The Rising Cost of Natural Disasters
 

The wide and smooth Potomac River flows lazily past the marble and concrete structures of Washington, D.C., and bends south in its course to the Chesapeake Bay. Before it reaches Mount Vernon, the hillside plantation that once belonged to the first president of the United States, the river flows through tree-lined parks and forest that hides quiet suburban neighborhoods. Kirsten and Graham McCoulloch and their two young sons live in one such neighborhood, a full six blocks, a highway, and a riverside park away from the river’s edge. On September 18, 2003, the family was at home waiting for Hurricane Isabel to blow over when the word came to evacuate. “They told us, ‘Go fast because we don’t want you driving during the storm,’” recalls Kirsten. “The next day, we couldn’t get near our neighborhood.” Flood water had rushed up from the Potomac and pooled around their house. A neighbor swam to his house and returned in a canoe. “He told us, ‘It’s worse than you can imagine. The water is as deep as the kitchen counters,’” says Kirsten.

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  Satellite image of Hurricane Isabel approaching the East Coats

The McCoullochs knew that their home was in a floodplain, but it was a 100-year floodplain. There had been some flooding in the 1960s, but since then, a dyke system had been installed to keep the neighborhood dry. The couple did not think their home was in danger and, in fact, had been reassured by neighborhood rumors that the community’s floodplain status might be lifted. Graham returned to the house a few days after the hurricane struck to find debris—trash, tree branches, household items—strewn everywhere. “The smell alone was so awful you couldn’t get near the house,” says Kirsten. Sewage and grime had mixed with the flood water and splashed through the house. On top of that, mildew formed on the walls and the contents of the house. “Everything was black.”

 

As Hurricane Isabel moved inland from the Atlantic coast, it pushed a surge of water northwards into the Chesapeake Bay. The storm surge flooded many cities and towns on the shores of the bay and along its low-lying tributaries, including Alexandria, Virginia. (Image courtesy Jacques Descloitres, MODIS Rapid Response team)

  Photograph of flodded street in Alexandria, Virginia in the aftermath of hurricane Isabel

It was mid-May 2004 before the family could start to re-build and a full year before they returned to their home. Although the McCoullochs had flood insurance and qualified for assistance from the Federal Emergency Management Agency (FEMA), they still had to take out a loan to cover the cost of rebuilding. “The water was only three feet deep. The insurance agency only paid for that,” explains Kirsten. The damages to the house alone cost well over $50,000, and that didn't include the additional expenses of rebuilding their lives. They had to repair the walls where the water splashed above three feet, buy new household items, pay for temporary housing, and re-landscape the yard. They had lost nearly everything.

The McCoullochs aren’t the only ones staggering under the expense of cleaning up after natural disasters. Munich-Re, the world’s largest re-insurance agency, reports that disaster-related economic losses topped US $145 billion in 2004, up from $65 billion in 2003, for about the same number (650) of natural disasters in each year, making 2004 the most expensive year to date. While the loss of human life from the devastating Asian tsunami is overwhelming, the economic cost was an estimated $10 billion. The majority of the losses in 2004 were caused by weather-related events: a string of powerful hurricanes in the Atlantic, a record 10 typhoons in Japan, and flooding across the globe. Is the rising cost of natural disasters an anomaly or part of an alarming trend?

As recently as the 1950s, the average cost of catastrophic events was a mere $3.9 billion per year. The cost of natural disasters is increasing, and some companies like Munich-Re say climate change is partly to blame. Others say that human factors like population growth and land use have more to do with the rising costs. Global climate models do predict that a warmer climate could lead to higher sea levels and coastal flooding, more intense storms, deadly heat waves, and more extreme flood-drought cycles in the twenty-first century. But what about today? Has humanity already begun to bear the cost of climate change?

 

At the height of the flooding downtown Alexandria, Virginia, was inundated by as much as 6 feet of water. Residents were allowed back to their homes only after the water had subsided. (Photograph courtesy Federal Emergancey Management Agency Photo Library)

Graph of the global cost of natural disasters since 1950
 

“Don’t blame global warming yet,” warns William Patzert with an emphasis on yet. The Earth’s climate has always changed, and will continue to do so, explains the oceanographer and climatologist from NASA’s Jet Propulsion Laboratory. Global warming will likely impact natural disasters in the next 100 years, but Patzert isn’t convinced that the rising cost seen in the past few years can be directly attributed to climate change. “It’s a controversial topic. There’s not much hard evidence to demonstrate that natural disasters are any worse now than they were in the past,” he says. “The twentieth century was relatively benign in comparison to the past. We’ve had worse volcanic eruptions, more severe storms, worse drought [in the past]. What overwhelms us is population.”

