Climate of. The Observed Climate, Climate Variability and Change. Mr. Robsen Silas Vanuatu Meteorological and Geohazard Department VMGD

Transcription

1 Climate of. The Observed Climate, Climate Variability and Change Mr. Robsen Silas Vanuatu Meteorological and Geohazard Department VMGD

2 Content Introduction Setting the Scene Brief Summary of the Climate of Vanuatu Surface Air Temperature, Rainfall Distribution, Wind Speed and Direction Climate Drivers ENSO and SPCZ Variability and Trends Temperature and Rainfall Summary Ways forward Open Discussion Presentation will be given with the assumption that everyone knows these systems, ENSO (El Nino/La Nino) Extreme Events Tropical Cyclones, Temperature and Rainfall (flooding/drought)

3 There are 2 main approaches to understanding climate change 1. Using Historical Data to understand what has happened in the past to determine variability, trends, frequency of events, etc and what courses them (drivers) Quantitative Data collected by NMS s Qualitative Data (Anecdotal Evidence) 2. Using Models and different Emission Scenarios to try and foretell what will happen between NOW and the FUTURE ( ) Based on 24 GCM models developed all over the world and approved by IPCC

4 PCCSP and NC The Pacific Climate Change Science Program (PCCSP) is a partnership between Australian science agencies and Pacific Island countries and Timor Leste, carried out in collaboration with Pacific regional organisations, with the objective being to conduct a comprehensive climate change science research program to provide better information about the likely impacts of climate change to stakeholders in participating countries. The Second National Communications is a commitment of signatories to the UNFCCC to report on related issues of climate change. A major component is the climate change science of a country.

5 Source of climate projection information for SIDS Main source of climate change projection information for small island developing States is the global information in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 2007

6 Small islands, small footprints Caribbean Indian Ocean Pacific Ocean

7 A unique opportunity The Pacific Climate Change Science Program represents a unique opportunity to provide a comprehensive scientific basis that will inform climate change adaptation in the Pacific islands and Timor Leste. It will place the Pacific islands ahead of the other small island regions of the world, which are still dependent on global projections for adaptation work.

8 How big is the Pacific region? U.K. and Western Union superimposed on central Pacific region encompassing 8 Pacific Island nations

9 Global Warming

10 1300 KM Introduction Philippines MAP OF THE SOUTHWEST PACIFIC MAP OF VANUATU Sola Vanua Lava PNG Santo Solomon Is. Santo North VANUATU Fiji Is. Samoa Malekula Lamap Australia New Caledonia Port Vila Efate South Erromango New Zealand New Zealand Tanna Aneityum Anelgauhat Total Area including Seas: 700,000 sq. km 65/83 Islands are inhabited Land Area = 12,190 sq. km NEW CALEDONIA CALEDONIA

11 Background Info cont estimated total population in the 2009 = 243,000 (Prelim count, Oct. 2009). Approximately 80% live in rural villages and live off the land The Predominant type of Agriculture is Subsistence Traditional crop calendars (based on seasonal rainfall variability) are used Limited use of pesticides and chemicals, giving advantage to the export of organic foods Agriculture (organic) contributes 23% of the total economy Climate variabilities such as ENSO events that destabilize the availability of water to plants are important

12 Rainfall Distribution Intertropical Convergence Zone Dry east Pacific South Pacific Convergence Zone

13 Average Monthly Rainfall (mm) Average Monthly Rainfall (mm) Average Monthly Rainfall (mm) Average Monthly Rainfall (mm) Summary of Vanuatu Climate Seasonal Temperature Variability and Rainfall distribution (winter rainfall) Mean Monthly Rainfall & Temperature ( ) for Sola Mean Monthly Rainfall & Temperature ( ) for Lamap Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month 20.0 Mean Monthly Rainfall & Temperature( ) for Port Vila Mean Monthly Rainfall & Temperature ( ) for Aneytium Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month 20.0

