American Elephants


Annoy a Green True Believer. Tell Them CO2 Makes Forests Grow. by The Elephant's Child

Hoh rainforest
Steven Hayward published an abstract from the coming issue of Forest Ecology & Management which includes an article that finds rising CO2 levels in the atmosphere are mostly beneficial for our forests. Here’s the complete abstract, which will annoy the Greens.

Physiological and ecological factors influencing recent trends in United States forest health responses to climate change

Abstract

The health of United States forests is of concern for biodiversity conservation, ecosystem services, forest commercial values, and other reasons. Climate change, rising concentrations of CO2 and some pollutants could plausibly have affected forest health and growth rates over the past 150 years and may affect forests in the future. Multiple factors must be considered when assessing present and future forest health. Factors undergoing change include temperature, precipitation (including flood and drought), CO2 concentration, N deposition, and air pollutants. Secondary effects include alteration of pest and pathogen dynamics by climate change. We provide a review of these factors as they relate to forest health and climate change. We find that plants can shift their optimum temperature for photosynthesis, especially in the presence of elevated CO2, which also increases plant productivity. No clear national trend to date has been reported for flood or drought or their effects on forests except for a current drought in the US Southwest. Additionally, elevated CO2 increases water use efficiency and protects plants from drought. Pollutants can reduce plant growth but concentrations of major pollutants such as ozone have declined modestly. Ozone damage in particular is lessened by rising CO2. No clear trend has been reported for pathogen or insect damage but experiments suggest that in many cases rising CO2 enhances plant resistance to both agents. There is strong evidence from the United States and globally that forest growth has been increasing over recent decades to the past 100+ years. Future prospects for forests are not clear because different models produce divergent forecasts. However, forest growth models that incorporate more realistic physiological responses to rising CO2 are more likely to show future enhanced growth. Overall, our review suggests that United States forest health has improved over recent decades and is not likely to be impaired in at least the next few decades.

The study is behind a paywall, but you can get the gist of it from this, and this bit from the conclusion.

The health of United States forests is of increasing concern among scientists and policymakers who predict that CO2-induced climate change will have negative effects on forest establishment and growth. However, when considered over long time frames, drought area does not appear to be increasing in the United States as a whole, though local and periodic excursions are to be expected and do occur. Multiple types of historical data indicate increasing forest productivity. Long-term data on trends for insect and disease incidence and impacts are mostly lacking. . . The IPCC (AR5, WGII p. 305) has reached a similar conclusion, stating: “There is low confidence that climate change is threatening the temperate forest carbon sink directly or indirectly.”

Forest Ecology and Management will probably not be anyone’s favorite bedtime reading, but we skeptics gather up whatever evidence we find to annoy the climate loonies. They are true believers, a sort of religion, and they are quite passionate about it. But wrong.


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