 

Since 1950, the cost of natural disasters worldwide has increased dramatically. Is this increase the result of disasters increasing in frequency and severity, or is there another cause, such as the growing human population? (Graph by Robert Simmon, based on data courtesy EM-DAT: The OFDA/CRED International Disaster Database (www.em-dat.net) Université Catholique de Louvain—Brussels, Belgium)

 

The “Nature” of the Problem: Population and Natural Disasters

 

Between 1950 and 2003, the world’s population grew from an estimated 2.5 billion to 6.3 billion, according to the U.S. Census Bureau. More people are affected by natural disasters today because there are more people in the world to be affected. But beyond basic statistics, natural disasters may be getting more expensive because more people are building more expensive infrastructure in areas that are prone to natural disasters, like coastal areas, fire-prone forests, steep mountain slopes, and riverbanks. If disasters are having a greater impact today, says Patzert, the culprit is not Mother Nature, it’s human nature.

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Graph of population and gross world product since 1950
 

Human factors like population density and where we choose to live can certainly account for the rising cost of hurricanes. In a paper published in Weather and Forecasting in 1998, Roger Pielke, Jr. and Christopher Landsea analyzed the cost of hurricanes in the United States between 1925 and 1995. “With respect to hurricanes,” they concluded, “the clearest evidence that explains increases in losses is changes in society, not in climate fluctuations.”

Among these changes in society, “goods and machinery are more susceptible to damage,” says Mark Gryc, Vice President and Chief Engineer at FM Global, the world’s largest commercial and industrial property insurer. He notes that everything from greeting cards to manufacturing equipment is now equipped with delicate computer electronics that cannot be repaired as easily as the mechanical machinery of the past. Also, business has become more efficient, making downtime more expensive now than it was in the past. Finally, more people and businesses are located in hazardous areas. As Pielke and Landsea observed, more people lived in south Florida’s Miami-Dade and Broward counties in 1990 than in the entire 103 counties along the hurricane-prone Atlantic and Gulf coasts from Texas through Virginia in 1930.

 

The Earth’s population increased rapidly during the 20th century, exposing more people to natural hazards. During the same period the value of goods and services produced globally increased even more swiftly. So far, the growth of population and increased global wealth accounts for the increased costs of natural disasters. (Graphs by Robert Simmon, based on data provided by the U.S. Census Bureau (left) and the Worldwatch Institute (right).

  Map of percent change in the population density of Florida counties, 1930 to 2000  

From 1930 to 2000, the population of Broward County, Florida, increased from 20,000 to 1,600,000 (8,000 percent), while Miami-Dade County rose from a population of 130,000 to 2,300,000 (1,800 percent). During the same period, the population of the United States as a whole only rose from 120,000,000 to 280,000,000 (230 percent). Americans are moving disproportionately into hurricane-prone areas. (Map courtesy U.S. Census Bureau)

 

Why would people put themselves in harm’s way? “People like to be near the beach and nice landscapes,” says Roger-Mark De Souza, the technical director of the Population, Health, and Environment Program of the Population Reference Bureau. “In the United States, we have a perception that we can adapt and that the risk is not immediate,” says De Souza. Indeed, as humanity’s knowledge of science has increased, we have developed the ability to provide early warning for disasters like hurricanes and volcanic eruptions. Engineering has improved the design of buildings to minimize many risks. These factors in mind, it’s possible that the risk of living in a disaster-prone area doesn’t seem as significant to people as the benefits. “We know it’s a risk, but we [believe we] can deal with it,” says De Souza.

  Photograph of hurricane damage on the Florida coast

As forecasters’ ability to predict hurricanes improves, and buildings become more resistant to high winds and waves, people become more comfortable accepting the risk of living on the coast, even though hurricanes continue to batter these areas. (Photograph courtesy Federal Emergency Management Agency Photo Library)

 

Population’s Impact on Nature

 

In addition to increasing the cost of natural disasters, population growth and the landscape changes that go with it may make some disasters more severe. When a swath of trees becomes a neighborhood or an office building, the ground changes from spongy, water-absorbing soil to impervious pavement. Rain that would otherwise have soaked into the ground now has nowhere to go, and runs off as flood water. When land is deforested and remains bare or sparsely vegetated, soil erosion can worsen flooding. Rapidly increasing population puts additional strain on water supplies during times of natural drought.

