GLOBAL WARMING AND CLIMATE CHANGE: A PLANET AT CROSS-ROADS

GLOBAL WARMING AND CLIMATE CHANGE: A PLANET AT CROSS-ROADS

By

Taddeo Rusoke

Lecturer, Nkumba University

[email protected], [email protected]

What is Global Warming & Climate Change?

Global warming is a term used for the observed century-scale rise in the average temperature of the Earth's climate system and its related effects. Scientists are more than 95% certain that nearly all of global warming is caused by increasing concentrations of greenhouse gases (GHGs) and other human-caused emissions.

Within the earth's atmosphere, accumulating greenhouse gases like water vapor, carbon dioxide, methane, nitrous oxide, and ozone are the gases within the atmosphere that absorb and emit heat radiation. Increasing or decreasing amounts of greenhouse gases within the atmosphere act to either hold in or release more of the heat from the sun.

Our atmosphere is getting hotter, more turbulent, and more unpredictable because of the “boiling and churning” effect caused by the heat-trapping greenhouse gases within the upper layers of our atmosphere. With each increase of carbon, methane, or other greenhouse gas levels in the atmosphere, our local weather and global climate is further agitated, heated, and “boiled.”

Global warming is gauged by the increase in the average global temperature of the Earth. Along with our currently increasing average global temperature, some parts of the Earth may actually get colder while other parts get warmer—hence the idea of average global temperature. Greenhouse gas-caused atmospheric heating and agitation also increase the unpredictability of the weather and climate, and dramatically increase the severity, scale, and frequency of storms, droughts, wildfires, and extreme temperatures.

Global warming can reach levels of irreversibility, and increasing levels of global warming can eventually reach an extinction level where humanity and all life on earth will end. In this book, irreversible global warming is defined as a continuum of increasing temperature that causes the global climate to rapidly change until those higher temperatures becomes irreversible on practical human time scales. The eventual temperature range associated with triggering and marking the beginning of the irreversible global warming processes is an increase in average global temperature of 2.2°-4° Celsius (4°-7.2° Fahrenheit) above preindustrial levels. 

Extinction level global warming is defined in this book as temperatures exceeding preindustrial levels by 5-6° Celsius (9-10.8° Fahrenheit) or the extinction of all planetary life, or the eventual loss of our atmosphere. If our atmosphere is also lost, this is referred to as runaway global warming. The result would be similar to what is thought to have happened to Venus 4 billion years ago, resulting in a carbon-rich atmosphere and minimum surface temperatures of 462 °C. The temperature levels described above for irreversible and extinction level global warming are not hard and rigid boundaries, but boundary ranges that describe the related consequences and their intensities within a certain level of global warming.

How long carbon dioxide remains in our atmosphere

Carbon dioxide is currently the most important greenhouse gas related to global warming. For the longest time, our scientists believed that once in the atmosphere, carbon dioxide remains there for about 100 years. New research shows that is not true. 75% of that carbon will not disappear for thousands of years. The other 25% stays forever. We are creating a serious global warming crisis that will last far longer than we ever thought possible.

"The lifetime of fossil fuel CO2 in the atmosphere is a few centuries, plus 25 percent that lasts essentially forever. The next time you fill your tank, reflect upon this...[the climatic impacts of releasing fossil fuel CO2 to the atmosphere will last longer than Stonehenge… Longer than time capsules, longer than nuclear waste, far longer than the age of human civilization so far." —“Carbon is forever,” Mason Inman

How carbon dioxide in our atmosphere is tracked 

Atmospheric carbon from fossil fuel burning is the main human-caused factor in the escalating global warming we are experiencing now. The current level of carbon in our atmosphere is tracked using what is called the Keeling curve. The Keeling curve measures atmospheric carbon in parts per million (ppm).

Each year, many measurements are taken at Mauna Loa, Hawaii to determine the parts per million (ppm) of carbon in the atmosphere at that time. At the beginning of the Industrial Revolution around 1880, before we began fossil fuel burning, our atmospheric carbon ppm level was at about 270.

What Is Climate Destabilization?

The global climate system or its key subsystem processes can quickly move from one fairly stable state of dynamic balance and equilibrium into a new transitional state of instability and greater unpredictability. Eventually the global climate will settle at a new, but different, stable state of dynamic equilibrium and balance, but it will be at a new level and range (a dynamic equilibrium is not static or unchanging; it varies within a range of some climate quality, e.g., average temperature, average humidity). The preceding suggests that a useful and accurate definition for climate destabilization.

“A transitional state of escalating global climate instability, this state is characterized by greater unpredictability, which lasts until the global climate eventually finds a new and different stable state of dynamic equilibrium and balance at some different level of temperature and other climate qualities from what it has held for hundreds or thousands of years." —Alexei Turchin, “The Structure of the Global Catastrophe”.

