Wrap Up of: RADIATIVE FORCING OF CLIMATE

Transcription

1 Wrap Up of: RADIATIVE FORCING OF CLIMATE

2 The Key To It All: RADIATIVE FORCING OF CLIMATE CLICKERS Ch 32 Class notes pp 83

3 The figure shows that the forcing mechanism that is BEST understood by scientists is also the one that leads to the greatest climatic impact. 1.TRUE 2. FALSE p 83

4 WHAT TO KNOW: If the forcing is NEGATIVE (to left of line) - COOLING + WARMING If the forcing is POSITIVE (to right of line) it means that an increase in that gas or factor contributes to COOLING in the troposphere. it means that an increase in that gas or factor contributes to WARMING in the troposphere. p 83

5 Enhanced GHE Dimming the Sun SOURCE: IPCC 2007 WG-1 Synthesis Report Summary for Policymakers p 83

6 Q -ALL of the forcing mechanisms shown here (X, Y, & Z) are linked to anthropogenic activity in some way: 1. TRUE 2. FALSE p 83

7 Q -The figure shows that forcing mechanism Z (Land-use as indicated by albedo) leads to COOLING.... The reason for this is that cooling occurs when surface albedo increases and hence MORE energy is absorbed. TRUE or FALSE? LESS energy is absorbed! p 83

8 REVIEW OF A COMMON MISCONCEPTION!

9 OZONE S DUAL PERSONALITY! X Y An INCREASE of Stratospheric Ozone will absorb more UV in the stratosphere less UV getting into the troposphere a COOLER Troposphere An INCREASE of Tropospheric (ground-level) Ozone will add to the Greenhouse Effect more IR staying in the troposphere a WARMER Troposphere

10 Q -According to the figure which forcing mechanism has a GREATER influence on global temperature? Therefore, the Stratospheric Ozone Hole is NOT the main cause of global warming! Stratospheric OZONE OR Tropospheric OZONE

11 Climate Change IPCC The Physical Science Basis Working Group 1 Report FAQ 2.1 How do Human Activities Contribute to Climate Change and How do They Compare with Natural Influences?

12 Mini ZOMBIE BREAK! WATCH YOUTUBE:

13 From Climate Science Basics Tutorials.... Whatever happened to global warming?

14 Solar Dimming may have masked the intensity of warming from the Enhanced GH Effect... until recently! Average Temperature Change over Global Land Surfaces ( ) More solar dimming Less solar dimming Thick-cloud air pollution common; health problems, deaths Clean Air Act of 1970 stronger law; EPA established later that year Clean Air Act of 1963 funding to study health effects; federal + state laws promote clean air Clean Air Act of 1990 EPA more implementation + enforcement authority; increased emphasis on cost-effectiveness

15 From Climate Science Basics Tutorials.... Whatever happened to global warming?

16 CLIMATE CHANGE:

17 From: skepticalscience.com

18 From: skepticalscience.com

19 ... and now How do we KNOW that the recent global warming is due primarily to human activities and not just natural climate forcing?

20 TOPIC # 15, PART C: Evidence from Natural Archives "The farther backward you can look, the farther forward you are likely to see. Class Notes p 84 - Winston Churchill

21 PROXY DATA or NATURAL ARCHIVES of CLIMATE Corals Ice cores Pollen Lake, bog & ocean sediments Tree rings!

22 3 iconic graphs of GLOBAL CLIMATE CHANGE... The Noodle The Hockey Stick The Spaghetti Plate

23 Cold Warm Cold Warm Cold Warm Review: from p 17 of Class Notes: deep-sea sediments Estimates of Mean Global Temperature Change -- based on various types of archives ICE AGE pollen data & alpine glaciers The Noodle Little Ice Age historical documents (emphasis on the North Atlantic region)

24 The CO 2 Hockey Stick Graph... Keeling Curve measurements SGC E-Text Chapter 1 Fig 1-3a Evidence from ice cores:

25 The Temperature Hockey Stick Graph proxy data + thermometer records middle graph on p 84

26 The Temperature Hockey Stick Graph (another view) Temperature change over the last 1000 years from multi-proxy records: shows there is NO period of global or hemispheric temperatures warmer than the 20 th century global mean Global Little Ice Age (15-19 th century) IS evident in data Yellow = an indicator of the uncertainty in the proxy estimates of past temperature Medieval Warm Period (9-14 th century) not very evident (more of a regional phenomenon) p 84

27 The Temperature Spaghetti Plate Graph CONVERGING EVIDENCE! Based on 12 independent reconstructions of past temperature: The general Hockey Stick shape has stood the test of time, despite intense scrutiny and debunking attempts! p 84

28 The Noodle The Scientific Process in action The Hockey Stick The Spaghetti Plate

29 TOPIC # 15, PART D: Evidence from Model Comparisons Natural vs. Anthropogenic Only Natural Forcing Natural + Anthropogenic Forcing Class Notes p 85

30 In addition to the Natural - Archive Paleo Approach, COMPUTER MODELS have been created to estimate the radiative forcings of the PAST! Estimates Of Natural & Human Impacts On Climate Over The Past 1000 Years On top of p 85 in Class Notes From Dire Predictions p 81

31 NATURAL FORCING Solar output variations, sunspots GHG s, soot, SO 2 Volcanic eruptions Surface Albedo Changes ANTHROPOGENIC FORCING

32 MODELED TEMPERATURE based on NATURAL FORCING ONLY: Models cannot reproduce the observed temperature trend since ~ 1980

33 MODELED TEMPERATURE based on NATURAL + ANTHROPOGENIC FORCING

34 MODELED TEMPERATURE based on NATURAL + ANTHROPOGENIC FORCING Spaghetti Plate of Model results: 58 runs of 14 different models Observations Volcanic eruption years Average of all model runs

35 SOURCE: IPCC 2007 WG-1 Synthesis Report Summary for Policymakers p 85

36 Individual Region Model Runs showed the same results! p 85

37 See you Wednesday for the GLOBAL CHANGE FILM FESTIVAL! Popcorn!