Global warming occurs when the Sun's heat is trapped within the Earth's atmosphere by so-called "greenhouse gases" such as methane and carbon dioxide (CO2). According to many scientists, this results in climate change and other phenomena such as extreme weather conditions and rising sea levels.
Life on Earth can adapt to naturally occurring, gradual climate change. However, since the twentieth century, global temperatures have been rising rapidly. Increased industrialization and other human factors are deemed responsible for this, prompting concerns over how people are going to adapt and survive in a world that is changing much faster than expected.
Aside from environmental issues such as changing weather patterns or melting polar ice, global warming also has an impact on human society. The destruction or changes in the natural environment can hamper economic activities, as food and water sources are depleted. Changes in the weather and the ecosystem can contribute to disease and other health conditions. There are also political implications to consider, as the destruction of the environment or the scarcity of resources can change patterns of human migration across the globe or plunge societies into a "crisis of adaptation."
Global warming is a self-perpetuating cycle, meaning that the world will continue to grow warmer without human intervention, and without human intervention the natural environment will continue to deteriorate. The effects of climate change are enormous and require considerable effort on a global scale. Mobilizing recovery efforts on such a wide-ranging scale can be difficult, however. It requires interdisciplinary cooperation between social and natural scientists.
The Emerging International Climate Change Regime
The greenhouse effect was first proposed in 1824 by French mathematician Joseph Fourier, who was the first to suggest that the heat-absorbing properties of atmospheric gases raise the temperature on the planet. This was further evidenced by other researchers. In the early 1900s, scientists observed that there had been an unprecedented increase in global temperatures since 1880, and that this trend was increasing. Emissions from fossil fuels and the like, spurred by advances in technology during the Industrial Revolution (1760–1840), were blamed for these rising temperatures. By the final decades of the twentieth century, many researchers were in agreement that the rapid rate of global warming was caused by human activity.
Climate change became more formally recognized in 1985 when it became a policy issue and prompted a wave of agenda-setting and negotiations. In 1988, the Intergovernmental Panel on Climate Change (IPCC), an international nongovernmental organization dedicated to providing information about climate change and its effects, was established by the United Nations (UN). The IPCC does not do its own research, but provides reports and assessments consolidated from published scientific works to support the agenda of the United Nations Framework Convention on Climate Change (UNFCCC)—the foremost international treaty on climate change.
The UNFCCC was first opened for signatures in 1992, at the United Nations Conference on Environment and Development (UNCED), also known as the Earth Summit. The conference was held in Rio de Janeiro, and was one of the most important events during the early years of climate change discussions. The UNFCCC was amended by the Kyoto Protocol in 1997, bringing the climate change agenda into the new millennium. The countries that signed the protocol, which is legally binding, agreed to reduce the greenhouse gases that contribute to global warming.
Scientific Consensus and Impact
In the 1995 Second Assessment Report on climate change, the IPCC concluded that "the balance of evidence suggests a discernible human influence on global climate." These findings were reinforced in succeeding reports; in 2013, the IPCC concluded in its Fifth Assessment Report that it is "extremely likely that human influence has been a dominant cause of the observed warming since the mid-20th century." Multiple studies from peer-reviewed scientific journals have reached a consensus that global warming is indeed caused by human activity, and organizations such as the International Research Institute for Climate and Society (IRI) support this assertion.
Climate models, including mathematical and computer simulations of the Earth's atmosphere and oceans, such as the general circulation model (GCM) or radiative-convective models (RCMs), help scientists study and predict weather patterns. Scientific studies on global warming, climate change, and the impact on the environment include examining the thickness of ice in the Arctic Ocean over an extended period. Scientific evidence points to an astonishing decline in sea ice, which affects many Arctic animals and, in turn, humans. The changing temperatures can also bring new flora and fauna into areas where they were previously unheard of, hence potentially disrupting local ecosystems.
The effects of global warming are not confined to the polar regions. Global warming is accelerating the global rise in sea level, increasing the risk of flooding in coastal regions.
In addition, scientific evidence points to an increase in extreme weather events. Higher summer temperatures have increased wildfire risk in forests, hurricanes have increased in intensity over the last few decades, heat waves have become more frequent, and droughts have become more severe, all with serious health risks to humans.
Climate Change Denial
Despite scientific consensus, global warming and climate change has started many debates on the nature, causes, and effects of global warming. Human responsibility for global warming has been dismissed or downplayed by those who contradict scientific findings on the subject.
A survey of more than 4,000 academic papers published over the last twenty years found that 97 percent of the scientific literature confirmed that humans are indeed responsible for climate change. Despite this evidence, only 13 percent of Americans are aware of this, according to the Yale Program on Climate Change Communication and the George Mason University Center for Climate Change. A 2017 Yale poll revealed that while 50 percent of Americans believe that climate change will "harm people in the United States," less than 40 percent believe it will "harm me, personally."
Some skeptics take issue with the methodology used to produce evidence on global warming. Other arguments in denial of global warming point to natural variability as the primary reason for recent trends in temperature. In addition, climate scientists have been accused of manufacturing results to serve their own personal agendas.
Because global warming is a large-scale issue, there are also political and economic motivations involved in disputing it. Energy companies dealing in coal, gas, and other fuels that commonly emit greenhouse gases have good reason to prevent the global climate change agenda from affecting their businesses. The current U.S. president, Donald Trump, is known for his stance against the scientific consensus on global warming. In 2012, Trump commented on social media, saying, "The concept of global warming was created by and for the Chinese in order to make U.S. manufacturing non-competitive."
