The Effect of Climate Change in Tropical Forests
Erin Florer

Northeastern State University

I. Introduction.
Climate change in the tropical forests has been an issue for years and the forests are facing repercussions of climate change more than ever. Scientists all over the world have been debating the reality of climate change in more recent studies. The cause of the change is more debated, but the evidence is strong that it results from human acidity. Data show that global temperature is rising. Over the past century, global average temperature has increased approximately 0.6 degrees Celsius and the expectation is that this trend will continue, if not intensify. (Kricher, 2011). The following paper will discuss some of the issues along with solutions of climate change in the tropical forests.

II. Effects of Climate Change in Tropical Forests.

II-A. Climate Change Defined.
The effect of climate change on tropical rainforests is of global and regional concern, in part due to the high diversity of these areas. Tropical forests house at least half of all the species in the world, indicating that changes will have enormous impact on global biodiversity. In addition, tropical forests are intrinsically linked to carbon, water, and nutrient cycles. For example, 40% of terrestrial vegetation carbon stocks are contained within tropical forests, making this land cover an important source of carbon sequestering. The various links that exist between tropical forests and other ecological processes how that climate change has a potentially great impact beyond simply one geographic area. (Zhu, 2007).

II-B. Carbon Dioxide.
The forcing of climate change is believed to be due to increasing levels of greenhouse gases in the atmosphere. Such gases include carbon dioxide, the principal gas emitted from fossil fuel burning, as well as nitrous oxides and methane. Of those Carbon dioxide is the most important. Carbon dioxide is released into the atmosphere by burning of fossil fuel and by deforestation. (Kricher, 2011). One of the consequences of deforestation is that the carbon originally held in forests is released to the atmosphere, either immediately if the trees are burned, or more slowly as unburned organic matter decays. Only a small fraction of the biomass initially held in a forest ends up stored in houses or other long-lasting structures. Most of the carbon is released to the atmosphere as carbon dioxide, but small amounts of methane and carbon monoxide may also be released with decomposition or burning. Cultivation also oxidizes 25-30% of the organic matter in the upper meter of soil and releases that to the atmosphere. Reforestation reverses these fluxes of carbon. While forests are regrowing, they withdraw carbon from the atmosphere and accumulate it again in trees and soil. Although deforestation, itself, may not release significant quantities of methane or nitrous oxide, these gases are often released as a consequence of using the cleared land for cattle or other ruminant livestock, paddy rice, or other crops, especially those fertilized with nitrogen. (Santilli et al., 2005).

File:Nasa AIRS CO2 July03.jpg
File:Nasa AIRS CO2 July03.jpg

II-C. Predictions of Climate Change.
The rapid increase in carbon dioxide emissions observed during the last 250 years is expected to continue for several decades to come. Various scenarios have been examined, depending on factors like fuel use and efficiency. Even the best case scenario predicts further increases in carbon dioxide emissions until about 2040. Many of the scenarios indicate that by the middle of the 21st century emissions of carbon dioxide should at least start to level off, though some predict increase in emissions throughout this century. Though the different scenarios predict a wide range of trends in carbon dioxide emissions, the predicted net effect on atmospheric carbon dioxide concentrations in the future is fairly consistent. All predict further increase in carbon dioxide concentrations by the end of the is century, with some of the scenarios predicting a doubling or even trebling of today's levels of carbon dioxide. If the predicted increases in greenhouse gas concentrations are then translated into temperature changes, a global temperature increase of between 1 and 5.5 degrees centigrade is predicted for 2100. The average predicted temperature increase over the next 100 years is around 3 degrees centigrade. This compares to an increase of about 1 degree centigrade due to previous man-made greenhouse gas emissions. The large amount of variation between predictions of the different scenarios underlines the complexity involved in making such predictions and the large amount of uncertainty inherent in climate change models. A common feature of global warming stories in the media is sea level rise. Sea level rise, through the thermal expansion of water and ice melt around the world, poses a potentially very serious threat to millions of people. Like temperature change, predictions vary widely, from a low of 20 cm to a high of around 60cm. The impact of such sea level rise is likely to be greatest in those low lying countries, like Bangladesh, least able to adapt to the sea level rise by building expensive sea defenses. (Reay, 2013).

III. Climate Change Effects Biodiversity.
Biological diversity or biodiversity refers to the total variability of life on Earth. It includes variation at the species level, at other taxonomic levels, and at the genetic level. It also pertains to variation in ecological functions such as those of pollinators and seed dispersers. As air temperatures and CO 2 concentrations rise, and as water and nutrient availability change, fundamental ecological processes will also be changed. Consequently, changes in biodiversity that have already been observed in temperate areas will likely occur. There will be, however, significant variations between species in response to climate change. Some species will surely suffer less than predicted due to greater-than-expected environmental tolerance, while others will decline at unexpectedly high rates. (Zhu, 2007).

III-A. Changes in Flora Populations.
Tress are particularly limited by geographic, physiological, and mobility constraints. Whereas some species have experienced range expansions and shifts as a result of climate change, trees are not equipped to adapt quickly to environmental changes because of their long maturation period and inability to move (CIDA 2007). As such, it is possible that extensive diebacks could occur as conditions become unfavorable to certain species; it is more likely that forests would experience shifts in species composition as a consequence of shifts in growing conditions. Lianas are woody climbers that use trees to climb up the canopy, where they spread from tree to tree to get as much light as possible. Changes in species composition and function within tropical rainforests were first indicated by a 1.7-4.6% increase in large liania density, relative to trees, in the past two decades (Philips et al. 2007). A larger, long-term monitoring study in Panama has also reported a substantial increase in both absolute and relative liana leaf-fall rates in this period, showing that lianas are becoming more dominant in that area (Wright et al. 2004). More recent studies have suggested shifts in the proportion of faster-growing, light-demanding, gap-favoring species, compared to more shade-tolerant trees (Korner 2004). In a well-studied old-growth tropical forest landscape in Brazil, Laurance et al. (2004) found that growth, mortality, and recruitment of faster-growing genera of canopy and emergent stature trees increased significantly over two decades. In contrast, slower-growing genera of sub-canopy or under-story trees decreased in density across the board. (Zhu, 2007).

