Fifty years of reforestation in the eastern United States probably created a cool barrier to extreme heat

[FernandoRoque]

Mallory Barnes from Indiana University led the research 'A Century of Reforestation Reduced Anthropogenic Warming in the Eastern United States.’ exposing the possible cooler temperatures in the southeastern USA due to a 50-year reforestation. Source: https://www.theguardian.com/environment/2024/feb/17/us-east-trees-warming-hole-study-climate-crisis  

I measured the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR, range values between 0 and 0.94 ) and the Land Surface Temperature (in Celsius degrees)  using Copernicus, Europe Earth observation program, in Florida, USA, from the year 2020 to May 2024. The technology used was Python and Arcgis with a rasterio library. It converts the geotiff raster images of FAPAR and Land Surface Temperature to numerical matrix to extract statistical analysis.

Northern Florida, part of the reforestation area of the study of Indiana University,  keeps the highest FAPAR and the lowest temperatures, as shown in the graphics below. The highest temperature since  2020 was in July 2023 in the Everglades, Southern Florida. Also, this region has the lowest FAPAR indicator of my research.  

The highest FAPAR levels reached a value of 0.68 in northern Florida during the study period from the year 2020 to April 2024. Central Florida, on the frontier to North Florida, is barely reaching a level of 0.6. The land surface temperature also depends on geographic location and further research is needed. For the matter of this study, Central Florida has a higher temperature than Northern as we can see on the Land Surface Temperature.It is a worrying matter since the Everglades is a protected area and it has an indicator around 0.3 which indicates desertification. Also, the Everglades keep the highest Land Surface Temperature of the state. It reached 30 degrees C. in July 2023. It keeps a higher temperature compared with its neighbor the South Florida Gulf Coast.

In Guatemala's eastern dry corridor, Camotan, Chiquimula, frontier to Honduras, a coffee recovery region of 7 square kilometers could help to lower the temperature of the region, refer to the gray line in the Land Surface Temperature statistical chart in figure 2. This area has number 2 on the map in Figure 2. Camotan is a dry area with the number 1 on the map and has the highest temperature from 2022 to June 2023.  The temperature measure is Celsius degrees. These regions have the same topography and altitude over the sea level. The geographic conditions are the same.

The seven square kilometers coffee recovery region is marked with number 2 on the map. This region has the orange line on the FAPAR chart. We can see the recovery of photosynthesis activity from the year 2014 to October 2023. We can see that it reaches high levels of FAPAR, around 0.83, compared with the larger rainforest of the region marked with numbers 3 and 4 on the map. On the contrary, we can see the low levels of FAPAR of the desertic region surrounding the coffee recovery region marked with number 1 on the map. It is the blue line on the FAPAR chart. We can see that these desertic regions barely reach 0.7 compared with the surrounding rainforests which reach 0.83. Remember we are studying similar regions in topography, altitude, and geography factors. 

 The soil temperature in the Trifinio region (number 3) and La Union, Zacapa (number 4) is lower than the land surface temperature (in degrees Celsius) of the Jocotan-Camotan region (number 1) from the year 2022 to June 2023. This may be attributed to high photosynthetic activity (FAPAR) as shown in the chart. The Camotan recovery area with coffee (number 2) has a lower soil temperature than the overall Camotan-Jocotan region (number 1). The high level of photosynthesis could help maintain the lower soil temperature. 

Conclusions

1. North Florida kept high levels of FAPAR, and photosynthesis levels from the year 2020 to April 2024 could be due to the preservation of the 50-year reforestation mentioned in the Indiana University research.
2. The lower temperature of Northern Florida compared to Central Florida could be geographic factors and not due to the higher levels of FAPAR in North Florida. 
3. The Everglades is a protected area with a high risk of desertification because it has just a 0.3 FAPAR indicator of a range of 0 to 0.94. Below 0.5, an area is at risk of desertification. It also has higher temperatures compared to its neighboring South Florida Gulf Coast.
4. The coffee recuperation area in the eastern dry corridor in Guatemala, frontier to Honduras shows a 10-year steady FAPAR growing probing the success of the reforestation. It also keeps a lower land surface temperature compared with its surrounding dry regions with similar topography, altitude, and geographic characteristics.