Climate Change Information Seminar Intergovernmental Panel on Climate Change Fourth Assessment Report (AR4) – the relevance to FAO’s activities

Climate Change Information Seminar

Intergovernmental Panel on Climate Change

Fourth Assessment Report (AR4)– the relevance to FAO’s activities

Claudia HiepeHideki Kanamaru

NRCB

Nov 27th Tuesday 14:00-15:30 German RoomDec 3rd Monday 10:00-11:30 Iran Room

Three Volumes of IPCC Fourth Assessment Report (AR4)

WG1 152 authors, 600 reviewers,

996pp., technical summary 74pp.

WG2 173 lead authors, 183

contributing authors, 910 reviewers,

976pp., technical summary 56pp.

WG3 168 lead authors + 85

contributing authors, 485 reviewers,

896pp., technical summary 70 pp.

IPCC 2007 WG 1– The Physical Science Basis

• Observed Changes in Climate• Attribution of Change• Projected Change

Observed changes since 1850

Figure SPM .3

Figure SPM .3

Figure SPM .3

Precipitation trend

Figure TS.9

Detection of Climate Change

• Observed change is significantly different (statistically) than natural internal variability of climate.

• Virtually certain > 99% probability• Extremely likely > 95% probability• Very likely > 90% probability• Likely > 66% probability

• Very high confidence : at least 9 out of 10 chance of being correct• High confidence : about 8 out of 10• Medium confidence : about 5 out of 10

Observed trends in climate with respect to natural internal climate

variability• Drought affected area increased since 1970s.

(likely)• Cold days and nights have become less frequent,

hot days and hot nights have become more frequent over the past 50 years. (very likely)

• Heat waves have become more frequent. (likely)• Heavy precipitation events have become more

frequent. (likely)• Average NH temperatures during 2nd half of the

20th century were higher than during any other 50-year period in the last 500 years (very likely) and the highest in at least the past 1300 years (likely).

Observed Changes in Natural and Human Environments due to recent warming

• Earlier timing of spring events. (very high confidence)

• Poleward and upward shifts in plant and animal ranges. (very high confidence)

• Shifts in ranges and changes in algal, plankton and fish abundance in some marine and freshwater systems. (high confidence)

• Agricultural and forestry management at NH higher latitudes – earlier spring planting of crops and alterations in disturbance regimes of forests due to fires and pests. (medium confidence)

Attribution of Change

• Demonstrate that observed changes are– Unlikely to be entirely within internal

climate variability.– Consistent with estimated responses to

external anthropogenic forcings, i.e., most importantly GHG emissions.

– Not consistent with other explanations.

• Most of the observed increase in globally-averaged temperatures since the mid-20th century is due to the observed increase in anthropogenic GHG concentrations. (very likely); on continental scale (likely); regional and smaller scales (attribution is difficult)

Changes in surface temperature since 1900 – obs vs model

Figure SPM .4

GHG concentrations variations over the last 10,000 years

Figure SPM .1Figure SPM .1

Figure SPM .1

CO2

CH4 N2O

• Global GHG emissions have grown since pre-industrial times, with an increase of 70% between 1970 and 2004. (high agreement, much evidence)

Human Activities and GHGs

• Global increases in CO2 concentrations are due primarily to fossil fuel use, with land-use change providing another significant but smaller contribution.

• CH4 concentration increase is predominantly due to agriculture and fossil fuel use.

• The increase in N2O concentration is primarily due to agriculture (fertilizers).

Global average radiative forcing

Figure SPM .2

warmingcooling

The net effect of human activities

since 1750 is warming. (very

high confidence)

Projected Changes

• Global GHG emission will continue to grow over the next few decades with current policies and practices. (high agreement and much evidence)

• Further warming during the 21st century would be larger than those observed during the 20th century. (very likely)

For the next two decades:• 0.2 °C per decade for a range of emissions scenarios.• 0.1 °C per decade even if GHG concentrations had been

kept constant at year 2000 levels.

2090-2099 projection relative to 1980-1999• 1.1-6.4 °C increase

Surface warming projections

Figure SPM .5

Projected surface temperature changes

Figure SPM .6

• Warming greatest over land and high latitudes NH.• Warming least over Southern Ocean and parts of

the North Atlantic Ocean.

Precipitation changes for the period 2090-2099, relative to 1980-1999

Figure SPM .7

• Precipitation increases in high latitudes. (very likely)• Precipitation decreases in most subtropical land

regions. (likely)

Projections of extreme events

• Warmer and fewer cold days and nights, warmer and more frequent hot days and nights (Virtually certain)

• Increase in frequency of hot extremes, heat waves, and heavy precipitation. (very likely)

• Increase in tropical cyclone intensity, drought affected area. (likely)