Connect molecular absorption, Earth’s energy balance and evidence-based climate claims.
Method and worked examples
Earth absorbs sunlight and emits longer-wavelength infrared radiation. CO2 and CH4 absorb selected infrared wavelengths through vibrations that change molecular dipole. Absorption and re-emission alter outgoing energy transfer. Increasing greenhouse-gas abundance initially reduces energy escaping to space; warming follows until incoming and outgoing energy again balance.
Use long-term annual means to distinguish a trend from seasonal variation. A short local weather record is different from a global climate average. Percentage increase is (final − initial)/initial ×100. Convert ppm as parts per million when the measurement basis is specified. Synthetic values in these drills are calculation data, not current atmospheric readings.
Example 1
A synthetic monitoring series rises from 320 ppm to 400 ppm. Find its percentage increase.
Increase =400−320=80 ppm. Percentage increase =32080×100=25%. These invented values illustrate a calculation, not a current atmospheric measurement.
Example 2
Why does a cold week not refute a long-term global warming trend?
A week at one site samples local weather. Climate conclusions use long-term, geographically representative observations and uncertainty estimates; short variability can occur within an increasing global trend.
Watch out:Their principal greenhouse action is absorbing and emitting outgoing infrared radiation, altering the energy balance.
Greenhouse gases and climate evidence | Year 12 Chemistry | Ascent Arcade