Climate trends, regional and national climate change projections

Gillian Cambers, SPC, GCCA: PSIS Project Manager

Outline of presentation

• Source of the science presented in this presentation – the Pacific Climate Change Science Program (PCCSP)

• Climate change and climate variability• How has the Pacific climate changed in the last 50

years?• Changes expected by 2055• Aid effectiveness and climate change science

1. Source of science presented here

Some of the PCCSP partners from National Meteorological Services

The Pacific Climate Change Science Program (PCCSP) is a partnership between the Australian Government and science agencies (the Bureau of Meteorology & CSIRO) in close collaboration with 14 Pacific island countries, East Timor and Pacific regional organisations. The science program is continuing until 2013 under the banner of PACCSAP.

Pacific Climate Change Science Program

Goal of the PCCSP

The Pacific Climate Change Science Program (PCCSP) is working closely with National Meteorological Offices as well as other national agencies in the 15 partner countries to better understand how their climate has changed in the past and how it may change in the future.

PCCSP products

• A technical, peer reviewed report Climate Change in the Pacific: Scientific Assessment and New Research, launched November 2011:Volume 1- Regional Overview; Volume 2- Country Reports

• Eight page brochures on the current and future climate of each country, English and local language versions

• All available at:

www.PacificClimateChangeScience.org

2. Climate change and climate variability

Rainfall observations: Niue

hours days months decadesyears centuries

Weather

Climate variability

Climate change

Rain squall

Typhoon

Wet season/dry season

El Niño- Southern

Oscillation (ENSO)

Pacific Decadal Oscillation (PDO)

Global warming&

ocean acidification

Climate variability and change

ClimateChange?

Climate change and variability: Tarawa

ClimateVariability

3. Pacific climate changes in last 50 years

Changes in the atmosphere

• Air temperatures have warmed across the Pacific since 1950 between 0.1 – 0.2oC/decade.

• Rainfall across the region has increased and decreased in response to natural climate variability, mainly due to the El Niño Southern Oscillation.

• No significant trends in the overall number of tropical cyclones, or in the number of intense tropical cyclones in the South Pacific Ocean between 1981 and 2007.

Changes in the ocean

• Sea-surface temperatures in the region have generally warmed since 1950.

• Changes in ocean saltiness mirror rainfall changes• Ocean acidity has increased• Sea level has risen

Key points

• Analysis of observations show the ocean and atmosphere have been changing over the past 50 – 60 years

• Considerable variation from country to country• Climate change signal is very small in comparison to

natural climate variability• Importance of accurate recording and analysis of

climate observations cannot be over-emphasized

4. Climate projections 2055

Preparation of climate projections

100-400 km

40 layers

Temp, wind, rain

Laws of physics

• The climate system is very complex: we cannot assume that current trends will continue

• Global climate models; theseare mathematical representations of the ocean and atmosphere based on the laws of physics and run on powerful computers

• 24 models are available from around the world

www.pacificclimatefutures.net

Projected climate changes in 21st century

• Increases in air temperature, sea-surface temperature, extreme rainfall and extreme temperature events, potential evapotranspiration, humidity, solar radiation, ocean stratification, sea level, ocean acidification

• Changes in rainfall, tropical cyclones, wind speed, salinity

Climate projections 2055

• Regional warming greatest near the equator • Large increases in extremely hot days and warm

nights• Increases in annual mean rainfall most prominent

near the SPCZ and ITCZ, little change elsewhere • More heavy and extreme rain days• Increases in potential evapotranspiration• Wind speed generally decreases in the equatorial and

northern parts of the region, while increases are indicated in the south, but changes are small

• Humidity and solar radiation changes are also small

Projected temperature and rainfall changes 2055

Greenhouse gas emissions Northern Marshall Islands Vanuatu

TEMPERATURE CHANGES RELATIVE TO 1980-2000

Low emissions 0.5 – 1.7 0.5 – 1.5

Medium emissions 0.9 – 2.1 0.8 – 2.0

High emissions 1.0 – 1.8 1.1 – 1.7

RAINFALL CHANGES RELATIVE 1980-2000

Low emissions -2% to +6% -11% to +13%

Medium emissions -7% to +19% -12% to + 18%

High emissions -14% to +31% -10% to +20%

• Intensified warming and freshening at the ocean surface is projected to make the surface ocean less dense compared to the deep ocean, so there is less vertical mixing

• Regional sea level rise is projected to be similar to the global average, but improved understanding of the processes responsible for ice-sheet changes are needed to improve estimates of the rate and timing

• Higher levels of CO2 will cause further ocean acidification, increasing risks to reef ecosystems

Climate projections - oceans

• Ocean acidification is simulated to continue throughout the 21st century; after 2050, levels of aragonite saturation in many parts of the Pacific are projected to fall below 3.5Ω - a critical level for coral reef health

Ocean acidification

Tropical cyclones

• South Pacific basin: most models indicate a decrease in the frequency of tropical cyclones by 2090 and an increase in the proportion of more intense storms

• North Pacific basin: models indicate a decrease in the frequency of tropical cyclones and a decrease in the proportion of more intense storms

Key points

• Climate change and climate variability are already taking place

• PCCSP’s “Climate Change in the Pacific” and the SPC book on the “Vulnerability of Pacific fisheries to climate change” contain rigorous scientific information on which to base adaptation planning

• Science is continually evolving and climate change projections are becoming more reliable as our knowledge grows

Climate science and aid effectiveness

• Do we need more climate science in the Pacific?• YES • Building the strength and capacity of national

Meteorological Services to provide the information on which to base adaptation planning

• Building the capacity of Pacific Island Countries to adapt to climate change over time frames longer than the normal project cycle

Thank you