14 Climate Drivers - Overview Driver Time of Year El Niño All year TC frequencies Drought Prolonged dry spells Impact on the Climate of Vanuatu La Niña All year Slight increase in the number of TC s Flooding Prolonged wet spells SPCZ November - April Prolonged rainfall over Vanuatu during La Niña years. During La Niña years the SPCZ is displaced towards the northeast of Vanuatu. ITCZ November-April Observed to merge with the SPCZ just north of Vanuatu during the summer of La Nina years. Subtropical frontal systems May-October Rainfall and often stormy conditions to the southern islands of Vanuatu MJO All year Brings active and break drought spells (El Niño) and prolonged rainfall especially during a La Niña Table 3.1: Main climate drivers affecting Vanuatu, their timing and impacts

15 El Niño Southern Oscillation (ENSO) What weather does it affect? Where tropical cyclones form The strength of winds Temperature and rainfall Sea level Other climate drivers

16 Features of normal Pacific climate 1. Trade Winds 2. Cool water in east, warm in west - thermocline 3. Return Walker Circulation 4. Convection/rain over warm pool in west

17 Features of El Niño 1. Trade Winds 2. Cool water in east, warm in west - thermocline 3. Return Walker Circulation 4. Convection/rain over warm pool in west 5. Warming water in east during El Niño 6. Change to winds and rain 7. La Niña has the opposite changes

18 Climate Drivers Southern Summer The SH summer circulation features in the SW Pacific region (Steiner, 1980) that shows the main climate drivers of Vanuatu.

19 Climate Drivers Southern Winter The SH Winter circulation features in the SW Pacific region (Steiner, 1980) that shows the main climate drivers of Vanuatu.

20 Climate Drivers - Indices NIÑO3.4 NIÑO3 NIÑO4 Multivariate ENSO Index Southern Oscillation Index Global Mean Temperature Dipole Mode Index Pacific Decadal Oscillation Southern Annular Mode SPCZ Position Index El Niño Modoki Index Climate Dataset for 30+ years Calculation base on annual data rather than monthly data Correlation Coefficient benchmark No. of years 30 ± ± ± ± ± ±0.20 Significant r

21 ENSO Indices Darwin (Australia) Papeete (Tahiti) SOI Area-averaged SST indices NINO3 NINO3.4 NINO4

22 Climate Drivers North Vanuatu SOLA (0.36) PEKOA (0.36) Index Tm Tn Tx Rain Index Tm Tn Tx Rain NIÑO NIÑO NIÑO NIÑO NIÑO NIÑO Multivariate ENSO Index Southern Oscillation Index Global Mean Temperature Dipole Mode Index Pacific Decadal Oscillation Southern Annular Mode SPCZ Position Index El Niño Modoki Index Multivariate ENSO Index Southern Oscillation Index Global Mean Temperature Dipole Mode Index Pacific Decadal Oscillation Southern Annular Mode SPCZ Position Index El Niño Modoki Index

23 Climate Drivers South Vanuatu WHITEGRASS (0.36) PEKOA (0.36) Index Tm Tn Tx Rain Index Tm Tn Tx Rain NIÑO NIÑO NIÑO NIÑO NIÑO NIÑO Multivariate ENSO Index Southern Oscillation Index Global Mean Temperature Dipole Mode Index Pacific Decadal Oscillation Southern Annular Mode SPCZ Position Index El Niño Modoki Index Multivariate ENSO Index Southern Oscillation Index Global Mean Temperature Dipole Mode Index Pacific Decadal Oscillation Southern Annular Mode SPCZ Position Index El Niño Modoki Index

24 Total Annual Rainfall (mm) Rainfall Variability- ENSO Annual Total Rainfall on Anelgauhat Station from Years Figure 3.5: The graph shows the total annual rainfall on the Aneityum station (southern part of Vanuatu) and highlighted by the warm episode years (1951, 1953, , 1963, 1965, 1969, , , , , , , 2002).

