The spectrum of the light directly correlates to the heat it makes. That is how they discovered IR radiation, read this article.
http://www.brynmawr.edu/chemistry/Chem/mnerzsto/Marshall-Infrared.html
It explains how IR was discovered and how it has a higher temp than other spectrums of light, the more IR in the light source the more heat it produces so not all lights produce the same amount of heat.
Sorry, I overlooked this comment. Wasn't ignoring it.
While IR is more readily absorbed by more molecules, it doesn't have any more energy to "heat" anything moreso than say blue light or green light.
The spectrum of light doesn't correlate to the heat it makes, rather it denotes the frequency at which those photons will be absorbed. The photon gets absorbed by a molecule and excites an electron which increases kinetic energy causing "heat".
IR (particularly long-wave) happens to be very absorptive especially to water molecules i.e. People and plants. But if all the visible light was equally absorptive, it would have the same heating effects as IR.
"Infrared radiation is popularly known as "heat radiation", but light and electromagnetic waves of any frequency will heat surfaces that absorb them. Infrared light from the Sun accounts for 49%
[19] of the heating of Earth, with the rest being caused by visible light that is absorbed then re-radiated at longer wavelengths. Visible light or
ultraviolet-emitting
lasers can char paper and incandescently hot objects emit visible radiation. Objects at room
temperature will
emit radiation concentrated mostly in the 8 to 25 µm band, but this is not distinct from the emission of visible light by incandescent objects and ultraviolet by even hotter objects (see
black body and
Wien's displacement law).
[20]
Heat is energy in transit that flows due to temperature difference. Unlike heat transmitted by
thermal conduction or
thermal convection, thermal radiation can propagate through a
vacuum. Thermal radiation is characterized by a particular spectrum of many wavelengths that is associated with emission from an object, due to the vibration of its molecules at a given temperature. Thermal radiation can be emitted from objects at any wavelength, and at very high temperatures such radiations are associated with spectra far above the infrared, extending into visible, ultraviolet, and even X-ray regions (i.e., the
solar corona). Thus, the popular association of infrared radiation with thermal radiation is only a coincidence based on typical (comparatively low) temperatures often found near the surface of planet Earth."
https://en.m.wikipedia.org/wiki/Infrared
https://en.m.wikipedia.org/wiki/Non-ionizing_radiation
Not to derail the "organic vs synthetic" discussion.