Annual maximum daily rainfall projection data for Hong Kong with more details

Following the information provided by the IPCC Interactive Atlas, the Observatory acquired additional data from a number of global climate models that underpin the IPCC Interactive Atlas. Based on this set of climate model data (as at July 2022), a complete set of rainfall projections for Hong Kong, including likely range of projection, is computed and shown in the table below. It should be noted that the projections for 2041-2060 and 2081-2100 may be slightly different from the initial projections released in December 2021.

Projected change in 20-year average of annual maximum daily rainfall of Hong Kong relative to the average of 1995-2014 under different greenhouse gas emissions scenarios. Average annual maximum daily rainfall at the Hong Kong Observatory during 1995-2014 is 203mm. It should be noted that rainfall exhibits significant regional variation.

	Low SSP1-2.6		Intermediate SSP2-4.5		High SSP3-7.0		Very high SSP5-8.5
	Mean (%)	Likely range (%)	Mean (%)	Likely range (%)	Mean (%)	Likely range (%)	Mean (%)	Likely range (%)
2021-2040	3.0	-12.9 – 14.9	7.8	-0.4 – 17.7	7.4	-7.9 – 22.2	5.8	-12.3 – 25.1
2031-2050	5.5	-8.4 – 17.4	8.7	-3.4 – 21.1	9.3	-8.1 – 29.6	7.5	-6.7 – 22.3
2041-2060	8.1	-11.1 – 23.4	10.7	-1.7 – 22.0	10.1	-5.3 – 28.7	10.0	-5.3 – 32.8
2051-2070	10.0	-6.0 – 27.4	10.5	-1.7 – 21.4	11.6	-9.6 – 29.9	12.7	-1.3 – 38.0
2061-2080	10.0	-0.5 – 37.5	11.2	-1.8 – 24.5	17.1	-0.5 – 34.1	16.2	2.2 – 39.5
2071-2090	11.1	-2.2 – 25.5	15.0	1.6 – 31.0	21.0	1.5 – 42.8	23.1	1.7 – 70.6
2081-2100	9.7	-3.0 – 19.8	15.7	-5.8 – 41.8	23.7	5.7 – 55.2	28.8	0.5 – 95.8

The probability for the likely range to cover the outcome is at least 66%. Data source: WCRP CMIP6 (not IPCC Interactive Atlas)

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