless floodwaters are constricted”as in narrow mountain valleys, amplified by dam failure, or arrive downstream with little warning (as in some desert areas), there is usually time for people to seek shelter on higher ground. Due to artificial engineering of the shipping channel, residents of the lower Mississippi Valley face compound risks from levee failure, which can direct huge, abrupt flows in unexpected directions. This can be compounded by sabotage, either local or national in origin, as it was below New Orleans in the great spring flood of 1927, and may be again under extreme duress. Relieving the river's raging flood at someone else's expense is only a few handfuls of dynamite away, an easy temptation for desperate people thrown into a kind of alluvial arms race of terror.
When winds compound flood
Coastal areas subject to tropical storms experience not only the problems of flooding, but of storm surge and particularly of high winds. Coastlines, even more than main river valleys, are heavily populated. This compounds the problem of evacuation. Hurricane-force winds (over 70 mph) are sufficient to lift a person off his feet, but the greater danger is from wind-borne objects. Metal roofing torn loose can be especially dangerous as it sails with great velocity and can strike with potentially lethal impact. Even where codes do not yet require it, hurricane strapping to secure the roof to the house frame is a good idea.
The danger from high winds is what leads public officials and anxious residents to evacuate coastal areas. Don't let complacency undermine your safety. In 1992, Hurricane Andrew was a wake-up call for Florida but the point was driven home even harder in 2004 when Charlie and Francis laid waste to the state in quick succession. Many attempted to flee, but fuel and food supplies quickly ran out and evacuation from the long peninsula became impossible for millions.
Coastal areas are more prone to floods as well as wind damage. Photo: Keith Johnson
Preparation is essential. There is no time in the midst of a catastrophe to gather supplies, practice rescue techniques, or find misplaced tools. Are you ready for storms, floods, power outages, or worse? The conditions are ripe for all these events to become more frequent. Florida may now be alert to the hazards, but areas which periodically but infrequently experience hurricanes, such as the Southern Appalachians and New England, are perhaps even more vulnerable because preparations there may be weaker. The human tendency is to dismiss what has not been recently in mind. All areas within 500 miles of the coast between the Rio Grande and Nova Scotia are at risk. The current pattern appears to move storm tracks farther west as the season advances. With longer storm seasons (beginning in July and continuing through November, more hurricanes are likely to make landfall on the US).
Know your weak points and be prepared to address them as soon as a storm threatens. Should vehicles be moved? Do loose tools or machinery need to be secured? Are water lines and critical infrastructure at risk? Are firefighting, construction and demolition tools, and emergency supplies ready at hand? After Francis disrupted infrastructure at Earthaven Ecovillage, which was built off-grid in steep mountain valleys of western North Carolina, village workers spent the days leading up to Ivan clearing logjams from the creeks so that they would stay in their channels, securing water lines to higher ground, preparing flood overflow channels, and protecting bridge abutments. It paid off. Though water levels weren't as high because overall rain was less with Ivan (5.5 inches in one day against 11.5 inches from Francis in two), there was no flood-related damage at all from the second storm. We did learn how vulnerable the community was to tall trees near houses, standing dead snags near trails, and similar potential wind hazards, all of which windy Ivan threw in our faces!
Protecting water supplies is the other chief concern in the face of flood. Centralized systems are wonderfully convenient, but also vulnerable. Distributed storage, as from roof catchment, will make any community more resilient against catastrophe. The ordinary household without a large tank could still mitigate the worst outcomes by keeping a supply of bottled water in the house (maybe not in the basement...). Five to ten gallons per person should be on hand at all. times. Another strategy for preparing against loss of water supply is to rig up one or more rain barrels under the downspouts to provide basic water for washing. This is fast and simple, and by making 50-100 gallons of water immediately available for household sanitation, can do much to make life during a emergency less stressful. In my experience, the permaculture ethic of self-reliance lays a good foundation for response to catastrophe. By creating local systems of power generation, water and food supply, and the capacity to manage basic infrastructure, our household has learned to do for ourselves what must be done for city dwellers by experts.
The other pillar of strength against adversity is community. In 2004, our village's many-layered and rich connections with each other came dramatically to the fore in the face of the common challenge of flooding and storms. In an admirable display of solidarity and compassion, the Japanese nation has organized itself to provide care and relief for all its members. All human communities have this latent capacity to one degree or another, but knowing in advance whom to call and how to reach one's neighbors can make a critical difference in times of crisis, when ordinary civil resources are unavailable. It is up to each of us to assess our situation and take the necessary steps to bolster collective security. Our well-being is always dependent to some degree on the health and safety of others around us, but in the event of natural disaster this bedrock of society is exposed for all to see.