Climate Change Very Likely to Slow Plant Growth in Northern Hemisphere

Future reversal of warming-enhanced vegetation productivity in the Northern Hemisphere

By: Yichen Zhang, Shillong Piao, Yan Sun, Brendan M. Rogers, Xiangyi Li, Xu Lian, Zhihua Liu, Anping Chen, Josep Peñuelas

Summarized by: Michael Hallinan

What data were used? No new data was generated for this study, instead existing data from different sources was used and combined. The majority of the data used in this study comes from FLUXCOM, an initiative that uses satellite remote sensing, meteorological data, and site level observations at a global scale. In addition, data was also sourced from the World Climate Research Program, including from a variety of contributors such as the Canadian Center for Climate Modeling and Analysis and the Indian Institute of Tropical Meteorology. Information on temperature, precipitation, surface downwelling shortwave radiation, maximum near-surface air temperature, and total influx of carbon into an ecosystem were used.

Methods: An earth climate model was created using the relationship between surface air temperature, summer carbon influx, precipitation, and surface downwelling radiation for the Northern Hemisphere. This model featured a moving 20-year window from 2001-2020 all the way to 2081-2100. Then using this model, analysis on carbon influx and surface air temperature was performed to generate a predictive model for temperature. From here, bias corrections were applied using observed data from 2001 to 2013 to help correct the model. Finally, projected temperatures were then compared to the historically observed optimal temperature for vegetation productivity. 

Results: Through this study it was discovered that there is a positive correlation between carbon fixation during summer and temperatures, although the correlation becomes negative at lower latitudes, specifically less than 45 degrees North, which could be a result of water deficits. Furthermore, it was also seen that about 48% of Northern vegetative land will see a significant decrease in the quantity of carbon fixed as a result of warming by 2060. Most regions will also experience a reduction in vegetative productivity as early as 2030-2070. This development will likely not reach the northern regions prior to the end of the modeled time frame (2100). However, in the worst case scenario most latitudes south of 50 degrees north such as much of the temperate United States, Asia, and the equatorial regions of Africa and South America were affected. It is important to note that study does not account for any of the southern hemisphere. 

A model of the earth, showing when temperature increase will begin to have a net negative effect on vegetative growth. Much of the northern hemisphere below 50 degrees north experiences this in 2030 or earlier. Slightly north of those regions the estimate is closer to 2070, with regions near the Artic and Tibetan Plateau not experiencing this till the end of the modeled time frame of 2100.
Map identifying the worst case scenarios climate model, showing timing of when temperature increase will begin to have a net negative effect on vegetative growth.

Why is the study important?: Climate change includes an increase in temperatures, which has caused an increase in vegetation productivity in the extratropical Northern Hemisphere since 1980. However, as climate change has begun to speed up, the positive benefits are estimated to change into a net negative effect on growth as temperature increases further. This study delves further into this idea and creates estimates based on different regions of when that will occur. This in turn can allow for preparedness, such as advancement of remediation plans to help us offset the negative effects of extreme temperatures on plant growth. 

The Big Picture: Vegetation is essential for agriculture, ecosystem balance, and general quality of life, so understanding the potential threat this aspect of climate change holds is essential for long-term sustainability and survival. Climate change has had a positive influence on plant growth in the extratropical Northern Hemisphere as early as 1980. However, this study has shown a shift in this to being a net negative influence as early as 2030 especially in regions below 50 degrees North. Regions closer to the Arctic and Tibetan Plateau are much less (or much slower) affected though, with a worst-case scenario not showing a tipping point prior to 2100 when net negative effects occur. Using these estimates, we can plan for this decrease in vegetative productivity as well as try to adapt and mitigate to minimize future negative impacts induced by the temperature increase.

Citation: Zhang, Y., Piao, S., Sun, Y. et al. Future reversal of warming-enhanced vegetation productivity in the Northern Hemisphere. Nat. Clim. Chang. 12, 581–586 (2022).

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