Scientists throughout the world now confirmed that global warming is taking place, this warming is responsible for the immense changes in the earth’s climate systems as well as the formation of acid rain. These changes had tremendous impact on global forest covers. About half of the earth’s forests have been lost by being burned, cleared or cut down by humans over many centuries. Just one-fifth of the earth’s original forest cover remains today (World Resources Institute, 1997).
Thus, forests can be considered one of our most vulnerable natural resources, particularly vulnerable to our earth’s changing climate as a result of global warming and acid rain. There are significant evidences that suggest that the earth’s climate is changing at a rapid pace, mostly due to human activities such as the burning of fossil fuels. One statistic estimates that by 2100, global average temperature will increase from 1.8 to 6.3 degrees Fahrenheit (Environmental Defense Fund, 1997). Along with this immense warming of the planet, the burning of fossil fuels by humans has also created the problem of acid rain which also has significant impact on wildlife and forests globally. To present one example of the extent to which acid rain has the capacity to destroy entire forests, half of Germany’s forests had already been damaged by acid rain as of 1992 (Benjamin, WSC Spring 2008). It is the focus of this paper to explore how these two factors, global warming and acid rain, affect the state of the world’s forest.
Although the direct impact that humans have on the world’s forests is apparent through logging, mining, industrialized agriculture, mostly monocultures, and other reasons for deforestation, it is important to also consider how human contributions to global warming led to rapid increases in climate and production of acid rain which has indirectly and negatively impacts on the world’s forests. Furthermore, this paper will also emphasize the importance of forests to our earth’s ecosystems, and how their destruction in turn is further contributing to global warming and immense changes in the earth’s climate systems.
The definition of what constitutes a forest varies it is continually evolving as we learn more about this precious resource which contains diverse plants and animal species. However, the Food and Agricultural Organization of the United Nations (FAO) defines “forest” “both by the presence of trees and by the absence of other land uses regardless of the legal status of the land” (FAO, 2000). The organization also defines forests as having at least 10% canopy cover, which was an international definition set in 2000 (FAO, 2000).
Climate change is occurring largely because of anthropogenic factors. Although greenhouse gases (GHGs), mainly carbon dioxide, methane, and nitrous oxide, exist naturally in our atmosphere and help to stabilize the temperature of the earth, the increased concentrations of these gases is largely due to anthropogenic causes. Human emissions of GHGs have been on the rise since pre-industrial times, but in the period from 1970 to 2004 alone, human GHG emissions increased by 70% (IPCC, 2007). The most common known cause of these emissions is transportation; passenger vehicles emit 300 tons of carbon dioxide per year in the U.S. alone (HSUS, 2007). However, agricultural activities and land use systems also contribute significantly to increasing GHGs in our atmosphere. The increase in farm animal productions is driving deforestation and wooded areas are being transformed into grazing land and cropland for growing feed for animals. For instance, there has been a rapid rise in exportation of beef from Brazil, resulting in accelerated destruction of the Amazon rainforest. In just ten years between 1990 and 2000, an area twice the size of Portugal was lost to grazing land for cattle (HSUS, 2007). What is problematic about this in terms of global warming and climate change is that forests are the “carbon sinks” of our planet, keeping carbon dioxide levels stabilized by absorbing and storing much of this gas from the atmosphere. Forests are thus a precious resource that should be appreciated, protected and considered part of the solution to climate change.
One medium through which climate change is negatively impacting world forests is by creating conditions favorable to pests and pathogen outbreaks. For instance, Alaska has experienced die-off of many acres of its spruce trees, as the climate becoming warmer and drier has created the conditions for an invasion by spruce bark beetles (NPCA, 2007). This same effect is occurring in the Appalachian region, where rare and ancient forests are threatened by increasing insect pests (NPCA, 2007). A more expansive example of the drastic effects that insects and pests can have on forests is the outbreak of mountain pine beetle in British Columbia over the past decade, which is unprecedented in its scale and magnitude. The outbreak has been tied to the expansion of the habitat that is climatically suitable for the mountain pine beetle, due to reduced minimum winter temperature, increased summer temperatures and reduced summer precipitation (Kurz et. al 2008). Outbreaks such as these contribute to a vicious cycle of climate change, as dying trees emit carbon dioxide into the atmosphere. With fewer trees, less carbon dioxide is absorbed from the atmosphere. As one author notes, “Insect outbreaks such as this represent an important mechanism by which climate change may undermine the ability of northern forests to take up and store atmospheric carbon” (Kurz et. al 2008, pg. 1).
