Global Warming. a.k.a. watch me take an hour to discuss what Time magazine says in three sentences

Transcription

1 Global Warming 45 mins a.k.a. watch me take an hour to discuss what Time magazine says in three sentences

2 Jason Farren I support strict air pollution control I support (smart) GHG & CO 2 control I support forced efficiency: CAFE Renewable energy, oil independence Energy-efficient appliances, etc I am an Environmental Engineer B.S. Chemical Engineering M.S. Environmental Engineering Registered Professional Engineer I am a registered Democrat I have a wife and two small kids

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4 Northampton, Massachusetts Mean Temperature (F) Tem perature (F) Δ εχ ϑαν Φεβ Φεβ Μαρ Απρ Απρ Μαψ ϑυν ϑυν

5 Northamton, Massachusetts Mean Temperature (F) December - July Tem perature (F) Dec Jan Feb Feb Mar Apr Apr May Jun

6 Northamton, Massachusetts Mean Temperature (F) Entire Year Tem perature (F) Jul Aug Oct Nov Jan Mar Apr Jun

7 Northamton, Massachusetts Mean Temperature (F) Entire Year Tem perature (F) Jul Aug Oct Nov Jan Mar Apr Jun

8 It is likely that the rate and duration of the warming of the 20 th century is larger than any other time during the last 1,000 years. The 1990s are likely to have been the warmest decade of the millennium in the Northern Hemisphere, and 1998 is likely to have been the warmest year. In light of new evidence and taking into account the remaining uncertainties, most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations. - IPCC, 2001 IPCC, 2001: Climate Change 2001

9 The Science is Settled 1. Atmospheric CO 2 is increasing and we are the cause. 2. The earth s climate is changing and it s getting warmer. 3. The current warming is unprecedented over the past 1,000 years. 4. Fossil fuels pollute the air with CO 2, the principal greenhouse gas that contributes significantly to global warming. 5. Earth's climate was relatively stable before the Industrial Revolution, when we started interfering with climate's "natural" state. 6. Global warming causing (1) more, and (2) stronger hurricanes.

10 The Science is Settled 1. Atmospheric CO 2 is increasing and we are the cause. 2. The earth s climate is changing and it s getting warmer. 3. The current warming is unprecedented over the past 1,000 years. 4. Fossil fuels pollute the air with CO 2, the principal greenhouse gas that contributes significantly to global warming. 5. Earth's climate was relatively stable before the Industrial Revolution, when we started interfering with climate's "natural" state. 6. Global warming causing (1) more, and (2) stronger hurricanes.

11 380 ppm = 0.04% 280 ppm = 0.03%

12 CO 2 Last 1000 Years CO2, ppm

13 Two key questions: 1. How warm is it? 2. Why is it getting warmer?

14 How warm is it? The Build-Up Up International Panel on Climate Change (IPCC) Established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) A main activity of the IPCC is to provide in regular intervals an assessment of the state of knowledge on climate change The First IPCC Assessment Report was completed in 1990 Second Assessment Report Climate Change 1995 The Third Assessment Report (TAR) Climate Change 2001 The IPCC completed its Fourth Assessment Report in 2007

15 How warm is it? The Build-Up Up IPCC Second Assessment Report

16 How warm is it? The Build-Up Up world climate history according to borehole evidence (Huang et al. 1998) Shaopeng Huang, Dept of Geological Sciences, University of Michigan Major analysis of over 6,000 borehole records from every continent Study went back 20,000 years

17 How warm is it? The Build-Up Up world climate history according to borehole evidence (Huang et al. 1998) Not included in 2001 IPCC report

18 How warm is it? The Build-Up Up Past Temperatures Directly from the Greenland Ice Sheet (Dahl-Jensen et al. 1998) D. Dahl-Jensen, Department of Geophysics, University of Copenhagen, Copenhagen, Denmark Measured temperatures down through an ice sheet relate directly to past surface temperature changes. Here, we use the measurements from two deep boreholes on the Greenland Ice Sheet to reconstruct past temperatures. Temperatures go back 100,000 years

19 How warm is it? The Build-Up Up Past Temperatures Directly from the Greenland Ice Sheet (Dahl-Jensen et al. 1998) Not included in 2001 IPCC report

20 How warm is it? The Build-Up Up /1999/2000 Michael Mann s Hockey Stick Dr. Michael Mann: Ph.D. Geology & Geophysics, Penn State 1998 Mann et. al; temps back to 1400 MBH Mann et. al; temps back to 1000 MBH 99

21 How warm is it? The Build-Up Up MBH 99: the late 20th century still appears anomalous: the 1990s are likely the warmest decade, and 1998 the warmest year, in at least a millennium

