Global Climate Change:

Transcription

1 Ottawa Security Workshop Global Climate Change: Science & Impacts; Uncertainty & Risk Jay Gulledge, PhD Senior Scientist Pew Center on Global Climate Change & Non-resident Senior Fellow Center for a New American Security

2 Observations: Surface & Ocean Warming Temperature Change ( F) Global Warming Trend Global surface temperature ( ) Ocean heat content ( ) meters depth Ocean Heat (10 22 joules) (Brohan, GRL 2006; Domingues, Nature 2008)

3 Observations: Surface & Ocean Warming

4 Observations: Sea Level Rise Sea level rise is accelerating 3.2 mm/year 2.0 mm/year 0.8 mm/year Church and White 2006, GRL 33:L01602

5 Observations: Mountain Glacier Retreat Europe Andes Arctic Central Asia NW USA/SW Canada Alaska/Coast Patagonia

6 Observations: Polar Ice Loss 18 Annual Extremes of Arctic Sea Ice Extent Winter Maximum Sea Ice Extent (Million km 2 ) Summer Minimum Historical observations, Satellite observations, Linear slope of satellite observations Historical average, Record minimum, September 2007 Rate of decline: 2.7% / decade Rate of decline: 11.1% / decade

7 Observations: Polar Ice Loss Satellite Measurements of Ice Sheet Mass Balance ± 15 Median Estimate (Shepherd 2007, Science 315:1529)

8 IPCC Consensus Statement Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level IPCC 2007

9 Observed Change: Temperature Extremes IPCC 2007-WGI, FAQ 3.3, Fig. 1

10 Observed Change: Extreme Precipitation IPCC 2007-WGI, Fig. 3.39

11 Observed Change: Drought IPCC 2007-WGI; FAQ 3.2, Fig. 1

12 Observed Change: Wildfire Fire Frequency Area burned in the Western US has increased 6-fold in the last 30 years. Western US area burned annually Millions of Acres Westerling et al Westerling et al. (2006) Science 313:940 Longer growing season Earlier snowmelt Hotter summers Slide: courtesy J. Holdren

13 Observed Change: Hurricane Intensity Elsner et al. (2008) Nature 455:92-95.

14 Observed Change: Ocean Acidity When CO 2 dissolves in water, it makes carbonic acid Ocean ph has dropped 0.1 unit since ~ unit drop damages shell-forming marine organisms Coral reefs provide ~70% of protein for lowlatitude developing countries and huge part of global biodiversity Planktonic algae are the base of the food chain in the open ocean Atlantic, Canary Islands Pacific, Hawaii Atlantic, Bermuda IPCC 2007-WGI, Fig. 5.9

15 IPCC Consensus Statement A global assessment of data since 1970 has shown it is likely * that anthropogenic warming has had a discernible influence on many physical and biological systems. *Likely: >66% chance IPCC 2007

16 What We Know Most of the observed increase in global average temperatures since the mid-20th century is very likely * due to the observed increase in anthropogenic greenhouse gas concentrations. *Very Likely: >90% chance IPCC 2007

17 Projections: Temperature Extremes? Regional? IPCC 2007-WGI, Fig

18 Risk Perception: Climate Extremes A shift of 1 standard deviation makes a 1 in 40 yr event into a 1 in 6 yr event New 1 in 40 yr event becomes more intense. 1 in 40 yr event Intensity of weather event (standard deviations) GCRP Weather & Climate Extremes, 2008

19 Projections: More Intense Hurricanes Total number of events decreases Average wind speed and rainfall increase Number of intense events increases (CCSP 2008, SAP3.3, Weather & Climate Extremes)

20 Example: Gulf of Mexico Energy Infrastructure Katrina Rita 3/4 th of the 4,000 offshore oil and gas platforms (under MMS) were directly in the combined paths of the two hurricanes. Leading up to each hurricane, virtually all Gulf coast production and import facilities and many of the region s refining/processing facilities were evacuated or operations were otherwise suspended. P. Hibbard, 2006 Slide: courtesy R. Bierbaum

21 Projections: Climate Extremes Projected climate extremes (a) precipitation intensity (b) dry days (c) heat waves AR4-WG1-Ch10 (2007)

