**5. Conclusions**

We analyzed the climate feedback on vegetation using CMIP5 model experiments for each climate-limited region. In contrast to the climate trend induced by the radiative effect, the positive trend in GPP and LAI can be attributed mainly to the CO2 fertilization effect. While CO2 fertilization was the main driver of the increasing trend in vegetation, the climate feedback on vegetation also contributed to 17% and 7% of vegetation growth in temperature-limited and radiation-limited regions, respectively. These feedbacks provide additional sensitivity to the CO2 fertilization, and can explain the discrepancy of the β factor between models and observation. The observed trend corroborates the importance of the climate feedback in explaining the greening earth.

**Author Contributions:** Conceptualization, H.H., R.R.N., G.B., L.C., S.G., W.W., C.M., R.E., T.L. and R.M.; data curation, A.R.M.

**Funding:** This research was funded by the NASA Earth science program.

**Acknowledgments:** Computational resources from NASA Earth Exchange helped facilitate the analysis.

**Conflicts of Interest:** The authors declare no conflict of interest.
