Key Findings of the IPCC WG1 AR5

Transcription

1 Key Findings of the IPCC WG1 AR5 Fredolin Tangang IPCC WG1 Vice-Chair Yann Arthus-Bertrand / Altitude

2 IPCC WG1 AR5 Climate Change 2013: The Physical Science Basis The IPCC has released its WG1 AR5 Climate Change 2013: The Physical Science Basis on 27 Sept 2013 in Stockholm, Sweden The Summary for Policymakers (SPM) can be downloaded from the IPCC website and This lecture highlights key findings of the report [SPM, TS, Underlying chapters] Cover Page: Folgefonna glacier on the high plateaus of Sørfjorden, Norway (60 14 N, 6 44 E).

3 Outline IPCC: Historical perspectives, role & functions Key findings based on observations Detection and attribution Future climate projections Summary

4 Inter-governmental Panel on Climate Change (IPCC) IPCC plenary comprises of all countries in the world IPCC Bureau comprises of 30 elected members with variable numbers for each of the WMO region; IPCC elects its bureau members once in a 6-7 years cycle 3 working groups & a Task Force on NGGI Authors, Contributors, Reviewers, Review Editors

5 Inter-governmental Panel on Climate Change (IPCC)

6 Why IPCC? Prior to the establishment of IPCC, growing number of literatures indicate the Earth s climate system is warming due to increasing GHG concentration in atmosphere Independent, objective, fair and transparent assessment of the state of global climate system is required For this reason, United Nations General Assembly (UNGA) 42 proposed the establishment of IPCC and in 1988 IPCC was established under WMO and UNEP The IPCC provides such assessment and this becomes the source of information particularly to policy makers and UNFCCC on 1. Causes of climate change, 2. Potential impacts on built and natural systems and socio-economic, 3. Possible response options. IPCC had published 5 assessment reports and various other reports. The latest is the IPCC Fifth Assessment Report (AR5), which was released on Sept 27, 2013, in Stockholm, Sweden.

7 IPCC Reports FAR 1990 SAR 1995 TAR 2001 AR AR IPCC had produced 5 Assessment Reports plus several other special reports including the recently released SREX & SRREN. SRREN (2011) SREX (2012)

8 How IPCC produces these reports? Independent research, Knowledge generation, publication of literatures by Scientific community IPCC Assessment Process IPCC Assessment Report IPCC doesn t involve at this stage

9 IPCC Assessment Process IPCC assessment is based on available peer-reviewed publications

10 Key SPM Messages 19 Headlines on less than 2 Pages Summary for Policymakers ~14,000 Words 14 Chapters Atlas of Regional Projections 54,677 Review Comments by 1089 Experts 2010: 259 Authors Selected 2009: WGI Outline Approved 10

11 The Relative Comprehensiveness of IPCC WG1 AR5

12 IPCC Fig 1.3

13 Key Statement / Headline of IPCC WG1 AR5 SPM Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased

14 Each of the last three decades has been successively warmer at the Earth s surface than any preceding decade since In the Northern Hemisphere, was likely the warmest 30- year period of the last 1400 years (medium confidence) (IPCC 2013, Fig. SPM.1a)

15 Over SEA increase trend ~ 1.0 o C per century (IPCC 2013, Fig. SPM.1b) Warming in the climate system is unequivocal

16 Evidence from Paleoclimate Archives IPCC 2013; Fig 5.7a)

17 Evidence from Paleoclimate Archives & Climate Simulation (IPCC 2013; Fig 5.8a) Continental-scale surface temperature reconstructions show, with high confidence, multi- decadal periods during the Medieval Climate Anomaly (year 950 to 1250) that were in some regions as warm as in the late 20th century. These regional warm periods did not occur as coherently across regions as the warming in the late 20th century (high confidence)

18 Temperature Ocean heat content Sea Level Snow Cover Glacier (IPCC Fig TS.1) Arctic Sea-ice extent

19 Wetter region gets more wetter and drier gets more drier since the second half of the 20 th century Extreme weather & climate events became more frequent (IPCC Fig SPM.2)

20 Glaciers and ice melting has accelerated in unprecedented speed in the last decade (IPCC Fig TS.3)

21 40% increase since pre-industrial period Ocean absorbed 30% of these emitted CO2 (IPCC Fig SPM.4a) The atmospheric concentrations of carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O) have increased to levels unprecedented in at least the last 800,000 years.

22 (IPCC Fig SPM.4b) Ocean became more acidic

23 (IPCC Fig TS.4) Contribution by Category to CO 2 Emission

24 Except volcanic, changes gradual Anthro. faster since ~1970, CO2 largest every decade since 1960s Time-averaged natural forcing small (IPCC Fig 8.18)

25 (IPCC Fig TS.6)

26 (IPCC Fig 8.20)

27 Earth has been in radiative imbalance, with more energy from the sun entering than exiting the top of the atmosphere, since at least circa It is virtually certain that Earth has gained substantial energy from

28 Detection and Attribution (IPCC Fig 1.13)

29 Periods of little or no warming can arise from internal variability Internal variability causes to a substantial degree the difference between the observations and the simulations (medium confidence) (IPCC 2013.Box TS.3 Fig.1)

30 Climate Models Responses to Various Forcings Natural + Anthropogenic Natural CO2 forcing only (IPCC Fig TS.9)

31 (IPCC Fig 10.7)

32 Human influence on the climate system is clear (IPCC Fig SPM.6)

33

34 Future Climate Projections For future climate projections, climate models requires Emission Scenarios. Models in AR5 use Representative Concentration Pathway (RCP)

35 Indicative Anthropogenic Radiative Forcing (RF) for RCPs RCP= Representative Concentration Pathway (IPCC Box TS.6)

36 (IPCC Fig 1.15)

37 Projected Global Average Temperature Change by end of 21 st Century (IPCC Fig SPM.7a) The temperature increase during the last 100 years was only about 0.8 o C.

38 Projected Global Average Temperature Change by end of 21 st Century 3-4 o C projected increase over Southeast Asia region (IPCC Fig SPM.8a) The temperature increase during the last 100 years is only about 0.8 o C.

39 Projected Precipitation Change by end of 21 st Some Centuryregions will become more wetter and others become more drier. Extreme precipitation events over wet tropical regions will very likely become more intense and more (IPCC Fig SPM.8b) frequent

40 Arctic will be nearly ice-free by the end of the 21 st (IPCC Fig SPM.8c) century

41 (IPCC Fig TS.20a)

42 Ocean will be more acidic by the end of the 21 st century (IPCC Fig TS.20b)

43 El Niño-Southern Oscillation (ENSO) There is high confidence that ENSO will remain the dominant mode of interannual variability in the tropical Pacific, with global effects in the 21st century. Due to the increase in moisture availability, ENSO-related precipitation variability on regional scales will likely intensify.

44 Global mean sea level will continue to rise during the 21st century (IPCC 2013, Fig. SPM.9)

45 m projected SLR around Southeast Asia region IPCC 2013 Fig 13.20b

46 Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions (IPCC 2013, Fig. SPM.10)

47 RCP2.6 would be the Emission Scenario to follow if we were to cap warming at 2 o C

48 SUMMARY Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased Human influence on the climate system is clear Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Global surface temperature change for the end of the 21st century is likely to exceed 1.5 C relative to 1850 to 1900 for all RCP scenarios except RCP2.6. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions

49 Further Information Yann Arthus-Bertrand / Altitude