2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/205040Recently a covariant entropy conjecture has been proposed for dynamical horizons. We apply this conjecture to concordance cosmological models, namely, those cosmological models filled with perfect fluids, in the presence of a positive cosmological constant. As a result, we find this conjecture has a severe constraint power. Not only does this conjecture rule out those cosmological models disfavored by the anthropic principle, but also it imposes an upper bound $10^{-60}$ on the cosmological constant for our own universe, which thus provides an alternative macroscopic perspective for understanding the long-standing cosmological constant problem.10 pages, 1 figure, JHEP style, references added, published versionHigh Energy Physics - TheoryAstrophysicsGeneral Relativity and Quantum Cosmologytext