Yes. Global warming is real, measurable, and well-documented across multiple independent lines of evidence. Earth’s average surface temperature has risen roughly 2°F (1.1°C) since the late 1800s, atmospheric carbon dioxide is 50% higher than before the Industrial Revolution, oceans have absorbed 372 zettajoules of extra heat since 1955, and Arctic sea ice is shrinking at 12.2% per decade. These aren’t projections or models. They’re direct measurements taken from thermometers, satellites, ice cores, and ocean sensors around the world.
What the Measurements Show
The most straightforward evidence comes from temperature records. Weather stations, ocean buoys, and satellites all track the same trend: a clear, accelerating rise in global average surface temperature. The increase of about 2°F since pre-industrial times may sound modest, but it represents an enormous amount of energy distributed across the entire planet. Small shifts in the global average translate to large changes in local weather patterns, ice coverage, and sea levels.
Meanwhile, carbon dioxide in the atmosphere has climbed from about 280 parts per million before the Industrial Revolution to 422.8 ppm in 2024. That’s a 50% increase, almost entirely from burning fossil fuels. Scientists can confirm the carbon is from fossil sources (rather than volcanic or biological) by examining its chemical fingerprint, specifically the ratio of different carbon isotopes.
How Greenhouse Gases Warm the Planet
The basic physics behind global warming has been understood since the 1800s. Earth’s surface absorbs sunlight and re-emits that energy as infrared radiation, which we feel as heat. Greenhouse gases in the atmosphere, primarily carbon dioxide, methane, and water vapor, absorb that infrared radiation and re-radiate it in all directions, including back toward the ground. This cycle of absorption and re-radiation slows the escape of heat into space. Without any greenhouse gases at all, Earth’s average temperature would be well below freezing. The problem isn’t the greenhouse effect itself. It’s that adding more greenhouse gases intensifies the effect, trapping more heat than the climate system is accustomed to.
Why Natural Cycles Don’t Explain It
Earth’s climate has always changed. Ice ages come and go, driven largely by slow shifts in Earth’s orbit and the tilt of its axis. These cycles, known as Milankovitch cycles, operate over tens of thousands to hundreds of thousands of years. The shortest of them spans about 23,000 years. The eccentricity cycle that paces major ice ages runs roughly 100,000 years.
Current warming is happening on a completely different timescale. The bulk of the temperature rise has occurred in about 150 years, with the sharpest increase in the last few decades. That’s thousands of times faster than orbital cycles can account for. Earth’s orbital parameters are actually in a phase that should be producing very gradual cooling, not warming. Solar output, volcanic activity, and other natural factors have been carefully measured and modeled. None of them, individually or combined, can reproduce the warming pattern observed since the mid-20th century. Only when human-produced greenhouse gas emissions are added to the models does the picture match reality.
The Evidence Beyond Temperature
Temperature records are just one piece. The physical consequences of a warming planet show up across dozens of independent systems, all telling the same story.
The oceans have absorbed the vast majority of the extra heat. As of December 2024, they’ve taken in roughly 372 zettajoules of energy above 1955 levels. For context, that’s hundreds of times more energy than all of humanity uses in a year. This heat absorption causes seawater to expand, which is one of two main drivers of sea level rise (the other being melting ice). Global sea level is currently rising at about 0.17 inches per year, and the total rise since 1993 alone is nearly 100 millimeters, close to 4 inches.
Arctic sea ice at its September minimum is shrinking at 12.2% per decade compared to the 1981-2010 average. Glaciers on every continent are retreating. Permafrost that has been frozen for thousands of years is thawing. These changes are consistent with each other and with what physics predicts for a warming world.
Effects on Weather Extremes
A warmer atmosphere holds more moisture and contains more energy, which shifts the odds for certain types of extreme weather. Scientists now have over a decade of “attribution” research connecting global warming to increases in the frequency and intensity of specific events. Heat waves show the strongest link, which makes intuitive sense: raise the baseline temperature and extreme heat becomes more likely. Heavy downpours also have a clear connection, because warmer air carries more water vapor. Coastal flooding has worsened as sea levels climb, making high-tide flooding deeper and more frequent.
This doesn’t mean every storm or drought is “caused by” climate change. Weather is complex, and natural variability still plays a role. But the background conditions have shifted in a way that loads the dice toward more extreme outcomes.
Where the Science Stands
Between 97% and 99.9% of peer-reviewed climate research agrees that the climate is changing as a result of human activity. The Intergovernmental Panel on Climate Change, which synthesizes findings from thousands of scientists worldwide, stated in its most recent major report that human activities have “unequivocally caused global warming.” That word, “unequivocally,” is as strong as scientific language gets.
Current national climate pledges, if fully implemented, still make it likely that warming will exceed 1.5°C during this century and make it harder to stay below 2°C. Limiting warming to 1.5°C would require reaching global net-zero carbon emissions by the early 2050s. Limiting it to 2°C pushes that deadline to around the early 2070s. Both targets require rapid emissions reductions starting now, not decades from now.
The question of whether global warming is real was settled in the scientific community years ago. The open questions today are about how much warming will occur, how quickly, and what societies will do about it.