From climate realism
By Linnea Lueken
A recent BBC article reports on a new study by Ohio State University (OSU) researchers who, using historical documents, have found that trees in the region have experienced a nearly month-long increase in their growing season compared to the 19th century. This is not surprising. Extensive research and hard data also show that plant life in general benefits from additional atmospheric CO2 and moderate warming.
The article “Climate change: trees grow for extra month as planet warms – study” describes an OSU study based in part on records by an Ohio farmer between 1883 and 1912. The farmer kept detailed records of meteorological data and tree growth on his property from season to season.
The study’s lead author then recorded data from the farmer’s hometown between 2010 and 2014 and compared contemporary hardwood growth to the farmer’s records. He concluded that leaves stay on trees 15 percent longer than they did in the 19th century. This corresponds to about one additional month of growth.
The BBC writes that the “effects of the longer growing season are unknown”, but also that trees absorb carbon dioxide from the atmosphere during photosynthesis, “researchers said a longer growing season probably meant they were doing more of it”.
The results of the study shouldn’t come as a surprise to those who have looked at the data on plant growth trends.
According to satellite data from NASA’s Vegetation Index, Earth’s vegetation cover has increased over the past twenty years. Depending on the statistical analysis method used, as explained here in a Climate Realism post, global greening has ranged from 5 to 10 percent over the past twenty years. (See image below)
In addition, a study by Harvard et al. from 2020, how the current greening trajectory alone will offset 17 years of man-made carbon emissions by 2100, and that about 70 percent of greening after the 1980s will be caused by carbon fertilization. Another study found that the Sahara shrank by about 8 percent over a similar period.
Greening the earth is good for people and animals alike. This is especially true in large growing regions, where supplemental CO2 fertilization has helped increase production and yield of key crops, as Climate Realism has shown here, here, and here, among many other posts.
Seemingly unable to end a story on climate change on a positive note, the BBC story’s authors and researchers warn that “higher, fluctuating temperatures may also be taking a toll on trees in ways previously unknown”.
The pathways are “previously unknown” because no evidence of dangerous stress has emerged despite more than a hundred years of warming, but the benefits certainly do.
The BBC endeavored to create an alarming message with this story because the net effects of additional atmospheric CO2 and modest long-term warming were mostly beneficial to plant life, including trees, not detrimental. Available data shows that extended growing seasons have been and will be good for forest growth and vital crop production around the world. The OSU research team and BBC reporters should not attempt to deny the findings of this study, which only confirms what previous research has shown about the benefits of climate change for crop growth.
Linnea Lueken is a Research Fellow at the Arthur B. Robinson Center on Climate and Environmental Policy. While an intern at the Heartland Institute in 2018, she co-authored a Heartland Institute policy brief, Debunking Four Persistent Myths About Hydraulic Fracturing.