Rising sea levels, record temperature highs and lows, depleting ozone layer, and melting glaciers are thought by many to be signs of global warming and steps have been taken internationally to prevent them from getting worse. What if these events are completely natural and not at all caused by human activity? Maybe they are a part of a natural warming period that the Earth will soon overcome and all efforts taken to ease global warming and climate change will be for nothing. This topic is heavily debated among the American public, but not among the scientific community. This issue covers a wide range of topics such as the use of greenhouse gases, the role of the sun, and the credibility of those providing the information that is consumed by the public. Among most climate researchers, human-created greenhouse gases are thought of to be the main cause of global warming. Gases such as carbon dioxide, water vapor, methane, nitrous oxide, and chlorofluorocarbons keep heat from escaping the atmosphere and create a greenhouse effect. The trapped heat makes the Earth’s surface warmer. Although water vapor is the most abundant greenhouse gas, carbon dioxide is discussed the most. It can be released by natural events such as volcanic activity, but is mainly caused by deforestation, certain land use changes, and the burning of fossil fuels which are all human activities. Methane is released by decomposing wastes in landfills, manure management of domestic livestock, and agriculture, particularly rice cultivation. Soil cultivation practices such as fossil fuel combustion, biomass burning, nitric acid production, and the use of organic fertilizers create nitrous oxide. Chlorofluorocarbons, now regulated due to their damage of the ozone layer, are especially human in that they are synthetics of industrial origin. 400,000 years ago, the carbon dioxide level had never reached above 300 parts per million (ppm) (“Climate Change Evidence”). The industrial revolution in the 18th century expelled more carbon dioxide into the air and the 300 ppm was exceeded only 200 years later in the 1900s (“Global Mean CO2”). 100 years afterwards, the levels are now at 400 ppm (“Climate Change Evidence”). Although the claim that the human expansion of greenhouse gases is generally accepted among scientists, some people are still unconvinced. Some scientists argue that carbon dioxide cannot have an effect on the environment and propose another reason for the warming. These scientists claim that higher carbon dioxide levels do not always mean global warming. During a glacial period 460 to 445 million years ago, carbon dioxide levels were five times higher than they are now. Patrick Moore, former Director of Greenpeace International says, “There is some correlation, but little evidence, to support a direct causal relationship between carbon dioxide and global temperature through the millennia.”. The Chinese Science Bulletin created a study that explained the Earth is experiencing a temperature oscillation that is causing current warming trends and will cease around 2030 (“Climate Change”). Researchers from the Oregon Institute of Science and Medicine (OISM) published a paper that claimed that no experimental data shows that extreme environmental harm will be caused by an increase in these trends. They even said that increased carbon dioxide emissions have actually had a positive impact on the Earth by encouraging the growth of plants (Robinson). Instead of greenhouse gases being a primary factor of global warming, these scientists suggest an entirely different problem: the sun. Climate scientists agree that the amount of solar energy the Earth receives affects the climate, but whether or not this is affecting current warming patterns is discussed. This solar variability explains most climate changes that have happened in the past and the Little Ice Age that occured between 1650 to 1850. This event was marked by advancing glaciers in the Alps and Greenland mostly being cut off by ice (“Climate Change Evidence”). The researchers from OISM assert that the Earth is currently recovering from the Little Ice Age, explaining that the warming trends are predictably typical for this circumstance. There was also a 0.19 percent increase in solar irradiance, the sun’s output of energy, between 1990 and 2000 that could be another factor. Furthermore, the Arctic surface temperature correlates more with solar irradiance than it does carbon use (Robinson). A minority of researchers believe that solar irradiance is causing global warming, while the majority argues against the those researchers.Other scientists believe that solar irradiance cannot be the reason behind modern global warming. They say that the sun’s energy output either stayed consistent or increased slightly since 1750, and does not account for current warming. If it was caused by increased solar energy, then an increase in temperature in all layers of the atmosphere would be observed. This is not the case. The lower layers and surface of the atmosphere are warming, while the upper layers are cooling. This can only be explained by greenhouse gases trapping heat in the lower