This paper was written as part of the 2005 Alaska Ocean Sciences Bowl high school competition. The conclusions in this report are solely those of the student authors.

Effects of Climate Change on Marine and Terrestrial Ecosystems in the Area of Juneau, Southeast Alaska

Authors

Ashley Kelly
Bekah Menze
Devon Kibby
Emily Peyton
Kelsey Potdevin

Team Steller
Juneau Douglas High School
10014 Crazy Horse Drive
Juneau, AK 99801

Table of Contents

1. Abstract
2. Introduction
3. Global Warming
4. Local Climate Change
5. Socio-economic Values
6. Conclusion
7. Recommendations
8. Figures and Tables
9. References

Abstract

Both natural and anthropogenic sources of CO₂ contribute to earth's warming atmosphere, but anthropogenic sources are contributing at an alarming rate. CO₂, possibly caused by the combustion of fossil fuels, are major contributors. Gases produced by fossil fuel combustion may linger in the atmosphere for decades, even centuries.

Climate change in Alaska is more dramatic than other places across the globe partly due to its latitude. In Juneau, Alaska, both the marine and terrestrial ecosystems are influenced and shaped by glaciers. Located on the southeast coast of Alaska, the Juneau Ice Field covers 1800 square miles and are situated in a location extremely sensitive to fluctuations on the Polar Front. In recent years, the snow pack around the Juneau Ice Field has reduced due to decreased snowfall and increased precipitation, negatively impacting stream hydrology and salmon populations.

Average local sea surface temperature has increased in recent decades. Water temperature is one of the most important characteristics of marine environments. Water temperature changes affect the metabolism and other processes of marine plants and animals with effects throughout the food web. Total marine food web productivity is negatively affected by the increase of CO₂. Any decreases in phytoplankton productivity further exacerbates biological uptake of CO₂.

The local climate trends have negative ecological and economic effects on southeast Alaska forests. The climate change has contributed to excellent growing conditions for spruce, but at the same time has provided conditions aiding the survival of the spruce bark beetle.

Recommendations are presented for managing terrestrial and marine ecosystems as well as energy policy.

Introduction

This paper explores causes of global warming, climate change and their effects on southeast Alaska both ecologically and economically. It also includes recommendations for energy and resource management.

Global Warming

It is generally accepted the planet's atmosphere is warming and that humans are partially responsible. Both natural and human factors have contributed to this well-supported theory. Scientists agree that greenhouse gases produced, especially CO₂ caused by the combustion of fossil fuels, are major contributors to gases produced by fossil fuel combustion may linger in the atmosphere for decades, and even centuries. Scientists predict as the level of greenhouse gases rises, so do average global temperatures (http://yosemite.epa.gov/oar/globalwarming.nsf/content/ImpactsPolarRegions.html).

Globally, concerns among the scientific community include damage to important and sensitive ecosystems such as wetlands, estuaries, and coral reefs. Also predicted are increased frequency and intensity of storms, hurricanes and El Niño events. Global warming has been linked to a rise in sea level and an increase in low land flooding.

The Greenhouse Effect and Human Contributions to Climate Change

The greenhouse effect is essential for life on earth to exist. Though CO₂ is a naturally occurring atmospheric gas, humans have the capability to speed its accumulation in the upper atmosphere by releasing an excess amount. This extra human contribution is known as the "enhanced greenhouse effect". If these gases were able to escape and not absorb the long-wave (infrared) radiation from the sun, the Earth would have an estimated temperature of -18?C, as opposed to the current average 15?C. When greenhouse gases absorb the infrared radiation, it is converted into heat energy and raises the atmospheric temperature (Gow et a.l, 1996).

Since the 1700's, around the time of the industrial revolution, there has been a rapid rise in anthropogenic greenhouse gases released into the atmosphere. By doubling the concentration of CO₂ in the atmosphere, the average Earth temperature could increase by 1°C to 3°C. CO₂ accounts for 55% of the intensity of global warming. The other 45% of warming is attributed to other human-released gases such as methane, chlorofluorocarbons (CFCs), nitrous oxide, and tropospheric ozone (Table 1) (Gow et a.l, 1996).

Carbon Cycle

The oceans interact with almost every part of Earth either directly or indirectly. The flow of nutrients between the world's forest and the ocean can be seen through observation of the carbon cycle (Figure 1).

Most of the carbon released into the atmosphere is gaseous carbon dioxide. CO₂ is released into the atmosphere in two notable ways, deforestation and the burning of fossil fuels. Most CO₂ is absorbed by carbon sinks (e.g. the ocean), but surplus CO₂ is released into the atmosphere where it accumulates.

