Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
Climate change projections for the western tropical Pacific
Kevin Hennessy
Overview
• PCCSP structure• Research activities• Climate projections
PCCSP structure
• The PCCSP is part of the International Climate Change Adaptation Initiative (ICCAI)
• Funded by AusAID• Research mainly done by CSIRO and the Australia Bureau of Meteorology
• $150 m from 2009‐2011
What is the ICCAI?
Pacific Climate Change Science
ProgramAUD 20m
National Adaptation Strategy Assistance
Program AUD 12m
Coordination & Implementation
AUD 60-70m
Multilateral Financing
AUD 40-50m
Recent Climate
Climate Drivers
Projections & Modelling
Ocean Processes
Information Synthesis
Formulate appropriate adaptation
strategies and plans
Mainstream adaptation into
decision-making
Enhance the capacity to assess key vulnerabilities
and risks
Platform
GEFSmall Grants
Climate Leaders
Bilateral Implementation
CROP Activities
Pilot Program
On-the-ground implementationResearch, planning, capacity-building
Immediate Adaptation Needs
South-East Asia and South Asia
Programs
Western tropical Pacific, including East Timor
15 PCCSP partner countries
Research activities
Climate change scientific information in the region is still very limited – see Chapter 16 of IPCC Working Group 2 report The PCCSP is working in four integrated areas:1. Current climate and trends2. Climate drivers3. Climate change projections4. Oceans and sea level rise
Climate projections
• Assessed performance of 24 global climate models, 18 of which were considered suitable for projections
• Three 20‐year periods and three emission scenarios
Climate projections
• Projections will be published as part of a 600‐page report in Nov 2011
• Volume 1 chapters 6 and 7: broad‐scale projections for the whole PCCSP region
• Volume 2 chapters 2‐16: country‐specific projections
• The following is a sneak preview
Temperature projections
• 2030: 0.5 to 1.0oC warmer, regardless of the emissions scenario
• 2055: 1.0 to 1.5oC warmer with regional differences depending on the emissions scenario
• 2090: the warming is around • 1.5 to 2.0oC for B1 (low emissions) • 2.0 to 2.5oC for A1B (medium emissions) • 2.5 to 3.0oC for A2 (high emissions)• Large increases in the frequency of extremely hot days and warm nights
Rainfall projections
• Increases in annual mean rainfall, most prominent near the SPCZ and ITCZ, with little change in the remainder of the region
18-model average change in rainfall for 2080-2099, relative to 1980-1999, under the A2 (high) emission scenario. Regions where at least 80% of models agree
on the direction of change are stippled
Rainfall projections
• The annual numbers of rain days (over 1 mm), light rain days (1‐10 mm) and moderate rain days (10‐20 mm) are projected to increase near the equator, with little change elsewhere in the region
• A widespread increase in the number of heavy rain days (20‐ 50 mm)
Tropical cyclones
• Tropical cyclone numbers are likely to decline in the Pacific Ocean over the 21st century – Good news!
• Many simulations with fine resolution models (downscaling) show an increase in the proportion of the most severe cyclones– Bad news!
Other atmospheric projections
• Greater potential evapotranspiration offsets some of the rainfall increases
• Surface wind speed decreases slightly in the equatorial and northern parts of the PCCSP region, with small increases in the south
• Projected changes in humidity and solar radiation are relatively small in the PCCSP region, i.e. less than 5% by 2090
Ocean salinity and stratification
• Warmer and less salty at the surface makes the surface ocean less dense than the deep ocean, so the ocean becomes more stratified
• Increased stratification inhibits mixing, thereby reducing the supply of nutrients from the deep to the surface ocean
• Consequences for biological productivity, particularly fisheries
Sea level rise
• Sea‐level rise in the PCCSP region is likely to be similar to the global average• 0.18 to 0.59 m by 2080-2099, relative to 1980‐1999, with potentially an extra 0.10‐0.20 m from the dynamic response of ice sheets
• Improved understanding of ice sheet dynamics is needed to improve estimates of the rate and timing of sea‐level rise
Ocean acidification
• Absorption of CO2causes ocean acidification and a decrease in aragonite saturation
• Aragonite values less than 3.5 result in stress for coral
• Values less than 3.5 reached by 2050 in much of the Pacific, and continue to decline
Southern Cook Islands
• Health of reef ecosystems is likely to be compounded by other stressors including coral bleaching, storm damage and fishing pressure
Summary
• Warmer• Generally wetter, with heavier rainfall• Greater potential evapotranspiration• Fewer tropical cyclones, but more intense• More sea level rise• More ocean acidification
Thank you
Kevin HennessyResearch ScientistPacific Climate Change Science ProgramEmail: [email protected]: +61 400 572 613
For further information
Dr Gillian CambersProgram ManagerPacific Climate Change Science ProgramEmail: [email protected]: +61 447 203 488