The effects of climate change on the water cycle has important knock-on effects on the availability of freshwater resources, as well as other water reservoirs such as oceans, ice sheets, atmosphere and land surface. The water cycle is essential to life on earth and plays a large role in the global climate and the ocean circulation. The warming of the earth is expected to cause changes in the water cycle for various reasons.[1] A warmer atmosphere can contain more water vapor which has effects on evaporation and rainfall. Oceans play a large role as well, since they absorb 93% of the increase in heat since 1971.[2] This has effects on the water cycle and on human society, since the ocean warming directly leads to sea level rise.[1]
Causes of intensifying water cycle
The increased amount of greenhouse gases leads to a warmer atmosphere.[1] The saturation vapor pressure of air increases with temperature, which means that warmer air can contain more water vapor. Because the air can contain more moisture, the evaporation is enhanced. As a consequence, the increased amount of water in the atmosphere leads to more intense rainfall.[3]
This relation between temperature and saturation vapor pressure is described in the Clausius-Clapeyron equation, which states that saturation pressure should increase 7% when temperature rises with 1°C.[4] This is visible in measurements of the tropospheric water vapor, which are provided by satellites, radiosondes and surface stations. The IPCC AR5 concludes that tropospheric water vapor has increased by 3.5% the recent 40 years, which is consistent with the observed temperature increase of 0.5 °C.[1] It is therefore expected that the water cycle is intensifying, but more evidence is needed to say so.
Impacts on the water cycle
Fresh water covers only 0.8% of the Earth's surface, but contains up to 6% of all life on the planet.[5] However, the impacts climate change deal to its ecosystems are often overlooked. Very few studies showcase the potential results of climate change on large-scale ecosystems which are reliant on freshwater, such as river ecosystems, lake ecosystems, desert ecosystems, etc. However, a comprehensive study published in 2009 delves into the effects to be felt by lotic (flowing) and lentic (still) freshwater ecosystems in the American Northeast. According to the study, persistent rainfall, typically felt year round, will begin to diminish and rates of evaporation will increase, resulting in drier summers and more sporadic periods of precipitation throughout the year.[6] Additionally, a decrease in snowfall is expected, which leads to less runoff in the spring when snow thaws and enters the watershed, resulting in lower-flowing fresh water rivers.[6] This decrease in snowfall also leads to increased runoff during winter months, as rainfall cannot permeate the frozen ground usually covered by water-absorbing snow.[6] These effects on the water cycle will wreak havoc for indigenous species residing in fresh water lakes and streams.
Impacts on freshwater resources
The freshwater resources that humans rely on are highly sensitive to variations in weather and climate.[7] The sustained alteration of climate directly impacts the hydrosphere and hydrologic cycle changing how humans interact with water across the globe In 2007, the IPCC reported with high confidence that climate change has a net negative impact on water resources and freshwater ecosystems in all regions.[8] The IPCC also found with very high confidence that arid and semi-arid areas are particularly exposed to freshwater impacts.[8] In addition, the IPCC forecasts increased uncertainty in the amount and frequency of precipitation from the year 2000 to 2100.[9]
As the climate warms, it changes the nature of global rainfall, evaporation, snow, stream flow and other factors that affect water supply and quality. Specific impacts include:
- Warmer water temperatures affect water quality and accelerate water pollution.[10]
- Sea level rise is projected to increase salt-water intrusion into groundwater in some regions. This reduces the amount of freshwater available for drinking and farming.[10][11]
- In some areas, shrinking glaciers and snow deposits threaten the water supply.[12] Areas that depend on melted water runoff will likely see that runoff depleted, with less flow in the late summer and spring peaks occurring earlier.[10] This can affect the ability to irrigate crops. (This situation is particularly acute for irrigation in South America,[13] for irrigation and drinking supplies in Central Asia, and for hydropower in Norway, the Alps, and the Pacific Northwest of North America.)
- Increased extreme weather means more water falls on hardened ground unable to absorb it, leading to flash floods instead of a replenishment of soil moisture or groundwater levels.[14]
- Increased evaporation will reduce the effectiveness of reservoirs.
