Analysis of Rainfall Trend in Australia

Abstract

Australia is renowned for its highly variable rainfall patterns, which make it a continent marked by both droughts and flooding rains. With global warming driving atmospheric warming and altering weather systems, this variability is projected to intensify. Despite this, the specific trends and extent of rainfall changes across the country remain uncertain. Within this context, in this study, the temporal variability of rainfall in Australia was examined at annual, seasonal, and monthly scales using rainfall data spanning 1920 to 2020. Specifically, non-parametric tests were employed to assess the magnitude and significance of rainfall trends across 505 rainfall series within the Australian region. Results showed a widespread increase in rainfall in summer and spring throughout the study area. By contrast, autumn and winter showed a marked decrease in rainfall, with the greatest evidence along the Queensland coast and in southern Western Australia. If these trends are confirmed in the coming years, these deficits could limit water resources, affecting agricultural areas, the conservation of natural areas, and national parks. In addition, these changes in rainfall could increase the risk of droughts and wildfires, which could also have socio-economic impacts.

Keywords

Rainfall / Trend / Non-parametric tests / Australia

Author Contributions

Conceptualization, R.G. and T.C.; methodology, A.R. and T.C.; software, T.C.; validation, R.G. and T.C.; formal analysis, A.R. and T.C.; investigation, A.R. and T.C.; resources, R.G. and T.C.; data curation, A.R. and F.F.; writing—original draft preparation, A.R. and T.C.; writing—review and editing, A.R. and T.C.; visualization, A.R. and T.C.; supervision, R.G. and T.C.

Ethics Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data presented in this study are available on request from the corresponding authors.

Funding

This research received no external funding.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

References

[1] IPCC. Summary for Policymakers. In IPCC, 2022: Climate Change 2022:Mitigation of Climate Change, Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change; Shukla PR, Skea J, Slade R, Khourdajie AA, Diemen RV, McCollum D, et al., Eds.; Cambridge University Press: Cambridge, UK, 2022.

[2] Caloiero T. Evaluation of rainfall trends in the South Island of New Zealand through the innovative trend analysis (ITA). Theor. Appl. Climatol. 2020, 139, 493-504.

[3] Salinger MJ, Griffiths GM. Trends in New Zealand daily temperature and rainfall extremes. Int. J. Climatol. 2001, 21, 1437-1452.

[4] Salinger MJ, Allan R, Bindoff N, Hannah J, Lavery BM, Lin Z, et al. Observed variability and change in climate and sea level in Australia, New Zealand and the South Pacific. In Greenhouse:Coping with Climate Change; Bouma WJ, Pearman GI, Manning MR, Eds.; CSIRO Publishing: Melbourne, Australia, 1996.

[5] Plummer N, Salinger MJ, Nicholls N, Suppiah R, Hennessy KJ, Leighton RM, et al. Changes in climate extremes over the Australian region and New Zealand during the twentieth century. Clim. Chang. 1999, 42, 183-202.

[6] Manton MJ, Della-Marta PM, Haylock MR, Hennessy KJ, Nicholls N, Chambers LE, et al. Trends in extreme daily rainfall and temperature in southeast Asia and the south Pacific: 1961-1998. Int. J. Climatol. 2001, 21, 269-284.

[7] Caloiero T. Analysis of rainfall trend in New Zealand. Environ. Earth Sci. 2015, 73, 6297-6310.

[8] Peel MC, McMahon TA, Finlayson BL. Continental differences in variability of annual runoff-update and reassessment. J. Hydrol. 2004, 295, 185-197.

[9] Nicholls N, Lavery B. Australian rainfall trends during the twentieth century. Int. J. Climatol. 1992, 12, 153-163.

[10] Suppiah R, Hennessy KJ. Trends in total rainfall, heavy rain events and number of dry days in Australia, 1910-1990. Int. J. Clim. 1998, 18, 1141-1164.

[11] Hennessy KJ, Suppiah R, Page CM. Australian rainfall changes, 1910-1995. Aust. Meteorol. Mag. 1999, 48, 1-13.

[12] Smith I. An assessment of recent trends in Australian rainfall. Aust. Meteorol. Mag. 2004, 53, 163-173.

[13] Alexander LV, Hope P, Collins D, Trewin B, Lynch A, Nicholls N. Trends in Australia's climate means and extremes: a global context. Aust. Meteorol. Mag. 2007, 56, 1-18.

[14] Liu DL, Teng J, Ji F, Anwar MR, Feng P, Wang B, et al. Characterizing spatiotemporal rainfall changes in 1960-2019 for continental Australia. Int. J. Climatol. 2020, 41, 2420-2444.

[15] Chowdhury R, Beecham S. Australian rainfall trends and their relation to the southern oscillation index. Hydrol. Process Int. J. 2010, 24, 504-514.

[16] Hope P, Timbal B, Fawcett R. Associations between rainfall variability in the southwest and southeast of Australia and their evolution through time. Int. J. Clim. 2009, 30, 1360-1371.

[17] Cai W, Cowan T. Southeast Australia Autumn Rainfall Reduction: A Climate-Change-Induced Poleward Shift of Ocean-Atmosphere Circulation. J. Clim. 2013, 26, 189-205.