Impervious Surfaces

Claire Jantz, a researcher at the Woods Hole Research Center, has observed urban growth in Landsat satellite images of the Baltimore-Washington area collected between 1986 and 2000. NASA funded Jantz to work with Steve Prince (University of Maryland) and Scott Goetz (The Woods Hole Research Center) and other colleagues to produce maps of impervious land surfaces and vegetation in the Chesapeake Bay watershed using Landsat data. Because impervious surfaces tend to be man-made, the maps reveal the effects of population growth. Jantz was stunned when she compared the impervious surface maps to maps of flood zones published by the Federal Emergency Management Agency (FEMA).

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  Map of impervious surfaces and floodplains along the Anacostia River

“It was a surprise to see how much development occurs in flood zones,” Jantz recalls. “To see large areas of pavement within a flood zone is impressive.” In 1990, 450 square kilometers (111,200 acres) of developed land lay in Special Flood Hazards Areas—100-year flood zones, where there is at least a one percent chance of complete or partial flooding in any given year. By 2000, the figure had grown to 767.7 square kilometers (189,700 acres), an increase of nearly 71 percent.

Jantz acknowledges that the figure is an estimate. It could be higher if additional development exists in the 38 percent of the Chesapeake watershed not covered by FEMA’s flood maps. It could be lower if some of the “new” impervious surfaces detected in 2000 had been there all along, but were detected for the first time because of quality improvements in Landsat 7 data compared to the Landsat 5 data from 1990. Finally, naturally impervious surfaces like beaches and bare rock undergo natural changes that can be confused with development. Even as she acknowledges these uncertainties, Jantz reports, “The magnitude of increase is probably accurate.”

These trends are disconcerting. Much of the world’s population—and the businesses that employ them—are in coastal areas that are subject to strong winds and floods. According to Munich-Re, storms and floods accounted for two-thirds of the world’s insured losses in 2003. In the future, climate change may increase wind and flood hazards in such regions. As Jantz observes, “Different precipitation patterns could be a serious problem given current patterns of development.”

 

Densely developed urban areas occupy many of the flood plains of the Chesapeake Bay watershed. Some of the construction has occured in the past 20 years. This map shows impervious surfaces—which correspond to developed areas— and Federal Emergency Management Agency flood zones near the confluence of the Anacostia and Potomac rivers near Washington, D.C. Black regions inside the red flood zones indicate dense development that occured between 1986 and 2000. Gray areas are covered by impervious surfaces, while light green areas are undeveloped. (Map by Robert Simmon, based on data provided by Claire Jantz, Woods Hole Research Center)

  Map of modelled precipitation change for the years 2071-2100

Deforestation

Impervious surfaces aren’t the only way that developed landscapes contribute to flooding. Even without pavement, deforested land can no longer anchor soil, and dirt washes into rivers, filling the river bottoms with silt. A shallower river is able to hold less water, increasing the flood hazard. This impact of land use on erosion and floods can be seen in satellite imagery, says Robert Brakenridge, the principle investigator behind the Dartmouth Flood Observatory. In forest-cleared areas, “flood waters are sediment rich, and flood channels are silted in.”

 

Global climate change caused by greenhouse gases is likely to shift rainfall patterns in addition to raising temperatures. This map shows computer model predictions of the difference in rainfall patterns between the thirty-year periods 2071–2100 and 1961–1990. The model predicted that green areas would receive more rainfall in 2071-2100, while orange regions would receive less. (Map courtesy IPCC Technical Paper V, Climate Change and Biodiversity)

  Landsat image of the Betsiboka River, filled with sediment
 

In 2004, tragic floods killed thousands of people in Haiti. Images of the flood regions taken by sensors on NASA’s Terra satellite show wide deposits of rocks and mud that washed off the bare hills and moved with the water through silted-in river channels. The images also show huge scars on the hillsides where the water cut new channels as it drained. “Such floods may have occurred in the past,” says Brakenridge, but without deforestation, “I suspect the damage wouldn’t have been as severe. You would not have debris moving with the water to block the channel capacity.”