- Increased precipitation can lead to changes in water-borne and vector-borne diseases.[15]
Droughts
![](https://web.archive.org/web/20220605231826im_/https://upload.wikimedia.org/wikipedia/commons/thumb/8/82/California_Drought_Dry_Riverbed_2009.jpg/280px-California_Drought_Dry_Riverbed_2009.jpg)
Climate change affects multiple factors associated with droughts, such as how much rain falls and how fast the rain evaporates again. Warming over land drives an increase in atmospheric evaporative demand which will increase the severity and frequency of droughts around much of the world.[17][18] Due to limitations on how much data is available about drought in the past, it is often impossible to confidently attribute droughts to human-induced climate change. Some areas however, such as the Mediterranean and California, already show a clear human signature.[19] Their impacts are made worse because of increased water demand, population growth, urban expansion, and environmental protection efforts in many areas.[20]
In 2019 the Intergovernmental Panel on Climate Change issued a Special Report on Climate Change and Land. The main statements of the report include:[21][22] Between 1960 and 2013 the area of drylands in drought increased by 1% per year. In 2015, around 500 million people lived in areas impacted by desertification between the 1980s and 2000s. People who live in areas affected by land degradation and desertification are "increasingly negatively affected by climate change".[citation needed]
According to a report issued by the UN "Drought in Numbers, 2022" climate change increase the frequency and the duration of droughts. Both increased by 29% from the year 2000 and by 2050 more than 75% of humanity will live in drought conditions if nothing is done. One of the proposed solutions is land restoration, especially by agroforestry which has already brought good results.[23]Water scarcity
Climate change could have significant impacts on water resources around the world because of the close connections between the climate and hydrological cycle. Rising temperatures will increase evaporation and lead to increases in precipitation, though there will be regional variations in rainfall. Both droughts and floods may become more frequent in different regions at different times, and dramatic changes in snowfall and snow melt are expected in mountainous areas. Higher temperatures will also affect water quality in ways that are not well understood. Possible impacts include increased eutrophication. Climate change could also mean an increase in demand for farm irrigation, garden sprinklers, and perhaps even swimming pools. There is now ample evidence that increased hydrologic variability and change in climate has and will continue have a profound impact on the water sector through the hydrologic cycle, water availability, water demand, and water allocation at the global, regional, basin, and local levels.[24]
The United Nations' FAO states that by 2025, 1.9 billion people will live in countries or regions with absolute water scarcity, and two-thirds of the world population could be under stress conditions.[25] The World Bank adds that climate change could profoundly alter future patterns of both water availability and use, thereby increasing levels of water stress and insecurity, both at the global scale and in sectors that depend on water.[26]
Overall, the effects of changes in population on water scarcity were found to be about four times more important than changes in water availability as a result of long-term climate change.[27]
![](https://web.archive.org/web/20220605231826im_/https://upload.wikimedia.org/wikipedia/commons/thumb/9/92/AfriqueStressHydrique2025.jpg/220px-AfriqueStressHydrique2025.jpg)
Water security
Water-related impacts from climate change impact people's water security on a day-to-day basis. They include: increased frequency and intensity of heavy precipitation, accelerated melting of glaciers, changes in frequency, magnitude and timing of floods; more frequent and severe droughts in some places; decline in groundwater storage and reduction in recharge and water quality deterioration due to extreme events.[29]: 4–8
Global climate change is "likely to increase the complexity and costs of ensuring water security".[30] It creates new threats and adaptation challenges.[31] This is because climate change leads to increased hydrological variability and extremes. Climate change has many impacts on the water cycle, resulting in higher climatic and hydrological variability, which means that water security will be compromised.[32]: vII Changes in the water cycle threaten existing water infrastructure and make it harder to plan future investments that can cope with uncertain changes in hydrologic variability.[31] This makes societies more vulnerable to extreme water-related events and therefore increases water insecurity.[32]: vII
Climate change is about uncertainty and is an important long-term risk to water security.[33]: 21 On the other hand, climate change must be seen in the context of other existing challenges for water security which include: existing high levels of climate variability at low latitudes, population growth, increased demand for water resources, political obstacles, increased disaster exposure due to settlement of hazard-prone areas, and environmental degradation.[33]: 22 Water demand for irrigation in agriculture will increase due to climate change. This is because evaporation rates and crop transpiration rate will be higher due to rising temperatures.[34]: 4
Climate change threatens the Sustainable Development Goal 6.1 of achieving universal access to safe drinking water.[35]See also
References
- ^ a b c d IPCC (2013). Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press.
