When I started reading IPCC reports, I became aware of the various type of droughts. The following is a brief description of the types. Also, a graphic showing the climate drivers of drought and a table showing the primary impacts from the different drought categories.
Drought
The primary contributing factor to drought is the lack of precipitation over a long enough period to cause severe hydrological impacts. See the Figure below for the climate drivers involved.
From: Douville et al., 2021
Meteorological drought
A persistent lack of precipitation over a long enough period causes a meteorological drought (Douville et al., 2021).
Hydrological drought
As the drought persists over time, water supply within soil, streams, lakes and reservoirs decreases(Douville et al., 2021). These can be widespread and affect many eco and social functions, as shown in Table 1 (Loon, 2015).
Agricultural drought
Agricultural drought occurs when soil moisture, due to a lack of precipitation and high atmospheric evaporation demand, becomes so abnormally low that the growing season and crop production are negatively affected (IPCC, 2021 & Douville et al., 2021).
Ecological drought
Like agricultural drought, abnormally low soil moisture affects land or terrestrial ecosystems, including forests (IPCC, 2021). Insufficient moisture in the total soil water column affects tree roots and their ability to transport water and impedes the carbon cycle, weakening and ultimately killing the tree (Seneviratne et al., 2021). The structure of the soil can be damaged as well.
Flash drought
Typically, droughts take time to develop; however, a flash drought can unexpectedly and rapidly evolve (Douville et al., 2021).
Megadrought
Megadrought is a drought that occurs over many years (Douville et al., 2021).
From: Van Loon, 2015.
References
Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, and O. Zolina. (2021). Water Cycle Changes. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1055–1210, https://doi:10.1017/9781009157896.010.
IPCC. (2021). Annex VII: Glossary [Matthews, J.B.R., V. Möller, R. van Diemen, J.S. Fuglestvedt, V. MassonDelmotte, C. Méndez, S. Semenov, A. Reisinger (eds.)]. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 2215–2256, https://doi:10.1017/9781009157896.022.
Seneviratne, S.I., X. Zhang, M. Adnan, W. Badi, C. Dereczynski, A. Di Luca, S. Ghosh, I. Iskandar, J. Kossin, S. Lewis, F. Otto, I. Pinto, M. Satoh, S.M. Vicente-Serrano, M. Wehner, and B. Zhou. (2021). Weather and Climate Extreme Events in a Changing Climate. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1513–1766, https://doi:10.1017/9781009157896.013.
Van Loon, A.F., (2015, July/August). Hydrological drought explained. WIREs Water 2015, 2:359–392. doi: 10.1002/wat2.1085