22 5. IPCC TAR How warm is it? The Build-Up Up 2000 First draft of IPCC TAR incorporates MBH IPCC TAR issued, incorporates MBH 99

23 How warm is it? IPCC, 2001: Climate Change 2001

24 How warm is it? IPCC, 2001: Climate Change 2001

25 How warm is it? IPCC, 2001: Climate Change 2001

26 How warm is it? How much has it warmed? 0.6 C IPCC, 2001: Climate Change 2001

27 How warm is it? The Canadian McQuestions McIntyre and McKitrick Stephen McIntyre Northwest Exploration Co,Toronto Ross McKitrick Department of Economics, University of Guelph April 2003: McIntyre curious how the Mann graph was made, and requested the MBH98 data set from Mann. Dear Dr. Mann, I have been studying MBH98 and 99. I located datasets for the 13 series used in and was interested in locating similar information on the 112 proxies referred to in MBH98 Yours truly, Stephen McIntyre Dear Mr. McIntyre, These data are available on an anonymous ftp site we have set up. I've forgotten the exact location. best regards, Mike Mann 2003 McIntyre and McKitrick report (MM03) they (1) cannot replicate the results, and (2) Mann s results could not be supported by the data Ross McKitrick, APEC Study Group, 2005

28 How warm is it? Enter the Calvary! US House Committee on Energy and Commerce Committee staff asked for advice as to the validity of the complaints of MM and related implications. Pro bono committee formed: Dr. Edward J. Wegman George Mason University (Ph.D Statistics) Dr. David W. Scott Rice University (Ph.D Mathematical Sciences) Dr. Yasmin H. Said The Johns Hopkins University (Ph.D Statistics) Ross McKitrick, APEC Study Group, 2005

29 How warm is it? Enter the Calvary! US House Committee on Energy and Commerce Wegman, Chairman of U.S. NAS Committee on Applied Statistics: The debate over Dr. Mann's methodology has been going on for nearly three years. When we got involved, there was no evidence that a single issue was resolved or even nearing resolution The climate science community seemed unable to either refute McIntyre's claims or accept them. The situation was ripe for a third-party review... Wegman et al, 2006

30 How warm is it? Enter the Calvary! US House Committee on Energy and Commerce Findings 1. We have attempted to address several broad issues Dr. Mann s responses had something of a confrontational tone. 2. We found MBH98 and MBH99 to be somewhat obscure and incomplete and the criticisms of MM03/05a/05b to be valid and compelling. 3. Our findings from this analysis suggest that authors in the area of paleoclimate studies are closely connected and thus independent studies may not be as independent as they appear on the surface. 4. Overall, our committee believes that Mann s assessments that the decade of the 1990 s was the hottest decade of the millennium and that 1998 was the hottest year of the millennium cannot be supported by his analysis. Wegman et al, 2006

31 So, what happened?

32 The Hockey Stick Analysis Important terms High frequency proxies Used to estimate annual changes - tree rings Multi-proxy technique Combines a variety of proxies (temperature & tree ring chronologies) Principal Components Analysis Replaces a group of series with a weighted average of those series Weights are chosen so new vector (called Principle Component, PC) explains as much of the variance of the original series PC Centering and Scaling Standardize data with different units center and appropriately scale the data Ross McKitrick, APEC Study Group, 2005

33 The Hockey Stick Independent Findings In Mann s program, he applied a scaling, but with a difference. Most of his proxy (tree ring) series do not look like hockey sticks, they look like flat static, and since they don t change in the 20th century this procedure did not make much difference. But some of the series trend upwards in the 20th century. For these, the Mann method has a huge effect. PC algorithms choose weights to maximize the explained variance of a group of data series. If one series in the group has a relatively high variance, its weight in the (principal component 1) PC1 gets inflated. The Mann algorithm did just this. It would, in effect, look through a data set and identify series with a 20th century trend, then load all the weight on them. In effect it data-mines for hockey sticks. Ross McKitrick, APEC Study Group, 2005

34 The Hockey Stick Independent Findings Ross McKitrick, APEC Study Group, 2005

35 The Hockey Stick Independent Findings Ross McKitrick, APEC Study Group, 2005

36 The Hockey Stick Independent Findings MBH98 Correct Wegman et al, 2006

37 MM2005(b) The Hockey Stick Independent Findings Test Mann s Algorithm: Generated a data sequence of trendless, random noise Carried out 10,000 repetitions Results: Mann s algorithm nearly always yielded PC1s with a hockey stick shape, some of which bore a quite remarkable similarity to the actual MBH98 temperature reconstruction Using the MBH98 transformation, a hockey stick occurs over 99% of the time. Noise MBH98 MM 2005(b)

38 The Hockey Stick Independent Findings Noise Noise Noise MBH98 Noise Noise Noise Noise Ross McKitrick, APEC Study Group, 2005

39 The Hockey Stick Independent Findings 10,000 repetitions of pure noise Hockey stick over 99% of the time 1 st Problem!

