HL only: Subtopic 6.2: Climate change causes and impacts. Weather stations directly measure atmospheric conditions at ground level, satellites use remote sensing to monitor large areas, and radar emits electromagnetic pulses to detect precipitation and movement. Long-term records from these technologies provide evidence of climatic trends.
How Each Technology Collects Data
| Technology | Data collection method | Uses and limitations |
|---|---|---|
| Weather stations | Instruments measure temperature, precipitation, pressure, humidity, wind speed, and wind direction at fixed locations. | They provide direct, repeated local measurements. However, coverage may be uneven, equipment may change, and one station represents only a limited area. |
| Satellites | Sensors detect reflected solar radiation and infrared or microwave radiation emitted by Earth's surface and atmosphere. Environmental variables are inferred from these signals. | They provide frequent, global coverage of clouds, surface temperature, ice, vegetation, sea level, and atmospheric gases. However, records are relatively short and require calibration and computer processing. |
| Radar | A transmitter emits pulses that are reflected by precipitation particles. The returning signal indicates location and intensity; Doppler radar also estimates movement. | It maps precipitation, storms, and wind at high temporal resolution. Mountains may block signals, while accuracy decreases with distance. |
A common misconception is that these technologies measure climate directly. They measure weather or environmental conditions at particular times. Climate evidence emerges when standardized observations are compiled into long-term data sets and analysed for trends.
Scientists improve reliability through triangulation, comparing independent records. For example, station temperature trends can be checked against satellite observations, while radar can be compared with rain gauges. Calibration, standardization, and uncertainty assessment are essential before data are used in climate models.
Exam Technique
For an IB ESS compare and contrast question, refer to every method throughout. Identify measurements, distinguish ground-based instruments from remote sensing, and give a strength and limitation for each. Never claim that one weather event proves climate change; evidence requires a long-term trend.