Regional Climate Variability and Change

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1 Regional Climate Variability and Change Dr. Cedric J. VAN MEERBEECK Climatologist Ms. Wazita B. SCOTT Assistant Climate Forecaster 1

2 Climate variability and predictability in the Caribbean 2

3 Weather, Climate Variability and Climate Change variability change variability 3 Adapted from: GFCS

4 Modes of Tropical Variability Decadal Oscillations 5/23/13 Laing, 2013 CARICOF Training Workshop 4

5 Main modes of variability influencing our climate at seasonal to interannual time scales ENSO NAO Saharan dust MJO 5

Niño is Warmer than normal sea surface temperatures across

America). Due to ocean currents and winds shift near equator.

tears up storm clouds and leads to dryness in our region

6 Why the ongoing drought? Our Caribbean Climate Outlook Newsletter tells us: EL NIÑO El Niño is Warmer than normal sea surface temperatures across the east-central equatorial Pacific (off the coast of South America). Due to ocean currents and winds shift near equator. Occurs every 2-7 years El Niño stabilises the atmosphere, tears up storm clouds and leads to dryness in our region EXCEPT northern Caribbean, where El Niños tend to bring more dry season rains. El Niño 2015, the 2 nd strongest since at least 1950, will last throughout the dry season. WET DRY Normal conditions DRY El Niño conditions WET WET DRY

7 Drought & El Niño in time Most of the intense droughts coincide with El Niño 6 St Lucia, G Charles SPI mth 3mth 6mth 12mth

8 La Niña Essentially the opposite of El Niño Unusually cold ocean temperatures in the tropical Pacific The impact on rainfall also mirrors El Niños 8

9 Currently in the news drought!! 2015: record dry in many places Antigua From August: No surface water exploitable, 83% desalination (Antigua & Barbuda Met Services) From October: 100% desalinated water Barbados record driest year resulting in water outages in central and northern part of the island. St. Kitts & Nevis water rationing resumes in January 2016 after second driest year on record. No water sold to cruise ships since September. St. Lucia two driest years on record in 2014 & 2015 led to water restrictions for all households. Dominica Tropical Storm Erika amidst drought: 1.3 billion EC$ damage and losses. Potworks Dam in Antigua Carraizo reservoir in Puerto Rico Mona reservoir in Jamaica

10 Currently in the news drought!! 2015: record dry in many places Antigua From August: No surface water exploitable, 83% desalination (Antigua & Barbuda Met Services) From October: 100% desalinated water Barbados record driest year resulting in water outages in central and northern part of the island. St. Kitts & Nevis water rationing resumes in January 2016 after second driest year on record. No water sold to cruise ships since September. St. Lucia two driest years on record in 2014 & 2015 led to water restrictions for all households. Dominica Tropical Storm Erika amidst drought: 1.3 billion EC$ damage and losses. Dominica after TS Erika

11 Currently in the news drought!! 2015: record dry in many places Belize Millions $ losses in agriculture. Cuba most severe drought since 2004 with water deficits in 45% of country and 100,000 people depending on water delivery by tanks. Dominican Republic 11% decrease in agricultural production. Guyana Guyana Water Inc. updated water rationing and management practices for Georgetown Haïti 200,000 families affected by ongoing drought, with a 30% reduction in harvest over 2015 Puerto Rico streamflows well below average, eastern PR under drought, rationed water supply to San Juan up till October. (PR Met Service) Potworks Dam in Antigua Carraizo reservoir in Puerto Rico Mona reservoir in Jamaica

How do we know? Our drought monitoring products E.g. the map below shows 12-month drought severity between February 2015 and January 2015 OBSERVATIONS: Short-term drought in Lesser Antilles & Guyana.

12 How do we know? Our drought monitoring products E.g. the map below shows 12-month drought severity between February 2015 and January 2015 OBSERVATIONS: Short-term drought in Lesser Antilles & Guyana. Medium- and long-term drought throughout the Antilles (except Cuba). LEGEND Source: Caribbean Drought Bulletin Exceptionally Dry most severe very rare Normal usual common Exceptionally Wet most severe very rare IMPLICATIONS: Areas in short- to mediumterm drought: (i) more bush fires, (ii) low agricultural yields, (iii) possible price increase in local goods. Areas in long-term drought: (i) unreliable water supply due to water shortages & (ii) water consumption restrictions.

13 When can we expect drought relief? The current El Niño and drought to subside by June 2016 El Niño subsiding El Niño weakening since December 2015; it is expected to disappear by June AND: more likely than not, El Niño might make way for opposite: La Niña. Drought subsiding after dry season BUT: As the dry season goes on, drought impacts will worsen. AND: In case of La Niña, higher flood risk during the wet/hurricane season.

strength of gradient between semi-permanent Azores- Bermuda High &

14 North Atlantic Oscillation NAO = interannual variability in winter (DJF) atmospheric circulation over North Atlantic region defined by strength of gradient between semi-permanent Azores- Bermuda High & Iceland Low. NAO-index = normalized pressure difference between Azores & Iceland. 14

NOAA CPC NAO monitoring Predictability of rainfall and NAO: A positive NAO carries drier air to the Eastern Caribbean, in particular during the early part of the year, along with stronger trade winds.

15 NOAA CPC NAO monitoring Predictability of rainfall and NAO: A positive NAO carries drier air to the Eastern Caribbean, in particular during the early part of the year, along with stronger trade winds. That means the east tends to be drier during positive NAO phases, and the opposite is true for negative phases, BUT: there is currently very limited predictability of the NAO itself. So even if we understand NAO influences rainfall, we can t use it for seasonal forecasting.

