Drought: Difference between revisions

| footer = Droughts cause a range of impacts and are often worsened by to the [[effects of climate change on the water cycle]]: a dry riverbed in [[France]]; sandstorm in [[Somaliland]] due to drought; droughts negatively [[Effects of climate change on agriculture|impact agriculture]] in [[Texas]]; drought and high temperatures worsened the [[2019–20 Australian bushfire season#Climate change|2020 bushfires in Australia]].

A '''drought''' is a period of drier-than-normal conditions.<ref name=":2">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: [https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter08.pdf Water Cycle Changes] {{Webarchive|url=https://web.archive.org/web/20220929084018/https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter08.pdf |date=2022-09-29 }}. 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, doi:10.1017/9781009157896.010.</ref>{{rp|1157}} A drought can last for days, months or years. Drought often has large impacts on the [[ecosystem]]s and [[agriculture]] of affected regions, and causes harm to the local [[economy]].<ref>[http://www.bom.gov.au/climate/drought/livedrought.shtml Living With Drought<!-- Bot generated title -->] {{webarchive|url=https://web.archive.org/web/20070218192510/http://www.bom.gov.au/climate/drought/livedrought.shtml|date=2007-02-18}}</ref><ref>[http://www.lilith-ezine.com/articles/environmental/Australian-Drought.html Australian Drought and Climate Change] {{Webarchive|url=https://web.archive.org/web/20180726021950/http://www.lilith-ezine.com/articles/environmental/Australian-Drought.html |date=2018-07-26 }}, retrieved. onRetrieved June 7th 2007.</ref> Annual dry seasons in the [[tropics]] significantly increase the chances of a drought developing, andwith subsequent increased [[wildfire]]s risks.<ref name="Brando">{{cite journal |last1=Brando |first1=Paulo M. |last2=Paolucci |first2=Lucas |last3=Ummenhofer |first3=Caroline C. |last4=Ordway |first4=Elsa M. |last5=Hartmann |first5=Henrik |last6=Cattau |first6=Megan E. |last7=Rattis |first7=Ludmila |last8=Medjibe |first8=Vincent |last9=Coe |first9=Michael T. |last10=Balch |first10=Jennifer |title=Droughts, Wildfires, and Forest Carbon Cycling: A Pantropical Synthesis |journal=Annual Review of Earth and Planetary Sciences |date=30 May 2019 |volume=47 |issue=1 |pages=555–581 |doi=10.1146/annurev-earth-082517-010235 |url=https://www.annualreviews.org/doi/10.1146/annurev-earth-082517-010235 |language=en |issn=0084-6597|doi-access=free |bibcode=2019AREPS..47..555B}}</ref> Periods[[Heat of heatwave]]s can significantly worsen drought conditions by hastening evaporation ofincreasing [[water vapourevapotranspiration]],.<ref name="Merzdorf">{{cite news |last1=Merzdorf |first1=Jessica |title=A Drier Future Sets the Stage for More Wildfires |url=https://climate.nasa.gov/news/2891/a-drier-future-sets-the-stage-for-more-wildfires/ |work=Climate Change: Vital Signs of the Planet |publisher=NASA |date=July 9, 2019}}</ref> dryingThis dries out forests and other vegetation, and increasingincreases the amount of fuel for wildfires.<ref name="Brando"/><ref name="Hartmann"/>

Drought is a recurring feature of the climate in most parts of the world, becoming more extreme and less predictable due to [[climate change]], which [[dendrochronological]] studies date back to 1900. There are three kinds of drought effects, environmental, economic and social. Environmental effects include the drying of [[wetland]]s, more and larger wildfires, [[Biodiversity loss|loss of biodiversity]]. Economic consequences include disruption of [[Water supply|water supplies]] for municipal economies; lower agricultural, forest, game, and fishing outputs; higher food-production costs; and problems with water supply for the [[Energy industry|energy sector]]. Social and health costs include the negative effect on the health of people directly exposed to this phenomenon (excessive [[heat wave]]s), high food costs, stress caused by failed harvests, [[water scarcity]], etc. Prolonged droughts have caused [[mass migration]]s and [[humanitarian crisis]].<ref name="Stanke">{{cite journal |last1=Stanke |first1=C |last2=Kerac |first2=M |last3=Prudhomme |first3=C |last4=Medlock |first4=J |last5=Murray |first5=V |title=Health effects of drought: a systematic review of the evidence. |journal=PLOS Currents |date=5 June 2013 |volume=5 |doi=10.1371/currents.dis.7a2cee9e980f91ad7697b570bcc4b004 |pmid=23787891 |pmc=3682759 |doi-access=free }}</ref><ref>{{cite journal |last1=Bellizzi |first1=Saverio |last2=Lane |first2=Chris |last3=Elhakim |first3=Mohamed |last4=Nabeth |first4=Pierre |title=Health consequences of drought in the WHO Eastern Mediterranean Region: hotspot areas and needed actions |journal=Environmental Health |date=12 November 2020 |volume=19 |issue=1 |pages=114 |doi=10.1186/s12940-020-00665-z |issn=1476-069X |doi-access=free |pmc=7659048 }}</ref>

According to [[National Integrated Drought Information System]], a multi-agency partnership, drought is generally defined as "a deficiency of precipitation over an extended period of time (usually a season or more), resulting in a water shortage". The National Weather Service office of the [[National Oceanic and Atmospheric Administration|NOAA]] defines drought as "a deficiency of moisture that results in adverse impacts on people, animals, or vegetation over a sizeable area".<ref>{{Cite web |title=Drought Basics |url=https://www.drought.gov/what-is-drought/drought-basics |access-date=2022-09-16 |website=Drought.gov |publisher=NOAA National Integrated Drought Information System |language=en}}</ref>

Drought is a complex phenomenon − relating to the absence of water − which is difficult to monitor and define.<ref name=":0">{{Cite web |title=Definition of Drought |url=https://www.ncei.noaa.gov/access/monitoring/dyk/drought-definition |access-date=2022-09-16 |website=www.ncei.noaa.gov |publisher=NOAA {{!}} National Centers for Environmental Information (NCEI)}}</ref> By the early 1980s, over 150 definitions of "drought" had already been published.<ref name=":32">{{Cite web |title=Types of Drought |url=https://drought.unl.edu/Education/DroughtIn-depth/TypesofDrought.aspx |access-date=2022-09-16 |website=drought.unl.edu |publisher=National Drought Mitigation Center}}</ref> The range of definitions reflects differences in regions, needs, and disciplinary approaches.

There are three major categories of drought based on where in the water cycle the moisture deficit occurs: meteorological drought, hydrological drought, and agricultural or ecological drought.<ref name=":2" />{{rp|1157}} A meteorological drought occurs due to lack of [[precipitation]]. A hydrological drought is related to low runoff, streamflow, and reservoir and groundwater storage.<ref>{{Cite journal|last=Van Loon|first=Anne F.|date=14 April 2015|title=Hydrological drought explained|url=https://wires.onlinelibrary.wiley.com/doi/10.1002/wat2.1085|journal=WIREs Water|volume=2|issue=4|pages=359–392|doi=10.1002/wat2.1085|bibcode=2015WIRWa...2..359V|issn=2049-1948}}</ref> An agricultural or ecological drought is causing plant stress from a combination of evaporation and low [[soil moisture]].<ref name=":2" />{{rp|1157}} Some organizations add another category: socioeconomic drought occurs when the demand for an economic good exceeds supply as a result of a weather-related shortfall in water supply.<ref name=":0" /><ref name=":32" /> The socioeconomic drought is a similar concept to [[water scarcity]].