III-B. Changes in Fauna Populations.
Past observations illustrate the possible severity of species declines due to climate change. A published study by Whitfield (2011) found that amphibian and reptile populations decreased by 75% since 1970 in a protected old-growth lowland rainforest of Costa Rica. Salamanders declined an average of 14.5% per year since 1970, followed by lizards (4.5%) and frogs (4%). The author singled out climate change as the primary agent behind this population collapse, citing that a combination of overly wet conditions and rising temperatures has negatively impacted critical microhabitats for many species. Interestingly, several other studies in different tropical rainforests have also found rapid amphibian declines, but cite as the primary cause regional temperature increases that raise cloud formation levels and effectively dry out the cloud forest moisture on which frogs like the golden toad depend. These findings indicate that climate-induced, systematic declines in amphibian populations occur not only in cooler climates (to date amphibian declines have mostly been observed in temperate regions or mountainous areas in the tropics), but are also possible in tropical rainforests. Along with amphibians and reptiles, various birds and mammals – especially those limited by geographic restraints (e.g. island-dwellers) – are also likely to be negatively impacted. (Zhu, 2007).

IV. Habitat Importance.
Forests are essential for life on earth. Three hundred million people worldwide live in forests and 1.6 billion depend on them for their livelihoods. Forests also provide habitat for a vast array of plants and animals, many of which are still undiscovered. They protect our watersheds. They inspire wonder and provide places for recreation. They supply the oxygen we need to survive. They provide the timber for products we use every day. Forests are so much more than a collection of trees. Forests are home to 80% of the world’s terrestrial biodiversity. These ecosystems are complex webs of organisms that include plants, animals, fungi and bacteria. Forests take many forms, depending on their latitude, local soil, rainfall and prevailing temperatures. Coniferous forests are dominated by cone-bearing trees, like pines and firs that can thrive in northern latitudes where these forests are often found. Many temperate forests house both coniferous and broad-leafed trees, such as oaks and elms, which can turn beautiful shades of orange, yellow and red in the fall. The most biologically diverse and complex forests on earth are tropical rainforests, where rainfall is abundant and temperatures are always warm. Forests also play a critical role in mitigating climate change because they act as a carbon sink—soaking up carbon dioxide and other greenhouse gases that would otherwise be free in the atmosphere and contribute to ongoing changes in climate patterns. But forests are being destroyed and degraded at alarming rates. Deforestation comes in many forms, including fires, clear-cutting for agriculture, ranching and development, unsustainable logging for timber, and degradation due to climate change. This impacts people’s livelihoods and threatens a wide range of plant and animal species. Some 46-58 million square miles of forest are lost each year—equivalent to 36 football fields every minute. The Amazon, the planet’s largest rainforest, lost at least 17% of its forest cover in the last half century due to human activity. In Indonesia, the island of Sumatra has lost 85% of its forests—primarily due to conversion for oil palm and pulp plantations—and a similar level of destruction is taking place on the island of Borneo. Deforestation also undermines the important carbon sink function of forests. It is estimated that 15% of all greenhouse gas emissions are the result of deforestation. (WWF, 2013).

Photo courtesy Indonesian Climate Change Center.
Photo courtesy Indonesian Climate Change Center.

IV-1. Humans Can Help.
The United States Environmental Protection Agency (EPA) is taking a number of common-sense steps to address the challenge of
climate change. The EPA collects various types of greenhouse gas emissions data. This data helps policy makers, businesses, and the Agency track greenhouse gas emissions trends and identify opportunities for reducing emissions and increasing efficiency.The Inventory of U.S. Greenhouse Gas Emissions and Sinks, provides the United States' official estimate of total national-level greenhouse gas emissions. This report tracks annual U.S. greenhouse gas emissions since 1990. The Greenhouse Gas Reporting Program collects and publishes emissions data from individual facilities in the United States that emit greenhouse gases in large quantities. The EPA is just one of many more agencies that are trying to help our world.

Climate change will not be removed but with the help of companies like EPA we can all do our part in making the world a better place to live.

V. Conclusion.
Humans have had very little to do with the evolution of rain forests, yet they are largely responsible for forest destruction. As Thomas Friedman, in his book Hot, Flat, and Crowded, stated “We are the only species in this vast web of life that no animal or plant in nature depends on for its survival—–yet we depend on this whole web of life for our survival.” (Mori, 2011). Humans will not be able to stop climate change from happening but they can help slow it down in the future. Even though we may not live in a tropical forest we as humans are still in need of what the forests have to offer even if we don’t see the benefits directly.

Photo by  katerha, 2007.
Photo by katerha, 2007.

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Santilli, M., Moutinho, P., Schwartzman, S., Nepstad, D., Curran, L., & Nobre, C. (2005). Tropical Deforestation and the Kyoto Protocol. Climatic Change, 71(3), 267-276. doi: 10.1007/s10584-005-8074-6
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