Observed and Projected Changes to Pacific Surface Climate
This content discusses the observed and projected changes in the Pacific surface climate, focusing on various aspects such as tropical marine research, global climate complexities, sea surface temperatures, seasonal weather cycles, tropical cyclones, and the El Niño-Southern Oscillation. Experts like Janice Lough, Jerry Meehl, and Jim Salinger provide insights into the current state and future projections of the Pacific climate, highlighting the influence of different climatic phenomena.
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Presentation Transcript
7thSPC HOF meeting Observed and projected changes to Pacific surface climate Janice Lough (AIMS) Jerry Meehl (NCAR) and Jim Salinger (NZ)
OUTLINE climate type of weather we expect surface climate of the Pacific climate change not a future event projecting the future and uncertainties summary AIMS: Australia s tropical marine research agency
NOAA National Climatic Data Center, State of the Climate: Global Analysis for December 2010, published online January 2011, retrieved on February 10, 2011 from www.ncdc.noaa.gov.sotc
Complexity of global climate Global annual mean energy budget (2000-2004) W m-2 all about movement of energy more energy trapped in climate system Trenberth et al 2009
Tropical Pacific heat engine of atmosphere vast ocean dominates island climates trade winds convergence zones Walker and Hadley circulations
Average sea surface temperature climate (1950-2007) west to east gradient dominates island temperature maximum >30oC in WPWP minimum > threshold for coral reef growth small annual range < 2oC
Tropical cyclones major destructive weather events rare within 5-10o of equator main influence in summer months average maximum ~ Vanuatu TC Yasi February 2011
El Nio-Southern Oscillation (ENSO) McPhaden 2004 major source of inter-annual climate variability centred in tropical Pacific evolves over 12-18 months b 3 2 std SST anomaly 1 0 -1 -2 -3 1871 1891 1911 1931 1951 1971 1991 Year
Typical El Nio and La Nia SST anomalies Large area warmer Large area cooler
Typical El Nio and La Nia rainfall anomalies Wetter or drier depending on location
ENSO shifts in SPCZ and tropical cyclones El Ni o SPCZ average (black) SPCZ further north El Ni o (red) SPCZ further south La Ni a (blue) La Ni a fewer TCs and further east El Ni o more TCs and further west La Ni a
Decadal modulation of Pacific surface climate (PDO) c 3 2 1 PDO index 0 -1 -2 -3 1871 1891 1911 1931 1951 1971 1991 Year cooler phase SPCZ displaced SW & ENSO variability stronger warmer phase SPCZ displaced NE & ENSO variability weaker
Results in average seasonal climate and variability i.e. what we expect at given place and time of year 1951-1980 monthly temperature and rainfall averages (data source: NIWA)
Why are climate scientists so sure climate is changing due to human activities? theory modelling evidence: instrumental measurements changes in the physical world changes in the biological world paleoclimate archives The climate system appears to be changing faster than earlier thought likely Steffen 2009
History of human influence on climate: 1896 A simple calculation shows that the temperature in the arctic regions would rise about 8o to 9oC, if the carbonic acid increased to 2.5 or 3 times its present value S. Arrhenius Philosophical Magazine and Journal of Science 1896 (1903 Nobel Prize winner) CO2 290 ppm
NATURAL greenhouse effect sustained life on earth without it ~30oC cooler! More greenhouse gases trap more energy and warm planet
Observed and projected increases in carbon dioxide Mauna Loa and Kiribati 2010 390ppm + 40% since 18th century possible increase by 2100 tracking high emissions Sources: World Data Centre for Greenhouse Gases; Meehl et al 2007
Observed warming of global temperatures 0.6 Annual global land & sea temperatures: 1850-2009 oC anomaly from 1961-90 average (1980-2009)-(1850-1879)= +0.58oC 0.3 Top 10 warmest Years Anomaly C 0.0 2010 0.62 -0.3 2005 0.62 y = 0.0044x - 0.5243 R2 = 0.6402 1998 0.60 -0.6 2003 0.58 1850 1880 1910 1940 1970 2000 2002 0.58 year Data source: HadCRU 2009 0.56 2006 0.56 10 of warmest years since 1998 2007 0.55 2004 0.54 2001 0.52
Rate of warming accelerating (1988-2007)- (1950-1969) warming of Pacific not uniform
Climate is about averages & includes variability One swallow does not a summer makeAristotle tropical oceans warming ~70% of global average
Projecting future climates Temperature (oC) Scenario IPCC-AR4 (2007) B1 A2 CO2 (ppm) +1.8 (1.1-2.9) +3.4 (2.0-5.4) 450-500 750-800 NEED high quality observations of climate and forcing factors understanding of complex physics of global climate system reliable modelling of climate projecting future trajectories of greenhouse gases downscaling to relevant spatial scales Explosion of Uncertainties
Projected Pacific surface temperature warming multi-model averages similar magnitude in short term larger differences in magnitude in long term the future will be WARMER IPCC 2007
Projected Pacific rainfall changes more uncertainty similar short term wetter convergence zones (blue) drier subtropics (orange) 5% but does not mean no change (grey) warmer = stronger hydrological cycle more extreme wet years more intense droughts IPCC 2007
Possible new climates Temperature 1951-1980 Observed 28.2 28.0 25.6 23.9 20.9 2035 2100 B1 A2 B1 A2 Tarawa Funafuti Nadi Raratonga Pitcairn 29.0-29.2 28.5-28.8 26.1-26.4 24.4-24.7 21.4-21.7 28.7-29.0 28.5-28.8 26.1-26.4 24.4-24.7 21.4-21.7 29.7-30.0 29.3-29.5 26.9-27.1 25.2-25.4 21.9-22.2 31.2-31.5 30.8-31.0 28.4-28.6 26.4-26.7 22.6-22.9 DJF rainfall 1951-1980 Observed 725 1,164 785 426 377 2035 2100 B1 A2 B1 >870 A2 Tarawa Funafuti Nadi Raratonga Pitcairn 761-798 761-798 798-870 1,280-1,397 864-942 469-511 302-339 1,222-1,280 447-469 339-358 339-358
Summary projected changes low and high emissions similar in short term but larger differences in long term warming will continue 0.5-1.0oC warmer by 2035 and 1-1.5oC (low) to 2.5-3oC (higher) by 2100 rainfall more uncertain but likely in convergence zones & in subtropics BUT warmer oceans = stronger hydrological cycle more extreme rainfall events warmer air temperatures = more intense droughts maybe fewer TCs but those that occur more intense UNCLEAR how ENSO might change
SUMMARY future will be warmer some islands wetter & some drier more frequent and more intense extreme weather events importance of RATE of change not just new climate regime for foreseeable future climate will be CHANGING
Thank you Warming of the climate system is unequivocal... (IPCC 2007) Most of the observed increase...is very likely due to the observed increase in anthropogenic greenhouse gas concentrations (IPCC 2007) ...volume of literature in refereed international journals relating to small islands and climate change since publication of the TAR is rather less than that between the Second Assessment Report in 1995 and the TAR in 2001 Mimura et al (2007) Many aspects of tropical climatic responses remain uncertain Christensen et al. (2007) j.lough@aims.gov.au