The planet absorbs CO₂ as forest growth and ocean phytoplankton production (Figure 1). Additional atmospheric CO₂ dissolves in the ocean forming a weak acid. As the ocean takes in more CO₂, the pH will lower. According to studies, this could have a profound effect on all parts of oceanic life. Although the salt water provides a strong buffer to pH change, the ocean surface pH is dropping. Effects of this will be seen in the bottom of the food chain, the phytoplankton. Some phytoplankton form calcium carbonate shells. Lower pH water it makes it harder for shell forming phytoplankton to gather enough carbonate ions. It's estimated that the rate at which these organisms form their shells could slow 25%-45% (Pickrell, 2004). This lower productivity could lessen sedimentation in the ocean, making for higher future carbon dioxide concentrations in the atmosphere and ocean. As for the creatures of the sea that rely on the phytoplankton; reductions in phytoplankton productivity would affect the food web all the way to the apex predators.

Local Climate Change

Climate change in Alaska is more dramatic than other places across the globe partly due to its latitude. Average temperature in Alaska has changed about 2.2°C (4°F) since the 1950's. Atmospheric CO₂ concentrations have steadily increased in Barrow, Alaska since the 1970's (http://www.besis.uaf.edu/global_warming/can_do.html).

Juneau, Alaska lies within the Alexander Archipelago in a temperate rainforest at the base of the Coastal Mountain Range, beneath the Juneau Ice Field. The environment, both marine and terrestrial, is influenced and shaped by glaciers. Melting glaciers, decreasing snow pack, increasing sea surface and atmospheric temperature, and rapidly changing forest ecosystems are a few local indicators of global climate changes.

Of Alaska's more than 2,000 glaciers, fewer than 20 are advancing (Mayell, 2001). Located on the southeast coast of Alaska, the Juneau Ice Field covers 1800 square miles and is situated in a location extremely sensitive to fluctuations in the Polar Front.

The Mendenhall Glacier, one of Juneau's premier tourist attractions, is thinning and receding at a substantial rate. In the past century its terminus has withdrawn nearly 3 km, thinned more than 200m and continues to thin at an accelerated rate. Although there have been brief years where the net change in volume has been positive, the overall trend in volume change is overwhelmingly negative. "These dramatic changes appear to be caused primarily by climatic changes" (Motyka et. al., 2002).

Atmospheric and Oceanographic Interactions

Ten miles north of downtown Juneau, Auke Bay is the site of the National Oceanic and Atmospheric Administration (NOAA) lab. Scientists there have been collecting oceanic and atmospheric data for decades (Figure 2).

Winds in this area predominantly come from the south, off of the Pacific Ocean. These warm and moisture-laden winds strike the high coastal ranges and result in plentiful precipitation, little sunshine, and moderate air temperatures. The annual precipitation trend between 1963 and 1993 shows an increase during this time period. (Figure 3) (Wing et. al., 1998).

In recent years the snow pack around the Juneau Ice Field has decreased due to reduced snowfall and increased rainfall. Shrinking winter snow pack has a negative effect on stream hydrology during the summer spawning season (Wing pers. comm. 12/1/04). Although there has been more precipitation in the winter, it is in the form of rain and does not benefit the salmon as summer water flow (Figure 4).

Average sea surface temperature has increased. This reflects the corresponding increase of precipitation during the same time period (Figure 5). Water temperature is one of the most important characteristics of marine environments. When the temperature changes, it affects the metabolism and other processes of marine life. Though surface temperature changes will likely affect the local marine food web, there are too many variables to know whether such changes will be positive or negative.

Climate Effects on Forest Systems

Local climate trends have a negative ecological and economical effect on southeast Alaska forests. Milder winters augment the spread of spruce bark beetles and favor their reproduction. Decreasing snow pack also make the yellow cedar, Chamaercyparis nootkatensis, roots more susceptible to freezing, thus increasing mortality (Wing et. al., 1998).

Southeast Alaska old-growth spruce/hemlock forests are considered to be healthy natural forest in that they are sustainable. Sustainable forest can be characterized by a simple cycle of when one tree dies it's replaced by another. The forest is static. Over a broad area, healthy forests change very little year to year. Even healthy forests are diseased, especially with internal wood decay of live trees or heart rot.

A forest that develops by clear-cut is generally free from disease in contrast to an old growth forest. Unfortunately, the clear-cut forest can't be viewed as healthy because they have lost much of their ecological function. Clear-cut forests are less successful at sustaining wildlife habitats due to their lack of habitat diversity.

