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When the Fifth National Climate Assessment (NCA5) debuted recently, it included some significant contributions from the USGS Earth Resources Observation and Science (EROS) Center.

The congressionally mandated interagency report from the U.S. Global Climate Change Research Program is published about every four years to relay information about climate change impacts, risks and responses to decision makers in federal, state, tribal and local governments in addition to areas such as agriculture, health care, business and research. 

The NCA5 helps them understand, plan, mitigate and adapt to changes as people in the United States face increased risks from extreme events such as longer-lasting heat waves. Actions already taken have ranged from emission reductions and green energy production to mitigation and adaptation efforts. The report contains a chart listing the number of mitigation and adaptation actions taken, per state, at the state and city levels of government.

The report covers chapters on key topics such as water, energy, land, forests and many more. EROS research physical scientist George Xian, who has a long history of using remote sensing data to characterize land cover and land cover change across the United States, led NCA5’s Chapter 6 titled Land Cover and Land-Use Change, in the Federal Coordinating Lead Author role. 

Man staring at his laptop with maps on the wall in the background
George Xian, a research physical scientist at the USGS Earth Resources Observation and Science (EROS) Center, works in his office at EROS.

The main source of data for Chapter 6 is Land Change Monitoring, Assessment and Projection (LCMAP), an EROS land cover mapping and change monitoring product derived from Landsat data. 

In addition, landscape ecologist and geographer Hua Shi, a contractor at EROS who works with Xian, contributed urban heat island information that appears graphically in three other areas of the report.

George Xian Leads Land Chapter

Initially, the Federal Coordinating Lead Author role for Chapter 6 was held by Bradley Reed, a USGS land change scientist who had worked in EROS science from the early 1990s to the mid-2000s and continued to keep in touch. His sudden death early in the production of NCA5 resulted in the nomination and selection of Xian as Reed’s replacement. A dedication of Chapter 6 to Reed also appears in the report.

Xian had contributed to a working group for the Fourth National Climate Assessment (NCA4), and he first had been invited to join a group for NCA5 that was interested in looking at Landsat surface temperature data as an indicator of climate change. Reed had been able to start some groundwork for Chapter 6, including organizing a team of authors, before Xian took over, but Xian said he did not know quite what he was in for.

NCA5 takes a more complex and comprehensive look at climate-related data compared to previous reports, Xian said. He received encouragement early on from retired EROS Chief Scientist Tom Loveland, who has since passed away. Loveland had served as the Federal Coordinating Lead Author for the land chapter in NCA4 and other roles in prior reports.

“It’s very complicated, and also a lot of work and a lot of time I’d have to spend,” Xian said. “I decided, OK, I could just spend my time on it. It’s a challenge, but it’s also a good opportunity for us, and for me, too.”

Screenshot of webpage with a title, two images side by side underneath as a large banner image, labels and text on the page
A screenshot of the beginning of Chapter 6, Land Cover and Land-Use Change, for the Fifth National Climate Assessment.

Xian’s role as Federal Coordinating Lead Author included providing a general guide to the chapter’s writing team of nine authors, along with making recommendations for science direction and some details, including to lead author Peter Thornton of the Oak Ridge National Laboratory, with whom Xian worked closely. The other authors hailed from a variety of universities and government agencies, including Zhe Zhu of the University of Connecticut, who also worked previously at EROS.

Xian met regularly with the team of authors, the lead author and an NCA5 coordinator to go over progress and any issues. He reviewed the writing and offered feedback. He also communicated with other chapter leaders to keep information and language consistent about topics that overlapped among chapters. 

Showcasing LCMAP Data

The LCMAP data used in Chapter 6 helped illustrate 35 years of land cover change in the United States—ranging from cropland, forest and urban land to shrubland and grassland. “Then you have to connect it to the climate impact,” Xian said. “For example, we mentioned in the West how drought and dry climate caused wildland fire and caused forest change that related to carbon and other ecosystem services.”

Other chapters used LCMAP data as well, Xian said, including the Southeast Region chapter and the Forests chapter. LCMAP’s use in NCA5, Xian said, “shows the value of EROS data to our user communities, including the government side and private sectors, and also other user groups. Our data played a vital role in this assessment.” 

In April 2023, Xian was able to see all of his chapter authors together in person for the first time in a meeting in the Washington, D.C., area, where all of the NCA5 chapters were given a review report by the National Academy of Science. They discussed the comments and provided feedback. Altogether, the NCA5 went through six drafts. The release of the final version in November 2023 marked the culmination of a four-year process involving more than 30 USGS scientists.

“We played a critical role in making sure that the report was not only accurate but also credible, understandable and timely,” Xian said.

He misses the weekly meetings with his chapter authors, but, he added, “I felt so happy, with so much time we spent, that we made valuable information and delivered it to society.”

More Data from EROS 

Man wearing a hat standing in front of a colorful map that's framed
Hua Shi works as a landscape ecologist and geographer at EROS.

Like Xian, Hua Shi has a history of working on land cover-related research at EROS that studies the interactions between people and ecosystems. Most recently, he has been working with Xian on surface urban heat island (SUHI) mapping, involving land surface temperature estimates from the Landsat satellite’s thermal sensor, SUHI intensity analysis and SUHI hotspot identification. Impervious surfaces in urban areas—such as roofs, roads and parking lots—that are unbroken by green spaces can produce hotspots in cities. 

A pilot project with a handful of U.S. cities looked at land surface temperatures, comparing temperature differences, or intensity, between urban and nonurban land cover dating back to 1985. The data recently expanded to include 50 cities across the United States, with their annual mean, maximum and minimum temperatures, and comparisons of intensity to identify the hotspots. The next step for the EROS effort will be to gather the same data for more than 800 cities in the conterminous United States with populations of 50,000 or more.

As a technical contributor for NCA5, Shi provided information about the cities of Atlanta, Georgia; Houston, Texas; and Minneapolis, Minnesota, to help illustrate Chapter 1, the Overview; Chapter 12, Built Environment, Urban Systems, and Cities; and Appendix 4, Indicators. The Chapter 1 and Chapter 12 graphics relate land surface temperature to median household incomes for the year 2020, with a trend analysis showing land surface temperature decreasing as income increases for all three cities. The Indicators graphic relates the urban heat intensity in the three cities in 2020 and the trend for each from 1985-2020.

Shi said the Landsat surface temperature information and result analysis EROS provided is valuable in its ability to look back in time and for its resolution across the globe. “Climate change is talking about decades. People are really paying attention. Remote sensing is excellent because it’s seeing many years very efficiently over a big area,” Shi said. “Our project provides detailed spatial and time series data.”

Shi was impressed when he saw the finished NCA5 report and expects it to be helpful. “It’s important to give all this information to the different levels, like decision makers, researchers or university professors, students or even just normal citizens. I think if people are interested, they can understand what's going on. There is a lot of scientific information, but it’s very visualized. They have a lot of beautiful maps and figures and charts, which make complex data more accessible and understandable, identify patterns and trends, and communicate data insights and findings to a wider audience.”


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