- ^ Durack, Paul (2015-03-01). "Ocean Salinity and the Global Water Cycle". Oceanography. 28 (1): 20–31. doi:10.5670/oceanog.2015.03. ISSN 1042-8275.
- ^ Trenberth, Kevin E.; Smith, Lesley; Qian, Taotao; Dai, Aiguo; Fasullo, John (2007-08-01). "Estimates of the Global Water Budget and Its Annual Cycle Using Observational and Model Data". Journal of Hydrometeorology. 8 (4): 758–769. Bibcode:2007JHyMe...8..758T. doi:10.1175/jhm600.1. ISSN 1525-7541.
- ^ Brown, Oliver L. I. (August 1951). "The Clausius-Clapeyron equation". Journal of Chemical Education. 28 (8): 428. Bibcode:1951JChEd..28..428B. doi:10.1021/ed028p428. ISSN 0021-9584.
- ^ Woodward, Guy; Perkins, Daniel M.; Brown, Lee E. (12 July 2010). "Climate change and freshwater ecosystems: impacts across multiple levels of organization". Philosophical Transactions of the Royal Society B: Biological Sciences. 365 (1549): 2093–2106. doi:10.1098/rstb.2010.0055. PMC 2880135. PMID 20513717.
- ^ a b c Brooks, Robert T. (6 January 2009). "Potential impacts of global climate change on the hydrology and ecology of ephemeral freshwater systems of the forests of the northeastern United States". Climatic Change. 95 (3–4): 469–483. Bibcode:2009ClCh...95..469B. doi:10.1007/s10584-008-9531-9. S2CID 154713741.
- ^ Heidari, Hadi; Arabi, Mazdak; Warziniack, Travis; Kao, Shih-Chieh (2020). "Assessing Shifts in Regional Hydroclimatic Conditions of U.S. River Basins in Response to Climate Change over the 21st Century". Earth's Future. 8 (10): e2020EF001657. Bibcode:2020EaFut...801657H. doi:10.1029/2020EF001657. ISSN 2328-4277.
- ^ a b Kundzewicz Z.W.; et al. (2007). "Freshwater resources and their management. In: Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change M.L. Parry et al. (eds.)". Cambridge University Press, Cambridge, U.K., and New York, N.Y., U.S.A. pp. 173–210. Retrieved 20 May 2009.
- ^ "Glossary – Global Warming of 1.5 °C". Retrieved 20 April 2021.
- ^ a b c "Dr. Kathleen Miller's Research: Climate Change Impacts on Water". Archived from the original on 31 October 2015. Retrieved 10 November 2009.
- ^ "EPA : Global Warming : Resource Center : Publications : Sea Level Rise : Sea Level Rise Reports". Archived from the original on 10 July 2009.
- ^ Kazakhstan: glaciers and geopolitics Archived 6 January 2018 at the Wayback Machine Stephan Harrison openDemocracy May 2005
- ^ News, BBC (9 October 2003). "Melting glaciers threaten Peru". BBC News.
- ^ "Climate Change and Mental Health". Psychiatry.org. Retrieved 26 February 2018.
- ^ Rahman, A. (2008). "Climate Change and its Impact on health in Bangladesh" (PDF). Regional Health Forum. 12: 16–26.
- ^ Irina Ivanova (June 2, 2022). "California is rationing water amid its worst drought in 1,200 years". CBS News. Retrieved June 2, 2022.