40 MM2005(b) The Hockey Stick Independent Findings 2 nd Problem! We showed that the data mining procedure did not just pull out a random group of proxies, instead it pulled out an eccentric group of bristlecone pine chronologies published by Graybill and Idso in 1993 They all turned out to exhibit a 20th century growth spurt that has not been fully explained, but is likely to be at least in part due to CO 2 fertilization and is known not to be a temperature signal since it does not match nearby temperature records. The original authors (and others) have stressed that they are not proper climate proxies. So we felt it was important to examine what would happen to the MBH98 results if the Graybill-Idso proxies were excluded from the NOAMER group. Ross McKitrick, APEC Study Group, 2005

41 The Hockey Stick Independent Findings Ross McKitrick, APEC Study Group, 2005

42 The Hockey Stick Independent Findings MM2005(b) The result is in the bottom panel of Figure 6 ( Censored ). It shows what happens when Mann s PC algorithm is applied to the NOAMER data after removing 20 bristlecone pine series. Without these hockey stick shapes to mine for, the Mann method generates a result just like that from a conventional PC algorithm, and shows the dominant pattern is not hockey stick-shaped at all. Ross McKitrick, APEC Study Group, 2005

43 The Hockey Stick Independent Findings MM2005(b) Of crucial importance here: the data for the bottom panel of Figure 6 is from a folder called CENSORED on Mann s FTP site. He did this very experiment himself and discovered that the PCs lose their hockey stick shape when the Graybill-Idso series are removed. In so doing he discovered that the hockey stick is not a global pattern, it is driven by a flawed group of US proxies that experts do not consider valid as climate indicators. Ross McKitrick, APEC Study Group, 2005

44 The Hockey Stick Independent Findings Wegman Independent Committee It is not clear that Dr. Mann and his associates even realized that their methodology was faulty at the time of writing the MBH paper. The net effect The of the graphics decentering is to preferentially choose the so-called hockey stick shapes. The graphics prominence together with the fact that it is based on incorrect use of PCA puts Dr. Mann and his co-authors While this error would have been less critical had the paper been overlooked like many academic papers are, the fact that their paper fit some in a policy difficult agendas has face-saving greatly enhanced their position. paper s visibility. Specifically, global warming and its potentially negative consequences have been central concerns of both governments and individuals. The hockey stick reconstruction of temperature graphic dramatically illustrated the global warming issue and was adopted by the IPCC and many governments as the poster graphic. Wegman et al, 2006

45 DISCREDITED Northamton, Massachusetts Mean Temperature (F) Entire Year Tem perature ( F ) Jul Aug Oct Nov Jan Mar Apr Jun It is likely that the rate and duration of the warming of the 20 th century is larger than any other time during the last 1,000 years. The 1990s are likely to have been the warmest decade of the millennium in the Northern Hemisphere, and 1998 is likely to have been the warmest year. In light of new evidence and taking into account the remaining uncertainties, most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations. - IPCC, 2001

46 Two key questions: 1. How warm is it? When the 20 th century warming is placed in the context of thousands of years of history, is it significant? What about the MWP and LIA? 2. Why is it getting warmer?

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48 Global Temperature Mann et al Esper et al Moberg et al Crow ley & Low ery 2000 Briffa 2000 NH Annual Land Temps D'Arrigo et al Temperature Anomoly (C)

49 Esper et al Jan Esper, Swiss Federal Research Institute, Switzerland The (Mann) reconstruction has been criticized for its lack of a clear MWP. Critics carefully argue that selected tree-ring records cannot tree-ring preserve chronologies can long-term, multicentennial temperature trends. We demonstrate that carefully selected tree-ring chronologies from 14 sites in the Northern trends Hemisphere can if proper methods preserve such of coherent analysis large-scale, are multicentennial used. temperature trends if proper methods of analysis are used. preserve large-scale, multicentennial temperature

50 Global Temperature Esper et al Temperature Anomoly (C) In addition, we show that the average of these chronologies support the large-scale occurrence of the MWP over the NH extratropics. Scared?