# [[Meteorology|Meteorological]] drought occurs when there is a prolonged time with less than average precipitation.<ref name="IGARSS2017">{{cite book |last1=Swain|display-authors=etal|first1=S |title=2017 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) |chapter=Application of SPI, EDI and PNPI using MSWEP precipitation data over Marathwada, India |volume=2017 |pages=5505–5507 |doi=10.1109/IGARSS.2017.8128250 |year=2017|isbn=978-1-5090-4951-6|s2cid=26920225}}</ref> Meteorological drought usually precedes the other kinds of drought.<ref name="NOAAsurprise">{{cite web|url=http://www.nws.noaa.gov/om/brochures/climate/Drought.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.nws.noaa.gov/om/brochures/climate/Drought.pdf |archive-date=2022-10-09 |url-status=live|title=What is a Drought?|date=August 2006|publisher=[[National Oceanic and Atmospheric Administration]]|access-date=2007-04-10}}</ref> As a drought persists, the conditions surrounding it gradually worsen and its impact on the local population gradually increases.

# [[Hydrology|Hydrological]] drought is brought abouthappens when the water reserves available in sources such as [[aquifer]]s, [[lake]]s and [[reservoir]]s fall below average or a [[Descriptive statistics|locally significant]] threshold. Hydrological drought tends to show uppresent more slowly because it involves stored water that is used but not replenished. Like anDue agriculturalto droughtthe close interaction with water use, this type of drought is can be heavily influenced by [[water management]]. Both positive and negative human influences have been discovered and strategic water management strategies seem key to mitigate drought impact.<ref>{{Cite journal|last1=Van Loon|first1=Anne F.|last2=Stahl|first2=Kerstin|last3=Di Baldassarre|first3=Giuliano|last4=Clark|first4=Julian|last5=Rangecroft|first5=Sally|last6=Wanders|first6=Niko|last7=Gleeson|first7=Tom|last8=Van Dijk|first8=Albert I. J. M.|last9=Tallaksen|first9=Lena M. |last10=Hannaford |first10=Jamie|last11=Uijlenhoet|first11=Remko|last12=Teuling|first12=Adriaan J.|last13=Hannah|first13=David M.|last14=Sheffield|first14=Justin|last15=Svoboda|first15=Mark|date=2016-09-08|title=Drought in a human-modified world: reframing drought definitions, understanding, and analysis approaches|url=https://hess.copernicus.org/articles/20/3631/2016/|journal=Hydrology and Earth System Sciences|volume=20|issue=9|pages=3631–3650|doi=10.5194/hess-20-3631-2016|doi-access=free|bibcode=2016HESS...20.3631V|issn=1027-5606|hdl=1885/152821|hdl-access=free}}</ref><ref>{{Cite journal|last1=Wendt|first1=Doris E.|last2=Van Loon|first2=Anne F.|last3=Bloomfield|first3=John P.|last4=Hannah|first4=David M.|date=2020-10-13|title=Asymmetric impact of groundwater use on groundwater droughts|url=https://hess.copernicus.org/articles/24/4853/2020/|journal=Hydrology and Earth System Sciences|volume=24|issue=10|pages=4853–4868|doi=10.5194/hess-24-4853-2020|doi-access=free|bibcode=2020HESS...24.4853W|issn=1027-5606}}</ref> Like agricultural droughts, hydrological droughts can be triggered by more than just a loss of rainfall. For instance, around 2007 [[Kazakhstan]] was awarded a large amount of money by the [[World Bank]] to restore water that had been diverted to other nations from the [[Aral Sea]] under [[Soviet Union|Soviet]] rule.<ref>{{cite news |date=2007-04-09 |title=BBC NEWS - Asia-Pacific -– Dam project aims to save Aral Sea |workpublisher=BBC News|url=http://news.bbc.co.uk/2/hi/asia-pacific/6538219.stm}}</ref> Similar circumstances also place their largest lake, [[Lake Balkhash|Balkhash]], at risk of completely drying out.<ref>{{cite news |date=2004-01-15 |title=BBC NEWS - Asia-Pacific -– Kazakh lake 'could dry up' |workpublisher=BBC News|url=http://news.bbc.co.uk/2/hi/asia-pacific/3397077.stm}}</ref>

* [[Palmer drought index]] (sometimes called the Palmer drought severity index (PDSI)): a regional drought index commonly used for monitoring drought events and studying areal extent and severity of drought episodes.<ref name="auto">{{Cite journal |last1=Mishra |first1=Ashok K. |last2=Singh |first2=Vijay P. |date=September 2010 |title=A review of drought concepts |url=https://linkinghub.elsevier.com/retrieve/pii/S0022169410004257 |journal=Journal of Hydrology |language=en |volume=391 |issue=1–2 |pages=202–216 |doi=10.1016/j.jhydrol.2010.07.012|bibcode=2010JHyd..391..202M}}</ref> The index uses precipitation and temperature data to study moisture supply and demand using a simple water balance model.<ref name="auto" /><ref>{{Cite journal |last=Van Loon |first=Anne F. |date=July 2015 |title=Hydrological drought explained: Hydrological drought explained |journal=Wiley Interdisciplinary Reviews: Water |language=en |volume=2 |issue=4 |pages=359–392 |doi=10.1002/wat2.1085 |doi-access=free|bibcode=2015WIRWa...2..359V}}</ref><ref>{{Cite journal |lastlast1=Liu |firstfirst1=Yi |last2=Ren |first2=Liliang |last3=Ma |first3=Mingwei |last4=Yang |first4=Xiaoli |last5=Yuan |first5=Fei |last6=Jiang |first6=Shanhu |date=January 2016 |title=An insight into the Palmer drought mechanism based indices: comprehensive comparison of their strengths and limitations |url=http://link.springer.com/10.1007/s00477-015-1042-4 |journal=Stochastic Environmental Research and Risk Assessment |language=en |volume=30 |issue=1 |pages=119–136 |doi=10.1007/s00477-015-1042-4 |bibcode=2016SERRA..30..119L|issn=1436-3240}}</ref>

* [[Keetch-Byram Drought Index]]: an index that is calculated based on rainfall, air temperature, and other [[meteorological]] factors.<ref>{{cite journal |author1=Keetch, John J. |author2=Byram, George M. |year=1968 |title=A Drought Index for Forest Fire Control |url=http://www.srs.fs.usda.gov/pubs/viewpub.jsp?index=40 |journal=Res. Pap. Se-38. Asheville, Nc: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station. 35 P |publisher=USDA Forest Service Southern Research Station |volume=038 |access-date=August 11, 2016 |quote=(Date: 1968) Res. Paper SE-38. 32 pp. Asheville, NC: U.S. Department of Agriculture, Forest Service}}</ref>

* Standardized precipitation index (SPI): It is computed based on precipitation, which makes it a simple and easy-to-apply indicator for monitoring and prediction of droughts in different parts of the world. The [[World Meteorological Organization]] recommends this index for identifying and monitoring meteorological droughts in different climates and time periods.<ref name=":3" />
* [[Standardised Precipitation Evapotranspiration Index|Standardized Precipitation Evapotranspiration Index]] (SPEI): a multiscalar drought index based on climatic data. The SPEI accounts also for the role of the increased atmospheric [[Potential evapotranspiration|evaporative demand]] on drought severity.<ref name=":3" /> Evaporative demand is particularly dominant during periods of precipitation deficit. The SPEI calculation requires long-term and high-quality precipitation and atmospheric evaporative demand datasets. These can be obtained from ground stations or gridded data based on reanalysis as well as satellite and multi-source datasets.<ref name=":3" />

The application of multiple indices using different datasets helps to better manage and monitor droughts than using a single dataset, This is particularly the case in regions of the world where not enough data is available such as Africa and South America. Using a single dataset can be limiting, as it may not capture the full spectrum of drought characteristics and impacts.<ref name=":3" />

[[File:Drought.jpg|thumb|upright|Contraction and desiccation cracks in the dry earth of the [[Sonoran desertDesert]], northwestern Mexico]]