The Point of No Return
Back in 2009, negotiators from many counties met in Copenhagen to discuss climate change. They agreed that the looming threat of increasing global warming must be diminished by limiting worldwide temperature increases to less than 2 degrees Celsius; to do this, nations must keep carbon dioxide below 530 parts per million (ppm). Limiting carbon emissions is crucial because carbon dioxide (CO2) is the primary greenhouse gas produced by human activities and a chief cause of global warming and climate change.
Because not all governments were in agreement with the steps proposed or the methodology used to arrive at target goals, many countries treated the Copenhagen Accord only as guidelines instead of a legally binding agreement.
The 2010 United Nations Climate Change Conference in Cancun was more successful in calling for funding and technology to combat global warming, but it was criticized for both failing to mandate the needed steps to combat climate change and neglecting to explain how its proposed Climate Fund would be financed.
Despite these lurching steps toward international agreement, the January 2014 Intergovernmental Panel on Climate Change (IPCC) report stated that greenhouse gas emissions have continued to grow at 2.2 percent per year, driven by an increasing world population and expanding economic growth. These two factors are fueling a demand for more electricity, which is cheap and readily available by burning coal and oil. Experts predict that unless a concerted effort is made by governments and industries to shift to clean energy, greenhouse gas emissions will double or triple by 2050. The carbon dioxide target of 530 ppm is already perilously close to being breached, having recently risen to almost 400 ppm.
Different aspects of global warming have a synergistic effect, which means that different parts of the trend work together to produce a stronger result. For example, "carbon sinks," which are areas on the planet that naturally absorb carbon dioxide, were able to keep up with both natural and man-made greenhouse gas emissions for centuries. The two largest natural carbon sinks are forests and oceans. In the last three decades, global warming has not only led to the production of more carbon dioxide but to a decline in the ability of natural carbon sinks to absorb these gases. Oceans have been compromised by the concurrent effects of rising surface temperatures and ozone depletion. Both are adversely affecting the oceans' ability to absorb carbon dioxide: Warmer water cannot absorb as much carbon dioxide as cool water; and ozone depletion contributes to winds, which churn up carbon-saturated deep water, which in turn cannot absorb more carbon dioxide. This synergistic effect makes reversing the trend of global warming much more difficult than simply preventing it in the first place by lowering emissions.
In 2010, one of the warmest years on record, public awareness of global warming was increasing although there remained a split in popular opinion as to whether climate change is primarily human-caused. By 2013, these perceptions had shifted again; According to polls, more than half the world's population viewed climate change as a serious global threat.
Businesses, inventors, scientists, and government officials are working together to find solutions to the climate change challenge. Analysts look to cleaner technologies to reach the 80 percent reduction in CO2 emissions necessary to reverse the effects of global warming. These technologies are designed to replace fossil fuels; they leverage alternative power sources such as solar panels, wave energy systems, geothermal plants, wind power, electric vehicles, and modernized energy grids. Observers applaud these innovations but point out that without government commitment to clean technology in the form of legislation, regulations, and subsidies for development, the efforts to combat climate change are too weak to undo the damage already done or to prevent future disaster.
The years 2014, 2015, and 2016 were the warmest years on record. Data released by NASA in March of 2016 confirmed that February of 2016 was the most "unusually warm" month ever measured globally, referring to temperature in deviation from the average. It confirmed what climate scientists have been contending: The Earth's temperature has surged dramatically, passing a major milestone.
In October of 2016, representatives of more than 170 countries met in Kigali, Rwanda, to negotiate an amendment to the Montreal Protocol of 1987, an international treaty that banned the use of the chlorofluorocarbons, known as CFCs, which harm the ozone layer. The delegates reached a legally binding agreement to cut worldwide use of hydrofluorocarbons, or HFCs, the chemical coolant used in refrigerators and air conditioners. Limiting the use of HFCs is a significant step in slowing down the heating of the planet; although HFCs are just one of the greenhouse gases in the atmosphere, they are extremely powerful. The Kigali accord took seven years to achieve and was made possible in part by President Barack Obama's continued efforts to push his climate change agenda.
In November of 2016, the Paris climate accord went into effect after it was ratified by 55 countries that produce 55 percent of the world's greenhouse gases. This global action plan, within the context of the United Nations Framework Convention on Climate Change (UNFCCC), is a historic agreement to limit global warming to "well below" 2 degrees Celsius by limiting carbon dioxide emissions from fossil fuels. It is a legally binding agreement. The E.U.'s goal is a 30 percent reduction in emissions by 2030, while the Obama administration's objective was to reduce carbon dioxide emissions to 26 to 28 percent below 2005 levels by 2025.
Also in November of 2016, the COP22 climate change conference was held in Morocco. The U.N. summit was attended by representatives from almost 200 countries, who met to tweak and implement the Paris accord. One of the topics debated was the recent threat by then President-elect Donald Trump to withdraw from or renegotiate the climate agreement. U.N. Secretary-General Ban Ki-moon said that the agreement was "unstoppable."
In 2017, Trump formally announced U.S. withdrawal from the Paris agreement. He called global warming a "hoax" and argued that the terms of the climate accord are "very unfair at the highest level" to the United States. However, due to the terms of the agreement, the withdrawal can only take effect in 2020 at the earliest. In the meantime, some state governments have pledged their support for the Paris accord and the U.S. Climate Alliance.