51 Global Temperature 1 Esper et al Temperature Anomoly (C) CO 2 level CO2, ppm Scared?

52 Moberg et al Anders Moberg, Department of Meteorology, Stockholm University, Stockholm Sweden Tree-ring data have a well-documented difficulty reproducing multicentennial temperature variability. Lake and ocean sediments have a lower time resolution, but provide climate information combining at multicentennial low-resolution timescales that may not proxies be captured with by tree-ring high-frequency data. proxies in It is thus important which to explore we other avoid techniques using and other each data proxy types, and type also to at use data from more regions than previously examined. timescales Here we construct where Northern it Hemisphere is most unreliable, temperatures for the but past instead 2,000 years use by it only combining where low-resolution it has proxies its greatest with high-frequency advantages. proxies in which we avoid using each proxy type at timescales where it is most unreliable, but instead use it only where it has its greatest advantages. explore other techniques and other data types by

53 Global Temperature Moberg et al Temperature Anomoly (C) According to our reconstruction, high temperatures similar to those observed in the twentieth century before 1990 occurred around AD 1000 to 1100, and minimum temperatures around AD This large natural variability in the past suggests an important role of natural multicentennial variability that is likely to continue. Scared?

54 Global Temperature 1 Moberg et al Temperature Anomoly (C) CO 2 level CO2, ppm Scared?

55 Global Temperature Esper et al Temperature Anomoly (C) Global Temperature Moberg et al Temperature Anomoly (C)

56 The Divergence Problem

57 The Divergence Problem Most proxy reconstructions end in about Then instrumental versions are spliced. If the proxies are any good, then the warm 1990s should have off-the-chart values. If they don t, how can we be confident that they would have picked up warm MWP decades? Shouldn t we validate proxies by bringing them up-to-date?

58 Global Temperature Mann et al Esper et al Moberg et al Crow ley & Low ery 2000 Briffa 2000 NH Annual Land Temps D'Arrigo et al Temperature Anomoly (C)

59 IPCC, 2001: Climate Change 2001

60 Global Temperature NH Annual Land Temp 0.5 Temperature Anomoly (C)

61 Global Temperature NH Annual Land Temp D'Arrigo et al Briffa et al Esper et al Temperature Anomoly (C)

62 Global Temperature Temperature Anomoly (C) NH Annual Land Temp D'Arrigo et al Briffa et al Esper et al

63 The Divergence Problem So, which one is correct? If the instruments are correct, how do we know the tree rings adequately captured past warming and cooling? If the proxies (tree rings) are correct, why are the instruments showing abrupt temperature rise? Global Temperature Global Temperature Temperature Anomoly (C) NH Annual Land Temp 0.7 D'Arrigo et al Briffa et al Esper et al Temperature Anomoly (C) 1 Mann et al Crow ley & Low ery 2000 NH Annual Land Temps Esper et al D'Arrigo et al Moberg et al Briffa

64 The Instrument Data What are we measuring?

65 The Instrument Data Are we possibly measuring something other than a global effect? Increased surface temperature Greenhouse gas vs. urbanization

66 The Instrument Data Urban Heat Island (UHI) Effect Cities are hotter than countryside Raw temperature data from cities is adjusted downward to compensate for the UHI effect Known?

67 The Instrument Data Global Temperature Mann et al Esper et al Moberg et al Crow ley & Low ery 2000 Briffa 2000 NH Annual Land Temps D'Arrigo et al Temperature Anomoly (C)

68 The Instrument Data Urban Heat Island (UHI) Effect Ian G. McKendry, 2003, Applied climatology UHIs continue to present a UHIs continue to present a problem for the detection of changes in the global surface problem temperature for record the detection (the so-called of greenhouse effect ). changes in the global surface temperature record Typically the urban bias is removed from the climate records on the basis of relatively simple regression models that utilize population size as an indicator of the urban excess. McKendry, 2003

69 New York, NY C 14 Temperature (C)

70 Albany, NY C 10 Temperature (C)

71 West Point, NY Flat 12 Temperature (C)

72 Tem perature (C) New York, NY Population ,000 7,300,000 (+ 950%) Albany, NY Tem perature (F) , ,000 (+ 210%) miles away West Point, NY Temperature (F) ??? 7, miles away

73 Las Vegas, Temperature (C) C Population , ,000 (+ 12,800%) (+ 46%) McGill, NV Flat??? Temperature (C)

74 The Instrument Data Urban Heat Island (UHI) Effect Is the increase temperature in NY city caused by global warming, or lots of concrete? If cities like NY become larger and hotter, will they raise global temperature measurements? As cities around the world expand, could we see an increase in ground temperatures simply because of urbanization?

75 Urban Heat Island (UHI( UHI) ) Effect Typically the urban bias is removed from the climate records 1 Mann et al Crow ley & Low ery 2000 Esper et al Moberg et al Briffa 2000 removed from the climate records 0.5 Global Temperature NH Annual Land Temps D'Arrigo et al Temperature (C) New York, NY Temperature Anomoly (C) Recent studies suggest that -1 attempts to remove attempts to remove urban bias from the long-term climate records (and hence identify the magnitude of the enhanced greenhouse effect) may be overly simplistic McKendry, 2003