Increased Atmospheric CO2 Effects on Forest Health

[MarkGraham]

It is well documented increased atmospheric CO2,from the 200,000 year baseline of 280 ppm to current 410 ppm (all happening in the last 60 years) has had a profound effect on ecosystems, including increased temperatures and more severe weather events, such as drought and larger tropical storms. Furthermore for tree species the warmer winters are preventing annual cold temperature kill off of native and invasive insectivores, killing forests and shifting species ranges. Of great concern is the effect of increased carbon absorption by the oceans, which may have catastrophic impacts.

However potentially alleviating some of the bad news is the fact the increased CO2 provides increased energy for plant photosynthesis. The increased growth vigor of many plant species since 1960 has been noted in multiple studies, There is also some positive growth effect from increased nitrogen in rainfall. Farmers in the southeast US have reduced summer fertilization due to rainfall now having a higher nitrogen content.

From a tree height perspective, this may increase canopy heights in some forests. For example, 20 of the 100 tallest redwoods known in the year 2000 had height increases of five feet or more between 2000 and 2015.

The link below is to a summary provided by NASA in 2016 on these issues.

https://climate.nasa.gov/news/2436/co2-is-making-earth-greenerfor-now/