 

The Betsiboka River in Madagascar is colored reddish-brown by the silt it carries from the agricultural regions of the central highlands. Where the flow of the river slows, the sediment is deposited in the stream channel, increasing the risk of flooding. (Image by Robert Simmon, based on Landsat 7 data provided by the Global Land Cover Facility)

  Satellite image pair showing before and after scenes of flood damage in Jimani, Haiti
 

Drought

Land use can also exacerbate the impact of drought when water users like farmers and landscapers, power plants, and urban populations must all draw from limited water supplies. Because of this, drought can impact everything from the availability and cost of food to the cost of electricity over a wide region. When comparing single events, i.e., one hurricane compared to one drought, drought is the most expensive natural disaster.

In wealthy countries with sophisticated disaster management agencies, natural disasters like drought or floods may primarily translate into economic losses, but in other regions, the effects can be far more tragic. Drought in central Africa causes famine and starvation, and it can take aid organizations several months to organize a response to such large-scale need. Floods in Southeast Asia can destroy rice crops and create food shortages for millions of people. Early notice of a developing famine or flood hazard can save both lives and money by improving planning. Satellite remote sensing can help reduce the impact and cost of natural disasters by providing responders with a timely, detailed look at affected regions that will let them target the areas with the greatest needs.

 

Heavy rains on the bare mountains of southeastern Haiti on May 24, 2004, triggered a series of floods and debris flows (mudslides) that killed about 2,000 people. These images show the town of Jimani before and after the flooding. Red areas are vegetated, and light blue regions are bare or covered by roads and buildings. The eastern half of the town was completely covered in flood debris. (NASA images by Jesse Allen, based on data provided by the ASTER Science Team)

 

Decreasing the Impact of Disaster with Remote Sensing

 

“In 2002, many rural families in Central America were suffering from hunger and acute malnutrition,” says Michael Budde, a remote sensing specialist with the Famine Early Warning Systems Network, funded by the U.S. Agency for International Development. Drought in 2001 destroyed the subsistence crops that these families relied on, and at the same time, a sharp drop in coffee prices deprived many of the people of their employment on coffee plantations—their second source of livelihood. “In 2002 there was great interest in having an early indication of harvest prospects to see if drought would strike again, and if so, where,” says Budde.

The scientists turned to NASA’s Tropical Rainfall Measuring Mission satellite to monitor rainfall across Central America. They tracked the amount of rain and when it fell in relation to the growing needs of maize, the primary crop of the region. The results revealed a clear drought corridor through Honduras and Nicaragua. “This was the first time a regional view of drought had been provided, and the pattern was confirmed by field reports. The information helped direct limited resources into specific sub-national areas, to the benefit of tens of thousands of families,” says Budde.

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  Map of crop water stress for Central America

A drought during 2002 led to a food shortage in rural Honduras and Nicaragua. USGS researchers helped the Famine Early Warning Systems Network map the extent of the drought with satellite measurements of rainfall. This map shows the rainfall received in the area during the 2002 growing season relative to the amount of rain necessary for healthy maize (corn) crops. The drought was most intense in western Nicaragua and southern Honduras, indicated by the orange coloring. (Map courtesy Michael Budde, USGS EROS Data Center)

     

 

 

On the forefront of drought monitoring in famine-prone nations, the Famine Early Warning System Network tracks developing droughts in Africa, Central America, and Afghanistan using a convergence of evidence from both NASA and National Oceanic and Atmospheric Administration satellites as well as ground reports. The network distributes the information to aid organizations and governments to help them plan a response to the food crisis.

   
  Map of vegetation anomaly in Africa for March 1 through 10, 2005

The United States Department of Agriculture’s Foreign Agricultural Service similarly uses NASA data to monitor crops in countries not covered by the famine network. One of the tools that both organizations rely on is the Moderate Resolution Imaging Spectroradiometer, MODIS, on NASA’s Terra and Aqua satellites. Unlike high-resolution sensors such as Landsat, MODIS acquires images of the entire world every day, providing an overview of the Earth with a level of detail that was not possible before. Further, MODIS data are free, making global monitoring projects possible for many organizations. Both the Famine Early Warning Network and the Foreign Agricultural Service use MODIS data to quantify how greatly crop production might be affected by natural disasters.

