33 1990s – Present Amie Zerwic

Climate Change From the 1990s to Present Day

Climate change is a pressing environmental issue that impacts people both in the United States as well as around the world. These issues are confronted on the local level every day, from the food we eat, the illnesses we experience, and the weather we encounter. The focus of this chapter is on the period of time from 1990 to 2025. The topics that will be covered include the factors that are contributing to climate change, the consequence of climate change on health and the environment, and finally, the political factors during this time period that have worsened or improved the climate. (AZ)

Factors Contributing to Climate Change

Climate change refers to long-term shifts in temperatures and weather patterns. Such shifts can be natural, due to changes in the sun’s activity or large volcanic eruptions. But since the 1800s, human activities have been the main driver of climate change, primarily due to the burning of fossil fuels like coal, oil and gas (The United Nations, n.d.-a). (AZ)

Gas contributions to global warming

Greenhouse gases refer to those gases that trap heat in the atmosphere. There are four major gases that contribute to the greenhouse effect (National Aeronautics and Space Agency, 2024). Carbon dioxide (CO2) is a gas that is released through natural events such as a volcanic eruption and through human activities such as burning fossil fuels (coal, natural gas, and oil). Methane is also produced from natural and human processes. It is formed when plant matter is broken down, it is released from landfills, is produced from livestock during digestion and manure, and is produced during the production of coal, natural gas, and oil. Nitrous oxide is produced when burning fossil fuels and burning vegetation. Chlorofluorocarbons are industrially created substances such as refrigerants and solvents. Of these four gases, the most abundant gas that contributes to greenhouse warming is CO2. (AZ)

The figure below illustrates the different economic sectors that contribute to greenhouse gas emissions. It also demonstrates those sectors that might have the biggest impact if changes are made to reduce emissions. The most significant contributor is transportation. This is a function of burning fossil fuels in cars, trucks, planes and trains. (AZ)

Figure 1 shows greenhouse gas emissions by the economic sector in 2022. Percentages may not add up to 100 percent due to independent rounding (Environmental Protection Agency, 2025). (AZ)

Deforestation

Deforestation is defined as the purposeful clearing and chopping down of forests. “About 2,000 years ago, 80 percent of Western Europe was forested; today the figure is 34 percent” (National Geographic, n.d.). Deforestation commonly occurs as a result of forests being cut down to allow for space for grazing, agriculture, to produce paper, timber, be used in manufacturing, and construction. As a result of deforestation, carbon is released into the atmosphere. This is because trees sequester, or take in carbon. This carbon is then trapped in the wood, where it remains until the tree is burned, releasing this carbon. Because of deforestation, there are less trees available to sequester and store this carbon. This results in CO2 accumulating in the atmosphere and accelerating global warming. Deforestation can also threaten biodiversity. When a tree is cut down, the animals and insects that live inside that tree are forced to relocate and may be driven to the point of extinction. Additionally, the loss of trees can contribute to soil erosion. This can make it harder for plants to grow and thrive (National Geographic, n.d.). (AZ)

Agriculture

The agricultural sector is a significant contributor to climate change. According to the Intergovernmental Panel on Climate Change’s (IPCC) 2019 Special Report on Climate Change and Land, “The industries associated with food production such as agriculture account for 23% of total net emissions of greenhouse gasses. This includes 13% of CO2, 44% of methane and 81% of nitrous oxide emissions from the years 2007 to 2016 (The Intergovernmental Panel on Climate Change, 2019). (AZ)

These emissions from the agricultural industry primarily come from livestock, land use, synthetic fertilizers, and machinery and transportation. First, livestock such as cows produce methane through burping and farting, and the storing of manure emits methane. Agriculture also contributes to the degradation of land. Practices such as deforestation, tilling, and monoculture are all unsustainable practices that contribute to ruining farmland. Machinery and transportation both use a lot of gas and contribute to CO2 emissions (Douglas, 2023). Fertilizers, such as ammonia take energy to produce and result in greenhouse gases after farmers apply them to their fields, both contributing to global emissions (Massachusetts Institute of Technology Climate Portal, 2021). All together, the agricultural industry is a significant contributor to climate change and produces many greenhouse gas emissions through machinery, land use, livestock, and synthetic fertilizer use and production. (AZ)

