Increased CO2 increases tree growth

From CO2 Science:

Two researchers have found that increased intrinsic water-use efficiency (iWUE) of ponderosa pine associated with rising CO2 can positively impact tree growth rate.

University of Western Sydney EucFACE study.
Effects of Anthropogenic CO2 Emissions on the Growth and Water Use Efficiency of Western U.S. Ponderosa Pine Trees

Soule, P.T. and Knapp, P.A. 2011. Radial growth and increased water-use efficiency for ponderosa pine trees in three regions in the western United States. The Professional Geographer 63: 379-391.

What it means
The two researchers say their findings suggest that "increased iWUE associated with rising CO2 can positively impact tree growth rates in the western United States and are thus an evolving component of forest ecosystem processes." And these CO2-induced iWUE increases are a mighty positive component, we might add, which is quite the opposite of what one would expect from what many climate alarmists claim to be a harmful air pollutant, which must be stopped from accumulating in the atmosphere at all costs.

This corresponds with a study by the University of Western Sydney EucFACE study. - see also HERE
Hawkesbury Institute scientist Professor David Ellsworth has said the project will show changes in growth and water consumption with the added CO2:"There may be debate about climate change but there is nobody out there who doesn't think CO2 levels are rising. It's a future we want to avoid but one we're unlikely to. Scientifically, there's huge alarm over carbon dioxide."
Cherry picked quote from Professor David Ellsworth - "....the short-term mechanism of photosynthetic response would suggest a large CO2 stimulation effect in interaction with some other climatic stresses (drought and warming)...."

HFE study
The forerunner to EucFACE at UWS was the Hawkesbury Experiment (HFE). The trees were originally encased under the HFE study.
Scientists have previously observed that plants respond to high CO2 levels by increasing photosynthetic activity which makes more fuel available for root mass growth and can lead to greater forest productivity. In addition high CO2 levels can cause the leaf stomata to close thereby reducing the plant’s requirements for water. This could impact the amount of water that flows into streams and rivers and groundwater recharge. However, climate change also involves a rise in temperatures and this will affect weather patterns including rainfall and humidity, which will also impact tree growth. According to HFE researchers there is an urgent need to study these effects on Australia’s native plant species ”to underpin Australia’s environmental and catchment management strategies for the 21st century”.
From Climate change and Forestry (pdf)
Under elevated CO2, plants open their stomata less, thus transpiring less water. Therefore, the water use efficiency of plants (i.e. the growth per unit of water transpired) is predicted to increase at higher CO2 concentration, which may offset negative impacts on growth in those areas in which rainfall is predicted to decline.
From Science Alert Nov 2010
A team of researchers including Craig Barton from Industry & Investment NSW (I&I NSW), and Jann Conroy and Burhan Amiji from the University of Western Sydney, is revealing how native forests will react to climate change.
The quest to discover how native trees respond to climate change is showing they are true Aussie battlers, with a capacity to conserve their resources and use less water as they continue to grow.
The knowledge gained from the project will underpin environmental and catchment management strategies for the 21st century.
It’s a world first, recently described to the International Union of Forest Research Organizations (IUFRO).


  1. With a minor rephrase of an old saying:
    Those who do not listen in school are doomed to repeat their homework later.
    - It is just too bad that they are getting paid good money to rediscover the bleeding obvious.


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