Zone 3: Regional snapshot of projected climate changes and hazards Eastern lower North Island (Te Ika ā Māui) extends from Hicks Bay (Wharekahika) to Palliser Bay (Te Waha o te Ika ā Māui) and back to the Ruahine and Kaweka ranges. Includes Gisborne, Hawke’s Bay and the Wairarapa catchment of Wellington. Hazard RCP 4.5 RCP8.5 Extra information Higher mean 2040: Annual average air temp 2040: Annual average air temp - Summer air temperature to warm temperatures: air to increase 0.7-0.9˚C; Coastal to increase 0.8-1.1˚C; Coastal the most; Spring air temperature the and water sea-surface temps to increase sea-surface temps to increase least. ~1.1˚C (6% change). ~1.5˚C (9% change). - Daily maximum air temperature is 2090: Annual average air temp 2090: Annual average air temp expected to increase faster than to increase 1.3-1.4˚C; Coastal to increase 2.8-3.1˚C; Coastal overnight daily minimum sea-surface temps to increase sea-surface temps to increase temperature. ~1.3˚C (8% change). ~3.3˚C (20.5% change). - Tasman Sea (Zones 2-3) expected to show the largest absolute sea temperature change: warming to exceed 1.3˚C (RCP4.5, ~2100) or 3.1˚C (RCP8.5, ~2100). Heatwaves: 2040: Increase 5-15 more hot 2040: Increase 5-25 more hot - No data available yet for Heatwaves increasing frequency days/year (>25˚C). Highest in days/year (>25˚C). Highest in >25˚C (3 consecutive days) or Extreme and magnitude Wairarapa. 6 day increase for Wairarapa. Heatwaves >30˚C (3 consecutive Wellington (12days/year), 19 Heatwaves >25˚C (3 days). day increase for Masterton consecutive days): Wellington, - 40-100% increase in hot days (50days/year). +2days (3/year); Masterton, (>25˚C) across New Zealand (RCP4.5, Heatwaves >25˚C (3 +17days (33/year). ~2050). consecutive days): Wellington, Extreme Heatwaves >30˚C (3 - 40-300% increase in hot days +2days (3/year); Masterton, consecutive days): Masterton, (>25˚C) across New Zealand (RCP4.5, +16days (32/year) 1/year. ~2100). 2090: Increase 5-25 more hot 2090: Increase 30-40 more hot days/year (>25˚C). Highest in days/year (>25˚C). Highest in Wairarapa and Hawke’s Bay. Wairarapa (>60days/year). 10 day increase for Wellington Extreme hot days/year (>30˚C) (16days/year), 30 day increase to increase +20 for Wairarapa for Wairarapa (61days/year). (21.5days/year) and +3 for Heatwaves >25˚C (3 Wellington (3days/year). consecutive days): Wellington, Heatwaves >25˚C (3 +4days (5/year); Masterton, consecutive days): Wellington, +30days (61/year) +15days/year; Masterton, Extreme Heatwaves >30˚C (3 +67days/year consecutive days): Masterton, Extreme Heatwaves >30˚C (3 2/year consecutive days): Masterton, +11days/year. More and longer dry 2040: 5-8 more dry days/year. 2040: Dry days/year and PED - The frequency of dry days (<1mm spells and droughts Increased Potential projections are the same as precipitation) increases with time and Evapotranspiration Deficit above for RCP4.5. The annual RCP. (PED) of 50-100mm in most probability of PED exceeding - Climate drought severity is areas. The annual potential 300mm (very dry), except for projected to increase. evapotranspiration deficit high altitudes in the Tararua - Drought probability up 50-70%. (PED) exceeding 300mm (very Ranges. - Time spent in drought to increase 5- dry conditions) increases Increased PED Low river flow 20%. throughout the region, except thresholds reached earlier in for highest Tararua Range the year (>40days earlier than altitudes. present for central North Greater Wellington territory: Island). 3day dry spells: Wellington Greater Wellington territory: +4days (185days/year), 3day dry spells: Wellington Masterton +7days +8days (189days/year). (177days/year). 5day dry spells: Wellington 5day dry spells: Wellington +7days (126days/year). +6days (125days/year), 10day dry spells: Wellington Masterton +7days +5days (32days/year). (121days/year). 10day dry spells: Wellington +6days (33days/year), Masterton +9 (37days/year). 2090: 5-15 more dry days/year. 2090: 10-20 more dry Increase of PED 100-150mm days/year. Increase in PED of for most areas. The annual PED 150-200mm for most areas. exceeding 300mm (very dry conditions) increases Drought probability up 50-70%. throughout the region, except Time spent in drought for highest Tararua Range increases 5-20%. altitudes. For the Wairarapa Low river flow thresholds PED >300mm increases 40-60% reached earlier in the year and 60-80%. (>40days earlier than present Greater Wellington territory: for central North Island). 3day dry spells: Wellington Decrease of 5% or more in +9days (190days/year), relative humidity. Masterton +10days (180days/year). 5day dry spells: Wellington +10days (129days/year), Masterton +7days (121days/year). 