Mechanisms of producing precipitation include [[convective]], [[Stratus cloud|stratiform]],<ref>{{cite journal |title=A convective/stratiform precipitation classification algorithm for volume scanning weather radar observations|author=Emmanouil N. Anagnostou|journal=[[Meteorological Applications]]|year=2004|volume=11|pages=291–300|doi=10.1017/S1350482704001409|issue=4|bibcode = 2004MeApp..11..291A |doi-access=free}}</ref> and [[orographic lift|orographic]] rainfall.<ref>{{cite journal |title=A model of annual orographic precipitation and acid deposition and its application to Snowdonia|author1=A.J. Dore |author2=M. Mousavi-Baygi |author3=R.I. Smith |author4=J. Hall |author5=D. Fowler |author6=T.W. Choularton |journal=Atmospheric Environment|volume=40|date=June 2006|pages=3316–3326|doi=10.1016/j.atmosenv.2006.01.043|issue=18|bibcode = 2006AtmEn..40.3316D }}</ref> Convective processes involve strong vertical motions that can cause the overturning of the atmosphere in that location within an hour and cause heavy precipitation,<ref name="convection">{{cite book|author=Robert Penrose Pearce|year=2002|url=https://books.google.com/books?id=QECy_UBdyrcC&pg=PA66|title=Meteorology at the Millennium|publisher=Academic Press|page=66|isbn=978-0-12-548035-2|access-date=2009-01-02}}</ref> while stratiform processes involve weaker upward motions and less intense precipitation over a longer duration.<ref>{{Cite book|title=Cloud dynamics|last=Houze| first=Robert A. Jr. |date=1993|publisher=Academic Press|isbn=9780080502106|location=San Diego|oclc=427392836}}</ref>

Precipitation can be divided into three categories, based on whether it falls as liquid water, liquid water that freezes on contact with the surface, or ice.

Droughts occur mainly in areas where normal levels of rainfall are, in themselves, low. If these factors do not support precipitation volumes sufficiently to reach the surface over a sufficient time, the result is a drought. Drought can be triggered by a high level of reflected sunlight and above average prevalence of high [[pressure system]]s, [[wind]]s carrying continental, rather than oceanic air masses, and ridges of [[high pressure area]]s aloft can prevent or restrict the developing of thunderstorm activity or rainfall over one certain region. Once a region is within drought, feedback mechanisms such as local arid air,<ref>{{cite book|url=https://books.google.com/books?id=3lbixDAw5DwC&pg=PA22|page=22|title=Greenhouse Effect, Sea Level and Drought|author1=Roland Paepe |author2=Rhodes Whitmore Fairbridge |author3=Saskia Jelgersma |date=1990|publisher=Springer Science & Business Media|isbn=978-0792310174}}</ref> hot conditions which can promote warm core ridging,<ref>{{cite book|url=https://books.google.com/books?id=PvJyVtw53Y4C&pg=PA48|pages=48–49|title=The Oryx Resource Guide to El Niño and La Niña|author1=Joseph S. D'Aleo |author2=Pamela G. Grube |date=2002|publisher=Greenwood Publishing Group|isbn=978-1573563789}}</ref> and minimal evapotranspiration can worsen drought conditions.

Within the tropics, distinct, [[wet season|wet]] and dry [[season]]s emerge due to the movement of the [[Intertropical Convergence Zone]] or [[Monsoon trough]].<ref name="Wang">{{cite book|author=Bin Wang|url=https://books.google.com/books?id=yRT57TENzT8C&pg=PT206|title=The Asian Monsoon|date=2006-01-13|publisher=Springer Science & Business Media|isbn=978-3540406105|page=206}}</ref> The dry season greatly increases drought occurrence,<ref>{{cite book|url= https://books.google.com/books?id=y6r9jUTzJiYC&pg=PA349|page=349|title=Monitoring and Predicting Agricultural Drought : A Global Study: A Global Study|author1=Vijendra K. Boken |author2=Arthur P. Cracknell |author3=Ronald L. Heathcote |date=2005-03-24|isbn=978-0198036784|publisher=Oxford University Press}}</ref> and is characterized by its low humidity, with watering holes and rivers drying up. Because of the lack of these watering holes, many grazing animals are forced to migrate due to the lack of water in search of more fertile lands. Examples of such animals are [[zebras]], [[elephants]], and [[wildebeest]]. Because of the lack of water in the plants, bushfires are common.<ref>{{cite web | url=http://burarra.questacon.edu.au/pages/seasons.html | title=Wet & Dry Seasons | access-date=2018-12-23 | archive-url=https://web.archive.org/web/20120320141721/http://burarra.questacon.edu.au/pages/seasons.html | archive-date=2012-03-20 | url-status=dead }}</ref> Since water vapor becomes more energetic with increasing temperature, more water vapor is required to increase relative humidity values to 100% at higher temperatures (or to get the temperature to fall to the dew point).<ref>{{cite web|url=http://www.ems.psu.edu/~fraser/Bad/BadClouds.html|title=Bad Meteorology: The reason clouds form when air cools is because cold air cannot hold as much water vapor as warm air|author=Alistair B. Fraser|date=1994-11-27|access-date=2015-02-17|archive-url=https://web.archive.org/web/20150316122724/http://www.ems.psu.edu/~fraser/Bad/BadClouds.html|archive-date=2015-03-16|url-status=dead}}</ref> Periods of warmth quicken the pace of fruit and vegetable production,<ref>{{cite book|url=http://www2.ca.uky.edu/agc/pubs/id/id128/id128.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www2.ca.uky.edu/agc/pubs/id/id128/id128.pdf |archive-date=2022-10-09 |url-status=live|page=19|title=Home Vegetable Gardening in Kentucky|author=Cooperative Extension Service|publisher=[[University of Kentucky]]|date=January 2014|access-date=2015-02-18}}</ref> increase evaporation and transpiration from plants,<ref>{{cite web|author=North Carolina State University|title=Evapotranspiration|url=https://www.nc-climate.ncsu.edu/edu/k12/.evapo|date=2013-08-09|access-date=2015-02-18|archive-url=https://web.archive.org/web/20150219045714/https://www.nc-climate.ncsu.edu/edu/k12/.evapo|archive-date=2015-02-19|url-status=dead|author-link=North Carolina State University}}</ref> and worsen drought conditions.<ref>{{cite web|url=http://www.noaanews.noaa.gov/stories/s909.htm|date=2002-05-16|access-date=2015-02-18|title= Warm Temperatures and Severe Drought Continued in April Throughout Parts of the United States; Global Temperature For April Second Warmest on Record|author=National Oceanic and Atmospheric Administration |url-status=dead |archive-url=https://web.archive.org/web/20150219055008/http://www.noaanews.noaa.gov/stories/s909.htm |archive-date= Feb 19, 2015 }}</ref>

The [[El Niño–Southern Oscillation]] (ENSO) phenomenon can sometimes play a significant role in drought. ENSO comprises two patterns of temperature anomalies in the central [[Pacific Ocean]], known as [[La Niña]] and [[El Niño]]. La Niña events are generally associated with drier and hotter conditions and further exacerbation of drought in [[droughts in California|California]] and the [[Southwestern United States]], and to some extent the [[Southeastern United States|U.S. Southeast]]. Meteorological scientists have observed that La Niñas have become more frequent over time.<ref>{{cite web|url=https://www.9news.com/article/news/nation-world/la-nina-west-coast-climate/507-f792ab4a-bc35-4e45-9de1-08d8379dfc9b|title= Weather's unwanted guest: Nasty La Niña keeps popping up|author=Seth Borenstein |publisher=9news.com.au.com|date=May 28, 2022|access-date=June 4, 2022|quote= Scientists are noticing that in the past 25 years the world seems to be getting more La Niñas than it used to… to...|url-status=live |archive-url=https://archive.today/20231206185338/https://www.9news.com/amp/article/news/nation-world/la-nina-west-coast-climate/507-f792ab4a-bc35-4e45-9de1-08d8379dfc9b |archive-date=6 DecDecember 2023 }}</ref>

