Lesson 6 of 6 · Climate evidence and attribution
Test explanations against several kinds of evidence
10 minute lesson · 3 checks along the way
Your goal for this lessonDistinguish observing climate change from attributing its causes, and connect multiple measurements with physical predictions.
Words with a dotted underline open a short definition right here in the lesson.
Build a record that extends beyond one thermometer
Evidence of modern change comes from many measurements: surface temperatures, ocean heat, land-ice mass, sea level, and atmospheric composition. They sample different parts of the system with different instruments and uncertainties. Their broad agreement is stronger evidence than a single photograph or an isolated unusually warm year. Long records require careful and treatment of changes in instruments, observation times, and coverage.
Older conditions can be investigated through such as ice cores, tree rings, and sediments. A proxy measures something related to climate, not always temperature directly, and its interpretation needs dating and calibration. For example, bubbles in ice preserve samples of past air, while properties of the surrounding ice provide other environmental evidence. Comparing these records requires respecting their time resolution and the distinction between when the ice formed and when its trapped air became enclosed.
Ask which explanation predicts the pattern
Observing warming is a detection question; determining its causes is . Human activities have increased greenhouse gases, especially through fossil-fuel use and land-use change, and human influence is the principal cause of recent global warming. This conclusion combines measured energy interactions, atmospheric composition, observed patterns, and comparisons of natural and human influences. It does not follow merely from two lines on a graph rising together.
Different proposed causes predict different combinations of changes. Solar energy measurements, volcanic effects, ocean , and greenhouse-gas changes can be compared with the observed history. Carbon add evidence about the source of added carbon dioxide: fossil carbon has a characteristic composition inherited from ancient organic material. That source evidence complements, rather than replaces, the radiative physics linking greenhouse gases with warming. No single measurement must carry the entire argument.
Check 1 of 3
10 pointsUse the reading above. You can try again without losing points.
Work through a decision
Compare predictions in a controlled toy test
Suppose two invented explanations predict changes in two independently measured indicators, A and B, expressed in the same arbitrary units. Model One predicts A=2 and B=−1. Model Two predicts A=2 and B=1. Measurements give A=2.1±0.2 and B=−0.9±0.2, where the stated intervals are the uncertainty bands used for this classroom comparison. Both models fall inside A’s band, but only Model One falls inside B’s band.
This makes B the discriminating indicator for these two predictions. It does not prove Model One is the only possible explanation: other models, uncertainty in the predictions, correlated errors, or a calibration mistake still need consideration. The example is not a real climate attribution calculation and its bands are not assigned a discovery significance. It demonstrates why matching several independently constrained features is more informative than matching one selected trend.
One matching prediction is not the whole test
Original hypothetical model comparison. A and B are abstract indicators with separate axes; shaded bands are the stated comparison intervals, not assigned Gaussian confidence levels. Agreement does not establish a unique explanation.
Open full-size diagram in a new tab: One matching prediction is not the whole testCheck 2 of 3
10 pointsUse the reading above. You can try again without losing points.
Report a strong conclusion with its actual limits
Confidence in a broad cause can coexist with uncertainty in local details. A well-established human contribution to global warming does not determine the exact rainfall on a particular future date. Regional outcomes depend on , geography, internal variability, and the future influences being considered. Projections should therefore identify their assumptions and uncertainty rather than presenting one map as an unconditional promise.
A useful reading exercise separates observation, method, conclusion, and open question in a climate report. Ask what was measured, which alternative explanations were tested, and what evidence would challenge the result. Also check whether a number is a historical observation, a projection, or an illustrative example. This approach lets learners treat uncertainty as something to quantify while recognizing conclusions supported by many independent physical and observational checks.
Check 3 of 3
10 pointsUse the reading above. You can try again without losing points.
Put it together
Your lesson progress
Each check connects to a part of the story. Complete all 3 to earn your 25-point lesson bonus.
Go to the source
Explore the evidence behind this lesson. These optional readings and videos open in a new tab.