Residential structures provide secure carbon storage to 2070 and beyond
Wood is infinitely useful. Critically important to our changing climate, trees store carbon. When trees are harvested for wood products like lumber, some of this carbon continues to be stored. Even after a wood product has been discarded, it continues to store carbon.
More than 90% of new single-family homes in the United States are built of wood. Approximately 400,000 homes, apartment buildings and other dwellings are destroyed each year by floods and other natural disasters or by decay. Houses are also being demolished to make way for new developments.
Homes store so much carbon that knowing how many homes will be built in the future is important to understanding the total carbon storage capacity of the United States.
Wood products harvested from residential structures will continue to increase carbon storage over the next 50 years, according to new USDA Forest Service research published in the journal PLOS ONE.
“Forests sequester carbon, and wood produced by forests can store that carbon for decades or centuries,” says Jeff Prestemon, lead author of the study and a research economist at the Southern Research Station. “Harvested wood has provided an important service to consumers for decades: shelter.”
Even after residential structures reach the end of their useful life, wood stored in landfills, a typical practice in the United States, does not immediately release its carbon. Thus, the wood retains its storage capacity for several more decades.
Prestemon and his colleagues, Prakash Nepal with the Forest Products Laboratory and Kamalakanta Sahoo with the University of Wisconsin-Madison, examined how population growth and income can be combined to project new housing construction rates at multiple scales ( county and region) and for different futures. as defined by the Intergovernmental Panel on Climate Change (IPCC). Additionally, they sought to understand how possible future trends in housing starts and housing inventory maintained through repairs and renovations might affect carbon storage in wood products.
“Until now, fine spatial scale projections of carbon in harvested wood products have not been described for the United States,” Prestemon says. “Localizing future stored carbon will help us better understand the risks of emissions from destructive structural disturbances such as hurricanes and wildfires.”
The research considers five possible futures for social and economic conditions in the country. Called Shared Socioeconomic Pathways (or SSPs), the futures include changes in population and income growth. The future highs (SSP5) and lows (SSP3) served as parentheses for a plausible range of carbon in harvested wood products in the coming decades.
The researchers described how future construction rates would vary widely across US counties. They translated these construction futures into trends in carbon stored in harvested wood products. These projections show increases in carbon stocks across much of the United States. In addition, carbon additions from construction activities largely offset the carbon lost or emitted by the destruction/demolition of structures. Although housing starts are expected to decline in the future, residential housing and the need to maintain structures will continue to increase carbon storage in wood products over the coming decades.
The study’s projections of single-family and multi-family housing starts at the county level in the five possible futures can also help answer questions about future demand for wood products for construction and where forests and other wild lands are more likely to be replaced by new housing development housing.
“The wood used to build homes will remain a growing and important component of the global forest carbon sink over the next 50 years, whether the US population grows or shrinks, and regardless of high or low economic growth,” Prestemon adds.