Two terms, two different subjects
The words weather and climate in these phrases are used differently, and the shared word causes confusion. In everyday weather, the atmosphere changes by the hour. Climate is the pattern of weather averaged over decades. The same split exists here, but with a bigger difference: space weather and climate change are not two time scales of the same thing.
- Space weather concerns conditions in space driven by the Sun: the solar wind, flares, coronal mass ejections and the resulting geomagnetic storms. Its effects play out over minutes to days and mostly concern technology and the upper atmosphere.
- Climate change refers to long-term shifts in Earth’s climate, mainly the lower atmosphere, oceans and ice. Scientific assessments attribute the warming of recent decades mainly to human emissions of greenhouse gases, as described in the treatment of the greenhouse effect and climate change drivers.
A solar storm does not cause global warming, and climate change does not cause solar storms.
Does the Sun explain climate change?
The Sun is the main energy source for Earth’s climate, so it is a natural question. Satellite instruments have measured the Sun’s total energy output since the late 1970s. It varies slightly over the roughly eleven-year solar cycle, by about a tenth of a percent. Over the same decades, global temperatures have risen, and the solar record does not show a matching upward trend. For this reason, assessments conclude that changes in solar output are not the main driver of recent warming, though they can contribute small natural variations.
What satellites measure for each
| Question | Typical space-based measurements |
|---|---|
| Space weather | X-ray and ultraviolet images of the Sun, solar wind speed and magnetic field, energetic particles, geomagnetic activity |
| Climate | Sea surface temperature, sea level, ice extent, atmospheric gases, clouds, Earth’s energy balance |
The first set mostly looks toward the Sun and into near-Earth space. The second mostly looks down at Earth. Both depend on long, consistent records, so instrument calibration and continuity are major concerns.
Where the research overlaps
There are real connections, and it helps to be exact about them.
- Solar variability as a small natural factor. Climate scientists include solar changes in their models, even though their effect is small compared with greenhouse gases.
- The upper atmosphere. Greenhouse gases warm the lower atmosphere but are understood to cool the very high atmosphere, which may reduce its density over long periods. Less density means less drag on satellites, which affects how long debris stays in orbit. This is an active research area, and details are still being studied.
- Atmospheric chemistry. Energetic particles can influence chemistry in the middle atmosphere, such as ozone, mostly in polar regions. Researchers study how large this effect is.
- Shared infrastructure and methods. Both fields use satellites, data assimilation and computer modeling, similar to what is done in climate modeling and numerical weather prediction.
Why keep them separate
Mixing the two can lead to bad conclusions. Someone who sees a news story about a solar storm might assume it relates to a warming planet, or vice versa. Understanding the difference helps readers judge claims. Space weather is mainly about risks to satellites, radio and electrical grids. Climate change is about changes to temperature, sea level and weather extremes, including the topics in extreme weather and sea level rise.
Both are subjects where uncertainty exists and scientists express it with ranges. Space-based observations are among the best tools for narrowing those ranges, because they provide a consistent view of a whole planet and of the star that powers it.