Industrial processes

According to the Center for Climate and Energy Solutions (United States Energy Information Administration, 2020), approximately 30% of greenhouse gas emissions in the United States come from industrial processes, including the direct emissions from industries’ consumption of electricity. The bulk of these emissions come from manufacturing, food processing, mining, and construction, but secondary or indirect emissions come from the electricity that this industry produces through combustion and chemical processes used in production. “If direct and indirect emissions are combined, the industrial sector is the largest emitting sector in the U.S. economy, responsible for 29.6 percent of total emissions” (Center for Climate and Energy Solutions, 2023). The figure below shows energy-related carbon dioxide emissions from industry in 2020 (United States Energy Information Administration, 2020). (AZ)

Figure 2. Shows energy-related carbon dioxide emissions from industry, 2020. Maroon indicates energy related carbon dioxide emissions from other sources. (US Energy Information Administration, 2020). (AZ)

Land Use Changes

If land is managed properly, it could help tackle climate change, but the incorrect use of land only exacerbates the effects of climate change. Land can be a sink for greenhouse gas emissions “the terrestrial biosphere absorbs almost 30% of anthropogenic CO2 emissions thanks to natural processes. However, this function is vulnerable to the impacts of climate change, such as increased drought and wildfires” (Menga, 2023). If we take up regenerative land practices such as afforestation, and crop rotation we can help reverse the effects of climate change through the use of land. The figure below shows the potential greenhouse gas emission reduction if we take up different land-management options. (AZ)

Figure 3. Shows potential greenhouse gas emission reduction as a result of different land-management options. Red boxes indicate extremely negative and green equals extremely positive (Menga, 2023). (AZ)

Although climate change can be caused by natural phenomena “climate scientists have shown that humans are responsible for virtually all global heating over the last 200 years” (The United Nations, n.d.). Human activities like the ones mentioned previously are causing greenhouse gases that are warming the world faster than at any time in at least the last two thousand years” (The United Nations, n.d.) and the average temperature of the earth is 1.2 degrees Celsius warmer than it was in the late 1800s. (AZ)

Consequence of Climate Change on Health (Human and Animal) and the Environment

Climate change has multiple drastic effects on health and the environment. These effects are wide ranging and impact insects, animals, humans, the places where we live, and the weather that we experience. These effects are caused by rising temperatures, loss of habitat, rising sea levels, changes in vector borne diseases and loss of biodiversity. These effects are detailed below. (AZ)

Rising Temperatures

As a result of climate change, temperatures are rising and extremely hot days are becoming more frequent. Heat waves are more common, meaning more humans and animals will experience heat stroke, heat illness, heat stress, and mortality will increase. High heat also can lead to habitat and crop loss through desertification and drought, thus leading to food insecurity, disrupting the food chain, and raising demand and prices for crops. Desertification is the process by which land becomes desert through drought or deforestation. Desertification can lead to increased need for pesticides, which reduces food quality, can end up killing animals, and harm human health. Desertification and dry temperatures may lead to more frequent and worse wildfires, posing a significant risk to human and animal life. Extreme temperatures can contribute to worsened air quality by increasing ground level ozone production, creating smog and damaging the respiratory system when inhaled. With increasing temperatures, air conditioner usage goes up, escalating costs and energy use (Center for Climate and Energy Solutions, 2023). The figure below shows the projected change in the number of days above 90 degrees Farenheit in the mid 21st century. This figure shows that heat waves in the United States are increasing dramatically and intensifying in effect. (AZ)

Figure 4. Shows projected changes in the number of days per year with a maximum temperature above 90 degree F and a minimum temperature below 32 F in the contiguous United States. Changes are the difference between the average for mid-century (2036-2065) and the average for near-present (1976-2005) under the higher scenario (RCP8.5). This map depicts a weighted multi-modal mean of 32 climate model projections” (Center for Climate and Energy Solutions, 2023). (AZ)

Sea Level Rise

Global sea level rise results from climate change primarily from two causes, the melting of glacier ice sheets and the expansion of sea water as it warms. According to the National Oceanic and Atmospheric Administration (NOAA), almost 30 percent of the United States population lives in coastal areas. Sea level rise is particularly harmful to urban areas because it can cause important infrastructure to be damaged which can lead to more destructive storms, increase high tide flooding, create stress on coastal ecosystems, and cause destruction of human homes and animal habitats (National Oceanic and Atmospheric Administration, 2023. (AZ)

