In recent time natural and, mostly, anthropic CO2 emissions in the atmosphere have severely exasperated Earth’s global warming. Knowledge that the planet will not be able to tolerate the CO2 increasing in the atmosphere should not be dismissed; and human effects, still rising, should certainly be monitored and mitigated. I propose the use of a device able to quantify and absorb atmospheric CO2 to be placed starting from the highly urbanized areas, in indoor and outdoor environments. This consists in three parts: a filter for CO2 absorbing from the atmosphere; a sensor for quantifying the CO2 trapped in the filter; and a monitor displaying, in situ and remote, the CO2 absorption-level; achieving the dual effect of lowering and monitoring the CO2 emissions. This may be placed near factories, in buildings, and also inserted as a new module as part of the air conditioners. In the latter case, even in indoor environments, you could keep down the level of CO2, and reduce the energy consumption costs due to the traditional air circulation (and accordingly prevent the further CO2 emissions!). I propose an innovative technology of algal mat (made out of cyanobacteria and sediments), now used for biofuel, but to be also applied to the realization of the filter absorbing the CO2; overcoming the ecological problem of mats’ overpopulation in the ocean, disrupting the underwater marine life. Finally, the captured CO2 (in the filter) will be supplied to the agro-alimentary industries.