Yellow Cedar Decline

The yellow-cedar (Chamaercyparis nootkatensis) has long bee both economically and ecologically valuable in southeast Alaska and British Columbia. The decline of the yellow-cedar began in the early 1800's. This hardy tree is capable for living for a millennium and has few natural pests. The decline has been attributed to bark beetles, root disease, and winter injury (Hennon et. al., 1990). Decline begins with the death of the shallow fine root system. The fine root system is destroyed when the soil surrounding the roots becomes heavily saturated, leading to low oxygen levels. The root death is followed by the discoloration of the crown foliage. This is followed by the death of the small-diameter roots, and then the larger roots developing necrotic cambial lesions that spread up the bole. Spruce bark beetles are the only pests found on the dead and dying trees, they usually infest in the later stages of the trees death (Hennon et. al., 1997). There has been an ongoing warming trend in much of Alaska since the late 1800s. Warmer winter temperatures at lower elevations lead to more rain and to a decrease in snow pack. Soils receiving too little snow pack are subsequently unprotected, thus the fine roots become more susceptible to freezing, leading to damage (Hennon et. al., 1990).

Spruce Bark Beetle Life Cycle

The change in climate has contributed to excellent growing conditions for spruce, but at the same time has provided conditions aiding the survival of the spruce bark beetle. Spruce bark beetles (Dendroctonus rufipennis) live in the thin phloem tissue found right underneath the bark. As a result, the wood remains undamaged by the beetles and commercially harvestable for some time.

Spruce bark beetles infest Sitka, white, and Lutz spruce most often and rarely attacks black spruce. The crowns of trees girdled by the beetles in one year usually turn red and die by the following year. Spruce bark beetles feed and breed on wind-thrown, fallen, or injured trees. Adult spruce bark beetles appear from May to October, depending on the weather conditions. Most of the attacks occur in early summer. Between May and July, the adults emerge from infested trees and fly to new host trees. From August to October, the adults move into hibernation sites.

Spruce bark beetles normally require two years to complete its life cycle. They may complete their life cycle in one year on warm sites at lower elevations or they will take up to three years in cool, well-shaded locations on north slopes.

Nearly two years after an attack, adults will emerge from over wintering sites and attack new host material. Some beetles winter-over in their pupal sites but the majority, 95%, of the beetles move to the base of the tree and bore into the bark near the litter line. Generally two successive cold winters will reduce survival of the over-wintering beetles to the point that it has little outbreak potential (Holsten et. al., 1997; Juday, 2004).

Recent climate warming in Alaska has favored spruce bark beetle populations. Winters especially have been milder and a few summers have been exceptionally warm. More than 2.3 million acres of spruce forests have been infested in Alaska in the last 7 years with an estimated 30 million trees killed per year at the peak of the outbreak (Holsten et. al., 1997).

Effects

Windstorms, some types of logging, the clearing of right-of-ways, drought, warm weather, and fire suppression all create conditions ripe for spruce bark beetles outbreaks. Under normal forest condition, spruce bark beetles dine only on wine-felled trees, and increase when climatic conditions are favorable for a rapid increase in beetle reproduction. Spruce trees can become a significant component of the new forest if a few mature spruce trees survive and shed seeds, or if a substantial, number of small under story spruce survives the spruce bark beetle outbreak.

It takes more than one beetle to attack and destroy a tree. Spruce bark beetles attack weak, dying, or freshly killed trees. They also attack wind-thrown, standing trees that are weak and diseased. Attacks occur when the trees have been damaged, are under water stress, have vascular diseases or are too old for plantation growth. Attacks can cause extensive tree mortality and modify stand structure by reducing the average tree diameter, height, and stand density.

Some standing trees may be attacked on only one side of the bole, creating a "strip attack" (Holsten et. al., 1997). The infested area may die, but the rest of the tree usually remains alive, so the foliage does not discolor. These signs are most visible during the summer of attack and become less noticeable the next season. Trees with "strip attacks" frequently are infested by subsequent spruce bark beetle generations and may host two or more generations simultaneously.

Acres of dead tree stands represent ecological and economic losses. They pose a fire threat and change the character of environment leading to further losses.

Socio-economic Values

Southeast Alaska forests provide many assets to out economy. While recent decline in local forest health affects many ecological aspects of our region, it also affects our economy. Recently, much of the Tongass has been closed to logging, but spruce and yellow-cedar are still valuable woods. The same climate changes that are affecting the forests can impact salmon runs that are valuable for commercial, sport and subsistence uses. Tourists visiting to see Alaska's natural beauty spend money that aids our economy substantially. They expect to see healthy forests and wildlife.