16 Saharan Dust impacts our weather Dust interacts with radiation influences on the energy budget Dust absorbs LW radiation warming of the layer these aerosols are located Is transported through the globe in layers throughout the depth of the atmosphere 16

17 MJO Impacts on Caribbean MJO can cause ½ a month or more of enhanced convection or suppression of convection Should monitor its state and forecast and explain its impact to users 5/23/13 Laing, 2013 CARICOF Training Workshop 17

18 MJO & Hurricane Activity 5/23/13 Laing, 2013 CARICOF Training Workshop 18

19 Observed trends in temperature and rainfall extremes in the Caribbean 19

20 Stephenson et al. (2014, Intl. J. Climatology) EGU GA Vienna Austria 20

21 Significant region-wide temperature trends!! a) TXmean b) TNmean increase TNmean +1.4 C vs TXmean C c) DTR decrease in diurnal temperature range (DTR). EGU GA Vienna Austria 21

22 Significant region-wide temperature trends!! a) TX90p b) TX10p c) TN90p d) TN10p Increase in frequency of warm days (TX90p) and warm nights (TN90p) by >+15% & warming of warmest days and nights by +1 C Decrease in frequency of cold days (TX10p) -7% and cold nights (TN10p) by - 10% & warming of coldest days and nights by +1 C 22

23 Significant region-wide rainfall trends?? a) PRCPTOT Despite recent apparent rise (boxed) b) SDII No annual RR change (PRCPTOT) c) CDD No change in single rainfall event intensity (SDII) No change in dry spells (CDD) EGU GA Vienna Austria 23

24 Significant region-wide rainfall trends?? a) R20mm b) RX5day No significant change in RR from heavy rainfall events c) R95p Significant rise in extreme rainfall (R95p) since about 1990 EGU GA Vienna Austria 24

25 Comparison to previous assessment A similar workshop in 2001 resulted in a paper by Peterson et al. (2002, JGR), noting: dramatic increase in # warm days and nights decrease in # very cool days and nights decrease in dry spell duration increase in # heavy rainfall events for a mean Caribbean. Those results were calculated from 16 stations for TX/TN and 29 stations for RR running from , including data gaps. All of their results except dry spell duration no significant decrease are corroborated by our findings. EGU GA Vienna Austria 25

26 Decadal variability tied to AMO? a) TX90p b) TN90p c) TN10p Tight coupling land temperature variability and Atlantic Multi-decadal Oscillation (AMO) d) SDII e) R50mm f) R50p Coupling very weak between rainfall and AMO EGU GA Vienna Austria

27 Take Home Messages The regional ETCCDI workshops continue to be a very efficient way of rescuing climate data and updating our knowledge of climate trends and extremes. Robust trends are: warming of mean and extreme daily maximum and minimum temperatures; increase in number and temperature of very warm days and nights; decrease in number and temperature of very cool days and nights. Despite that models predict an increase in extreme precipitation, longer dry spells and reduced annual rainfall in the Caribbean, no long-term change is observed as yet save for an emerging rising trend in extreme rainfall since EGU GA Vienna Austria 27

28 Future Climate Change projections for the Caribbean 28

Climate Change Downscaled climate change projections for the end of 21 st Century (using IPCCC SRES scenarios) Mean changes in the annual rainfall for 2071-2099 with respect to 1961-1989, as

29 Climate Change Downscaled climate change projections for the end of 21 st Century (using IPCCC SRES scenarios) Mean changes in the annual rainfall for with respect to , as simulated by PRECIS_ECH and PRECIS_Had for SRESA2 and SRESB general drying trend for the Caribbean Basin - Drying of 25% to 30% - November to April possibly wetter far north Adapted from: Taylor et al. (GFCS Caribbean RWCS, Trinidad, 2013)

30 Projected Precipitation Change EARLY WORKS MODEL PROJECTIONS Drying exceeds natural variability June-October wet season drier! 30 Adapted from: Taylor et al. (GFCS Caribbean RWCS, Trinidad, 2013)

(using IPCCC RCP scenarios) - same drying trend for

31 Projected Precipitation Change More recent climate change projections for the end of 21 st Century (using IPCCC RCP scenarios) - same drying trend for the Caribbean Basin - April to September likely drier 31

32 Projected Precipitation Change Why? hotter hot 32 Taylor et al. (2011) Adapted from: Taylor et al. (GFCS Caribbean RWCS, Trinidad, 2013)

33 Projected Precipitation Change Correlation of 925 zonal wind & Precipitation Why? more heating in east Pacific than in Caribbean more subsidence over Caribbean + stronger easterlies less rainfall Munoz et al /23/13 Laing, 2013 CARICOF Training Workshop 33

Warming far exceeds natural variability Mean changes in the annual mean surface temperature for

34 Projected Temperature Change Warming by the end of 21 st Century 1 to 5 o C Warming consistent with projections for other parts of globe. Warming far exceeds natural variability Mean changes in the annual mean surface temperature for with respect to , as simulated by PRECIS_ECH and PRECIS_Had for SRESA2 and SRESB2. Adapted from: Taylor et al. (GFCS Caribbean RWCS, Trinidad, 2013)

35 Projected Temperature Change More recent climate change projections for the end of 21 st Century (using IPCCC RCP scenarios) Same conclusions as before 1 o C to 5 o C warming 35

36 Questions? 36

An introduction to drought indices

An introduction to drought indices WMO-ETSCI Workshop, Barbados 17 February 2015 Acacia Pepler Australian Bureau of Meteorology "Drought" by Tomas Castelazo - Own work. Licensed under CC BY 3.0 via Commons