25 ENSO Rainfall Figure 3.6: Mean monthly rainfall at Sola for the different ENSO phases Figure 3.7: Mean monthly rainfall at Aneityum for the different ENSO phases

26 Rainfall Anomaly (mm) SOI Rainfall Anomaly (mm) SOI Rainfall Anomaly (mm) SOI Rainfall Anomaly (mm) SOI Rainfall Variability - ENSO A. Sola Annual Rainfall and SOI Anomalies Lamap Annual Rainfall and SOI Anomalies 2000 Sola RF Anom SOI Lamap RFAnom SOI Years Years Port Vila Annual Rainfall and SOI Anomalies Aneityum Annual Rainfall and SOI Anomalies 2000 Port Vila RF Anom SOI Aneityum RF Anom SOI Years Years -20.0

27 Annual Av SOI Annual Total Rainfall anomalies (mm) Rainfall Variability and ENSO Annual Av. Rainfall (mm) Anomalies and SOI Av SOI RF Anonaly Period (Years)

28 SOI (Std Dev) Annual Av. Temp Anomaly (deg Cel) Temperature Variability and ENSO Annual average Temperature Anomalies and SOI Av SOI Temp Anomaly Period (years)

29 Annual Av SOI Annual Av Pressure Anomalies (hpa) Pressure Variability and ENSO Annual average Surface Pressure Anomaly (mb) and SOI 15.0 Av SOI Annual Average Pres Anomaly Period (Years)

30 Climate Drivers - SPCZ Driver Time of Year Impact on the Climate of Vanuatu SPCZ November - April Prolonged rainfall over Vanuatu during La Niña years. During La Niña years the SPCZ is displaced towards the northeast of Vanuatu.

31 SPCZ and ITCZ Schematic view of the main convergence zones, the ITCZ and the SPCZ along with the annual mean sea level pressure contours and surface wind streamlines. (Extracted from Trenberth, 1991)

32 ENSO vs SPCZ EL NIÑO LA NIÑA Mean SPCZ location as a function of different polarities of ENSO and IPO (Folland et al., (2002). West of about 140 W, both the SOI and IPO strongly influence the SPCZ latitude, but farther east only the SOI is a significant factor. Only near 170 W is there any indication of an interaction between the two factors.

33 La Nina Impact Flooding April 2008

34 El Nino Impact Death of Livestock Fires Shortage of Water Supply Contradiction with Traditional Believes Reduction in Export Products Food Shortages in rural Communities

35 Tropical Cyclones distribution The map above gives a summary of the distribution of cyclones in the southwest Pacific over a period of 20 years ( ), (Gray, 1975).

36 Climate change and tropical cyclones Climate is changing on a global scale. For this reason, it is important to monitor changes in regional tropical cyclone frequencies, intensities and tracks. There has been an increase in hurricane intensity in the North Atlantic since the 1970s, and that increase correlates with increases in sea surface temperature There is no clear trend in the number of hurricanes Other regions appear to have experienced increased hurricane intensity as well IPCC (2007), Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K. B. Averyt, M. Tignor and H. L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 996 pp.

37 Tropical Cyclone Trends Change in the number and percentage of hurricanes in categories 4 and 5 for the different ocean basins: and Webster, P.J., Holland, G.J., Curry, J.A., and Chang, H.-R Changes in Tropical Cyclone Number, Duration, and Intensity in a Warming Environment. Science, 309, 1844; DOI: /science

38 Tropical Cyclone Trends Other authors (e.g. Chan 2006; Landsea et al. 2006) reject these findings on the basis that changes in observation technologies and analysis techniques have created artificial trends Chan, J. C. L Comment on Changes in Tropical Cyclone Number, Duration, and Intensity in a Warming Environment, Science, 311, Landsea, C. W., B. A. Harper, K. Hoarau, and J. A. Knaff Can we detect trends in extreme tropical cyclones, Science, 313,

39 Trends in tropical cyclones in South Pacific No apparent trends in total numbers of TCs or severe TCs in the South Pacific Annual numbers of TCs with minimum central pressure <995 hpa 1981/ /07 seasons Kuleshov, Y., R. Fawcett, L. Qi, B. Trewin, D. Jones, J. McBride, and H. Ramsay (2010), Trends in tropical cyclones in the South Indian Ocean and the South Pacific Ocean, J. Geophys. Res., 115, D01101, doi: /2009jd