The Alaska forest products industry is at its lowest point in half a century. Three major trends have caused this decline. Alaska's primary buyer, Japan, has experienced stagnation in their once thriving economy. Allowable harvest in the Tongass National Forest and private native corporation lands has been greatly decreased. Employment has been decreasing since 1999. In 2002, revenue from the wood products industry decreased by 26% (www.dced.state.ak.us/dca/pub/AEPR2003.pdf).

Alaskan fisheries account for much of the state's annual economy. Total commercial harvests have remained stable over the past years, but the value of the catch has been declining. In 2002 the number of employees participating in Alaskan fisheries fell from 25,300 in 2001 to 22,900 in 2002. Personal income for residents participating in seafood processing and fisheries also fell. 54% of the 2002 national seafood harvest came from Alaska (www.dced.state.ak.us/dca/pub/AEPR2003.pdf).

In 2002 tourists spent $1.5 billion dollars in Alaska. Southeast Alaska benefits from a very healthy cruise industry in which hundreds of thousands of visitors pay to cruise through the inside passage in order to see our pristine waters, wildlife, and forests. Alaska's tourism industry is successful because of our extensive natural beauty (Table 2).

Conclusion

Southeast Alaska's climate is changing as a result of global warming. These effects manifest in increased sea surface and atmospheric temperature, rapidly receding glaciers, and the decline of forest ecology and value. The marine environment is changing in an unpredictable manner that may negatively impact food web interrelations and seafood industries.

Recommendations

International cooperation is required to create long-term solutions to global warming. As the US is the lead consumer of fossil fuels, we have a responsibility to lead and cooperate in the international effort to curb consumption of fossil fuels. Countries must apply new regulations to reduce greenhouse gas emissions by curbing consumption of fossil fuels.

Decreasing Dependence and Conservation

Nationally, we need to reduce dependence on fossil fuels. Our country needs to make a goal of reducing consumption of fossil fuels by taxing them heavily. Tax incentives for alternative energy sources must be created so they become more attractive. Alternative sources should be researched and refined in order to be affective. Money appropriated by increased taxes should be used to fund research for alternative sources.

Investing more of the national economy into the public transportation infrastructure can relieve some of our dependence on fossil fuels. The United States has seen a large influx of large personal vehicles on the roads. National fuel economy standards must be emplaced to lower fuel consumption and reduce emissions.

Nuclear Alternatives

Notwithstanding the problems associated with nuclear waste, US should develop nuclear power resources. Nuclear energy is powerful and creates no emissions or greenhouse gases (Lovelock, 2004).

Alaska Fossil Fuel Resources

We recommend that Alaska National Wildlife Refuge remain closed to oil development. We should develop our natural gas resources because of their high-energy efficiency compared with emissions of greenhouse gases.

Hydroelectric

In southeast Alaska, the mountainous rivers that aren't anadromous are prime for hydroelectric development. This is a clean, efficient source of energy.

Forest Management

In Southeast spruce forests, we recommend harvesting stands of beetle killed spruce trees. This results in increasing the vigor of the remaining forests so that the spruce beetles don't continue to spread and will minimize the effects of the attacks. In turn, the harvested timber will contribute to the local economy. Further research is needed to learn how to save the declining valuable yellow-cedar.

Figures

Figure 1.

The global carbon cycle. This schematic representation shows the global carbon reservoirs in gigatonnes of carbon (1GtC = 10¹² kg) and the annual fluxes and accumulation rates in GtC/year, calculated over the period 1990 to 1999. The values shown are approximate and considerable uncertainties exist as to some of the flow values. Click to veiw larger image. (http://www.bom.gov.au/info/climate/change/gallery/9.shtml).

Figure 2.

Auke Bay, Alaska and surrounding area (Wing, 1977).

Figure 3.

Annual total precipitation at Auke Bay, 1963-93. Solid horizontal line is the overall mean, and the dashed line is the trend (Wing, 1998).

Figure 4.

Annual total snowfall at Auke Bay, 1963-93. Solid line is the overall annual mean, and dashed line is the trend (Wing, 1998).

Figure 5.

Annual average of monthly average daily sea surface temperatures at Auke Bay, Alaska, 1975-93. The solid line is the overall annual mean, and the dashed line is the trend (Wing, 1998).

Table 1. Gases Involved in the Greenhouse Effect: Past and Present Concentration Sources

This table represents the gases involved in the enhanced greenhouse effect and their accumulation and concentration differences over a period of time, along with natural and anthropogenic sources of these gases. (http://www.livinglandscapes.bc.ca/thomp-ok/env-changes/index.html)

Table 2. 1,310,100 Summer Visitors (Year 2003)

Breakdown of visitor by mode of transportation to Alaska (www.dced.state.ak.us/dca/pub/AEPR2003.pdf).

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