Extreme Weather Events

Climate change exacerbates and increases the frequency of extreme weather events from wildfires to tsunamis. Carbon Brief is a well-regarded source that has mapped every published study on how climate change has impacted severe weather. Of the almost 750 mapped extreme weather events and trends, “74% were made more likely or more severe because of climate change. This includes multiple cases where scientists found that an extreme was virtually impossible without human influence on global temperatures” (McSweeney & Tandon, 2024). In 2004 researchers calculated the specific contribution that anthropogenic climate change made to an individual extreme weather event. To do this, these researchers studied the European heatwave in the summer of 2003, a devastating event which resulted in more than 70,000 deaths. These scientists found human influence had at least doubled the risk of this event, providing concrete evidence that climate change is not distant, but a looming threat. (AZ)

Figure 5. The map shows 735 extreme events and trends. The circles reflect the number of events with red reflecting more and blue reflecting less severe through climate change. Yellow shows events where no human influence is suspected and grey corresponds to inconclusive data.  (McSweeney and Tandon, 2024). (AZ)

Ocean Acidification

Carbon dioxide (CO2) from the atmosphere dissolves into the ocean, where it interacts with water creating carbonic acid which then breaks into hydrogen and bicarbonate ions, decreasing the ocean’s pH and resulting in acidification. According to the National Oceanic and Atmospheric Administration:

In the 200-plus years since the industrial revolution began, the concentration of CO2 in the atmosphere has increased due to human actions. During this time, the pH of surface ocean waters has fallen by 0.1 pH units….approximately a 30 percent increase in acidity (National Oceanic and Atmospheric Administration, 2025). (AZ)

Ocean acidification particularly affects ocean species like clams, corals, some fish, and seaweeds. For calcifying organisms like clams and corals, the process of ocean acidification makes it harder for them to obtain carbonate ions to build and maintain their shells. For non-calcifying organisms like fish, ocean acidification can alter their behaviors. Clownfish, for example, have a harder time detecting predators in lower pH. Conversely, algae and seaweed benefit from ocean acidification as they require CO2 for photosynthesis, and increased CO2 levels equals increased rate of photosynthesis. Although algae growth is not inherently bad, we are experiencing increased algae blooms. These blooms can release toxins, deplete oxygen in the water and contaminate water sources (National Institute of Environmental Health Sciences, 2025). For humans, ocean acidification can result in reduced ability for fishing, resulting in less food available and potential economic loss resulting from that industry. (National Oceanic and Atmospheric Administration, 2025). (AZ)

Biodiversity Loss

Due to climate change, we may experience the consequences of biodiversity loss. Rising sea levels may push animals near the coast further inland and destroy food sources. Wildfires may burn and lead to the destruction of ecosystems and also destroy available food sources. Similarly, hurricanes, desertification, tornadoes, and other disasters that are exacerbated by climate change may also cause destruction of habitats, food sources, loss of life, and cause forced relocation and extinction. For humans, this loss of biodiversity may lead to decreased crops and animals available for food. Also, loss of biodiversity may force animals to migrate into human settlements, posing a danger to both animal and human life. (AZ)

Shifts in Species Distribution and Migration

Climate change causes shifts in species distribution and migration. For example, as a result of increased water temperatures, fish and invertebrates off the United States coast will migrate northward and move to deeper waters towards cooler temperatures. The figure below shows what happened to three fish and shellfish from 1974-2022. The top figure shows the average distance moved in miles (latitude) and the bottom shows distance moved in depth (feet). The change in latitude and depth varied by region, but most frequently these fish and shellfish species moved northward and into deeper waters. (AZ)

Figure 6. (the top figure) Shows change in Latitude and Depth of Marine Species, 1974-2022 (AZ)

Figure 7. (the bottom figure) Shows average Locations of Three Fish and Shellfish Species in the Northeast, 1974-2022 (Environmental Protection Agency, 2025). (AZ)

Figure 8. 157 marine fish and invertebrate species shifted northward almost 17 miles between 1989 and 2019 and moved an average of 0.6 feet deeper (Environmental Protection Agency, 2025). (AZ)

In the northeastern United States, many species have shifted northward due to warmer waters resulting from climate change. Changes in temperature can cause mass migration of animals. As seen in the graph above, changes in water temperature can cause shifts in marine migration patterns. Marine species are especially sensitive to climate changes, and warming waters cause these species to shift northward or to deeper waters that are cooler and more comparable to their natural habitat. When these species migrate they can also affect fisheries through loss in catch, causing loss of jobs, economic downturn, and harming livelihood of those who rely on fisheries. (AZ)