Conversely, during El Niño events, drier and hotter weather occurs in parts of the [[Amazon River]] Basin, [[Colombia]], and [[Central America]]. Winters during the El Niño are warmer and drier than average conditions in the Northwest, northern Midwest, and northern Mideast United States, so those regions experience reduced snowfalls. Conditions are also drier than normal from December to February in south-central Africa, mainly in [[Zambia]], [[Zimbabwe]], [[Mozambique]], and [[Botswana]]. Direct effects of El Niño resulting in drier conditions occur in parts of [[Southeast Asia]] and [[Northern Australia]], increasing [[bush fire]]s, worsening [[haze]], and decreasing air quality dramatically. Drier-than-normal conditions are also in general observed in [[Queensland]], inland [[Victoria (Australia)|Victoria]], inland [[New South Wales]], and eastern [[Tasmania]] from June to August. As warm water spreads from the west Pacific and the [[Indian Ocean]] to the east Pacific, it causes extensive drought in the western Pacific. Singapore experienced the driest February in 2014 since records began in 1869, with only 6.3&nbsp;mm of rain falling in the month and temperatures hitting as high as 35&nbsp;°C on 26 February. The years 1968 and 2005 had the next driest Februaries, when 8.4&nbsp;mm of rain fell.<ref>{{cite web|url=http://www.channelnewsasia.com/stories/singaporelocalnews/view/1040778/1/.html |websitepublisher=channelnewsasia.comChannel NewsAsia|title=February 2010 is driest month for S'pore since records began in 1869 |first1=Joanne |last1=Chan |date=3 March 2010|access-date=5 November 2017 |archive-url=https://web.archive.org/web/20100303222328/http://www.channelnewsasia.com/stories/singaporelocalnews/view/1040778/1/.html|archive-date=3 March 2010}}</ref>

[[File:Global warming and extreme weather.svg|thumb|upright=1.35| There will likely be multiplicative increases in the frequency of [[extreme weather]] events compared to the pre-industrial era for [[heat waveswave]]s, droughts and heavy precipitation events, for various climate change scenarios.<ref name="IPCC6AR_ExtremeEvents">{{cite web |title=Climate Change 2021 / The Physical Science Basis / Working Group I contribution to the WGI Sixth Assessment Report of the Intergovernmental Panel on Climate Change / Summary for Policymakers |url=https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM_final.pdf |publisher=Intergovernmental Panel on Climate Change |archive-url=https://web.archive.org/web/20211104175351/https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM_final.pdf |archive-date=4 November 2021 |page=SPM-23 |date=9 August 2021 |url-status=live }} Fig. SPM.6</ref>]]

The [[IPCC Sixth Assessment Report]] also pointed out that "Warming over land drives an increase in atmospheric evaporative demand and in the severity of drought events"<ref>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: [https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter08.pdf Chapter 8: Water Cycle Changes]. In [https://www.ipcc.ch/report/ar6/wg1/ 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, doi:10.1017/9781009157896.010.</ref>{{rp|1057}} and "Increased atmospheric evaporative demand increases plant water stress, leading to agricultural and ecological drought".<ref>Caretta, M.A., A. Mukherji, M. Arfanuzzaman, R.A. Betts, A. Gelfan, Y. Hirabayashi, T.K. Lissner, J. Liu, E. Lopez Gunn, R. Morgan, S. Mwanga, and S. Supratid, 2022: [https://www.ipcc.ch/report/ar6/wg2/downloads/report/IPCC_AR6_WGII_Chapter04.pdf Chapter 4: Water]. In: [https://www.ipcc.ch/report/ar6/wg2/ Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change] [H.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B. Rama (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, USA, pp. 551–712, doi:10.1017/9781009325844.006.</ref>{{rp|578}}

There is a rise of compound warm-season droughts in Europe that are concurrent with an increase in potential [[evapotranspiration]].<ref>{{Cite journal |last1=Markonis |first1=Yannis |last2=Kumar |first2=Rohini |last3=Hanel |first3=Martin |last4=Rakovec |first4=Oldrich |last5=Máca |first5=Petr |last6=AghaKouchak |first6=Amir |dateyear=2021 |title=The rise of compound warm-season droughts in Europe |journal=Science Advances |language=en |volume=7 |issue=6 |pages=eabb9668 |bibcode=2021SciA....7.9668M |doi=10.1126/sciadv.abb9668 |issn=2375-2548 |pmc=7857689 |pmid=33536204}}</ref>

Human activity can directly trigger exacerbating factors such as over-farming, excessive [[irrigation]],<ref name="Galilee">{{cite news |title=A biblical tragedy as Sea of Galilee faces drought |newspaper=BelfastTelegraph.co.ukBelfast Telegraph|url=http://www.belfasttelegraph.co.uk/news/world-news/a-biblical-tragedy-as-sea-of-galilee-faces-drought-13956116.html}}</ref> [[deforestation]], and [[erosion]] adversely impact the ability of the land to capture and hold water.<ref>{{cite web |title=Kenya: Deforestation exacerbates droughts, floods |url=http://forests.org/shared/reader/welcome.aspx?linkid=63511&keybold=climate%20drought%20water%20catchment |url-status=dead |archive-url=https://web.archive.org/web/20110927024422/http://forests.org/shared/reader/welcome.aspx?linkid=63511&keybold=climate%20drought%20water%20catchment |archive-date=2011-09-27 |access-date=2008-05-24 |work=forests.org}}</ref> In arid climates, the main source of erosion is wind.<ref name="Erosion">{{cite web |author1=Vern Hofman |author2=Dave Franzen |year=1997 |title=Emergency Tillage to Control Wind Erosion |url=http://www.ag.ndsu.edu/disaster/drought/emergencytillagetocontrolerosion.html |access-date=2009-03-21 |publisher=[[North Dakota State University]] Extension Service|archive-date=2012-04-17|archive-url=https://web.archive.org/web/20120417232250/http://www.ag.ndsu.edu/disaster/drought/emergencytillagetocontrolerosion.html|url-status=dead}}</ref> Erosion can be the result of material movement by the wind. The wind can cause small particles to be lifted and therefore moved to another region (deflation). Suspended particles within the wind may impact on solid objects causing erosion by abrasion (ecological succession). Wind erosion generally occurs in areas with little or no vegetation, often in areas where there is insufficient rainfall to support vegetation.<ref>{{cite web |author=United States Geological Survey |author-link=United States Geological Survey |year=2004 |title=Dunes&nbsp;– Getting Started |url=http://geomaps.wr.usgs.gov/parks/coast/dunes/index.html |url-status=dead |archive-url=https://web.archive.org/web/20120427204448/http://geomaps.wr.usgs.gov/parks/coast/dunes/index.html |archive-date=2012-04-27 |access-date=2009-03-21}}</ref>

Drought is one of the most complex and major [[natural hazards]], and it has devastating impacts on the environment, economy, water resources, agriculture, and society worldwide.<ref name=":3">{{Cite journal |lastlast1=Gebrechorkos |firstfirst1=Solomon H. |last2=Peng |first2=Jian |last3=Dyer |first3=Ellen |last4=Miralles |first4=Diego G. |last5=Vicente-Serrano |first5=Sergio M. |last6=Funk |first6=Chris |last7=Beck |first7=Hylke E. |last8=Asfaw |first8=Dagmawi T. |last9=Singer |first9=Michael B. |last10=Dadson |first10=Simon J. |dateyear=2023 |title=Global high-resolution drought indices for 1981–2022 |url=https://essd.copernicus.org/articles/15/5449/2023/ |journal=Earth System Science Data |language=en |volume=15 |issue=12 |pages=5449–5466 |doi=10.5194/essd-15-5449-2023 |issn=1866-3516|doi-access=free|bibcode=2023ESSD...15.5449G|hdl=10754/693396|hdl-access=free}} [[File:CC-BY icon.svg|50px]] Text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License]</ref>