Harsh or extreme weather as a result of climate change also drastically impacts the world’s forests. Although the connection between extreme weather events and climate change is not yet clear, there is mounting evidence that the two are related. As Dr. Richard Moss, the World Wildlife Foundation’s vice president for climate change stated, “While no single storm can be directly attributed to climate change, the scientific evidence clearly shows that as the climate warms, extreme weather events will become more intense and more frequent” (Pouliot, 2008). For instance, episodes of sugar maple tree declines in southeastern Quebec in the 1980s have been tied to winters with periods of loss of snow-cover, followed by extreme cold, followed by summer drought. Snow-cover provides protection to tree roots from extreme cold; however, in the northern hemisphere snow-cover has been on the decline since 1988 (Environmental Defense Fund, 1997). Hurricanes and severe storms which cause high winds can also be deleterious to forests. Hurricanes Katrina and Rita resulted in the loss of 2 million hectares of forest in the gulf coast states of the U.S. (Beach et. al, 2008). One explanation for such destruction is that the weakening of trees by the increase in pest and pathogen outbreaks may be further increasing forests’ vulnerability to extreme weather events, which they could otherwise withstand.
Along with the effects of global warming and climate change on forests, acid rain also has a significant impact on the state of forests. Acid rain, also referred to as acid deposition or acid precipitation, is caused by the burning of fossil fuels by power plants, factories, and automobiles, thereby releasing sulfur oxides and nitrogen oxides into the air. These chemicals are eventually flushed from the atmosphere by precipitation and resulting rainfall is much higher than normal in acidity (Benjamin, WSC Spring 2008). Acidic compounds can also fall to the earth in dry form, such as gases, aerosols and particles (NAPAP, 2005). The reach of acid deposition can be widespread due to blowing of particles by the wind; thereby the source of the pollution causing the deposition is not always clear. This disruption of the pH balance in precipitation can have widespread effects, not only on forests but also on the acidity of oceans and degrades the habitat of many ocean species who cannot survive once acidity reaches a certain point. Furthermore, acid deposition is also detrimental for public health, including increased rates of respiratory conditions such as asthma.
One way in which acid deposition can harmfully affect forests is by changing the composition of the soil in these forests. Data collected in the White Mountains of New Hampshire suggests that acid rain leads to the loss of large amounts of calcium and magnesium from the soil, nutrients essential for plant growth and development. The loss of calcium may also lead to release of aluminum in soils, which is toxic to tree roots in high concentrations (Environmental Defense Fund, 1997). Trees leeched of their nutrients are left weak and with little resistance to natural threats to their survival, including pest outbreaks, drought and extreme weather events, all of which are thought to be occurring more frequently due to climate change.
Additionally, forests are negatively affected by ground-level ozone which is formed when nitrous oxide emissions interact with volatile organic carbons (VOCs) (NAPAP, 2005). Ozone has acute toxic effects on plant leaves and chronic toxic effects (NAPAP, 2005). Several forests in the U.S. are showing signs of nitrogen saturation, whereby the inputs of nitrogen exceed the forests’ needs. This excess nitrogen is leached into surrounding waterways (NAPAP, 2005). Thus, the entire interconnected forest ecosystem is affected by acid rain, not just the trees and plants in the forests. A significant program in the U.S. to combat acid deposition instituted in 1990 is called Title IV of the Clean Air Act Amendments. This legislation requires significant reduction in the emission of sulfur oxides and nitrous oxides, the pollutants causing acid rain (NAPAP, 2005), and has resulted in significant reductions of industrial sources of these emissions.
However, no forests in the U.S. have yet showed recovery in terms of reversal of soil acidification (NAPAP, 2005). Reduced emissions may be slow to impact forest recovery, as compared to aquatic ecosystems; forests may only show improvement in the long-term because of the complex processes of nutrient cycling which must occur before changes in soil composition are seen. The assessment methods of forest health under Title IV have also been limited as compared to the assessment of other ecosystems’ recovery from acid deposition. This may be due to a combination of the complexity of the nutrient cycling process in forests as well as difficulty in quantifying which proportion of the acid deposition in forests is occurring due to anthropogenic emissions versus natural factors.
