Colorado losing 15% of its aspen due to drought. Some of the worst wildfires on record burning millions of acres in Texas. The Euphorbia trees of southern Africa succumbing to heat and water stress.
All of these are real-world examples of rapid tree decline. For homeowners in pine beetle infested areas it is effecting industry and jobs, property values and even the power of local government to enforce tree preservation.
According to an October 1st article in the New York Times, dozens of tree habitats showing signs of accelerated stress and massive degradation.
Scientists are struggling to predict how serious large-scale forest decline may become. What is at stake is the timetable of climate change. This timetable is what drive policy for infrastructure changes and clean energy adoption.
The current consensus is that we can wait until midcentury, gradually phasing in cleaner energies to reduce emissions. Scientists also believe that by then, man made carbon control solutions will be feasible.
However accelerated forest decline would jeopardize that time table for one main reason. Trees are one of two main long term storage depots for stored carbon, the ocean being the second. Upset that fragile balance, could we create a tipping point from which we can’t return.
Trees serve to store carbon dioxide through the creation of wood and leaves. The inner bark layers effectively hold the carbon dioxide until the tree dies or is cut down.
While other plants may absorb carbon dioxide, most of it is returned to the atmosphere through decaying, burning or be eaten. Scientists estimate that during the northern hemisphere growing season 120 billion tons of carbon are inhaled from atmosphere. They exhale nearly the same amount.
However that can change in a heartbeat. Uncontrolled forest fires like the ones we’ve seen in Arizona this year not only burn trees but create huge carbon dioxide release events.
This contributes to further warming of the Earth as a whole, but may be felt sooner within a microclimate, say a national forest. In British Columbia and other pine beetle effected areas, mountain pine beetle attack has changed local weather patterns.
Even with recent insect epidemics, trees are still packing in a billion tons of carbon into long-term storage every year. Another unexpected finding is that forests appear to be growing more vigorously, even old-growth mature forests.
This development has overturned decades “ecological dogma.”
Studies by Harvard University have discovered that every forest has a carbon flux which is the amount of carbon dioxide that is being inhaled and exhaled. They have isolated variances throughout the day.
As we know more about the respiration process of trees we may be able to find ways to complement it.
Scientists skeptical of human influence on climate believe that these trends may represent a greening of the earth over the next 50 years not a large-scale degradation. As the Earth warms more trees will grow bigger and absorb more carbon.
After all, after clear cutting by early settlers, Eastern US forests are regrowing and recovering forest is an important carbon sponge.
However as the Earth warms it also helps many of their natural insect predators survive longer as well.
The mountain pine beetle’s natural predator is the cold. Temperatures of -40° Fahrenheit in the Canadian and US Rockies used to kill off large portions of the beetle population. However, over the past decade temperatures are just not reached that level on a consistent basis.
Furthermore warming may actually evaporate more water, especially in semi arid climates meaning the trees have less water to work with which could make the, them more vulnerable to insect and weather events.
As long as this trend continues, shuttered saw mills and declining tourist business is effecting communities and will continue to spread.
