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[Abridged] The inner few AU of disks around young stars are best probed inthe infrared. The James Webb Space Telescope (JWST) is now starting tocharacterize the chemistry of these regions in unprecedented detail. Onepeculiar subset of sources are the so-called ``CO2-only sources'', in whichonly a strong 15 $\mu$m CO2 feature was detected in the spectrum. One scenariothat could explain the weak emission from H2O is the presence of a small, innercavity in the disk. If this cavity were to extend past the H2O snowline, butnot past the CO2 snowline, this could strongly suppress the H2O line fluxw.r.t. that of CO2. In this work, we aim to test the validity of thisstatement. Using the thermo-chemical code Dust And LInes (DALI), we created agrid of T Tauri disk models with an inner cavity, meaning we fully depleted theinner region of the disk in gas and dust starting from the dust sublimationradius and ranging until a certain cavity radius. We present the evolution ofthe CO2 and H2O spectra of a disk with inner cavity size, showing that, when alarge-enough cavity is introduced, a spectrum that was initially dominated byH2O lines can become CO2-dominated instead. However, the cavity size needed forthis is around 4-5 AU, exceeding the nominal position of the CO2 snowline in afull disk. The cause of this is most likely the alteration of the thermalstructure by the cavity, which pushes the snowlines outward. Alternativeexplanations for bright CO2 emission are also briefly discussed. Our modelingwork shows that it is possible for the presence of a small inner cavity toexplain strong CO2 emission in a spectrum. However, the cavity needed to do sois larger than what was initially expected. As such, this scenario will beeasier to test with sufficiently high angular resolution (millimeter)observations.

Mid-infrared spectra of T Tauri disks: Modeling the effects of a small inner cavity on CO2 and H2O emission