The Three Degrees of Climate Destabilization

Climate destabilization can be said to come in three degrees. The three degrees defined below help individuals and organizations better understand the relative boundary ranges and levels of threat that is occurring or will occur based on measured increases in global warming. The temperature, carbon ppm, and loss or cost levels described below for each degree of climate destabilization are not hard and rigid boundaries, but boundary ranges designed to help you think about a set of related consequence intensities closely associated with that degree of climate destabilization. The temperature, carbon, cost and loss boundary levels below may be modified by future research.

The three degrees and definitions for climate destabilization are:

1. Catastrophic climate destabilization is associated with a measurement of carbon 400-450 ppm. At the estimated current 1.2 Celsius (2.2° Fahrenheit) of temperature increases, we are already in the beginning stages of catastrophic climate destabilization. The eventual temperature range associated with catastrophic climate destabilization will be an increase in average global temperature of about 2.7° Celsius (4.9° Fahrenheit). When global warming-caused storms, floods, seasonal disruption, wildfires, and droughts begin to cost a nation 30 to 100 billion dollars per incident to repair, we will have reached the level of catastrophic climate destabilization. We are already in this phase of climate destabilization. Hurricane Sandy in New York cost the United States between 50 and 60 billion dollars to repair.

2. Irreversible climate destabilization is associated with a measurement beginning around carbon 425 ppm and going up to about carbon 550-600 ppm. The eventual temperature range associated with triggering irreversible climate destabilization is an increase in average global temperature of 2.2°-2.7° Celsius (4°-4.9° Fahrenheit) to 4° Celsius (7.2° Fahrenheit).

Irreversible climate destabilization occurs when we have moved away from the relatively stable dynamic equilibrium of temperature and other key weather conditions, which we have experienced during the hundreds of thousands of years of our previous cyclical Ice Ages. Once a new dynamic equilibrium finally stabilizes for the climate in these carbon ppm ranges, we will have crossed from catastrophic climate destabilization into irreversible climate destabilization.

Irreversible climate destabilization is a new average global temperature range and a set of destabilizing climate consequences we most likely will never recover from—or that could take hundreds or even thousands of years to correct or re-balance. Irreversible climate destabilization will eventually cost the nations of the world hundreds of trillions of dollars.

3. Extinction-level climate destabilization. Extinction-level climate destabilization as defined here is associated with beginning around the measurement of carbon parts per million in the atmosphere in the range of 600 ppm or more. The eventual temperature range associated with extinction-level climate destabilization is an increase in average global temperature of 5° to 6° Celsius (9° to 10.8° Fahrenheit).

Extinction-level climate destabilization is also defined as the eventual extinction of approximately up to half or more of the species on earth and most, if not all, of humanity. This occurs when the climate destabilizes to a level where the human species and/or other critical human support species can no longer successfully exist. Extinction-level climate destabilization has occurred several times previously during Earth's evolution. 

Extinction-level climate destabilization will cost the nations of the world hundreds of trillions of dollars and potentially billions of lives—maybe the survival of the human species itself. There is a possibility that extinction-level climate destabilization may never correct or re-balance itself to some new equilibrium level. If the climate were able to correct or re-balance itself from this level of destabilization, it could take hundreds, thousands or even hundreds of thousands of years.

To make matters worse, every time we enter a new level of climate destabilization, the frequency, severity, and scale of global warming consequences will increase and everything becomes more unpredictable.

Today’s climate destabilization can become a fatal threat to our future

Our global climate has held many different, relatively stable states over its 4.5-billion-year history. For hundreds of thousands of years, our planet’s climate has moved within a fairly stable range of dynamic equilibrium, known as the cycle of Ice Ages. This is an alternating pattern of an Ice Age, followed by a period of receding ice.

Humanity has flourished since the last Ice Age because of the warmer, agriculture-friendly temperatures and lack of glacial ice cover. As our current global climate moves into a human-caused destabilization period (from its previously stable state of the Ice Age to non-Ice Age cyclical periods) and into a new state of dynamic equilibrium, many rapid changes are occurring. These changes are characterized, in part, by droughts, floods, wildfires, super storms, and the changing of previously established seasonal weather patterns. These changes are now also occurring with increasing unpredictability as well as with greater magnitude and frequency because of our continually escalating temperature.

We are already experiencing major changes in rainfall and snowfall, with either too much or too little at one time. These transitional conditions will remain unstable or worsen until we have completed the transition to a new, more stable, climate temperature equilibrium and range. 

