The U.S. Environmental Protection Agency and most atmospheric scientists agree that temperatures have continually fluctuated over the past 400 millennia and we are now experiencing another global warming trend. Our planet has survived five major warming peaks over that time, based on studies of estimated antarctic temperatures and ice core-measured levels of the main greenhouse gas, carbon dioxide (CO2).
So, scientists are relatively certain, citing land-based temperature records, that the Earth is currently as warm as it has been compared to other warm peaks over the past 400,000 years. A report by the Intergovernmental Panel on Climate Change (IPCC) found the recent warming to be summed up here: "eleven of the last twelve years (1995 to 2006) rank among the 12 warmest years in the instrumental record of global surface temperature (records since 1850)". These changes in Earth's temperature have correspondingly been associated with increased atmospheric carbon dioxide (as well as methane and nitrous oxide) levels in the atmosphere.
It is the very prestigious, Nobel Prize winning IPCC's contention that greenhouse gasses are for the most part man-caused due to increases in fossil fuel use and to land use changes associated with deforestation and urbanization. They further state that current agricultural practices are to be blamed for the increase in methane and nitrous oxide gas. The Earth's increase in human activity is causing the climate change we are now experiencing according to IPCC.
The Nongovernmental International Panel on Climate Change (NIPCC) leads the contrarian view on climate change. These detractors of "human activity events" being associated with global warming, point out the up-down cyclical nature of temps/gasses and that tend not to support a man-caused warming event. There is also an agreement within this community that natural causes (ex: sunspots) far exceed anything being done by any human action. Supporters do not acknowledge the validity of terrestrial temperature data collection methods used in the United Nations report. They insist that land-based temperature readings are located in convenient urban "heat zones" while no satellite nor weather balloon data is considered.
A Forests Effect on Global Warming and Climate Change
I have been in the forest data collection business for over three decades. I understand political and economic agendas and will not attempt to justify either side of the climate change issue. I do want to report what forests and forest managers, who have a great stake in the climate change outcome, are faced with and the opportunities they have toward mitigating climate change.
"Forests are shaped by climate" is a familiar quote that occurs over and over in climate change literature. One thing to remember is that while this is very true, climate is also "shaped by forests". Quoting from the Society of American Foresters (SAF) definitive report Forest Management Solutions for Mitigating Climate Change in the United States (PDF format), forests act as "windbreaks, and forest canopies influence the interactions of soil, water, and temperature". Forests can also "act as a carbon sink, helping to offset greenhouse gas emissions and forests sequestered more than 750 million tonnes of CO2 equivalent" according to a US EPA study done in 2005.
The forester's role in encouraging afforestation by establishing new forests in certain areas will "reduce surface reflectivity, or albedo, such that any reductions in radiative forcing (warming) gained from increases in carbon sequestration are offset". This simply means that these forests will become new sponges that lock-up atmospheric CO2 in the form of carbon. Creating a new forest is not the only way forest managers can lower greenhouse gases (GHG) and I want to go into that next.
Ways Foresters and Forest Owners Can Help Reduce Global Warming
Wood and Biomass Substitution - by substituting wood products manufacturing (that demand less energy to make than non-wood plastic and metal products) for high-energy demanding products, fossil fuel consumption during the manufacturing process is reduced. Using a biomass fuel substitute, these new technologies will ultimately reduce fossil fuel emissions and our dependance on them. All this is predicated on sound forestry and sustainable forest management.
Wildfire Behavior Modification - Reducing wildland fires, a major source of GHG emissions, limits the release of carbon stored in the forest into the atmosphere. Wildfires in many parts of the world, including the United States, have been increasing in size and severity which exacerbates the global warming problem. Foresters and forest owners can play a part in wildfire GHG emission reduction by using prescribed fire only under appropriate, planned conditions and timing that reduces smoke. Removing existing otherwise non-merchantable biomass for alternative fuels will become more important as the use of wood energy increases.
Avoiding Land Use Changes - More carbon is stored in woody plant dominated forests than in agricultural or developed land. Unfortunately, forest land prices lag way behind urban land prices and alternate land-use deforestation due to economics is way up, especially in the southeastern United States. The only way out of this economic problem is sustained forest management that encourages income from timber, hunting/fishing leases, carbon credits, biomass utilization and for pay recreation.
Promoting Carbon Credits - There are several market-based schemes, using carbon credits, that take advantage of a forest's ability to store carbon and thus "off-set" some of the GHGs released into the atmosphere. If a forester can manage a forest at full stocking, maintain tree health, minimize soil disturbance and reduce losses due to tree mortality, wildfires, insect, and disease - a carbon "sink" is created. This storing of carbon can be traded to high carbon emitters at a cost.