Climate change – the latest news

Paul HolperCSIRO Marine and Atmospheric ResearchScientists in Schools, Newcastle, 25 October 2007

Sunday Age, 28 M

ay 2006

Outline

• Climate change – the basics• The latest science

• IPCC Fourth Assessment Report• Climate change in Australia• Impacts of climate change• What to do

The greenhouse effect

Cape Grim Baseline Station

Atmospheric carbon dioxide concentrations

Carbon dioxide concentrations are now greater than at any time during the past 650,000 years.

Svante Arrhenius – “On the influence of carbonic acid in the air …”

Svante August Arrhenius b. February 19, 1859, Wijk, Sweden

d. October 2, 1927, Stockholm, Sweden

“Doubling CO2 leads to increase of ~5°C”

Carbon dioxide and temperature last 420, 000 years

100

150

200

250

300

350

0100,000200,000300,000400,000years before present

CO

2 (pp

m)

-10

0

10

20

tem

pera

ture

(o C)

Longer-term changes

Average Australian surface temperature

Australian annual mean temperatures have increased by approximately 0.9°C since 1910

IPCC 2007: Observed changes

• Rises in global average air and ocean temperatures

• 0.7ºC increase over past 100 years in surface air temp.

• Eleven of the last 12 years are the warmest since 1850

• Mountain glaciers and snow cover have declined in both hemispheres

• Annual average Arctic sea ice extent has shrunk • Increased drying due to higher temperatures and

decreased rainfall has contributed to more intense and longer droughts since the 1970s

• Frequency of heavy rainfall events has increased • Hot days and nights and heatwaves have become

more frequent. Cold days and nights and frosts have become rarer.

Decrease in snow, permafrost glaciers & sea ice

Source: w

ww

.ncar.ucar.edu/eo/kids/green/warm

ing6.htm/nsidc.org/data/g00472.htm

lMuir Glacier, Alaska, August 13, 1941 Muir Glacier August 31, 2004William O. Field Bruce F. Molnia (USGS).

Arctic changes, 1861 - 2100

Arctic sea ice

International findings: IPCC 2007

• Warming of the climate system is unequivocal.

• Very likely that anthropogenic greenhouse gas emissions caused most of the warming since the 1950s (>90% confidence)

• Likely that greenhouse gases alonewould have caused more warming than observed as volcanic eruptions and aerosols have offset some of this warming

CO2 concentrations, stabilisation and future temperature

Even if CO2 concentrations are stabilised, temperature and sea level will continue rising

CO2 growth rate rising

Rahmstorf et al.Growth rate has risen from <1% pa in the 1900s to > 2.5% pa from 2000 to 2005.

Tracking at high end of IPCC temp. projections

Rahmstorf et al.

Rahmstorf et al.

Tracking at very high end of sea level rise projections

Earth at night

Fuel use

Country size represents proportion of global fuel use.www.worldmapper.com

Climate change in Australia

CSIRO-Bureau of Meteorology (2007)Australian Climate Change Science Program Australian Greenhouse Office, DEWR

• The most comprehensive report on climate change for Australia

• Detailed 148 page technical report with 291 scientific references. Over 50 authors, contributors, reviewers and editors.

• 8-page brochure, impacts brochure, CD

www.climatechangeinaustralia.gov.au

Projected warming in 2030: 50 percentile, A1B

A1B mid-range scenario, best estimate projected warming 2.8ºC by 2100

ºC

Projected warming in 2030: Model range

10 percentile, A1B 90 percentile, A1B

Projected warming in 2030: Model range, A1B

A1B mid-range scenario, best estimate projected warming 2.8ºC by 2100

Chance of at least a 1, 2, 3 or 4°C warming

New South Wales temp. change 50th percentile annual

Temperature projections to 2100

Stippling indicating where decrease is ‘likely’ (more than 67% probability of decrease)

No areas show ‘likely’ increase

Projected rainfall change 2030: 50 percentile, A1B

A1B mid-range scenario, best estimate projected warming 2.8ºC by 2100

Comprehensive projections: other variables

• Wind speed mainly increases• Relative humidity small decreases• Solar radiation increases in the south• Potential evaporation increases• Sea surface temperature increases, especially Tasman sea

Impacts of climate change

Australia is already experiencing impacts from recent climate change

• increasing stresses on water supply and agriculture, changed natural ecosystems and reduced seasonal snow cover

Ongoing vulnerability to extreme events• substantial economic losses caused by

droughts, floods, fire, tropical cyclones and hailMore heat waves, fires, floods, droughts and storm

surges. More intense cyclones and hail storms.Water security problems to intensify by 2030 in

southern and eastern AustraliaSignificant loss of biodiversity to occur by 2020 at sites

including the Great Barrier Reef and Queensland Wet Tropics

Increased risks to major infrastructure

What to do?

• Adaptation (‘climate-proofing’) • maximising opportunities and minimising threats from current and

likely future climatic changes, particularly in vulnerable areas

• Mitigation (reducing greenhouse gas emissions or enhancing sinks)

• reducing the risk of larger and dangerous changes in climate andassociated impacts to which we cannot adapt

Big solutions!

Deploy 16 trillion sunlight-refracting shades. Each mirror would span less than a square metre and block 2% of sunlight.

Conclusions

• Climate change is real and underway• Most of the warming of the past 50 years is due to human activities• Climate change will continue in the 21st century• Detailed information on climate change in Australia is now

available• Great value in understanding likely impacts to reduce damage and

increase benefits (adaptation)• Slowing climate change will require large and global reductions in

emissions (mitigation)

Thank you

CSIRO Marine and Atmospheric ResearchPresenter’s namePresenter’s title

Phone: +61 3 9545 2176Email: Name.Name@csiro.auWeb: www.cmar.csiro.au

CSIRO Marine and Atmospheric ResearchPresenter’s namePresenter’s title

Phone: +61 3 9545 2176Email: Name.Name@csiro.auWeb: www.cmar.csiro.au/group

Contact UsPhone: 1300 363 400 or +61 3 9545 2176

Email: Enquiries@csiro.au Web: www.csiro.au

CSIRO Marine and Atmospheric ResearchPaul Holper

Phone: +61 3 9239 4661Email: paul.holper@csiro.auWeb: www.csiro.au