Human Dimensions of Global Warming



Adaptation Along the Coasts

Houseboats along a dock in the Netherlands
Houseboats in the Netherlands. The Dutch adapted to life at or below sea level centuries ago.

Although climate change impacts are readily apparent in most coastal zones and the peril posed by not taking action is great, adaptation is not underway in most places –– mostly because the cost of adaptation is enormous. Imagine how much money it would take to build a sea wall around New York, for instance. Still, the cost of damages without adaptation far outstrips the cost of these adaptation measures. It would cost perhaps hundreds of times more than the cost of a sea wall to repair New York’s subways, telecommunications networks, sewers, and water systems if they were flooded.

The costs of inaction are even greater than most economic analyses suggest. Many post-event costs are typically not counted when considering the economic impacts of climate change and the money expended or saved by adaptation. Moreover, the uninsured costs incurred by businesses and institutions through interruptions are seldom accounted for in financial calculations. Economic cost-benefit analyses of adaptation also never consider non-monetary costs, including such items as the psychological trauma incurred by individuals and families, or the losses to natural ecosystems that provide no visible economic returns. Returning to the New York example, adding the damages suffered by global financial markets and the individuals invested in those markets to the calculations makes a sea wall seem like a bargain in comparison. Add to those damages, the damages to the psychological suffering of the city’s residents, and it is clear, that given the inevitability of sea level rise, the cost of building a sea wall around New York would be much, much less than the cost of inaction.

In sum, most experts agree that continued human occupation of today’s low-lying coastal zones is not viable without adaptation. Those adaptations might involve building hard structures, like erecting sea walls, or they could involve changing land use, such as replacing the built environment with green space or agricultural land. In any case, the costs will be staggering, but adaptation will be cheaper than letting the impacts occur without adaptation.

Adaptation in Cities

Big Ben and London at night from the Thames River.
London, England.

The capacity for adaptation by cities is generally high. Even so, there are four things about cities and climate change adaptation that are important to consider. First, the prospects for adaptation depend on the rate and magnitude of climate change. All things being equal, rapid-onset, high-magnitude climate change makes adaptation more difficult than slow-onset, low-magnitude climate change. One exception to this rule is that the time with the most potential for taking strong adaptation measures is immediately after an extreme event. Decision-makers are much more likely to take action while the memory of an extreme event –– a hurricane, a flood, a disease outbreak –– is fresh. With time, these memories fade and day-to-day problems demand more attention than an event that “may never happen again,” thereby making it much less likely that decision-makers will invest in adaptation measures.

Image of Cape Town stadium
Cape Town, South Africa.

The second consideration is that a city’s climate change adaptation strategies do not occur in isolation. Instead, they are linked to other economic, political, technical, and social systems at scales ranging from local to regional, national, and global. For instance, if New York City were to attempt to adapt to sea level rise by building a sea wall around Manhattan, Staten, and Long Islands, there would be significant implications for the communities on Long Island and Manhattan that are not one of the five boroughs of the city, as well as for other areas of the metropolitan area in Connecticut, New Jersey, and New York. These local and intraregional implications might involve a host of issues, such as bonds and taxes (and therefore politics), infrastructure, transportation, and environmental justice. Because New York City is crucial to the nation and the world, repercussions of the decision to build the sea wall would undoubtedly spread beyond the immediate vicinity.

A third thing to consider is that climate change is only one of many risks that cities manage. Every day, cities make risk management decisions. For instance, a city might decide whether or not to ban automobiles (i.e., eliminate risk), build a levee (i.e., reduce risk), or buy more insurance (i.e., transfer risk). If the city decides not to ban automobiles, build the levee, or buy more insurance, it assumes the risk associated with each of those things. Finances, politics, and perceptions mediate a city’s risk management decisions, perhaps placing climate change adaptation at the head of the line or at the back of the line.

Finally, adaptation can have unintended consequences. For instance, if a coastal city were to build a dam upstream to prevent climate change-induced flooding, that dam could reduce downstream flow and enable the saltwater front to penetrate farther inland, fouling city water supplies. Increasing air conditioning to reduce heat stress could put added burden on a struggling energy-supply system and emit more greenhouse gases to the atmosphere. Full-cycle accounting must be an integral part of a city’s adaptation planning to avoid such inadvertent outcomes.