The long-term “good” news is that unless we hit irreversible global warming, sooner or later a destabilized global climate will seek to establish equilibrium at some new level of temperature and other climate quality states. A stable climate is generally always better than an unstable climate when it comes to our overall global climate. But . . . any new equilibrium we eventually arrive at may not be friendly to us as humans. 

Fueled by increasing population and human-caused global warming, we have already radically increased the destabilization of our climate and our average global temperature. The climate destabilization process is already increasing the rates of reef collapse, desertification, deforestation, coastline loss, wildfires, droughts, super storms, floods, productive soil degradation, growing season changes, water pollution, and species extinction.

It is possible we may soon tip the climate into a new, fairly stable equilibrium quite unlike the 12,000-year Ice Age cycles we have been experiencing for hundreds of thousands of years. The very bad news is that billions of humans could soon be suffering and dying because this climate destabilization will also destabilize our global financial, political, agricultural, and social systems.

Aquatic Ecosystems and Climate Change

Aquatic ecosystems are critical components of the global environment. In addition to being essential contributors to biodiversity and ecological productivity, they also provide a variety of services for human populations, including water for drinking and irrigation, recreational opportunities, and habitat for economically important fisheries. However, aquatic systems have been increasingly threatened, directly and indirectly, by human activities. In addition to the challenges posed by land-use change, environmental pollution, and water diversion, aquatic systems are expected to soon begin experiencing the added stress of global climate change.

The geographic ranges of many aquatic and wetland species are determined by temperature. Average global surface temperatures are projected to increase by 1.5 to 5.8oC by 2100 (Houghton, 2001), but increases may be higher in the United States (Wigley, 1999). Projected increases in mean temperature in the United States are expected to greatly disrupt present patterns of plant and animal distributions in freshwater ecosystems and coastal wetlands. For example, cold-water fish like trout and salmon are projected to disappear from large portions of their current geographic range in the continental United States, when warming causes water temperature to exceed their thermal tolerance limits. Species that are isolated in habitats near thermal tolerance limits (like fish in Great Plains streams) or that occupy rare and vulnerable habitats (like alpine wetlands) may become extinct in the United States. In contrast, many fish species that prefer warmer water, such as large mouth bass and carp, will potentially expand their ranges in the United States and Canada as surface waters warm.

The productivity of inland freshwater and coastal wetland ecosystems also will be significantly altered by increases in water temperatures. Warmer waters are naturally more productive, but the particular species that flourish may be undesirable or even harmful. For example, the blooms of “nuisance” algae that occur in many lakes during warm, nutrient-rich periods can be expected to increase in frequency in the future. Large fish predators that require cool water may be lost from smaller lakes as surface water temperatures warm, and this may indirectly cause more blooms of nuisance algae, which can reduce water quality and pose potential health problems.

Effects of climate change on aquatic ecosystems

Increases in water temperatures as a result of climate change will alter fundamental ecological processes and the geographic distribution of aquatic species. Such impacts may be ameliorated if species attempt to adapt by migrating to suitable habitat. However, human alteration of potential migratory corridors may limit the ability of species to relocate, increasing the likelihood of species extinction and loss of biodiversity.

Changes in seasonal patterns of precipitation and runoff will alter hydrologic characteristics of aquatic systems, affecting species composition and ecosystem productivity. Populations of aquatic organisms are sensitive to changes in the frequency, duration, and timing of extreme precipitation events, such as floods or droughts. Changes in the seasonal timing of snowmelt will alter stream flows, potentially interfering with the reproduction of many aquatic species.

Climate change is likely to further stress sensitive freshwater and coastal wetlands, which are already adversely affected by a variety of other human impacts, such as altered flow regimes and deterioration of water quality. Wetlands are a critical habitat for many species that are poorly adapted for other environmental conditions and serve as important components of coastal and marine fisheries.

Aquatic ecosystems have a limited ability to adapt to climate change. Reducing the likelihood of significant impacts to these systems will be critically dependent on human activities that reduce other sources of ecosystem stress and enhance adaptive capacity. These include maintaining riparian forests, reducing nutrient loading, restoring damaged ecosystems, minimizing groundwater withdrawal, and strategically placing any new reservoirs to minimize adverse effects.

Warming in Alaska is expected to melt permafrost areas, allowing shallow summer groundwater tables to drop; the subsequent drying of wetlands will increase the risk of catastrophic peat fires and the release of vast quantities of carbon dioxide (CO2) and possibly methane into the atmosphere.

In addition to its independent effects, temperature changes will act synergistically with changes in the seasonal timing of runoff to freshwater and coastal systems. In broad terms, water quality will probably decline greatly, owing to expected summertime reductions in runoff and elevated temperatures. These effects will carry over to aquatic species because the life cycles of many are tied closely to the availability and seasonal timing of water from precipitation and runoff. In addition, the loss of winter snowpack will greatly reduce a major source of groundwater recharge and summer runoff, resulting in a potentially significant lowering of water levels in streams, rivers, lakes, and wetlands during the growing season.