Environmental effects of droughts include: lower surface and subterranean water-levels, lower flow-levels (with a decrease below the minimum leading to direct danger for amphibian life), increased [[Water pollution|pollution of surface water]], the drying out of [[wetland]]s, more and larger [[wildfire]]s, higher deflation intensity, [[Biodiversity loss|loss of biodiversity]], worse health of trees and the appearance of pests and dendroid diseases.<ref name="Zimmer">{{cite journal |last1=Zimmer |first1=Katarina |title=Dead trees around the world are shocking scientists |journal=Knowable Magazine {{!}} Annual Reviews |date=17 August 2023 |doi=10.1146/knowable-081723-2|doi-access=free |url=https://knowablemagazine.org/article/food-environment/2023/dead-trees-shocking-scientists |language=en}}</ref><ref name="Hartmann">{{cite journal |last1=Hartmann |first1=Henrik |last2=Bastos |first2=Ana |last3=Das |first3=Adrian J. |last4=Esquivel-Muelbert |first4=Adriane |last5=Hammond |first5=William M. |last6=Martínez-Vilalta |first6=Jordi |last7=McDowell |first7=Nate G. |last8=Powers |first8=Jennifer S. |last9=Pugh |first9=Thomas A.M. |last10=Ruthrof |first10=Katinka X. |last11=Allen |first11=Craig D. |title=Climate Change Risks to Global Forest Health: Emergence of Unexpected Events of Elevated Tree Mortality Worldwide |journal=Annual Review of Plant Biology |date=20 May 2022 |volume=73 |issue=1 |pages=673–702 |doi=10.1146/annurev-arplant-102820-012804|doi-access=free |languagepmid=en 35231182|bibcode=2022ARPB...73..673H|issn=1543-5008}}</ref> Drought-induced mortality of trees lacks in most [[climate model]]s in their representation of forests as [[Carbon sink|land carbon sink]].<ref>{{Cite news|last=Greenfield|first=Patrick|date=2024-10-14|title=Trees and land absorbed almost no CO2 last year. Is nature's carbon sink failing?|url=https://www.theguardian.com/environment/2024/oct/14/nature-carbon-sink-collapse-global-heating-models-emissions-targets-evidence-aoe|access-date=2024-11-02|work=The Guardian|issn=0261-3077}}</ref>

* Alteration of [[Functional diversity (ecology)|diversity of plant communities]], which can have an impact on net [[primary production]] and other [[ecosystem service]]s.<ref>{{Cite journal |lastlast1=Griffin‐Nolan Griffin-Nolan|firstfirst1=Robert J. |last2=Blumenthal |first2=Dana M. |last3=Collins |first3=Scott L. |last4=Farkas |first4=Timothy E. |last5=Hoffman |first5=Ava M. |last6=Mueller |first6=Kevin E. |last7=Ocheltree |first7=Troy W. |last8=Smith |first8=Melinda D.|author-link8=Melinda D. Smith|last9=Whitney |first9=Kenneth D. |last10=Knapp |first10=Alan K. |date=September 2019 |editor-last=Jones |editor-first=Holly |title=Shifts in plant functional composition following long‐termlong-term drought in grasslands |url=https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2745.13252 |journal=Journal of Ecology |language=en |volume=107 |issue=5 |pages=2133–2148 |bibcode=2019JEcol.107.2133G|doi=10.1111/1365-2745.13252 |issn=0022-0477|doi-access=free }}</ref>

* [[Wildfires]], such as [[Australian bushfires]] and [[wildfires in the United States]], become more common during times of drought and may cause human deaths.<ref name="autogenerated1">{{cite web |title=TFS Article |url=http://txforestservice.tamu.edu/shared/article.asp?DocumentID=406&mc=fire |archive-url=https://web.archive.org/web/20030711082443/http://txforestservice.tamu.edu/shared/article.asp?DocumentID=406&mc=fire |archive-date=11 July 2003 |work=tamu.edu}}</ref>

* [[Snake]] migration, which results in snake-bites<ref>{{cite news |date=2007-01-20 |title=BBC NEWS - Asia-Pacific -– Australians face snake invasion |url=http://news.bbc.co.uk/2/hi/asia-pacific/6282075.stm |workpublisher=bbc.co.ukBBC News}}</ref>

* Reduced [[electricity generation|electricity production]] due to reduced water-flow through [[hydroelectric energy|hydroelectric]] [[dam]]s<ref>[http://www.dailyestimate.com/article.asp?idcategory=35&idSub=175&idArticle=12286 Drought affecting US hydroelectric production | Daily Estimate<!-- Bot generated title -->] {{webarchive |url= https://web.archive.org/web/20111002124428/http://www.dailyestimate.com/article.asp?idcategory=35&idSub=175&idArticle=12286 |date= October 2, 2011 }}</ref>

* Shortages of water for [[Private industry|industrial]] users<ref>{{cite web|url= http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2005/03/06/MNGE2BL7161.DTL|title= Parched village sues to shut tap at Coke / Drought-hit Indians say plant draining groundwater|work=San SFGateFrancisco Chronicle|date= 2005-03-06}}</ref><ref>{{cite web|url= http://www.greenpeace.org/international/news/sweden-nuclear-closure-040806|title= Sweden closes nuclear plants over safety fears|workpublisher= Greenpeace International|access-date= 2016-02-06|archive-url= https://web.archive.org/web/20090110184749/http://www.greenpeace.org/international/news/sweden-nuclear-closure-040806|archive-date= 2009-01-10|url-status= dead}}</ref>

{{Further|Effects of climate change on agriculture}}[[File:Soil moisture and climate change.svg|thumb|upright=1.35|[[Effects of climate change|Impacts of climate change]] on soil moisture at 2&nbsp;°C of global warming. A reduction of one [[standard deviation]] means that average soil moisture will approximate the ninth driest year between 1850 and 1900.]]Droughts can cause land degradation and loss of soil moisture, resulting in the destruction of cropland productivity.<ref>{{Cite journal |last1=Seka |first1=Ayalkibet Mekonnen |last2=Zhang |first2=Jiahua |last3=Prodhan |first3=Foyez Ahmed |last4=Ayele |first4=Gebiaw Teshome |last5=Finsa |first5=Mekuanenet Mulunhie |last6=Sharma |first6=Til Prasad Pangali |last7=Melesse |first7=Assefa Mekonnen |dateyear=2022 |title=Hydrological drought impacts on water storage variations: a focus on the role of vegetation changes in the East Africa region. A systematic review |url=https://link.springer.com/10.1007/s11356-022-23313-0 |journal=Environmental Science and Pollution Research |language=en |volume=29 |issue=53 |pages=80237–80256 |doi=10.1007/s11356-022-23313-0 |issn=0944-1344 |pmid=36197619 |bibcode=2022ESPR...2980237S|s2cid=252713722}}</ref> This can result in diminished [[crop yield|crop growth or yield productions]] and [[carrying capacity]] for [[livestock]]. Drought in combination with high levels of grazing pressure can function as the tipping point for an ecosystem, causing [[Woody plant encroachment|woody encroachment]].<ref>{{Cite journal |last1=Koch |first1=Franziska |last2=Tietjen |first2=Britta |last3=Tielbörger |first3=Katja |last4=Allhoff |first4=Korinna T. |date=November 2022 |title=Livestock management promotes bush encroachment in savanna systems by altering plant–herbivore feedback |url=https://onlinelibrary.wiley.com/doi/10.1111/oik.09462 |journal=Oikos |language=en |volume=2023 |issue=3 |doi=10.1111/oik.09462 |issn=0030-1299 |s2cid=253299539 |doi-access=free}}</ref>

