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Published byMaría Concepción Benítez Marín Modified over 5 years ago
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Changes in surface climate of the tropical Pacific
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Based on Chapter 2
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Outline and key messages
Main features of region’s climate system We are affecting the climate system - climate is already changing Future will be warmer Extreme weather likely to be more extreme Our climate will be changing for foreseeable future
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Main climate features of the region
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Pacific atmospheric circulation
Trade winds Convergence zones Nauru sensitive to SPCZ position Walker and Hadley circulations
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El Niño-Southern Oscillation (ENSO)
Major source year-year climate variations
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Typical El Niño and La Niña rainfall anomalies
Wetter (green) or drier (orange)
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Typical El Niño and La Niña rainfall
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Typical El Niño and La Niña SST anomalies
Warmer (red) or cooler (blue)
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Sea surface temperature
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Projected changes in climate
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Redistributing sun’s energy = climate system
Global annual mean energy budget W m-2 Trenberth et al 2009 Without the atmosphere the Earth would be ~30oC cooler More greenhouse gases trap more energy in climate system
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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
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Measured increase in carbon dioxide
18th century = 280ppm air bubbles in ice cores 2011= 391ppm Mauna Loa
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Observed warming of global temperatures
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Projecting future climates
Emisions Scenario IPCC-AR4 (2007) Temperature (oC) 2100 Rainfall 2035 2050 Low (B1) ppm CO2 ? 5-15% 10-20% High (A2) ppm CO2 5-20% Predicting future forcing – how much more greenhouse gases? Range of possible futures but he future will be WARMER
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Spatial variation in warming
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Preparing for TC Jasmine Vanuatu
Extremes The answer to the oft-asked question of whether an event is caused by climate change is that it is the wrong question All weather events are affected by climate change because the environment in which they occur is warmer and moister than it used to be Trenberth 2012 Preparing for TC Jasmine Vanuatu
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Important points to note
Extremes will become more extreme Unclear how ENSO will change – continued influence
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For foreseeable future, climate will be CHANGING
Summary Future for Nauru will be warmer and wetter Not just a “new climate” to which we can adapt For foreseeable future, climate will be CHANGING
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