22 Example: Chicago Heat Waves Chicago 10 fold increase from 2000 to 2050 Source: U.S. CCSP Draft Unified Synthesis Product, 14 July, Slide: courtesy R. Bierbaum

23 Projected Impacts: Water Availability Projected Surface Water in 2050 Relative to Milly et al. Nature 2005, updated

24 Projected Impacts: Crop Sensitivity IPCC 2007-WGII, Fig. TS7

25 Example: Food Insecurity W.R. Cline (2007) Global Warming and Agriculture: Impact Estimates by Country, Center for Global Development, Washington D.C. degraded improved Food insecurity likely to increase in developing world

26 Projections: Sea Level Rise

27 Example: Mekong Delta Mekong Delta 1 meter Vietnam's rice bowl 20 million people Grain exporting region

28 Example: Niger Delta Niger Delta, Nigeria Massive wetlands lost 6000 km 2 croplands 250 oil fields 1 meter

29 Projections: Ocean acidification Slide: courtesy J. Holdren

30 What We re Confident About Changes are under way; further change is unavoidable Net effects will be negative for most regions Continued GHG emissions will increase the severity 21 st century change will be larger than 20 th Damage occurs at the extremes, not the averages Sea level, water, weather extremes will affect billions Developed and developing countries are vulnerable Adaptive capacity can be overwhelmed

31 What We re Not Confident About Equilibrium climate sensitivity Future GHG emissions and other forcings Timing and magnitude of future change Regional details of future change Timing/effect of positive feedbacks Thresholds/tipping points/irreversibility

32 Uncertainties: Climate Sensitivity IPCC 2007 Equilibrium Climate Sensitivity ( C)

33 Risks Associated with Doubled CO 2 Warming 0 C Food Water Ecosystems Extreme Weather Falling crop yields in developing regions first, then developed regions later Mountain glaciers disappear; Decreased water in some areas Extensive damage to coral reefs Many more areas suffer from low water availability Sea level rise threatens major cities Rising numbers of species extinctions Rising intensity of storms, wildfires, droughts, floods, heatwaves Risk of Irreversible or Abrupt Changes Rising risk of dangerous positive feedbacks, Rapid SLR and collapse of Atlantic conveyor Adapted from IPCC 2007 Best estimate ~10% Risk ~3% Risk

34 Uncertainties: Permafrost Carbon 950 Gt Carbon (UNEP Global Snow & Ice Outlook, 2007)

35 Uncertainties: Projections Underestimate Sea level rise >50% faster than projected (Rahmstorf et al. 2007, Science) Polar ice sheets losing ice 100 years early (IPCC 2007; Shepherd & Wingham 2007, Science) Small glaciers & ice caps losing ice faster (Meier et al. 2007, Science) Boreal forests moving north sooner (Soja et al. 2007, Global & Planetary Change) Global precipitation changing 2X faster (Wentz et al. 2007, Science; Zhang et al. 2007, Nature) Observed Arctic sea ice loss is 3X faster (Stroeve et al. 2007, Geophysical Research Letters)

36 Uncertainties: Projections Underestimate WGBU 2006

37 Uncertainties: Projections Underestimate (Stroeve et al. GRL 2007)

38 Asymmetry of Uncertainty = Added Risk Probability Normal view of scientific uncertainty 2008 U.S. Defense Auth. Act Assessment requirement View of uncertainty based on recent observations Increasing Climate Change Impacts Severity Risks are biased toward more damage.

39 Uncertainties: Sea Level Rise 2008 NDA requirement IPCC Uncertainty Range 39 Pew Center Science Brief 2

40 Uncertainties: Sea Level Rise 2008 NDA requirement Full Uncertainty Range IPCC Uncertainty Range 40 Pew Center Science Brief 2

