In this principle we examine how, due to basic physics of heat trapping gases and exponential rise in population and energy consumption, humans have become a force of nature. Clearly, this is a complex topic with enormous political, socio-economic and emotional dimensions, but the scientific results show clearly that:

• Human activities, particularly the combustion of fossil fuels, are altering the climate system.
• Human-driven changes in land use and land cover such as deforestation, urbanization, and shifts in vegetation patterns also alter the climate, resulting in changes to the reflectivity of the Earth surface (albedo), emissions from burning forests, urban heat island effects and changes in the natural water cycle.
• Because the primary cause of recent global climate change is human, the solutions are also within the human domain.
• Transparency about the causes of climate change allows for effective solutions to be developed and deployed.

Quite simply, this principle is challenging to teach because some sectors of the public continue to debate whether these ideas can be true, despite the well-established science. There are several possible reasons why students may resist the conclusion that humans are altering the climate. This concept may be uncomfortable to students due to feelings of guilt, political resistance or genuine lack of scientific understanding. Furthermore, projections of the effects of climate change on our society can frighten, overwhelm, or discourage students. This can result in denial or resistance to learning. Thus educators are encouraged to introduce this topic with generous scaffolding that establishes the foundations of the process of science, the underlying principles of climate science, and a reliance on the robust scientific research that supports this conclusion. Several strategies are presented on this page about Teaching Controversial Environmental Issues which emphasizes students' affective domain.

Source: Climate Literacy & Energy Awareness Network

Middle school students will be familiar with climate change/global warming gathered from the media, family or at school. This can be an opportunity to develop their understanding of how human activities connect to climate change, particularly the increase in CO2 in the atmosphere. See the activity Automotive Emissions and the Greenhouse Effect.

High school educators can help students understand the many connections between human activities and the climate system. This can be done from a historical perspective, or can employ an Earth-systems science approach. See Mauna Loa CO2 Collection Data.

The introductory undergraduate level students can be challenged to apply their understanding of the science in a social context. The activity Global Climate Change: The Effects of Global Warming examines trends in carbon dioxide emissions and considers the human influences on atmospheric carbon dioxide concentrations.

Upper-level college students can examine datasets and employ models that illustrate the anthropogenic contributions to climate change. By having students work directly with the data and models, students can discover their own conclusions about the linkages. For an example, see Using a mass balance model to understand carbon dioxide and its connection to global warming.

From the 2007 IPCC Forth Assessment Report summary for policymakers: Causes of Climate Change, or for greater detail see the more complete discussion in the section about drivers of climate change

How do we know that recent CO2 increases are due to human activities? - a scientific summary from RealClimate.org

The human fingerprint in coral - This page from the Skeptical Science website provides clear answers to common questions and misunderstandings about climate change.

Solar Variability & Global Climate Change - This summary from the Standford Solar Center describes the relationship between sunspots, solar irradiance and climate change

New statistical analysis confirms human role in climate change - A summary of physics research that uses a simple, statistical approach to understand causes of climate change.

Causes of Climate Change - This NASA web page describes the greenhouse effect, the role of human activity and the evidence that changes in solar irradiance are not related to recent temperature increases.

Global Warming's Six Americas - This report from a large national survey of American adults identifies six unique audiences within the American public that each responds to the issue in their own distinct way. This is a great way to learn about the possible audiences among your student population.

Examining the Scientific Consensus on Climate Change, P. Doran, M. Zimmerman. EOS, Transactions American Geophysical Union, 2009, vol. 90, no. 3, p. 22, 200. This article compares the consensus views of scientists and the general public on climate change.