[18] Davis CJ, Hanna EG. Temperature and rainfall trends in northern Australia 1911-2013: implications for human activity and regional development. Clim. Res. 2017, 71, 1-16.

[19] Yildirim G, Rahman A. Homogeneity and trend analysis of rainfall and droughts over Southeast Australia. Nat. Hazards 2022, 112, 1657-1683.

[20] Rauniyar SP, Power SB. Past and future rainfall change in sub-regions of Victoria, Australia. Clim. Chang. 2023, 176, 92.

[21] Fu G, Chiew FHS, Post DA. Trends and variability of rainfall characteristics influencing annual streamflow: A case study of southeast Australia. Int. J. Climatol. 2023, 43, 1407-1430.

[22] Oliver JE. Encyclopedia of World Climatology; Springer: Amsterdam, The Netherlands, 2005.

[23] Sen PK. Estimates of the Regression Coefficient Based on Kendall’s Tau. J. Am. Stat. Assoc. 1968, 63, 1379-1389.

[24] Mann HB. Non-parametric tests against trend. Econometrica 1945, 13, 245-259. doi:10.2307/1907187.

[25] Kendall MG. Rank Correlation Methods; Oxford University Press: New York, NY, USA, 1975.

[26] Yu B, Neil DT. Long-term variations in regional rainfall in the south-west of Western Australia and the difference between average and high intensity rainfalls. Int. J. Climatol. 1993, 13, 77-88.

[27] Wheeler M, McBride JL. Australasian monsoon. In Intraseasonal Variability in the Atmosphere-Ocean Climate System; Springer: Berlin, Germany, 2012.

[28] Theobald A, Mcgowan H, Speirs J. Trends in synoptic circulation and precipitation in the Snowy Mountains region, Australia, in the period 1958-2012. Atmos. Res. 2016, 169, 434-448.

[29] Montazerolghaem M, Vervoort W, Minasny B, McBratney A. Long-term variability of the leading seasonal modes of rainfall in south-eastern Australia. Weather Clim. Extrem. 2016, 13, 1-14.

[30] Allan RJ, Haylock MR. Circulation Features Associated with the Winter Rainfall Decrease in Southwestern Australia. J. Clim. 1993, 6, 1356-1367.

[31] Haylock M, Nicholls N. Trends in Extreme Rainfall Indices for an Updated High Quality Data Set for Australia, 1910-1998. Int. J. Climatol. 2000, 20, 1533-1541.

[32] McKay RC, Boschat G, Rudeva I, Pepler A, Purich A, Dowdy A, et al. Can southern Australian rainfall decline be explained? A review of possible drivers. WIREs Clim. Chang. 2023, 14, e820.

[33] Wasko C, Stephens C, Peterson TJ, Nathan R, Pepler A, Hettiarachchi S, et al. Understanding the implications of climate change for Australia’s surface water resources: Challenges and future directions. J. Hydrol. 2024, 645, 132221.

[34] Post DA, Timbal B, Chiew FHS, Hendon HH, Nguyen H, Moran R. Decrease in southeastern Australian water availability linked to ongoing Hadley cell expansion. Earth’s Future 2014, 2, 231-238.

[35] Timbal B, Drosdowsky W. The relationship between the decline of Southeastern Australian rainfall and the strengthening of the subtropical ridge. Int. J. Climatol. 2013, 33, 1021-1034.

[36] Fogt RL, Marshall GJ. The Southern Annular Mode: Variability, trends, and climate impacts across the Southern Hemisphere. WIREs Clim. Chang. 2020, 11, e652.

[37] Abram NJ, Wright NM, Ellis B. Coupling of Indo-Pacific climate variability over the last millennium. Nature 2020, 579, 385-392.

[38] Freund MB, Henley BJ, Karoly DJ, McGregor HV, Abram NJ, Dommenget D. Higher frequency of central pacific El Niño events in recent decades relative to past centuries. Nat. Geosci. 2019, 12, 450-455.

[39] Borowiak A, King A, Lane T. The Link between the Madden-Julian Oscillation and Rainfall Trends in Northwest Australia. Geophys. Res. Lett. 2023, 50, e2022GL101799.

[40] Stephens CM, McVicar TR, Johnson FM, Marshall LA. Revisiting Pan Evaporation Trends in Australia a Decade on. Geophys. Res. Lett. 2018, 45, 164-172.

[41] Ho M, Nathan R, Wasko C, Vogel E, Sharma A. Projecting Changes in Flood Event Runoff Coefficients under Climate Change. J. Hydrol. 2022, 615, 128689.

[42] Peterson TJ, Saft M, Peel MC, John A. Watersheds may not recover from drought. Science 2021, 372, 745-749.

[43] Wasko C, Shao Y, Vogel E, Wilson L, Wang Q, Frost A, et al. Understanding trends in hydrologic extremes across Australia. J. Hydrol. 2021, 593, 125877.

[44] Environment Protection Authority. Available online: https://soe.epa.sa.gov.au/files/documents/SOER-Summary-Report.pdf (accessed on 31 December 2024).