41 Food Water Ecosystems Extreme Weather Warming Relative to Pre-industrial ( C) Falling crop yields in developing regions first, then developed regions later Mountain glaciers disappear; Decreased water in some areas Extensive damage to coral reefs Avoiding the Greatest Risks Many more areas suffer from low water availability Rising numbers of species extinctions Sea level rise threatens major cities Rising intensity of storms, wildfires, droughts, floods, heatwaves Risk of Irreversible or Abrupt Changes Rising risk of dangerous positive feedbacks, Rapid SLR and collapse of Atlantic conveyor Today Commitment 450 ppm 550 ppm 650 ppm 750 ppm ppm ppm Adapted from IPCC 2007

42 Summary Global warming is unequivocal The primary cause is manmade GHGs Many impacts are already happening and more are unavoidable Future projections imply serious risks Uncertainty is asymmetrical and skewed toward greater risk Adequate security assessment requires accounting for the full range of risk Ultimate amount of change depends on future GHG emissions.

43 Reserve Slides

44 C Risk Assessment: Reasons for Concern Five Reasons for Concern developed to characterize risk Red is more dangerous, white is less so Included in TAR (2001) but not in AR4 (2007) Updated post-ar4 by Smith et al. (2009) Smith et al. (2009)

45 Observed Greenhouse Gas Fingerprint tropopause troposphere stratosphere increased Solar irradiance increased greenhouse gases temperature

46 Observed Greenhouse Gas Fingerprint Stratosphere Temperature change ( C) Troposphere Data & Figures: Remote Sensing Systems

47 Causes of Global Warming There is considerable evidence for solar influence on the Earth s pre-industrial climate and the Sun may well have been a factor in post-industrial climate change in the first half of the last century. Here we show that over the past 20 years, all the trends in the Sun that could have had an influence on the Earth s climate have been in the opposite direction to that required to explain the observed rise in global mean temperatures. Lockwood & Frölich, 2007 Proc. R. Soc. A 463:2447

48 Causes of Global Warming Temperature change ( C) CO 2 (ppm) The increase of CO 2 can explain recent warming Sunspot number Sun s activity cannot explain recent Stanford Solar Center

49 Attribution to specific forcing(s) Observations Combined natural and manmade forcings Natural forcings (sun volcanoes) Slide: Courtesy S. Solomon Agung Pinatubo Chichon IPCC WG1 (2007) ch 9 and summary

50 IPCC Consensus Statement Most of the observed increase in global average temperatures since the mid-20th century is very likely * due to the observed increase in anthropogenic greenhouse gas concentrations. *Very Likely: >90% chance IPCC 2007

51

52 Sea Level Rise Delta Vulnerability

53 Sea Ice Loss Coastal Erosion Copyright Shishmaref Alaska Erosion & Relocation Coalition

54 Sea Ice Loss Permafrost Thaw Area of added warming covers arctic permafrost (UNEP Global Snow & Ice Outlook, 2007)

55 (GlobalWarmingArt.com)

56

57 What We Know Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level IPCC 2007

58 Risk Perception is Key Risk is great for high-impact outcomes even if probability is thought to be low Uncertainty tempts people, including scientists, to underestimate risk Security assessments should evaluate the full range of uncertainty. Scientists should conduct risk assessment in addition to scientific assessment.

59 Three decades of satellite measurements cover the main period of global warming While intensity waxes and wanes on an 11 year cycle, there has been no overall trend

60 Is the Earth Cooling? - No. Climate is defined by long term averages. When five year averages are taken for both the Hadley and the NASA GISS data sets, we see that average annual temperature has

61 Ocean Warming Heat Content Heat absorbed by climate component Heat required to melt cryopshere component World ocean (145) Continents (9) Atmosphere (7) Continental glaciers (8) Antarctic sea ice (3) Mountain glaciers (1) Arctic sea ice (0.05) Heat Uptake (10 21 Joules) (Levitus 2005, GRL 32: L02604)

62 Ocean Warming Heat Content Ocean depth (m) Ocean Warming Profile ( ) Oceans have warmed from the surface down Heat source is from atmosphere, not internal Temperature Change ( C decade -1 ) (L. Allison, Hadley Center 2004)

63 2005

64 2007

65 2008

66 Observations: Arctic Change February Average, February Sea Ice Age (years)

67 Polar Changes: Antarctica Temperature increase per decade ( C) Steig et al. (2009) Nature; Image Courtesy NASA Earth Observatory 67