Water stress affects plant development and quality in a variety of ways: firstly drought can cause poor germination and impaired seedling development.<ref>{{cite journal |vauthors=Farooq M, Wahid A, Kobayashi N, Fujita D, Basra SM |date=March 2009 |title=Plant drought stress: effects, mechanisms and management |url=https://www.agronomy-journal.org/articles/agro/abs/2009/01/a7175/a7175.html |journal=Agronomy for Sustainable Development |language=en |volume=29 |issue=1 |pages=185–212 |doi=10.1051/agro:2008021 |bibcode=2009AgSD...29..185F|s2cid=12066792}}</ref> At the same time plant growth relies on cellular division, cell enlargement, and differentiation. Drought stress impairs [[mitosis]] and cell elongation via loss of [[turgor pressure]] which results in poor growth.<ref name=":1">{{cite journal |display-authors=6 |vauthors=Fahad S, Bajwa AA, Nazir U, Anjum SA, Farooq A, Zohaib A, Sadia S, Nasim W, Adkins S, Saud S, Ihsan MZ, Alharby H, Wu C, Wang D, Huang J |date=29 June 2017 |title=Crop Production under Drought and Heat Stress: Plant Responses and Management Options |journal=Frontiers in Plant Science |volume=8 |pages=1147 |doi=10.3389/fpls.2017.01147 |pmc=5489704 |pmid=28706531 |doi-access=free}}</ref> Development of leaves is also dependent upon turgor pressure, concentration of nutrients, and carbon assimilates{{Clarify|date=March 2022}} all of which are reduced by drought conditions, thus drought stress lead to a decrease in leaf size and number.<ref name=":1" /> Plant height, biomass, leaf size and stem girth has been shown to decrease in maize under water limiting conditions.<ref name=":1" /> Crop yield is also negatively effected by drought stress, the reduction in crop yield results from a decrease in photosynthetic rate, changes in leaf development, and altered allocation of resources all due to drought stress.<ref name=":1" /> Crop plants exposed to drought stress suffer from reductions in leaf water potential and transpiration rate. [[Water-use efficiency]] increases in crops such as wheat while decreasing in others, such as potatoes.<ref>{{cite journal |display-authors=6 |vauthors=Kahiluoto H, Kaseva J, Balek J, Olesen JE, Ruiz-Ramos M, Gobin A, Kersebaum KC, Takáč J, Ruget F, Ferrise R, Bezak P, Capellades G, Dibari C, Mäkinen H, Nendel C, Ventrella D, Rodríguez A, Bindi M, Trnka M |date=January 2019 |title=Decline in climate resilience of European wheat |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=116 |issue=1 |pages=123–128 |bibcode=2019PNAS..116..123K |doi=10.1073/pnas.1804387115 |pmc=6320549 |pmid=30584094 |doi-access=free}}</ref><ref>{{cite journal |vauthors=Abbate PE, Dardanelli JL, Cantarero MG, Maturano M, Melchiori RJ, Suero EE |dateyear=2004 |title=Climatic and Water Availability Effects on Water-Use Efficiency in Wheat |journal=Crop Science |volume=44 |issue=2 |pages=474–483 |doi=10.2135/cropsci2004.4740}}</ref><ref name=":1" />

There are negative effects on the health of people who are directly exposed to this phenomenon (excessive [[heat wave]]s). Droughts can also cause limitations of water supplies, increased water pollution levels, high food-costs, stress caused by failed harvests, [[water scarcity]], etc. Reduced water quality can occur because lower water-flows reduce dilution of pollutants and increase [[contamination]] of remaining water sources.<ref>Mosley LM (2014). Drought impacts on the water quality of freshwater systems; review and integration. Earth-Science Reviewss. {{doi|10.1016/j.earscirev.2014.11.010}}.</ref><ref>10. Mosley LM, Zammit B, Leyden E, Heneker TM, Hipsey MR, Skinner D, and Aldridge KT (2012). The Impact of Extreme Low Flows on the Water Quality of the Lower Murray River and Lakes (South Australia). Water Resources Management 26: 3923–3946.</ref>

This explains why droughts and water scarcity operate as a factor which increases the gap between [[Developed country|developed]] and [[Developing country|developing countries]].<ref>{{Cite journal |last=Prokurat |first=Sergiusz |dateyear=2015 |title=Drought and water shortages in Asia as a threat and economic problem |url=http://yadda.icm.edu.pl/yadda/element/bwmeta1.element.desklight-95d2a7ec-8c5f-474d-84ed-8b8baed8f8c0/c/235_PDFsam_Joms_3_26_2015.pdf |url-status=live |journal=Journal of Modern Science |volume=26 |issue=3 |archive-url=https://ghostarchive.org/archive/20221009/http://yadda.icm.edu.pl/yadda/element/bwmeta1.element.desklight-95d2a7ec-8c5f-474d-84ed-8b8baed8f8c0/c/235_PDFsam_Joms_3_26_2015.pdf |archive-date=2022-10-09 |access-date=4 August 2016}}</ref>

* [[Water scarcity]], [[Harvest|crop failure]], [[famine]]<ref>{{cite book |last1=García |first1=R. V. |title=The constant catastrophe : malnutrition, famines, and drought |last2=Escudero |first2=J. C. |date=1981 |publisher=Pergamon Press |isbn=9781483189666 |edition=1st |location=Oxford ; New York |page=3}}</ref> and [[hunger]] – drought provides too little water to support food crops; [[malnutrition]], [[dehydration]] and related diseases

* [[Mass migration]], resulting in [[internally displaced person|internal displacement]] and international [[refugee]]s

* Social [[unrest]]

{{cite web |title=Toxins from freshwater algae found in San Francisco Bay shellfish |url=http://news.ucsc.edu/2016/10/microcystin-toxin.html |access-date=5 November 2017}}

[[Aeolian processes|Wind erosion]] is much more severe in arid areas and during times of drought. For example, in the [[Great Plains]], it is estimated that soil loss due to wind erosion can be as much as 6100 times greater in drought years than in wet years.<ref>{{Cite book |author=Wiggs, Giles F.S. |title=Arid Zone Geomorphology: Process, Form and Change in Drylands |publisher=John Wiley & Sons |year=2011 |isbn=978-0-470-71076-0 |editor=Thomas, David S.G. |page=588 |chapter=Geomorphological hazards in drylands |chapter-url=https://books.google.com/books?id=swz4rh4KaLYC&pg=PA588}}

[[Loess]] is a homogeneous, typically nonstratified, porous, [[friable]], slightly coherent, often calcareous, fine-grained, [[silt]]y, pale yellow or buff, windblown ([[Aeolian processes|Aeolian]]) [[sediment]].<ref>{{cite journal |author=F. von Richthofen |year=1882 |title=On the mode of origin of the loess |url=https://zenodo.org/record/1880729 |journal=Geological Magazine (Decade II) |volume=9 |issue=7 |pages=293–305 |bibcode=1882GeoM....9..293R |doi=10.1017/S001675680017164X |s2cid=131245730}}</ref> It generally occurs as a widespread blanket deposit that covers areas of hundreds of square kilometers and tens of meters thick. Loess often stands in either steep or vertical faces.<ref>{{cite book |author1=K.E.K. Neuendorf |title=Glossary of Geology |author2=J.P. Mehl, Jr. |author3=J.A. Jackson |publisher=[[Springer-Verlag]], New York |year=2005 |isbn=978-3-540-27951-8 |page=779}}</ref> Loess tends to develop into highly rich soils. Under appropriate climatic conditions, areas with loess are among the most agriculturally productive in the world.<ref>{{cite book |author=Arthur Getis |url=https://archive.org/details/introductiontoge00geti/page/99 |title=Introduction to Geography, Seventh Edition |author2=Judith Getis and Jerome D. Fellmann |publisher=[[McGraw-Hill]] |year=2000 |isbn=978-0-697-38506-2 |page=[https://archive.org/details/introductiontoge00geti/page/99 99]}}</ref> Loess deposits are geologically unstable by nature, and will erode very readily. Therefore, windbreaks (such as big trees and bushes) are often planted by farmers to reduce the wind erosion of loess.<ref name="Erosion" />

