"Global Warming and Climate Change."
Although the terms global warming and climate change are often used interchangeably, they apply to different phenomena. Climate change refers to changes in Earth's temperature, humidity, air pressure, wind, clouds, and precipitation patterns over time. Global warming is a contributing factor to climate change and refers specifically to the effect of greenhouse gases on Earth's average surface temperature. The term global warming first appeared in geochemist Wallace Broecker's 1975 Science magazine article, "Climatic Change: Are We on the Brink of a Pronounced Global Warming?" Scientists began studying the effect of greenhouse gases on Earth's climate more than a century prior, however, as early as 1820. It was during this time that French scientist Joseph Fourier first discovered that Earth's atmosphere functions to retain the sun's heat. In the early 1900s, Serbian astrophysicist Milutin Milankovitch also identified the long-term climate effects of natural fluctuations in Earth's orbit as well as the tilt and precession of its axis. Since then, scientists and policymakers have worked to better understand the workings of the atmosphere, as well as how to respond to challenges created by climate change.
Causes of Climate Change
Earth's atmosphere contains various gases that act as a blanket to trap heat from the sun and prevent it from escaping back into space. This process is known as the greenhouse effect, and the gases are referred to as greenhouse gases. The main greenhouse gases that occur in nature are carbon dioxide, methane, and nitrous oxide. Without the greenhouse effect, the planet would be too cold to support life.
Natural processes on Earth constantly create and destroy greenhouse gases. The decay of plant and animal matter, for example, produces carbon dioxide, which plants then absorb during photosynthesis. This natural cycle keeps the level of carbon dioxide in the atmosphere fairly stable. Shifts in the planet's crust and changes in ocean patterns impact weather, as do fluctuations in the sun's output of radiation. Volcanic activity also affects the climate because eruptions discharge greenhouse gases and other pollutants into the atmosphere. Climate change scientists at the National Aeronautics and Space Administration (NASA) and other federal and international agencies recognize that these natural factors continue to play a role in climate change but contend that the impact of these factors alone does not explain the substantial rise in Earth's temperature. Natural causes of climate change are referred to as naturogenic, while human-made causes of climate change are referred to as anthropogenic. Earth's vegetation releases and absorbs more than two hundred billion metric tons of carbon dioxide annually. Human activities, such as the burning of fossil fuels, add an extra seven billion metric tons per year. Over time, these additions have had a dramatic effect on the atmosphere. In the past 150 years, the concentration of carbon dioxide in the atmosphere has risen by more than 30 percent. Deforestation has also played a role in this increase by eliminating forests that would otherwise absorb tons of carbon dioxide.
Climate Change Predictions
Climate science measures changes that occur to a large geographical area over a long period of time, making it difficult to provide definitive answers to climate change questions. However, multiple studies have been conducted since the 1990s to determine how the scientific community collectively views anthropogenic climate change. These studies included surveys as well as analyses of peer-reviewed articles and have concluded that at least 97 percent of actively publishing climate scientists around the world agree that human activities have contributed to rising global temperatures.
Though surveys indicate that many Americans remain skeptical toward arguments and evidence put forth by climate scientists, reports suggest that belief in global warming has grown steadily in the twenty-first century. According to annual polls conducted by Gallup, the public's belief that global warming is caused by human activity, that climate change has begun to take effect, and that global warming will soon pose a serious threat has increased since 2001. Researchers have observed a strong correlation between people's political affiliations and their levels of concern regarding global warming and acceptance of climate science. A total of 64 percent of all Americans polled reported a belief that human activity contributes to global warming in 2018, which included 89 percent of Democrats, 62 percent of independents, and 35 percent of Republicans. Similarly, 91 percent of Democrats responded that they worried significantly about global warming, compared to 62 percent of independents and 33 percent of Republicans. Democrats also reported much higher confidence (86 percent) that scientists have reached a consensus that global warming is real than Republicans (42 percent). Gallup's polling further indicates that people age 55 and older are more likely than younger respondents to believe that the media exaggerates the threat of climate change. Foundations linked to the prominent Koch family, for example, donated over $100 million to such organizations between 1997 and 2015, as reported by the environmental organization Greenpeace.
