Is climate change real?

Yes, climate change is real.

An overwhelming consensus of the global scientific community—including NASA, the National Oceanic and Atmospheric Administration (NOAA), the Intergovernmental Panel on Climate Change (IPCC), and the national academies of science in dozens of countries—agrees that the Earth's climate is warming rapidly and that human activities are the primary driver.

Here is a breakdown of how we know it is happening, what is causing it, and the evidence supporting it.

1. What is causing it? (The Greenhouse Effect)

The Earth's temperature is regulated by a natural process called the greenhouse effect. Gases in our atmosphere, such as carbon dioxide ($CO_2$), methane ($CH_4$), and nitrous oxide ($N_2O$), trap heat from the sun to keep the planet warm enough to support life.

However, since the Industrial Revolution in the mid-1800s, human activities have drastically increased the concentration of these gases in the atmosphere.

•Burning fossil fuels: Burning coal, oil, and gas for electricity, heat, and transportation is the largest source of $CO_2$ emissions.

•Deforestation: Trees absorb carbon dioxide. Cutting down forests releases stored carbon and reduces the planet's ability to absorb future emissions.

•Agriculture and industry: Raising livestock produces large amounts of methane, while certain industrial processes and fertilizers release potent greenhouse gases.

Because of this, the concentration of $CO_2$ in the atmosphere is now higher than at any point in at least the last 800,000 years.

2. The Evidence of Climate Change

Scientists monitor the planet using satellites, weather stations, ocean buoys, and paleoclimatic data (like ice cores and tree rings). The evidence of rapid warming is clear across multiple indicators:

•Rising Global Temperatures: The average surface temperature of the Earth has risen by about 1.1 to 1.2 degrees Celsius (2 degrees Fahrenheit) since the late 19th century. The vast majority of this warming has occurred in the past few decades.

•Warming Oceans: The oceans absorb over 90% of the excess heat trapped by greenhouse gases. This warming is causing marine heatwaves and disrupting marine life.

•Shrinking Ice Sheets and Glaciers: The Greenland and Antarctic ice sheets are losing billions of tons of mass per year, and glaciers in almost every mountain range in the world are retreating.

•Declining Arctic Sea Ice: The extent and thickness of Arctic sea ice has shrunk rapidly over the last several decades, altering weather patterns globally.

•Rising Sea Levels: Global sea levels have risen by about 8 inches (20 centimeters) in the last century, driven by meltwater from glaciers and ice sheets, as well as the thermal expansion of seawater as it warms. The rate of rise is accelerating.

•Ocean Acidification: Since the Industrial Revolution, the acidity of surface ocean waters has increased by about 30%. This is because the oceans absorb about 20% to 30% of human-made $CO_2$ emissions, making it harder for shellfish and coral reefs to build their shells and skeletons.

•Extreme Weather Events: Heatwaves, heavy rainfall, droughts, and high-intensity tropical storms are becoming more frequent and severe around the world.

Why does a small temperature change matter?

A global average temperature increase of 1 or 2 degrees might sound small, but on a planetary scale, it represents a massive amount of accumulated heat.

During the last Ice Age, when much of North America and Europe was covered by massive glaciers, the average global temperature was only about 5 to 6 degrees Celsius colder than it is today. Small shifts in global temperature lead to massive shifts in the global environment, impacting food supply, water availability, human health, and biodiversity.

Is climate change real?

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