A climate change model that leaves this out isn't credible - and most do

Svensmark, Enghoff, Shaviv, and Svensmark in "Nature".

Here is a link to the paper "Increased ionization supports growth of aerosols into cloud condensation nuclei.

Climate models do not include all possible sources of climate change.  In fact, they include just a few. A climate model that leaves out possibly important sources of climate change cannot be trusted. Yet such models' implications are treated as gospel by much of the media, politicians, and even many climate scientists - particularly the modelers.  Contrary to what you have been led to believe, some scientists question the "revealed truth" of those who tend to accuse them of being "climate deniers".

SES's paper is "real science" and its implications include taking the "official" climate models with a grain of salt.  Perhaps for this reason, the Authors have been attacked by some of those whose models are deficient or whose financial interests lie with climate alarmism. The Authors' have shown that these attacks and criticism are incorrect, yet their responses have largely been ignored by the "Climate Change Cabal".

Here are some excerpts.
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Introduction

Clouds are a fundamental part of the terrestrial energy budget, and any process that can cause systematic changes in cloud micro-physics is of general interest. To form a cloud droplet, water vapor needs to condense to aerosols acting as cloud condensation nuclei (CCN) of sizes of at least 50–100 nm, and changes in the number of CCN will influence the cloud microphysics. One process that has been pursued is driven by ionization caused by cosmic rays, which has been suggested to be of importance by influencing the density of CCN in the atmosphere and thereby Earth’s cloud cover. Support for this idea came from experiments, which demonstrated that ions significantly amplify the nucleation rate of small aerosols (≈1.7 nm). However, to affect cloud properties, any change in small aerosols needs to propagate to CCN sizes 50–100 nm, but such changes were subsequently found by numerical modeling to be too small to affect clouds. The proposed explanation for this deficit is that additional aerosols reduce the concentration of the gases from which the particles grow, and a slower growth increases the probability of smaller aerosols being lost to pre-existing aerosols. This has lead to the conclusion that no significant link between cosmic rays and clouds exists in Earth’s atmosphere.

This conclusion stands in stark contrast to a recent experiment demonstrating that when excess ions are present in the experimental volume, all extra nucleated aerosols can grow to CCN sizes. But without excess ions in the experimental volume, any extra small aerosols (3 nm) are lost before reaching CCN sizes, in accordance with the above mentioned model results. The conjecture was that an unknown mechanism is operating, whereby ions facilitate the growth and formation of CCN. Additional evidence comes from atmospheric observations of sudden decreases in cosmic rays during solar eruptions in which a subsequent response is observed in aerosols and clouds. Again, this is in agreement with a mechanism by which a change in ionization translates into a change in CCN number density. However, the nature of this micro-physical link has been elusive.

In this work we demonstrate, theoretically and experimentally, the presence of an ion mechanism, relevant under atmospheric conditions, where variations in the ion density enhance the growth rate from condensation nuclei (≈1.7 nm) to CCN. It is found that an increase in ionization results in a faster aerosol growth, which lowers the probability for the growing aerosol to be lost to existing particles, and more aerosols can survive to CCN sizes. It is argued that the mechanism is significant under present atmospheric conditions and even more so during prehistoric elevated ionization caused by a nearby supernova. The mechanism could therefore be a natural explanation for the observed correlations between past climate variations and cosmic rays, modulated by either solar activity or caused by supernova activity in the solar neighborhood on very long time scales where the mechanism will be of profound importance.