The current understanding regarding the potential impacts of climate change on U.S. aquatic ecosystems:

1. Aquatic and wetland ecosystems are very vulnerable to climate change. The metabolic rates of organisms and the overall productivity of ecosystems are directly regulated by temperature. Projected increases in temperature are expected to disrupt present patterns of plant and animal distribution in aquatic ecosystems. Changes in precipitation and runoff modify the amount and quality of habitat for aquatic organisms, and thus, they indirectly influence ecosystem productivity and diversity.

2. Increases in water temperature will cause a shift in the thermal suitability of aquatic habitats for resident species. The success with which species can move across the landscape will depend on dispersal corridors, which vary regionally but are generally restricted by human activities. Fish in lowland streams and rivers that lack northward connections, and species that require cool water (e.g., trout and salmon), are likely to be the most severely affected. Some species will expand their ranges in the United States.

3. Seasonal shifts in stream runoff will have significant negative effects on many aquatic ecosystems. Streams, rivers, wetlands, and lakes in the western mountains and northern Plains are most likely to be affected, because these systems are strongly influenced by spring snowmelt and warming will cause runoff to occur earlier in winter months.

4. Wetland loss in boreal regions of Alaska and Canada is likely to result in additional releases of CO2 into the atmosphere. Models and empirical studies suggest that global warming will cause the melting of permafrost in northern wetlands. The subsequent drying of these boreal peat lands will cause the organic carbon stored in peat to be released to the atmosphere as CO2 and possibly methane.

5. Coastal wetlands are particularly vulnerable to sea-level rise associated with increasing global temperatures. Inundation of coastal wetlands by rising sea levels threatens wetland plants. For many of these systems to persist, a continued input of suspended sediment from inflowing streams and rivers is required to allow for soil accretion (Cochrane et al., 2009).

6. Most specific ecological responses to climate change cannot be predicted, because new combinations of native and non-native species will interact in novel situations. Such novel interactions may compromise the reliability with which ecosystem goods and services are provided by aquatic and wetland ecosystems.

7. Increased water temperatures and seasonally reduced stream flows will alter many ecosystem processes with potential direct societal costs. For example, warmer waters, in combination with high nutrient runoff, are likely to increase the frequency and extent of nuisance algal blooms, thereby reducing water quality and posing potential health problems.

8. The manner in which humans adapt to a changing climate will greatly influence the future status of inland freshwater and coastal wetland ecosystems. Minimizing the adverse impacts of human activities through policies that promote more science-based management of aquatic resources is the most successful path to continued health and sustainability of these ecosystems. Management priorities should include providing aquatic resources with adequate water quality and amounts at appropriate times, reducing nutrient loads, and limiting the spread of exotic species.

Overall, these conclusions indicate climate change is a significant threat to the species composition and function of aquatic ecosystems in the United States. However, critical uncertainties exist regarding the manner in which specific species and whole ecosystems will respond to climate change. These arise both from uncertainties about how regional climate will change and how complex ecological systems will respond. Indeed, as climate change alters ecosystem productivity and species composition, many unforeseen ecological changes are expected that may threaten the goods and services these systems provide to humans.

REFERENCES

Cochrane K, C. De Young and D. Soto (2009). Climate change implications for fisheries and aquaculture: Overview of current scientific knowledge. Fisheries Technical Paper, 530. FAO, Rome, 2009, 216pp.

Houghton, M. (2001). Climate Change 2001: The Scientific Basis; Climate Change 2001: Impacts, Adaptation, and Vulnerability; Climate Change 2001: Mitigation

N. LeRoy Poff, Mark M. Brinson, John W. (2002). Aquatic Ecosystems and Global Climate Change: Potential Impacts on Inland Freshwater and Coastal Wetland Ecosystems in the United States. Prepared for the Pew Center on Global Climate Change.

Wigley, T.M.L., (1999). The Science of Climate Change: Global and U.S. Perspectives. Pew Center on Global Climate Change, Arlington, Virginia, 48 p.

About the Author:

Rusoke Taddeo is a lecturer of conservation, cultural and natural heritage studies at Nkumba University, Uganda, He holds a Bachelor of Science in Wildlife Management and Master of Science Degree in Environmental Health. Before joining Nkumba University, Rusoke was a Conservation Education Volunteer at Uganda Wildlife Education Centre, Entebbe Zoo, Uganda; He is a wildlife Enthusiast, Researcher and Animal Welfare Activist, he was among the researchers that participated in research that led to the formation of Igongo Museum/Cultural Centre, Mbarara Uganda in 2009.