In 2005, parts of the [[Amazon basin]] experienced the worst drought in 100 years.<ref name=":4">{{cite web |author=<!--Staff writer(s); no by-line.--> |title=Amazon Drought Worst in 100 Years |url=http://www.ens-newswire.com/ens/oct2005/2005-10-24-05.asp |url-status=dead |archive-url=https://web.archive.org/web/20191115094341/http://www.ens-newswire.com/ens/oct2005/2005-10-24-05.asp |archive-date=2019-11-15 |access-date=5 November 2017 |website=www.ens-newswire.com}}</ref><ref name=":5">[http://www.commondreams.org/headlines06/0717-07.htm Drought Threatens Amazon Basin -– Extreme conditions felt for second year running] {{webarchive|url=https://web.archive.org/web/20130527104721/http://www.commondreams.org/headlines06/0717-07.htm|date=May 27, 2013}}</ref> A 2006 article reported results showing that the forest in its present form could survive only three years of drought.<ref>[https://www.independent.co.uk/arts-entertainment/law-mixed-year-begins-and-ends-wrapped-up-in-straw-1191932.html ''Amazon rainforest 'could become a desert' ''] {{Webarchive|url=https://web.archive.org/web/20170825064419/http://www.independent.co.uk/arts-entertainment/law-mixed-year-begins-and-ends-wrapped-up-in-straw-1191932.html|date=2017-08-25}}, [[The Independent]], July 23, 2006. Retrieved September 28, 2006.</ref><ref>[https://www.independent.co.uk/news/fishermen-braced-for-quota-cuts-1191880.html ''Dying Forest: One year to save the Amazon''] {{Webarchive|url=https://web.archive.org/web/20170825060909/http://www.independent.co.uk/news/fishermen-braced-for-quota-cuts-1191880.html|date=2017-08-25}}, [[The Independent]], July 23, 2006. Retrieved September 28, 2006.</ref> Scientists at the Brazilian [[National Institute of Amazonian Research]] argue in the article that this drought response, coupled with the effects of [[deforestation]] on regional climate, are pushing the rainforest towards a "[[tipping point (climatology)|tipping point]]" where it would irreversibly start to die. It concludes that the [[rainforest]] is on the brink of being turned into [[savanna]] or [[desert]], with catastrophic consequences for the world's climate. According to the [[World Wide Fund for Nature|WWF]], the combination of [[Deforestation and climate change|climate change]] and deforestation]] increases the drying effect of dead trees that fuels forest fires.<ref>[https://web.archive.org/web/20080518192545/http://www.panda.org/news_facts/newsroom/index.cfm?uNewsID=64220 ''Climate change a threat to Amazon rainforest, warns WWF''], [[World Wide Fund for Nature]], March 9, 2996. Retrieved September 28, 2006.</ref>

The 1997–2009 [[2000s Australian drought|Millennium Drought]] in Australia led to a water supply crisis across much of the country. As a result, many desalination plants were built for the first time ([[List of desalination plants in Australia|see list]]).

By far the largest part of [[Australia]] is [[Deserts of Australia|desert]] or semi-arid lands commonly known as the [[outback]]. A 2005 study by Australian and American researchers investigated the desertification of the interior, and suggested that one explanation was related to [[human]] settlers who arrived about 50,000 years ago. Regular burning by these settlers could have prevented [[monsoon]]s from reaching interior Australia.<ref>[https://www.geosociety.org/news/pr/05-01.htm Sensitivity of the Australian Monsoon to insolation and vegetation: Implications for human impact on continental moisture balance] {{Webarchive|url=https://web.archive.org/web/20100615232508/http://geosociety.org/news/pr/05-01.htm|date=2010-06-15}}, Geological Society of America</ref> In June 2008 it became known that an expert panel had warned of long term, maybe irreversible, severe ecological damage for the whole [[Murray-Darling basin]] if it did not receive sufficient water by October 2008.<ref>[http://news.bbc.co.uk/2/hi/asia-pacific/7460492.stm Australian rivers 'face disaster'] {{Webarchive|url=https://web.archive.org/web/20210813205109/http://news.bbc.co.uk/2/hi/asia-pacific/7460492.stm|date=2021-08-13}}, BBC News</ref> Australia could experience more severe droughts and they could become more frequent in the future, a government-commissioned report said on July 6, 2008.<ref name=":6">[https://www.reuters.com/article/idUSSYD6747620080707 Australia faces worse, more frequent droughts: study] {{Webarchive|url=https://web.archive.org/web/20210203120930/https://www.reuters.com/article/idUSSYD6747620080707|date=2021-02-03}}, Reuters</ref> Australian environmentalist [[Tim Flannery]], predicted that unless it made drastic changes, [[Perth, Western Australia|Perth]] in [[Western Australia]] could become the world's first [[ghost town|ghost metropolis]], an abandoned city with no more water to sustain its population.<ref>[http://news.bbc.co.uk/2/hi/science/nature/6620919.stm Metropolis strives to meet its thirst] {{Webarchive|url=https://web.archive.org/web/20210906083308/http://news.bbc.co.uk/2/hi/science/nature/6620919.stm|date=2021-09-06}}, BBC News</ref> The long Australian [[2000s Australian drought|Millennial drought]] broke in 2010.

=== East Africa and Sahel ===

[[File:Drought affected area in Karnataka, India, 2012.jpg|thumb|Drought-affected area in [[Karnataka]], [[India]] in 2012.|alt=|left]]Approximately 2.4&nbsp;billion people live in the [[drainage basin]] of the Himalayan rivers.<ref>{{cite web |title=People & the Planet > climate change > newsfile > big melt threatens millions, says un |url=http://www.peopleandplanet.net/pdoc.php?id=3024 |archive-url=https://web.archive.org/web/20070819200515/http://www.peopleandplanet.net/pdoc.php?id=3024 |archive-date=19 August 2007 |work=peopleandplanet.net}}</ref> [[India]], [[China]], [[Pakistan]], [[Bangladesh]], [[Nepal]] and [[Myanmar]] could experience floods followed by droughts in coming decades. More than 150 districts in India isare drought vulnerable, mostly concentrated in the state of Rajasthan, Gujarat, Madhya Pradesh and its adjoining Chhattisgarh, Uttar Pradesh, northern Karnataka and adjoining Maharashtra of the country.<ref name=":9">Nandy, S.N. (2021) Analysis of drought vulnerability indices of Indian districts using Fuzzy logic approach. International Water Resources Association Journal (IWRA -– India), 10(2): 11-17. https://www.indianjournals.com/ijor.aspx?target=ijor:iwra&volume=10&issue=2&article=002</ref> [[Drought in India]] affecting the Ganges is of particular concern, as it provides [[drinking water]] and agricultural [[irrigation]] for more than 500&nbsp;million people.<ref>{{cite web |title=Ganges, Indus may not survive: climatologists |url=http://www.rediff.com/news/2007/jul/24indus.htm |work=rediffRediff.com}}</ref><ref>{{cite web |title=People's Daily Online -– Glaciers melting at alarming speed |url=http://english.peopledaily.com.cn/90001/90781/90879/6222327.html |work=peopledaily.com.cnPeople's Daily}}</ref><ref>{{cite news |date=2004-11-10 |title=BBC NEWS - Science/Nature -– Himalaya glaciers melt unnoticed |url=http://news.bbc.co.uk/2/hi/science/nature/3998967.stm |workpublisher=BBC News}}</ref>

=== North America ===
The west coast of [[North America]], which gets much of its water from [[glacier]]s in mountain ranges such as the [[Rocky Mountains]] and [[Sierra Nevada (U.S.)|Sierra Nevada]], also would be affected.<ref>{{cite web |title=Glaciers Are Melting Faster Than Expected, UN Reports |url=https://www.sciencedaily.com/releases/2008/03/080317154235.htm |work=ScienceDaily}}</ref><ref>[httphttps://articleswww.latimes.com/2008archives/la-xpm-2008-may/-02/local/-me-snowpack2-story.html Water shortage worst in decades, official says] {{Webarchive|url=https://web.archive.org/web/20110219211005/http://articles.latimes.com/2008/may/02/local/me-snowpack2|date=2011-02-19}}, ''Los Angeles Times''</ref>

Agriculturally, people can effectively mitigate much of the impact of drought through irrigation and [[crop rotation]]. Failure to develop adequate drought mitigation strategies carries a grave human cost in the modern era, exacerbated by [[population growth|ever-increasing]] population densities.

