FAITH AND FLOODING: How Sea Level Rise Threatens America’s Houses of Worship

Research brief by Climate Central

Unchecked warming emissions are projected to leave hundreds of houses of worship in areas vulnerable to chronic flooding by midcentury.

Marylanders first prayed at the Old Trinity Church, on the Eastern Shore of the Chesapeake Bay, more than three hundred years ago. Built in the 1670s, Old Trinity is among the oldest churches in the continental United States. Veterans of every American war are buried in its waterfront cemetery.

Thanks to humanity’s greenhouse gas emissions, this century could be Old Trinity’s last. Anthropogenic climate change is pushing up sea levels. The church lies on land just a few feet above the high tide line. Unless the world makes deep cuts to warming pollution or local adaptive measures are taken, Old Trinity’s site will be at risk of permanent inundation by 2100 and in danger of chronic flooding well before then.

Old Trinity is not an exception. 499 houses of worship in America’s coastal states will be in areas vulnerable to flooding at least once each year on average by 2050, if greenhouse gas emissions continue to grow unchecked. (Today, some 217 houses of worship stand on land vulnerable to such flooding.) 2,407 will be in areas at risk of chronic flooding by 2100. But deep global reductions in emissions of warming pollution would reduce the number of American religious buildings in zones vulnerable to chronic flooding by 66 percent by the end of the century.

Congregations across the United States are already contributing to that effort. By improving the energy efficiency of their facilities and by generating clean electricity of their own, they are reducing emissions, saving money, and setting powerful examples of environmental stewardship.

Before the Flood

Some of America’s most religious places are particularly vulnerable to sea level rise. Alabama, Georgia, Louisiana, Mississippi, North Carolina, and South Carolina all rank among the country’s ten most religious states, measured by how often their residents attend religious services. All of those states lie on the Gulf or Southeast coasts, which are particularly exposed to sea level rise because of factors including low coastal topography and a slowing Gulf Stream, which pushes seawater against the East Coast.

In no state are congregations more vulnerable than in Louisiana, where nearly half of all residents attend religious services every week. There, 88 houses of worship stand on ground that will lie below the level of annual floods in 2050, under unchecked emissions growth. Florida and North Carolina are close behind (see maps). (Places of worship on the West Coast are less immediately vulnerable, thanks partly to ocean currents, the unequal distribution of sea level rise around the world’s oceans, and variations in coastal topography).

By reducing greenhouse gas pollution, humanity could protect some of these churches from chronic flooding. By 2050, moderate emissions cuts, roughly in line with the Paris agreement, would modestly reduce the total at risk from 499 to 462. By the end of the century, our emissions choices make will make a profound difference. Under unchecked emissions, 2,407 houses of worship will be in areas at risk of flooding an average of once per year by 2100, including 525 congregations in Florida, 337 in Louisiana, and 250 in Virginia. Moderate cuts would slash that total nearly in half, to 1,351. Deep, immediate cuts, in line with something like a global Green New Deal, would reduce it by two thirds, to 825.

It’s important to note that houses of worship that are not directly threatened by rising seas are still exposed to the other effects of climate change. Last year, the most destructive wildfire in California’s history incinerated more than half of the churches in the inland town of Paradise. During Hurricane Florence, heavy rain flooded a number of churches in North Carolina’s interior, including the South Lumberton Church of Christ — the second time in two years that the church had been inundated during a storm. Climate change makes wildfires more likely, hurricanes wetter, and heavy precipitation more common. The damage worsens as humanity dumps more warming pollution into the atmosphere.

Carbon and Congregations

America is home to about 412,000 houses of worship. In 2012, the most recent year for which data were available, those buildings used about 173 trillion British thermal units (BTUs) of energy — more than the total for all of the U.S. buildings owned by the federal government. (One BTU is the amount of energy needed to heat one pound of water by one degree Fahrenheit, roughly equal to the energy released by burning a kitchen match.)

By improving the energy efficiency of their facilities and by generating renewable electricity on site, congregations can cut their emissions — a step that can provide financial benefits and set a powerful example for their members.

Congregations can boost their energy efficiency without big up-front investments. They can install energy-efficient light bulbs; place caulking around windows and doors to prevent heat loss; switch to programmable thermostats; plug insulation leaks; and regularly clean and repair their heating, ventilation, and air conditioning systems, which account for a major share of most congregations’ energy use. They can also take a number of cost-free steps, from unplugging unused appliances and electronics to leaving rooms slightly cooler in the winter and warmer in the summer. Over time, such changes can produce savings. Scheduling an energy audit with the local power utility can help congregations learn which interventions are most affordable and effective.

Another option is for houses of worship to generate renewable electricity on site, cleanly powering their own operations and even returning some power to the grid. There are a number of ways to manage the up-front costs of a solar array. Under solar-power purchase agreements, for instance, developers cover the cost of buying or installing the system and then sell the electricity it produces to customers at a rate typically below the retail cost of power from the local utility. The savings can go to faith-oriented projects. In some states, congregations also have the option of buying renewable electricity directly from a local utility.

Congregations vulnerable to coastal flooding can take adaptive measures, from elevating their facilities to building stabilizing features such as “living shorelines,” which use marsh plants to reduce erosion and lessen the effects of flooding.

Because more than two thirds of Americans attend religious services at least a few times each year, the examples of environmental stewardship set by congregations can resonate far beyond their walls.

Methodology: Local sea level projections are based on a recent peer-reviewed research paper (Kopp et al. 2017) building off of global projections from the Intergovernmental Panel on Climate Change and emerging research on the potential instability of Antarctic ice sheets (DeConto and Pollard 2016), which could lead to significantly more sea level rise in the second half of the century. Climate pollution scenarios modeled include “unchecked pollution” (Representative Concentration Pathway 8.5, or RCP 8.5), “moderate cuts” (RCP 4.5), and “deep cuts” (RCP 2.6), this last choice meaning a peak in emissions near the year 2020 followed by a sharp decline to zero near 2070 and then by net negative emissions. Median projections under each scenario for the years 2050 and 2100 are used, reflecting mid-range sea level sensitivity to climate pollution. For more details on the sea level projections in this report, as well as flood risks, see the methodology for Climate Central’s Surging Seas Risk Finder.

As in Climate Central’s Surging Seas Risk Finder, geographic records of houses of worship come from the Geographic Names Information Systems (GNIS) database, which is managed by the U.S. Geological Survey (USGS) and the U.S. Board on Geographic Names. However, this report uses data downloaded in 2018, and Risk Finder uses data downloaded in 2013, so counts of houses of worship in this report may differ from those in Risk Finder.

The GNIS database was created largely by compiling information from federal maps. The dataset is periodically updated with information from approved sources, including government agencies from the local to federal level. As USGS notes, “the completeness, currency, and accuracy of [GNIS] data varies by area depending on the quality and timeliness of that input.”

Before conducting analysis for this report, Climate Central removed features that the database’s managers have confirmed no longer exist. However, there may be other houses of worship that have moved or closed and are nonetheless listed as existing in the GNIS database. Similarly, it is possible that new houses of worship have opened.

The analysis for this report includes all GNIS records with the feature classification “church”; these records are not limited to Christian houses of worship. There are no national guidelines for feature classifications in the GNIS database, and USGS notes that “although the terms are generally consistent with dictionary definitions, they may not conform exactly and are not always intuitive.”

Report image: Martin LaBar/flickr/Image rotated from original