Do Humans Cause Climate Change?

Global warming and climate change are terms that are often interchanged but mean different things. Global warming is specific to the rise in global temperatures, primarily due to increases of greenhouse gas (GHG) emissions in the atmosphere. However, climate change refers to various measures of climate over time like precipitation and wind in addition to temperature impacts like global warming would focus on (USGS n.d.). Based on the most comprehensive set of information available and research by the scientific community, man-made influences are impacting global warming and subsequently climate change due to increases in temperature that create additional impacts to oceans, precipitation patterns, and ecosystems.

Independent Lines of Evidence

The most recent reports by the Intergovernmental Panel on Climate Change (IPCC) provide a massive amount of detail regarding the measurements from independent lines of evidence like ice-core samples, atmospheric observations, and more that show the impacts of human activities on global warming and climate change (IPCC 2018). Nevertheless, there are many different interpretations of the data available, and many counter arguments have been made about the degree of impact humans have truly created. However, most of these arguments have been countered with deeper analysis.

Figure 1. Human Activities Impacting Climate

Source: Cook 2010.

Natural Versus Man-Made Emissions

Looking at some of the commonly debunked climate denial arguments helps illuminate the data that shows how human activities are an issue for global warming and climate change. It is often stated that human emissions are small when compared to natural phenomena. However, this ignores the fact that those emissions and absorptions were balanced before human activities began negatively impacting that balance after the industrial revolution. These impacts are seen directly in the ocean where increased carbon dioxide is being absorbed, effecting the pH of the water. These carbon dioxide isotopes are directly tied to human activities and not natural ones (Cook 2010). Natural events have also impacted that balance and created temperatures rises historically as well, indicating that carbon dioxide levels are important to the temperature balance of the planet.

Figure 2. Carbon Dioxide Sources and Sinks Imbalance Due to Human Activities

Source: Cook 2010.

Figure 3. Carbon Dioxide Uptake in the Ocean Increases Acidity

Source: Cook 2010.

Figure 4. Carbon Dioxide Isotopes Indicate Direct Connection to Man-Made Emissions

Source: Cook 2010.

Emissions Lag Temperature

When looking at natural events of the past, another common argument put forth is that emissions lag temperature in the historic record and that Milankovitch orbital cycles are the primary cause of temperature change, not emissions. Orbital cycles did initial trigger warming, however, more than 90% of the glacial-interglacial warming occurred after the atmospheric carbon dioxide increase as seen in figure 6 (Cook 2010). This indicates that carbon dioxide emissions are tied to rising global temperatures.

Figure 5. Ice Core Samples from the Past 400,000 Years

Source: Cook 2010.

Figure 6. Average Global Temperatures (Blue) Occur After Antarctic Temperatures (Red) and Atmospheric Carbon Dioxide Concentrations (Yellow)

Source: Cook 2010.

Need for Action

Independent lines of data all point to the fact that carbon dioxide leads to global warming and climate change. In 2019, humans emitted over 33.1 billion metric tons of carbon dioxide to the atmosphere that overwhelms the natural system balances of emissions and absorption (USGS n.d.). Fossil fuel emissions from our energy generation mix not only increase global temperatures and exacerbate climate change, but they also create fatal air pollution issues, contaminate waterways, and create toxic waste. Based on the breakout of energy use in the United States, utilizing carbon neutral fuels like hydrogen or renewable natural gas for transportation, building heating, and industrial use as well as implementing renewable carbon neutral energy sources for electricity production will remove nearly 90% of carbon emissions (EPA 2020). Transitioning to renewable energy resources that decarbonize our energy systems is critical to reducing global warming and climate change impacts, as well as other environmental issues, so should be prioritized to minimize the damage that has already been inflicted on our planetary system.

Figure 7. United States Emission by Sector

Source: EPA 2020.

Author: Logan Callen


Cook, John. 2010. “The Scientific Guide to Global Warming Skepticism.” Skeptical Science. Accessed May 19, 2021.

EPA. 2020. “Sources of Greenhouse Gas Emissions.” EPA. Accessed May 19, 2021.

IPCC. 2018. “Summary for Policymakers.” IPCC. Accessed May 1, 2021.

USGS. n.d. “What is the Difference Between Global Warming and Climate Change?” Accessed May 19, 2021.

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