Effects of Global Warming
The consequences of global warming remain an issue of great debate and uncertainty, and some researchers predict dramatic and serious problems for future generations. Warmer oceans could result in stronger and more frequent hurricanes. As temperatures climb, some regions could experience frequent heat waves and devastating droughts and wildfires. During the 1990s and first decade of the twenty-first century, many areas in the United States endured record-breaking heat and drought. In 2012, severe drought plagued the Wheat Belt of the United States, located in the North American Great Plains. In the beginning of 2013, Australia experienced a heat wave that caused hundreds of wildfires throughout the country. Climate change has also been linked to the severe drought that occurred in California between 2011 and early 2017. In 2018 California has further endured massive wildfires that have led to the displacement of thousands of residents, widespread destruction of property, and the deaths of at least eight people. Scientists have attributed the fires, which included the largest wildfire in California history to date, to the presence of extremely dry vegetation, brought on by rising temperatures, that created conditions that allowed the fires to spread rapidly and burn intensely. California governor Jerry Brown lamented that such fires have become increasingly common in the southwestern United States and warned that fires would likely become more intense as climate change continues. Furthermore, people would also face serious problems. Loss of farmland, for example, would cause disruptions in the food supply, bringing about famine in many areas. Scientists have noted that various species of disease-carrying mosquitoes have expanded their habitats to areas where they could not have lived before the rise in atmospheric temperature. More frequent and intense heat waves could result in more heat-related deaths, and changes in air quality could also affect human health. A 2018 study in the environmental science journal Nature Climate Change determined that rising temperatures are contributing to increased rates of suicide, anticipating that the trend will continue without a widespread response to climate change that addresses the impact of humans on the environment.
Economic and political issues inform how governments choose to respond to anthropogenic climate change. To reduce global warming in years to come, nations may need to implement policies with the potential to inhibit their economies. Efforts to further tighten restrictions on greenhouse emissions may include a market-based system such as a cap-and-trade program that limits a firm's total greenhouse gas output but allows a firm to purchase additional emissions credits. Regulations that place higher industry standards on performance and technology provide another way to reduce emissions. Both approaches, however, have the potential to reduce current production capacity, foreign investment, and household purchasing power, as well as lead to higher consumer prices. For these reasons, governments have encountered great difficulty in agreeing on a global plan to deal with Earth's changing climate.
Wealthier countries produce significantly larger amounts of greenhouse gases than poorer countries, thus contributing more to the process of global warming. At the same time, the negative effects of climate change impact developing countries to a greater degree than developed countries. Therefore, many people believe that industrialized nations should take responsibility for reducing emissions of these gases. The leaders of these nations, however, have been resistant to this idea.
Since the 1995, the United Nations has hosted annual conferences to discuss climate change as part of the United Nations Framework Convention on Climate Change (UNFCCC), which was drafted in 1992 and ratified in 1994. In 1997, delegates gathered in Kyoto, Japan, to negotiate an international treaty known as the Kyoto Protocol. This treaty required industrialized countries to reduce their emissions of greenhouse gases by a certain percentage over a five-year period. The treaty was strongly supported by the European Union and other developed countries. The United States opposed the agreement, however, claiming that it could harm the US economy and was unfair because huge emitters such as China and India were not required to cut emissions because they were considered developing countries. As of August 2018, 192 parties, composed of 191 countries and the European Union as a political-economic union, had ratified the Kyoto Protocol. Notable exceptions from the list of signatories include the United States, which has never ratified the treaty, and Canada, which announced its withdrawal from the agreement in 2011. Amendments proposed in 2012, which would expand the protocol and extend it until 2020, have not been put in force because they have not been ratified by a minimum of 144 signatories.
In 2015, world leaders crafted new climate goals at the UNFCCC conference in Paris, France. This new agreement aimed to limit the rise in global temperatures to less than 2 degrees Celsius (approximately 3.6 degrees Fahrenheit) above preindustrial levels and provide countries with the tools needed to best combat climate change. President Barack Obama played a central role in brokering the Paris Agreement and pushed for greater environmental restrictions during his presidency. On November 4, 2016, the Paris Agreement went into effect with the commitment of the United States and seventy-three other parties.