Climate Change Science: What s New?

Transcription

1 [1] Webinar Thursday, April 7, :00-3:30pm EDT Climate Change Science: What s New? Panelists: Hon. Brian P. Kalk, Ph.D., Commissioner, North Dakota PSC, and Chair, NARUC Subcommittee on Clean Coal and Carbon Management Dr. Judith Curry, Professor, School of Earth and Atmospheric Sciences, Georgia Institute of Technology, and President, Climate Forecast Application Networks Dr. Joe Casola, Deputy Director of the Climate Impacts Group, College of the Environment, University of Washington Moderator: Kimberly Jones, Sr. Analyst, NC Utilities Commission, and Chair of NARUC s Staff Subcommittee on Electricity

2 [2] Introductory Remarks Moderator: Kimberly Jones North Dakota Commissioner Brian Kalk, PhD 3

3 [3] Climate Change Science What s New? Joe Casola Deputy Director, Climate Impacts Group College of the Environment University of Washington NRRI Webinar 7 April 2016 Climate Science in the Public Interest

4 [4] The BIG picture 1) Carbon dioxide (CO 2 ) and other greenhouse gases make the planet warmer 2) CO 2 is accumulating in the atmosphere 3) The planet is warming 4) Warming is best explained by humans emissions of CO 2 and other greenhouse gases 5) Future warming should be expected

5 1) Greenhouse gases (GHGs) warm the planet [5] GHGs absorb and re-emit infrared radiation back to the surface GHGs naturally keep the Earth about 60 F warmer than it would be without them

6 2) CO 2 is accumulating in the atmosphere [6]

7 [7] 3) The Earth is warming 2000 s were the warmest decade in the data record Every decade has been warmer than the previous one since the 1970s

8 Warming nearly everywhere throughout 20 th century [8]

9 [9] Warming is consistent with other global changes

10 4) Warming is unusual; best explained by our emissions [10] Magnitude and rate of warming is large (warmer than in last 400 years) Spatial and vertical pattern of warming matches what greenhouse gases should do Changes in other factors that drive climate (like the Sun) don t explain warming Models can only replicate 20 th century warming when greenhouse gases are included

11 5) Future climate likely to be much warmer [11] IPCC AR5 WG1, Figure SPM.7 RCP - Representative Concentration Pathways [in W/m 2 ]

12 Potential for dramatic sea level rise in 21 st century [12] National Climate Assessment Figure 2.26

13 Increasing CO 2 More acidic oceans Pteropod exposed to 2100 seawater (water that has 50% greater acidity than present day) [13] National Geographic and NOAA Pacific Marine Environmental Lab IPCC AR5 WG1 Figure SPM.7

14 [14] Extreme events Evidence for *some types* of extreme events grows stronger Heat Waves (frequency and severity) Cold Waves (frequency and severity) Amount of Rainfall during Heaviest Rains Area burned by wildfires Other changes in extreme are less straightforward Changes in seasonal rainfall regionally variable Hurricanes potentially more intense, but frequency changes could be small or negative Tornadoes??

15 Communities and businesses are sensitive to climate variations Transportation Energy Public Health Agriculture Water Resources Ecosystems Climate Matters [15]

16 What does this mean for regulators and the electricity sector? The BIG PICTURE is not a subject of debate within the scientific community There ARE many aspects of climate that are not completely understood, but do not undermine the BIG PICTURE understanding Best translation into a policy context = RISK MANAGEMENT approach Compared to other business and environmental risks, we actually have lots of information about climate change! [16]

17 State of the Climate Debate Judith Curry Georgia Institute of Technology Climate Forecast Applications Network [17] Confusion Uncertainty Disagreement

18 Agreement: Surface temperatures have increased since 1880 Humans are adding carbon dioxide to the atmosphere [18] Carbon dioxide and other greenhouse gases have a warming effect on the planet Disagreement: Whether the warming since 1950 has been dominated by human causes How much the planet will warm in the century Whether warming is dangerous Whether we can afford to radically reduce CO2 emissions, and whether reduction will improve the climate 21 st

19 [19] Composition

20 Global surface temperature anomaly vvvvvv [20] IPCC AR5: It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by [humans]. The best estimate of the human induced contribution is similar to the observed warming over this period.