10day dry spells: Wellington +4days (31days/year), Masterton +2 (30days/year). Changes in climate 2040: Warming greatest in 2040: Warming greatest in - Spring and autumn frost-free land to seasonality with summer and autumn. Warming summer and autumn. Warming at least triple by 2080 (RCP8.5, longer summers and least in winter and spring. least in winter and spring. ~2100). - Up to 60 more hot days (>25˚C) by short winters 2090: Warming greatest in 2090: Warming greatest in summer and autumn. Warming summer and autumn. Warming 2090 (RCP8.5, ~2100) least in winter and spring. least in winter and spring. Increasing fire- 2040: Increased fire risk. 2040: Increased fire risk. - Fire season length to increase weather conditions: Increase in days with very high Increase in days with very high (RCP4.5 & RCP8.5, ~2100). harsher, prolonged and extreme fire danger index and extreme fire danger index. - Fire season to start earlier and/or from around 0-400%. finish later (RCP4.5 & RCP8.5, ~2100). season Seasonal Severity Rating: Seasonal Severity Rating: Lower North Island areas, - Fire climate severity is likely to rise Taupo, increase of 30-50%. increase of +100-150%. significantly with climate change in Lower North Island, increase of Remainder of North Island many parts of the country as a result 20-30%. areas, increase of +30-50% of increases in temperature, wind Wellington and East Cape, Very High + Extreme Fire speed and lower rainfall and/or humidity. increase of <20%. Danger: Potential for significantly increased number of days of fire risk. 2090: Increased fire risk. 2090: Increased fire risk. Increase in days with very high Increase in days with very high and extreme fire danger index and extreme fire danger index. from around 0-700%. 44-48 more days of fire risk. Seasonal Severity Rating: Wellington has the highest risk Central North Island areas, increase of 89%. increase of +20-40%. Seasonal Severity Rating: Wellington, no change. Central and lower North Island, Very High + Extreme Fire increase of >50%. Danger: Very High + Extreme Fire Central and eastern areas, Danger: increase of +50%. Most areas, increase of >150%. East Cape, increase of <50% Increased storminess 2040: Extreme wind speeds 2040: Extreme wind speeds - Increases in extreme wind (esp. for and extreme winds increase up to 10%. increase up to 10%. Frequency southern North Island). and rainfall Intensity of (ex)tropical of extreme winds is likely to - Increases in rainfall intensity cyclones projected to increase. increase in winter and projected everywhere. - Moderately extreme daily Rainfall events see righthand decrease in summer. precipitation (99th percentile of wet column. Mean westerly flow of wind to increase ~20% in spring and days) increases. Very extreme daily ~70% in winter; decrease by precipitation increases in frequency. ~20% in summer and autumn. - Short duration (1-in-100-year, 1hour duration) extreme rainfalls increase Intensity of (ex)tropical +13.6% for every 1˚C increase. Long cyclones projected to increase. duration rainfall events (1-in-2-year, Rainfall events see righthand. 120hour duration) increase +4.8% for 2090: Poleward shift of mid- 2090: Poleward shift of mid- every 1˚C increase. latitude and possible small latitude and possible small reduction in frequency. The reduction in frequency. The most severe ex-tropical most severe ex-tropical cyclones are expected to be cyclones are expected to be stronger. stronger. Intensity of (ex)tropical Frequency of extreme winds is cyclones projected to increase. likely to increase in winter and Rainfall events see righthand decrease in summer. column. Intensity of (ex)tropical cyclones projected to increase. Occurrence conditions conducive to storm development is projected to increase by 3-6%, relative to the period 1970-2000. Rainfall events see righthand column. Change in mean 2040: Minimal change in 2040: Small reduction in - The largest rainfall changes by annual rainfall annual rainfall, most change annual rainfall. Largest ~2100 will be seasonal rather than seen at seasonal scale. decreases in winter and spring. annually. Reduction in rainfall in winter Greater Wellington territory: and spring, and small increases decrease in annual wet days in summer. and wet spells. Greater Wellington territory: Annual rain-days: minimal change in annual wet >10mm, Wellington -0.1days days and wet spells. (35.9days/year), Masterton +0days (20days/year). >20mm, Wellington +0.9days (14.9days/year), Masterton +0.2days (4.2days/year). >30mm, Wellington +0.7days (7.7days/year), Masterton 0.3days (1.3days/year). Annual number of wet-day spells >1mm rain/day: 3-day wet spells: Wellington -6 (65days/year), Masterton -3 (74days/year). 5-day wet spells: Wellington -3 (23days/year), Masterton -1 (26days/year). 10-day wet spells: Wellington 0 (2days/year), Masterton -1 (0days/year). 2090: Minimal change in 2090: Annual rainfall decrease annual rainfall, most change of 5-15%. Decreases in all seen at seasonal scale. Small seasons esp. summer and decrease in annual rainfall. winter. Largest decrease in winter and Greater Wellington territory: spring (e.g. spring, -6% decrease in annual wet days Gisborne, -5% Napier). and wet spells. Greater Wellington territory: Annual rain-days: decrease in annual wet days >10mm, Wellington -0.1days and wet spells.