Soil and paleosol profiles record data about global processes that take place over different time and spatial scales. For example, the ratio of ¹³C/¹²C in pedogenic CaCO₃ is controlled by vegetation that, in turn, is controlled by climate. Consequently, this isotopic ratio has become an important tool for understanding climates of the past. However, the connection between ¹³C/¹²C in pedogenic CaCO₃ and paleoclimate involves crossing four scales where complexities arise that may lead to inaccurate interpretations. At the first scale, the rhizosphere scale, carbonates crystallize on a time scale of 10⁰ to 10² years over distances of 10^-6 to 10^-2 meters. In this micro-environment, some plant species produce crystals on their roots that exibit ¹³C/¹²C fractionations greater than the 14 to 16 ‰ typically observed between soil CO₂ and pedogenic carbonate. At the second scale, the soil profile scale (10⁰ to 10⁴ yr and 10^-3 to 10² m), newly precipitated CaCO₃ overprints previously precipitated CaCO₃. At the third scale, the landscape scale (10¹ to 10⁶ yr and 10¹ to 10⁵ m), the lateral variability in soil type, topography, and hydrology produce heterogeneous C3 and C4 vegetation patterns within a small area. At the fourth scale, the biome scale (10² to 10⁷ yr and 10⁴ to 10⁹ m), two boundaries exist between C3 and C4 vegetation: one at the C3 desert shrubland/C4 grassland boundary and one at the C4 grassland/C3 woodland boundary. Addressing these complexities at each of the four scales leads to more accurate paleoclimatic interpretations and an increased understanding of the climate-vegetation-soil system.