21 Northern Hemisphere paleoclimate surface temperature reconstructions [21] IPCC AR Temperatures have been warming for the past years; only the warming since 1950 is being attributed to humans

22 Implications for the future: I. Consensus IPCC view [22] The amount of warming depends on the emission of greenhouse gases

23 Growing divergence: models vs observations [23] Figure courtesy of Ed Hawkins Are climate models too sensitive to greenhouse forcing? Is modeled natural climate variability inadequate? Are model projections of 21 st century warming too high?

24 Implications for the future: II. View emphasizing natural variability The slowdown in warming will continue at least another decade (into the 2030 s?) Climate models are too sensitive to human forcing; 21 st century warming will be on the low end of IPCC projections (or even below) Solar variations & volcanoes: wild card. Most are predicting solar cooling in the near term Can t rule out unforeseen surprises [24] 2/17/15 Judith Curry

25 Implications for utility regulators [25] There is a great deal of uncertainty in our understanding of what has caused the 20 th century warming and how the 21 st century climate might evolve. We have oversimplified both the climate change problem and its solution

26 [26] News Item #1 Oceans rising faster than anytime in the last 2,800 years, scientists calculate New York Times, 2/23/16 27

27 A significant global sea level acceleration began in the 19th century and [27] yielded a 20th century rise that is extremely likely to be faster than during any of the previous 27 centuries. Kopp et al Comment: the temporal resolution of this analysis is insufficient to resolve periods of less than 50 years

28 Recent global sea level rise acceleration started over 200 years ago [28] Jevrejeva et al. 2008

29 Is the IPCC s sea level rise conclusion justified? [29] IPCC AR5 IPCC AR5: Since the early 1970 s, glacier mass loss and ocean thermal expansion from warming together explain about 75% of the observed global sea level rise (high confidence)

30 Data from satellite altimeters available since Interannual variability from El Nino and La Nina [30]

31 Oceans rising faster than last several millennia [31]

32 [32] News Item #2 Torrid 2015 Set a Record: Hottest Year Ever New York Times, 1/21/16 33

33 Hottest year in temperature record [33]

34 Global surface temperature anomalies 2015 warmest year [34] El Nino El Nino El Nino El Nino El Nino El Nino El Nino Figure courtesy Nick Stokes 2015 was striking as warmest year, since there had been very little warming after 1998

35 [35] Lower atmospheric temperatures from satellite was 3 rd warmest year in the satellite data set, although there is a large spike for Feb 2016 from El Nino

36 [36] News Item #3 Some Extreme Weather Events Linked to Climate Change National Academy of Sciences, March

37 [37] What does the report say? Confidence in attribution findings of anthropogenic influence is greatest for those extreme events that are related to an aspect of temperature, such as the observed long-term warming of the regional or global climate, where there is little doubt that human activities have caused an observed change. In particular, for extreme heat and cold events, changes in longterm mean conditions provide a basis for expecting that there should also be related changes in extreme conditions. Heavy rainfall is influenced by a moister atmosphere, which is a relatively direct consequence of human-induced warming, though not as direct as the increase in temperature itself. Attribution of Extreme Weather Events in the Context of Climate Change, p6

38 National Academies Attribution of Extremes [38]

39 National Academies Attribution of Extremes [39]

40 US Annual Heat Wave Index, [40] Source: EPA It is likely that the frequency of heat waves has increased in large parts of Europe, Asia and Australia. (since 1950) IPCC AR5

41 Fraction of global drought since 1982 [41] Hou et al Contiguous US drought (PDSI)

42 Are hurricanes made worse by climate change? Source: Ryan Maue [42] Global tropical cyclone ACE US landfalling hurricanes Source: Roger Pielke Jr

43 Human Cost of Weather Related Disasters - UNISDR[43]

44 [44] News Item #4 Ancient trees emerge from frozen forest tomb Juneau Empire, 9/13/13 45

