Understanding Climate Change: How Do We Know What We Know?
By Olivia Kuper
Climate change is one of the most important issues of our time, but how do scientists actually know that it is happening? This is the question that I am asked most often by students. More importantly, how do scientists distinguish between natural variations in climate and human-caused changes? Understanding the science behind climate change requires looking at multiple lines of evidence, from ancient ice cores to modern satellite data.
Historical Climate Records
One primary way we track climate change is through historical climate records. Scientists analyze tree rings, ice cores, and sediment layers to reconstruct Earth’s climate over thousands of years. These natural record-keepers contain trapped air bubbles and chemical signatures that reveal past temperatures, atmospheric composition, and even volcanic activity.
For instance, ice cores extracted from Antarctica and Greenland provide data going back 800,000 years. These cores show a clear correlation between carbon dioxide (CO2) levels and global temperatures, indicating that higher CO2 concentrations have historically coincided with warmer climates.
Here’s a great video that I show my students that explains how ice cores are analyzed. It’s a little long – about 12 minutes, but worth the watch:
How Ancient Ice Proves Climate Change is Real
Modern Observations: The Role of Satellites and Temperature Data.
The current rate of change is 10 times faster than any warming event in the last 65 million years, according to Scientific American.
Beyond historical records, modern satellite technology and global temperature measurements allow us to observe climate trends in real-time. NASA, NOAA, and the European Space Agency continuously monitor Earth’s temperature, greenhouse gas concentrations, and ice coverage.
According to NASA, global surface temperatures have risen by approximately 1.2°C (2.2°F) since the late 19th century, with the most rapid changes occurring in the last few decades. Satellite imagery also shows significant reductions in Arctic sea ice, rising sea levels, and increased frequency of extreme weather events.
The Greenhouse Effect and Human Impact
The greenhouse effect is a well-established scientific principle that explains how gases like carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) trap heat in the Earth’s atmosphere. While these gases are naturally occurring, human activities such as burning fossil fuels and deforestation have drastically increased their concentrations, leading to accelerated global warming.
Carbon isotopes provide further evidence of human influence, according to realclimate.org. When fossil fuels are burned, they release a distinct chemical signature that scientists can trace in the atmosphere. About 75% of the increase in CO2 since the Industrial Revolution is directly attributable to human activity, according to the Environmental Protection Agency.
Debunking Climate Myths
Despite overwhelming scientific consensus, misinformation about climate change persists. One common argument suggests that the climate has always changed naturally. Natural factors, such as solar activity and volcanic eruptions, cannot account for the rapid warming observed today.
What Can We Do?
Understanding climate change is the first step toward action. Reducing greenhouse gas emissions, transitioning to renewable energy, and advocating for climate policies can help reduce the worst effects of global warming. Individuals can also contribute by adopting more sustainable lifestyles, such as reducing waste, recycling, conserving energy, and supporting environmental initiatives.