* [[Dam]]s – many dams and their associated reservoirs supply additional water in times of drought.<ref>{{cite news |author1=Matt Weiser |author2=Jeremy B. White |date=2014-06-01 |title=Should California build dams, reservoirs to help with future droughts? |url=http://www.fresnobee.com/2014/06/01/3956458/should-calif-add-new-dams.html |url-status=dead |archive-url=https://web.archive.org/web/20150320040153/http://www.fresnobee.com/2014/06/01/3956458/should-calif-add-new-dams.html |archive-date=2015-03-20 |access-date=2015-02-18 |newspaper=Fresno Bee}}</ref>

* [[Cloud seeding]] – a form of intentional weather modification to induce rainfall.<ref>{{cite web |title=Cloud seeding helps alleviate drought<!-- Bot generated title --> |url=http://www.chinadaily.com.cn/english/doc/2004-07/24/content_351196.htm |work=chinadaily.com.cnChina Daily}}</ref> This remains a hotly debated topic, as the [[National Research Council (United States)|United States National Research Council]] released a report in 2004 stating that to date, there is still no convincing scientific proof of the efficacy of intentional weather modification.<ref>{{cite book |last1=NRC |title=Critical Issues in Weather Modification Research |year=2003 |isbn=978-0-309-09053-7 |doi=10.17226/10829}}</ref>

Throughout history, humans have usually viewed droughts as "disasters"[[disaster]]s due to the impact on food availability and the rest of society. Drought is among the earliest documented climatic events, present in the [[Epic of Gilgamesh]] and tied to the [[Bible|Biblical]] story of [[Joseph (Hebrew Bible)|Joseph]]'s arrival in and the later [[The Exodus|Exodus]] from [[ancient Egypt]].<ref>{{cite web |title=BBC - Weather Centre -– Features -– History and Religion -– Weather in the Bible -– Drought and Famine<!-- Bot generated title --> |url=http://www.bbc.co.uk/weather/features/bible_drought.shtml |url-status=dead |archive-url=https://web.archive.org/web/20040110002457/http://www.bbc.co.uk/weather/features/bible_drought.shtml |archive-date=10 January 2004 |access-date=5 November 2017}}</ref> Hunter-gatherer migrations in 9,500 BC Chile have been linked to the phenomenon,<ref>{{cite web |title=Ancient Chile Migration Mystery Tied to Drought |url=http://news.nationalgeographic.com/news/2002/10/1024_021024_ChileAtacama.html |archive-url=https://web.archive.org/web/20021028200916/http://news.nationalgeographic.com/news/2002/10/1024_021024_ChileAtacama.html |url-status=dead |archive-date=October 28, 2002 |work=nationalgeographic.comNational Geographic}}</ref> as has the exodus of early humans [[Recent African origin of modern humans|out of Africa]] and into the rest of the world around 135,000 years ago.<ref>[http://azstarnet.com/all-headlines/205715m/ Drought pushed ancient African immigration ]{{dead link|date=December 2016|bot=InternetArchiveBot|fix-attempted=yes}}</ref>

Droughts can be scientifically explained in terms of physical mechanisms, which underlie [[natural disasters]] and are influenced by [[human impact on the environment]].<ref name="Savelli">{{cite journal |last1=Savelli |first1=Elisa |last2=Rusca |first2=Maria |last3=Cloke |first3=Hannah |last4=Di Baldassarre |first4=Giuliano |title=Drought and society: Scientific progress, blind spots, and future prospects |journal=WIREs Climate Change |date=May 2022 |volume=13 |issue=3 |doipages=10.1002/wcc.761 e761|urldoi=https://wires.onlinelibrary.wiley.com/doi/full/10.1002/wcc.761 |language=en |issn=1757-7780|doi-access=free |pmid=35864922|pmc=9286479|bibcode=2022WIRCC..13E.761S}}</ref>

Beliefs about drought are further shaped by cultural factors including local knowledge, perceptions, values, beliefs and religion. In some places and times, droughts have been interpreted as the work of [[supernatural]] forces.<ref name="Salite"/> Globally, people in many societies have been more likely to explain natural events like drought, famine and disease in terms of the supernatural than they are to explain social phenomena like war, murder, and theft.<ref name="Wrethman">{{cite news |last1=Wrethman |first1=Emily |title=How societies use supernatural forces to explain earthly events |url=https://mdhs.unimelb.edu.au/news-and-events/how-societies-use-supernatural-forces-to-explain-earthly-events |work=Faculty of Medicine, Dentistry and Health Sciences |date=4 April 2023 |language=en}}</ref><ref name="Jackson">{{cite journal |last1=Jackson |first1=Joshua Conrad |last2=Dillion |first2=Danica |last3=Bastian |first3=Brock |last4=Watts |first4=Joseph |last5=Buckner |first5=William |last6=DiMaggio |first6=Nicholas |last7=Gray |first7=Kurt |title=Supernatural explanations across 114 societies are more common for natural than social phenomena |journal=Nature Human Behaviour |date=May 2023 |volume=7 |issue=5 |pages=707–717 |doi=10.1038/s41562-023-01558-0 |url=https://www.nature.com/articles/s41562-023-01558-0 |language=en |issn=2397-3374|doi-access=free |pmid=37012368}}</ref>

Historically, [[Ritual#Rites of affliction|rituals]] have been used in an attempt to prevent or avert drought. [[Rainmaking (ritual)|Rainmaking rituals]] have ranged from dances to [[scapegoating]] to [[human sacrifice]]s. Many ancient practices are now a matter of [[folklore]] while others may still be practiced.<ref name="Spring">{{cite book |last1=Spring |first1=Úrsula Oswald |last2=Brauch |first2=Hans Günter |title=Decolonising Conflicts, Security, Peace, Gender, Environment and Development in the Anthropocene |date=25 January 2021 |publisher=Springer Nature |isbn=978-3-030-62316-6 |pages=385–410 |url=https://books.google.com/books?id=qioXEAAAQBAJ&pg=PA394 |language=en}}</ref>

In areas where people have limited understanding of the scientific basis of drought, beliefs about drought continue to reflect indigenous beliefs in the power of spirits and Christian philosophies that see drought as a divine punishment. Such beliefs can influence people's thinking and affect their resilience and ability to adapt to stress and respond to crises.<ref name="Salite">{{cite journal |last1=Salite |first1=Daniela |title=Explaining the uncertainty: understanding small-scale farmers' cultural beliefs and reasoning of drought causes in Gaza Province, Southern Mozambique |journal=Agriculture and Human Values |date=1 September 2019 |volume=36 |issue=3 |pages=427–441 |doi=10.1007/s10460-019-09928-z |url=https://link.springer.com/article/10.1007/s10460-019-09928-z |language=en |issn=1572-8366|doi-access=free }}</ref> In the case of [[Creationism]], curricula sometimes give religious explanations of natural phenomena rather than scientific ones. Teaching explicitly denies [[evolution]], that human agency is affecting climate, and that climate change is occurring.<ref name="Scaramanga">{{cite journal |last1=Scaramanga |first1=Jenna |last2=Reiss |first2=Michael J. |title=Evolutionary stasis: creationism, evolution and climate change in the Accelerated Christian Education curriculum |journal=Cultural Studies of Science Education |date=1 September 2023 |volume=18 |issue=3 |pages=809–827 |doi=10.1007/s11422-023-10187-y |url=https://link.springer.com/article/10.1007/s11422-023-10187-y |language=en |issn=1871-1510|doi-access=free |pmid=37360053|pmc=10191816|bibcode=2023CSSE...18..809S}}</ref>

{{Reflist|30em}}

{{Portal bar|Water}}
* {{Commons category-inline|Drought}}

* {{wiktionary-inline|drought}}

* {{wikibooks inline|Drought}}