## 1 Introduction  
Plants are the main component of the terrestrial biosphere, and can affect climate through matter and energy exchange between the land surface and the atmosphere. Photosynthesis and plant respiration can influence carbon exchange between the land surface and the atmosphere, and therefore can affect the global carbon balance by adjusting atmospheric carbon dioxide (CO\({}_{2}\)) concentration. Furthermore, interception and transpiration of water by plants can change the distribution of water by altering evaporation, runoff, soil water, and groundwater, thereby regulating water and heat exchange between the land surface and the atmosphere, ultimately changing the climate [1; 2; 3; 4]. Roots are one of the most important components of plants; they couple the aboveground vegetation and the soil media, and connect the soil environment to the atmosphere through water and energy flux exchanges between the vegetation canopy and the atmosphere. Moreover, roots are also responsible for nutrient uptake, which may control carbon (C) synthesis [5].  
It is important to understand the role that roots play in global carbon and hydrological cycles, and their subsequent influence on climate. Unfortunately, roots are arguably the least understood portion of both the ecosystem and land-surface processes. As a result, they are represented idealistically in many process-based land-surface models (LSMs), and remain the most simplistic component of contemporary Earth system models (ESMs). The vertical distribution of roots, which is one of their most important properties, is an essential component of many eco-hydrological models [6] and LSMs [7; 8; 9]; it mainly controls the extent of root water uptake among soil layers, and therefore soil water stress. Soil water stress further influences transpiration, C assimilation, and subsequently other C and water fluxes [10; 11; 12]. Hence, a realistic representation of root distribution is very important for hydrological, ecological, and climate modeling [13; 14; 15; 16; 17; 18]. Due to the difficulty of measuring entire root distributions throughout the soil profile [18; 19], the root distribution in most LSMs is simplified and treated as a static component [11; 19]. The parameters in static root distribution schemes depend only on plant type, with root distributions spatially and temporally invariant. It has been demonstrated that plants tend to allocate C to enhance acquisition of a limited resource [20], and therefore tend to grow more roots in zones where soil moisture is more freely available [21; 22; 23], and where more nutrients can be acquired [24]. These observations imply that root systems have the plasticity to respond dynamically to environmental conditions such as water and nutrient availability [25; 26; 27], indicating that static schemes are insufficient to describe actual root distributions and need to be improved. [PERSON] et al. [28] incorporated a dynamic root scheme into the Community Land Model version 4.5 (CLM4.5) that describes root growth as a compromise between water and nitrogen availability, and investigated the effects of dynamic root distribution on eco-hydrological modeling in the Amazon. Their results showed that vegetation responses to seasonal drought were better captured by the new dynamic root distribution scheme.  
Despite this, feedback loops among roots, soil, and vegetation are expected to influence ecosystem responses to climate change. Therefore, there is an urgent need for scientists to improve prognostic approaches to understand how roots govern changes in resource availability, and how root responses influence climate. In this study, the dynamic root distribution scheme mentioned above [28] was incorporated into the Community Earth System Model version 1.2.0 (CESM1.2.0), to further investigate the effects of dynamic root distribution on global climate, and the analysis focused on gross primary production (GPP), evapotranspiration (ET), 2-m air temperature (TA), and land precipitation (PR).