As a result of climate change, birds will migrate to avoid the colder winters. This is a problem because birds are more vulnerable to predators, starvation, fatigue, and mortality during longer migratory journeys. The figure below shows the average distance moved north in miles. (AZ)

Figure 9. Shows change in Latitude of Bird Center Abundance, 1996-2014. Data source: National Audubon Society (Environmental Protection Agency, 2025). (AZ)

Certain species have moved extremely far, over 200 miles, in response to climate change, while others have barely moved. Certain animals, such as fish and birds are able to migrate further, but other animals that have nests and burrows may be forced to stay where they are. “Of the 305 species studied, 186 (61 percent) have shifted their wintering grounds northward since the 1960s, while 82 (27 percent) have shifted southward. Some others have not moved at all” (Environmental Protection Agency, 2025). As these figures show, many animals are forced to migrate due to climate change. This can disrupt pre-existing ecosystems from migrating to and from different areas, which can lead to increased or decreased competition, spread of disease, lead to an unbalanced food chain, and predator/prey relationships. (AZ)

Increased Disease Risk

The increased disease that comes from climate change also affects both human and animal health. Air pollution increases ground level ozone which worsens lung function leading to increased hospital visits and premature death (Centers for Disease Control, 2024a). Food and waterborne diarrheal diseases are more common in warmer weather and during extreme rainfall events (Centers for Disease control, 2024b). (AZ)

The higher temperatures that come from global warming increases vector/pathogen adaptation, shifting or expanding their geographic locations, thus enhancing the spread of vector-borne diseases. There are numerous vector borne diseases in the United States including West Nile virus, Lyme disease, and Rocky Mountain Spotted Fever (Center for Disease Control, 2024c) (AZ)

The health of animals is also at risk from global warming. As temperatures rise animals are increasingly at risk for heat stroke. They may experience decreased immunity from disease and increased risk of parasites and pathogens (Ali, Carlile, Giasuddin, 2020). The loss of habitat contributes to a compromised supply of water and nutrition. (AZ)

The Cost of Climate Change: Billion-Dollar Disasters

Billion dollar disasters is the term for disasters that result in damages of at least one billion dollars, adjusted for inflation. Billion-dollar disasters are occurring more frequently as a result of climate change. (AZ)

Since 1980, the U.S. has sustained 258 weather and climate disasters where the overall damage costs reached or exceeded $1 billion (including adjustments based on the Consumer Price Index, as of January 2020). The cumulative cost for these 258 events exceeds $1.75 trillion (National Oceanic and Atmospheric Administration, 2020). (AZ)

Figure 10. The billion-dollar weather and climate disasters in the United States in 2019 (National Oceanic and Atmospheric Administration, 2020). (AZ)

The figure above accounts for the year 2019 alone. There are 14 billion-dollar events that occurred. The number of billion-dollar events has been rising each year as a result of climate change, and shows no sign of stopping. (AZ)

Figure 11. The number of billion-dollar disasters (average per year), associated costs (average per year), and associated fatalities (average per year). (National Oceanic and Atmospheric Administration, 2020). (AZ)

As the figure shows the number of disasters since the 1980s, associated costs, and average fatalities has dramatically increased. As well, this figure records only disasters that are at least a billion dollars in damages. Most climate events do not cause a billion dollars in damages, so the costs, fatalities, and disasters from climate disasters are actually much higher than this. (AZ)

Hurricane Dorian; Example of a Prominent Billion-Dollar Disaster in 2019.

In September 2019 this hurricane fell upon the Outerbanks of North Carolina. The hurricane was first classified as a Category 1 hurricane, but quickly moved to Category 5. This storm ended up causing irrevocable damage to many coastland homes, severe flooding, and lives lost. The total damage added up to 1.6 billion dollars and 10 deaths. (AZ)

Figure 12. Shows a satellite image of hurricane Dorian over the Bahamas (National Oceanic and Atmospheric Administration, 2020). (AZ)

Major Political Events From the 1990s to Present Day

Politics play a huge role in whether or not climate change is acted upon. Policies can be put in place that force countries to reduce greenhouse gasses and emissions, thus making progress to address climate change, but lack of political action and consensus may also hinder progress and hurt people in the process. In the 1990s significant advances in addressing climate change occurred, with the risks of climate change starting to emerge into the public eye. Of note, climate change was confirmed to be anthropogenic, or human-caused. Laws and protocol on limiting and/or fighting climate change also started to come into effect. These following paragraphs go over major political events from the 1990s to present day, highlighting the drastic impact that politics has on causing or hindering progress in addressing climate change. (AZ)