45 [45] Ancient Alaskan forests Possible explanations: it was warmer in Alaska 1,000 years ago, or it had not been cold enough for long enough, or it could have been drier Local conditions can differ from the BIG PICTURE changes even with contemporary climate change Globally, most glaciers are receding

46 Retreat of the Mendenhall Glacier reveals the remains of trees which grew more than 2,000 years ago. A subglacial exposure of undisturbed vegetation has been found below cold-based glacier Longyearben. Dating demonstrates that the study site was covered by the advancing glacier no later than 1104 yrs BP. Before that, the site was ice- free for at least 800 years and possibly much longer. (Humlum et al. 2004) Green Alps theory: Hannibal was able to cross the Alps since it coincided with a period when the glaciers were in severe recession (218 BC) [46]

47 Arctic temperature anomalies in the 1930s were apparently as large as [47] those in the 1990s and 2000s. There is still considerable discussion of the ultimate causes of the warm anomalies in the 1920s and 1930s. (IPCC AR5) Surface air temperatures 70-85N Sea ice extent (European Arctic) Mahoney et al. 2008

48 [48] IPCC AR5: A recent multi-proxy 2000-year Arctic temperature reconstruction shows that temperatures during the first centuries were comparable or even higher than during the 20th century (Hanhija rvi et al., 2013; PAGES 2k Consortium, 2013).

49 [49] News Item #3 The Paris Climate Talks: Three Reactions Dr. Judith Curry Dr. Joe Casola Commissioner Brian Kalk, PhD 50

50 Concerns about the Paris Agreement [50] In-country legal, political & economic issues nonbinding agreement and voluntary compliance by developing countries ensures that emissions will continue to rise Technical feasibility: no known technologies that are feasible, economic and scalable to substantially reduce CO 2 emissions from power, transportation, agriculture, cement on the timescale of a few decades Confounding factors: Global population increase Bringing grid electricity to undeveloped countries (esp Africa) Rapid economic development in developing and undeveloped countries

51 Can we limit the warming to 2 o C? [51] Yes, if the climate sensitivity is at lower end of estimates (emissions reductions will make little difference) No, if natural climate variability is dominating the warming (emissions reductions will make little difference) If the IPCC climate model projections are correct: even dramatic reductions in carbon dioxide emissions by 2050 would have a small impact on temperatures in the 21 st century.

52 Paris Agreement: costs/benefits [52] Assuming that the IPCC climate model projections are correct: First round commitments (by , continued to 2100) have been estimated to cost as much as $1 trillion per year, to prevent a maximum of 0.2 o C warming by 2100 Much deeper reductions than are currently committed to by 2050 would prevent less than 1 o C of warming by Current commitments fall far short of keeping the warming below 2 o C from pre-industrial Future commitments and later implementation will have less impact on 21 st century temperatures owing to thermal inertia in the climate system

53 Climate policy conundrum [53] There is increasing evidence that the threat from global warming is overstated However, if the threat is not overstated, there are major shortfalls in current and proposed solutions.

54 Paris Context emissions have been growing [54] Gray ~4 C (~7 F) Pink C (~6 F) Orange C (~4 F) Blues <2 C (3.6 F)

55 What does the Paris Agreement do? Countries have put forth reduction targets for the next years - US = 26% reduction by 2025; 28% reduction by 2030 (from 2005 levels) - China = emissions to peak by 2030; 20% non-fossil energy - EU = 40% reduction by 2030 (from 1990 levels) Countries will submit new goals every 5 years Assistance to developing countries for low-carbon tech and adaptation Agreement will not solve problems stemming from warming, but it establishes an ongoing international process for doing so that IS NEW [55]

56 [56] Webinar Q&A Climate Change Science: What s New? Moderator: Kimberly Jones, NC Utilities Commission Panelists: Commissioner Brian Kalk, North Dakota PSC Dr. Judith Curry, Georgia Institute of Technology Dr. Joe Casola, University of Washington