In light of the stark reality facing our forests today and in the near future, including increased vulnerability to pests and extreme weather, and acidification of soils due to acid deposition, we must consider how the forest ecosystem as a whole as well as how other ecosystem will be affected by this damage. The degradation of forests will likely result in the loss of biodiversity as many species are dependent on forests for their habitat. For instance, one of the threatened forests, the Great Smoky Mountains National Park in the Appalachian region, is home to one of the few remaining strips of eastern old forest as well as a host of species of trees and this one park has more tree species than all of Europe (NPCA, 2007).
Degradation of forests will also impact our river, streams, and other waterways. “Stream narrowing” has been evidenced as occurring in streams without forest cover. This can have serious ecological consequences, resulting in 54% less surface area to provide habitat for aquatic organisms. Also, forest cover helps to shade the stream from solar radiation and thereby cools the stream. Ecosystems in streams without forested cover have shown reduced productivity and diversity (Schueler, 2000). These examples are just some of the many means through which forests are necessary for our earth’s ecosystems to function.
In conclusion, this paper’s assessment of the impacts of global warming and acid rain on forests covers and in turn forest ecosystems and other ecosystem suggest that forests are particularly vulnerable to these environmental factors। Pollutants being pumped into our atmosphere now will likely have lingering effects into the future for forests. Significant changes must be made in how we as humans and as consumers interact with our environment, as our very survival is dependent on forests and other natural resources also being negatively affected by climate change. Although individuals can make small changes in their consumption patterns, by using renewable sources of energy and decreasing our reliance on fossil fuels, governments and international organization such as the United Nations (UN) and the Inter-Governmental Panel on Climate Change (IPCC) must continue to make policies to reduce the impacts of climate change and global warming on forest covers, it’s ecosystems, and also to strictly enforce these policies on both the local and global levels with serious consequences if any nation fails to follow these policies. Protecting, conserving and sustaining the earth and its forests should be our primary responsibilities as individuals, communities and nations if our continual existence on earth is significant, because without forests the earth will be a “living hell” for humans.
The Human Society of the United States. (2007). An HSUS report: The impact of animal agriculture of global warming and climate change. Retrieved March 11, 2009, from http://www.hsus.org/web-files/PDF/farm/animal-agriculture-and-climate.pdf
Intergovernmental Panel on Climate Change (IPCC). (2007). Climate Change 2007: Synthesis Report. Retrieved March 25, 2009, from http://www.ipcc.ch/ipccreports/assessments-reports.htm
World Resources Institute. (1997). The last frontier forests: ecosystems and economies on the edge. Retrieved March 24, 2009, from http://www.wri.org/publications/ecosystems?page=1
Environmental Defense Fund. (1997). Seasons of change: global warming and New England’s White Mountains. Retrieved March 11, 2009, from http://www.edf.org/page.cfm?tagID=825&template=1359
Benjamin, P. (WSC Spring, 2008). Global Environmental Change [PowerPoint slides]. Retrieved from Worcester State College Blackboard site: http://blackboard.worcester.edu
National Parks Conservation Association. (2007, July). Unnatural Disaster: global warming and our national parks. Retrieved March 11, 2009, from http://www.npca.org/media_center/reports/
Kurz, W.A., Dymond, C.C., Stinson, G., Rampley, G.J., Neilson, E.T., Carroll, A.L., et al. (2008). Mountain pine beetle and forest carbon feedback to climate change. Nature, 452, 982-990.
Pouliot, J. (2008, June 19). Climate Change Fueling Extreme Weather Events, Government Study Finds. [Press Release]. Washington: World Wildlife Fund.
Beach, R.H., Sills, E.O., Liu, T., Pattanayak, S.K. (2008). Severe Weather and Forest Impacts. In Forest Encyclopedia Network. Retrieved March 25, 2009, from http://www.forestencyclopedia.net/p/p2993/view
National Acid Precipitation Assessment Program. (2005). National Acid Precipitation Assessment Program report to Congress: An integrated assessment. Retrieved March 25, 2009, from http://www.ny.cf.er.usgs.gov/napap/Information/NAPAP%20Report%208-22-05.pdf
Schueler, T. (2000). Impact of riparian forest cover on mid-Atlantic stream ecosystems. In T. Schueler and H. Holland (Eds.), The Practice of Watershed Protection (p. 19). Ellicott City, MD: Center for Watershed Protection.