40 Southern Hemisphere Tropical Cyclone Climatology Kuleshov, Y., L. Qi, R. Fawcett, and D. Jones (2008), On tropical cyclone activity in the Southern Hemisphere: Trends and the ENSO connection, Geophys. Res, Lett., 35, L14S08, doi: /2007gl032983

41 El Niño-Southern Oscillation (ENSO)

42 Southern Hemisphere Tropical Cyclone Climatology Kuleshov, Y., L. Qi, R. Fawcett, and D. Jones (2008), On tropical cyclone activity in the Southern Hemisphere: Trends and the ENSO connection, Geophys. Res, Lett., 35, L14S08, doi: /2007gl032983

43 Southern Hemisphere Tropical Cyclone Climatology

44 No. of Cy clones Tropical Cyclone in Vanuatu Number of cyclones recorded for each month to have passed through Vanuatu Territory from 1969 to Total No. of Cyclones '69-00' Severe cyclones 5 0 Sep Oct Nov Dec Jan Feb Mar Apr May Jun Month The map above gives a summary of the cyclones that have passed through within 400km from Port Vila from A total of 92 cyclones were recorded. Frequency of cyclones in the Vanuatu area of responsibility from The highest frequency is in January. The months from January to March represent about 72% of the cyclones. Source: Vanuatu Meteorological Tropical Cyclone Archive

45 TC and ENSO Total Number of Tropical Cyclone within 400 km from Port Vila from 1969/70 to 2006/07 El Niño La Niña Neutral All Seasons Total Number of Seasons Used El Niño La Nina Neutral All Seasons Average Number of Cyclone per Season for Port Vila from 1969/70 to 2006/07 El Niño La Niña Neutral All Seasons Table 1.1: Table showing the total and the average number of cyclones to have affected Port Vila from 1969/70 to 2006/07

46 Monthly Rainfall Trends - North Homogenised Rainfall for Sola with a trend line (North Vanuatu) Homogenised Rainfall for Pekoa with a trend line (North Vanuatu)

47 Monthly Rainfall Trends - South Homogenised Rainfall for Tanna/Whitegrass with a trend line (South Vanuatu) Homogenised Rainfall for Aneityum with a trend line (South Vanuatu)

48 Annual Temperature Trend - Bauerfield y = x R² = y = x R² = y = x R² =

49 Monthly Temp. Trends - Tx

50 Monthly Temp. Trends - Tn

51 Extreme Temperature Aneityum Number of days with Tx >32 C Whitegrass with number of Days Tx>32 C y = x R² = y = x R² =

52 Tropical Nights Aneityum Tropical Nights Tn > 20 C Sola Tropical Night Tn > 20 C

53 Sola Cool Days vs Warm Days Cool Days: Percentage of days when TX<10th percentile Warm Days: Percentage of days when TX>90th percentile y = x R² = y = x R² =

54 Whitegrass Cool Days vs Warm Days 35 Cool Days: Percentage of days when TX<10th percentile Warm Days: Percentage of days when TX>90th percentile y = x R² = y = x R² =

55 Extreme Rainfall Periods 100 mm 200mm 250mm 300mm 350mm yrs 6.12 yrs yrs yrs 96.85yrs yrs 2.21 yrs 4.25 yrs 9.54 yrs yrs Observed daily Rainfall for Aneityum comparing changes in return periods for extreme daily rainfall events (100mm, 200mm, 250mm, 300mm and 350mm) for the periods and Dataset may be too short

56 Efate Rainfall in VanuaClim - =

57 Summary Historical Rainfall Trends not very clear Temperature Trends show and studies are ongoing There is no clear trend in the number of South Pacific cyclones since 1981 Investigation and studies of TC still ongoing and better outcome will come later Length of datasets used are different. They need to be more consistent

58 Way Forward for Vanuatu on Climate Change Science Strengthening of Observation systems and installation of at least 2-3 reference climate stations Continue to consolidate data to lengthen data series