The Intergovernmental Panel on Climate Change Establishment in 1988

In 1988 the United Nations Environment Program and the World Meteorological Organization established the first Intergovernmental Panel on Climate Change (the IPCC). This report was one of the first of its kind and established that human caused (or anthropogenic) activities were driving climate change and immediate action needed to be taken to combat this issue (Lindwall, 2023). (AZ)

The United Nations Framework Convention on Climate Change in 1992

The United Nations Framework Convention on Climate Change was adopted in the year 1992 at the Earth Summit in Rio de Janeiro, Brazil. It provided the first global framework for tackling climate change which emphasized the need for developed nations to take the lead in reducing greenhouse gas emissions (United Nations, 1992). (AZ)

The Kyoto Protocol in 1997

In 1997 the Kyoto Protocol was signed. It held legally binding emission reduction targets for developed countries. The protocol recognized the principle of common yet differentiating responsibilities, advocating that the developed countries which have contributed the most to climate change because of their higher emissions should take the lead in reducing them. The protocol was one of the political agreements that made the biggest strides throughout the 1990s, but the United States ultimately withdrew from the Kyoto Protocol citing economic concerns as the reason (United Nations, 1997). (AZ)

From the 2000s on more of the public became aware of the causes and impacts of climate change. More awareness was raised on the risks associated with climate change on humans, animals, the environment, and biodiversity. Although awareness of the risks associated with climate change increased, political challenges and disagreement led to little action. (AZ)

The Third and Fourth Intergovernmental Panel on Climate Change Reports in 2001 and 2007

The third report from the Intergovernmental Panel on Climate Change came out in 2001 and the fourth was published in 2007. Both reports emphasized that climate change was human caused, or anthropogenic. The public started to become more aware of the topic of climate change after both these reports were published (Lindwall, 2023). (AZ)

Climate Change Denial

In the 2000s climate skepticism started gaining traction. Despite stronger scientific consensus that climate change was real and was caused by humans, more people doubted the research. This doubt mainly stemmed from the echoing of voices from conservative and fossil fuel industry groups, where it was in their best interest to deny climate change science because of conflicting interests. (AZ)

The Copenhagen Accord in 2009

The United Nations Climate Change Conference occurred in Copenhagen in 2009. The United Nations was supposed to create a more comprehensive climate agreement, but ultimately the Copenhagen Accord fell short. The Copenhagen Accord acknowledged that global warming needed to be limited to below 2°C, but there were no legally binding commitments to this, and political disagreement led to no progress being made (Euinside, 2010). (AZ)

Climate Change- A National Security Risk

Climate change can pose threats to national security both directly and indirectly. Direct threats include threats to infrastructure and higher demand for military resources. Both sea level rise and storms can damage power lines, military infrastructure, and supply chains. Because more disasters are occurring due to climate change, the military may be called upon to help with relief, meaning there is a higher demand for military help and there is less help available to go around. Climate change can pose indirect threats through displacement, increased civil unrest, conflicts, and competition for resources. Because of the increased risk of disease, food and water insecurity, land degradation, and the destruction of structures caused by climate change, migration increases.(AZ)

As migrants enter countries or regions unprepared to deal with them, tensions rise. As we already see on the U.S. southern border, migrants from Guatemala, El Salvador, Honduras, Mexico, Venezuela, and other nations fleeing poverty, violence, and extreme weather are causing enormous political turmoil (Renee Cho, 2023). (AZ)

As well, climate change increases poverty, violence, and political and social instability. When a government cannot provide for these citizens in times of instability, political unrest ensues. Indirectly, conflict about reducing greenhouse gasses may cause tension and conflict between countries. Lack of resources, instability, and damage caused by environmental disasters may cause mass migration and lack of resources may also result in increased competition. (AZ)

Climate change is a pressing environmental issue that impacts people both in the United States as well as around the world. These issues are confronted on the local level every day, from the food we eat, the illnesses we experience, and the weather we encounter. It is important that we take collective action now, before climate change poses irrevocable damages to our planet. (AZ)

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Word Count with personal section included is 4,513