- ^ IPCC AR6 WG1 Ch8 2021, p. 8-6, line 37
- ^ Cook, Benjamin I.; Mankin, Justin S.; Anchukaitis, Kevin J. (12 May 2018). "Climate Change and Drought: From Past to Future". Current Climate Change Reports. 4 (2): 164–179. doi:10.1007/s40641-018-0093-2. ISSN 2198-6061. S2CID 53624756.
- ^ Mukherjee, Sourav; Mishra, Ashok; Trenberth, Kevin E. (23 April 2018). "Climate Change and Drought: a Perspective on Drought Indices". Current Climate Change Reports. 4 (2): 145–163. doi:10.1007/s40641-018-0098-x. ISSN 2198-6061. S2CID 134811844.
- ^ Mishra, A. K.; Singh, V. P. (2011). "Drought modeling – A review". Journal of Hydrology. 403 (1–2): 157–175. Bibcode:2011JHyd..403..157M. doi:10.1016/j.jhydrol.2011.03.049.
- ^ IPCC SRCCL 2019, pp. 7, 8
- ^ IPCC SRCCL Summary for Policymakers 2019, p. 7,8
- ^ Rosane, Olivia. "More than 75% of the world could face drought by 2050, UN report warns". World Economic Forum. Ecowatch. Retrieved 24 May 2022.
- ^ "Water and Climate Change: Understanding the Risks and Making Climate-Smart Investment Decisions". World Bank. 2009. Archived from the original on 7 April 2012. Retrieved 2011-10-24.
- ^ FAO Hot issues: Water scarcity Archived 25 October 2012 at the Wayback Machine. Fao.org. Retrieved on 27 August 2013.
- ^ The World Bank, 2009 "Water and Climate Change: Understanding the Risks and Making Climate-Smart Investment Decisions". pp. 21–24. Archived from the original on 7 April 2012. Retrieved 24 October 2011.
- ^ Matti Kummu; Philip J Ward; Hans de Moel; Olli Varis (2010-08-16). "Is physical water scarcity a new phenomenon? Global assessment of water shortage over the last two millennia". Environmental Research Letters. 5 (3): 034006. Bibcode:2010ERL.....5c4006K. doi:10.1088/1748-9326/5/3/034006. ISSN 1748-9326.
- ^ "GEO-2000 overview overview" (PDF). unep.org. Archived (PDF) from the original on 7 February 2017. Retrieved 22 September 2016.
- ^ 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: Water (Chapter 4). In: 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. In Press.
- ^ Grey, David; Sadoff, Claudia W. (2007). "Sink or Swim? Water security for growth and development" (PDF). Water Policy. 9 (6): 545–571. doi:10.2166/wp.2007.021. ISSN 1366-7017.
- ^ a b Sadoff, Claudia; Grey, David; Borgomeo, Edoardo (2020), "Water Security", Oxford Research Encyclopedia of Environmental Science, Oxford University Press, doi:10.1093/acrefore/9780199389414.013.609, ISBN 978-0-19-938941-4, retrieved 2022-04-12
- ^ a b UN-Water (2013) Water Security & the Global Water Agenda - A UN-Water Analytical Brief, ISBN 978-92-808-6038-2, United Nations University
- ^ a b WaterAid (2012) Water security framework. WaterAid, London
- ^ PETER GLEICK, CHARLES ICELAND, AND AYUSHI TRIVEDI (2020) ENDING CONFLICTS OVER WATER Solutions to Water and Security Challenges, World Resources Institute
- ^ Charles, Katrina J.; Howard, Guy; Villalobos Prats, Elena; Gruber, Joshua; Alam, Sadekul; Alamgir, A.S.M.; Baidya, Manish; Flora, Meerjady Sabrina; Haque, Farhana; Hassan, S.M. Quamrul; Islam, Saiful (2022). "Infrastructure alone cannot ensure resilience to weather events in drinking water supplies". Science of the Total Environment. 813: 151876. Bibcode:2022ScTEn.813o1876C. doi:10.1016/j.scitotenv.2021.151876. PMID 34826465.
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