 

Satellite measurements of vegetation health compared to the average vegetation at a specific time of year can reveal patterns of drought. Orange colors indicate vegetation that is less dense and healthy than normal, while green represents healthier than normal vegetation. This image of vegetation anomaly from March 1–10, 2005, shows stressed vegetation in the Sahel, on the north shore of Lake Victoria, and Mozambique. (Image courtesy Molly Brown, NASA GSFC Biospheric Sciences Branch.)

  Map of water contained in the Afghanistan snowpack
 

At the Dartmouth Flood Observatory, Brakenridge tracks floods using MODIS. When a flood occurs, Brakenridge compares MODIS images of the flood area with images taken before the flood to map out exactly which areas are flooded. In some instances, he has provided flood maps to the United States Army and the U.S. State Department, which provides the information to local government for flood response. The maps also provide a record of flooding, which can be valuable in future planning.

 

The thick snows covering Afghanistan’s mountains on March 13, 2005, are contributing to flooding as the spring melt progresses. This map shows snow water equivalent, which represents the amount of liquid water contained in the snow. The measurements, derived from satellite data, help predict flooding. (Map courtesy FEWS NET)

  Satellite image pair showing flooding of salt pans in Afghanistan and Iran
   

Following the winter’s heavy snowfall, the once-dry Hamoun wetlands along the Afghan/Iranian border filled with water. These images compare the wetlands on February 1, 2005 (left), and March 14, 2005 (right). The wetlands had been drying due to a severe drought that started in 1998 and increased irrigation along the Helmand River. (NASA images courtesy MODIS Rapid Response System)

 

The Impact of Climate Change on Natural Disasters

 

Climate change may not be responsible for the recent skyrocketing cost of natural disasters, but it is very likely that it will impact future catastrophes. Climate models provide a glimpse of the future, and while they do not agree on all of the details, most models predict a few general trends. First, according to the Intergovernmental Panel on Climate Change, an increase of greenhouse gases in the atmosphere will probably boost temperatures over most land surfaces, though the exact change will vary regionally. More uncertain—but possible—outcomes of an increase in global temperatures include increased risk of drought and increased intensity of storms, including tropical cyclones with higher wind speeds, a wetter Asian monsoon, and, possibly, more intense mid-latitude storms. (For more information, see Global Warming: Potential Effects of Global Warming)

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Diagrams of the effects of rising temperatures on extreme weather events

Changes in climate not only affect average temperatures, but also extreme temperatures, increasing the likelihood of weather-related natural disasters. If global climate change causes the global average temperature to rise (top), there will be less cold weather, and a greater probability of hot and record hot weather. An increase in temperature variability will extend the extremes of temperature, both cold and hot. An increase in average temperature combined with increased variance will have little effect on cold weather, but hot weather will be more common and record hot weather will increase greatly. (Figure adapted from Climate Change 2001: The Scientific Basis)

 

Global warming could affect storm formation by decreasing the temperature difference between the poles and the equator. That temperature difference fuels the mid-latitude storms affect the Earth’s most populated regions. Warmer temperatures could increase the amount of water vapor that enters the atmosphere. The result is a hotter, more humid environment. At the equator, where conditions are already hot and humid, the change isn’t expected to be large. At the poles, however, the air is cold and dry; a little extra heat and water vapor could raise temperatures greatly. As a result, global warming may cause the temperature difference between the poles and the equator to decrease. and as the difference decreases, so should the number of storms, says George Tselioudis, a research scientist at NASA Goddard Institute for Space Studies (GISS) and Columbia University.

But even as a warming climate might decrease the overall number of storms that form, it could increase the number of intense storms. As temperatures continue to rise, more and more water vapor could evaporate into the atmosphere, and water vapor is the fuel for storms. “If we are creating an atmosphere more loaded with humidity, any storm that does develop has greater potential to develop into an intense storm,” says Tselioudis.

The combined result of increased temperatures over land, decreased equator-versus-pole temperature differences, and increased humidity could be increasingly intense cycles of droughts and floods as more of a region’s precipitation falls in a single large storm rather than a series of small ones. A warmer, wetter atmosphere could also affect tropical storms (hurricanes), but changes to tropical storms are harder to predict and track. Some scientists have speculated that a warmer climate that allows more intense storms to develop would also spawn more hurricanes. Warmer temperatures may also heat ocean waters farther from the Equator, expanding the reach of large tropical storms. But there is little evidence to support the either of these theories, says Kerry Emanuel, a professor of tropical meteorology and climate in the Massachusetts Institute of Technology’s Program in Atmospheres, Oceans, and Climate.