atmosphere. Computer models that replicate this solar irradiance cannot reproduce current changes in climate without the added increase of greenhouse gases (“Climate Change Evidence”). However, skeptics of human-caused global warming, also known as anthropogenic climate change, say that these computer models are known to be over sensitive and inaccurate (“Climate Change”). Despite these doubts, most scientists still believe that solar irradiance does not play a part. Even though there is major scientific support of anthropogenic climate change, there are many influential organizations that claim it does not exist. Take the American Enterprise Institute for Public Policy Research for example that says there is no consensus for the significance and causes of global warming. The Competitive Enterprise Institute has a similar stance on the topic, with the argument that although global warming exists, there is no scientific consensus as to whether or not it will cause serious climate change. Cato Institute’s website claimed that humans were a major cause of global warming since 1975. However, when questioned if this information was true the vice president responded, “We don’t know.”. Cato also advised Congress against passing laws to reduce carbon dioxide emissions (“Skeptic Organizations”). The American Legislative Exchange Council (ALEC) is a major political proponent on the topic of global warming and climate change. This organization states that these events are unavoidable. ALEC says that it uses sound science to decide what is best politically and economically. It believes that efforts to prevent the emissions of greenhouse gases to reduce global warming would not only be unsuccessful, but do more harm than good. Trying to restrict emissions would prove to be economically damaging and people’s way of life would decline. International cooperation to complete this task is also impossible (“ALEC Energy Principles”). However, these organizations are known for their spreading of misinformation and profit off of the fossil fuel industry (“Skeptic Organizations”). All of these organizations have a hand in politics and policy making and many people are on their side when it comes to their stance on global warming. Some have found reason to distrust sources that deny anthropogenic climate change beyond the basis of scientific fact. The Proceedings of the National Academy of Sciences (PNAS) gathered extensive information of climate research publications to measure the credibility of scientists that support and deny human causes of global warming. It measured this by considering the amount of publications of the scientists and how many times their publications were cited. The amount of publications a scientist has reflects on the amount of work and research they have done on the topic while how many times their work is cited shows the impact of their contributions. PNAS collected information about the work of 908 distinguished climate scientists that had a minimum of 20 climate publications. PNAS found that of the top 50 most credible climate researchers, only two percent of the researchers were those whose publications spoke against anthropogenic climate change. In a list of the top 200, it was only two point five percent. These findings correlate with expert surveys that say 97 percent of climate scientists agree with the claim that human activity is a primary cause of global warming. The top climate researchers that support anthropogenic climate change have an average of 408 publications. The top researchers that do not support it have an average of 89 publications and this group makes up 80 percent of the researchers with less than 20 publications. Even though they are experts, this data suggests that because they have less publications, they have less information about the topic and weaker arguments. Scientists who wrote papers that supported anthropogenic climate change were cited on an average of 133 times and those who do not support it had an average of 84 times. This shows that these researchers have less presidence (William). The research concludes that scientists whose publications speak against anthropogenic climate change are shown to be less credible due to them having significantly less publications and citations.Due to the amount of information regarding the effects of greenhouse gases, the fact that solar irradiance has barely increased, and the reputation of those who deny the role of people, human activity is most likely a primary cause of global warming. Most scientists in and out of the field of climate science support the statement. Those that say it is not true, tend to be less reliable because of their twisting of facts or spreading of misinformation. However, even if anthropogenic climate change is not real, would it hurt to reduce the emission of greenhouse gases like ending deforestation, increasing the use of solar and wind power, and trying to find resources other than the quickly depleting fossil fuels? Even if the world is just experiencing a temporary warming that will lessen in the next 20 or 30 years, why not go ahead and create a cleaner, healthier planet?