The one way in which global warming could impact hurricanes is by making them more intense. More heat and water in the atmosphere and warmer sea surface temperatures could provide more fuel to increase the wind speeds of tropical storms. Warming that has already occurred since 1980 has increased sea surface temperatures 0.3 degrees Celsius, which should increase the maximum potential wind speed of hurricanes by 1 knot, according to hurricane intensity models. But increases that small could not have been observed yet. “At present, hurricane intensity is measured only to an accuracy of plus or minus five knots, so it is not possible to discern any change that might have occurred owing to warming that has already taken place,” says Emanuel.

   
Graph of predicted sea-level rise

Even if tropical storms don’t change significantly, other environmental changes brought on by global warming could make the storms more deadly. Melting glaciers and ice caps will likely cause sea levels to rise, which would make coastal flooding more severe when a storm comes ashore. In their 2001 report, the Intergovernmental Panel on Climate Change stated that global warming should cause sea levels to rise 0.11 to 0.77 meters (0.36 to 2.5 feet) by 2100.

 

Scientists use climate models to estimate changes in future sea level rise, one of the expected effects of global warming. This graph shows sea level changes predicted by six climate models, each of which ran 35 different greenhouse gas emission scenarios. The center dark region shows the predicted sea level rise for the models averaged over the 35 emission scenarios. The lighter blue region shows the range of the maximum and minimum model predictions. The outer, lightest blue section includes the uncertainties of land-ice changes, permafrost changes and sediment deposition (not including the possiblity of melting of the West Antarctic Ice Sheet). The top curve is the extreme worst case scenario and the bottom curve shows the least expected change. (Graph adapted from Climate Change 2001: The Scientific Basis)

 

Weathering Climate Change

 

Higher sea levels could send the cost of natural hazards soaring by increasing the hazard of flooding in coastal regions, especially if urban development and land clearing in coastal areas and flood plains increase. In such conditions, smaller storms could cause the same amount of damage as large storms have in the past, and large storms become even more devastating. In densely populated coastal regions, built to withstand the storms and floods of the past, the problem has the potential to be serious. “The number one vulnerability of the New York region is enhanced flooding,” says Cynthia Rosenzweig. “We have a tremendous amount of vulnerable infrastructure,” she says, pointing to the region’s three major airports, which are built on drained coastal land, and Lower Manhattan, which sits at a low elevation. A single, powerful event has the potential to cost the city up to $100 billion, about ten percent of the gross regional product. The Head of Climate Impacts at NASA Goddard Institute for Space Studies, Rosenzweig led a multi-disciplinary group that evaluated the potential impact of climate change on New York City and the surrounding region.

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  Map of population density and height above sea level, Coney Island New York
 

In their evaluation, Rosenzweig and the team of geographers, geologists, economists, and others analyzed past climate trends, current response to extreme events, and predictions of what the climate may be in the future. After correcting for the city’s “heat island” effect (in which loss of natural vegetation can increase urban temperatures by six to eight degrees Fahrenheit relative to surrounding suburban and rural areas), the scientists found that New York has warmed by more than 1 degree Celsius since 1900. They also found “indication of greater variability of droughts and floods,” says Rosenzweig, though there is no clear trend yet. In the future, the group expects warmer temperatures and possibly more extreme droughts and floods.

To determine how these changes might impact the New York Metropolitan Region, the team looked at how the region responded to disasters in the past. They then predicted how things like public health, water supplies, and energy demand could be affected based on climate predictions and past climate trends. The group took their findings to decision makers who will likely have to deal with climate change to show them how their responsibilities might change. This bottom-up approach to climate change—starting with first responders instead of high-level government officials— Rosenzweig hopes, will help regions prepare for extreme events now and climate change in the future.

“With the greenhouse gases we have already emitted into the atmosphere, we will have climate change, but it’s uncertain how much,” says Rosenzweig. One thing she is certain of is the need for preparation. “We’re building infrastructure now that needs to withstand a change in climate. We need to think about it now.”

 

Like many coastal cities worldwide, New York is threatened by sea level rise. Densely populated neighborhoods are adjacent to the coast. This map shows the population density and coastal topography of Coney Island. Each contour (light-blue to dark blue) represents a five-foot change in elevation. Even with a modest sea level rise of 1.5 feet, the frequency of flooding will increase greatly. (Map adapted from Climate Change and a Global City)