A number of spurious criticisms regarding the Mann et al (1998) proxy-based temperature reconstruction have been made by two individuals McIntyre and McKitrick ( McIntyre works in the mining industry, while McKitrick is an economist). These criticisms are contained in two manuscripts (McIntyre and McKitrick 2003 and 2004–the latter manuscript was rejected by Nature; both are collectively henceforth referred to as “MM”). MM claim that the main features of the Mann et al (1998–henceforth MBH98) reconstruction, including the “hockey stick” shape of the reconstruction, are artifacts of a) the centering convention used by MBH98 in their Principal Components Analysis (PCA) of the North American International Tree Ring Data Bank (‘ITRDB’) data, b) the use of 4 infilled missing annual values (AD 1400-1403) in one tree-ring series (the ‘St. Anne’ Northern Treeline series), and c) the infilling of missing values in some proxy data between 1972 and 1980. Each of these claims are demonstrated to be false below. [Read more…] about False Claims by McIntyre and McKitrick regarding the Mann et al. (1998) reconstruction
Archives for 2004
Antarctic cooling, global warming?
) by Eric Steig and Gavin Schmidt
Long term temperature data from the Southern Hemisphere are hard to find, and by the time you get to the Antarctic continent, the data are extremely sparse. Nonetheless, some patterns do emerge from the limited data available. The Antarctic Peninsula, site of the now-defunct Larsen-B ice shelf, has warmed substantially. On the other hand, the few stations on the continent and in the interior appear to have cooled slightly (Doran et al, 2002; GISTEMP). At first glance this seems to contradict the idea of “global” warming, but one needs to be careful before jumping to this conclusion.
What does the lag of CO2 behind temperature in ice cores tell us about global warming?
) This is an issue that is often misunderstood in the public sphere and media, so it is worth spending some time to explain it and clarify it. At least three careful ice core studies have shown that CO2 starts to rise about 800 years (600-1000 years) after Antarctic temperature during glacial terminations. These terminations are pronounced warming periods that mark the ends of the ice ages that happen every 100,000 years or so.
Does this prove that CO2 doesn’t cause global warming? The answer is no.
Michaels misquotes Hansen
Pat Michaels (under the guise of the Greening Earth society) is particularly fond of misquoting Jim Hansen, director of the NASA GISS laboratory (and in the interests of full disclosure, GS’s boss).
Recently he claimed that Dr. Hansen has now come around to the ‘skeptics’ (i.e. Pat Michaels) way of thinking and suggests that they agree on the (small) amount of warming to be expected in the future. Michaels quotes Hansen from a 2001 PNAS paper:
Climate model scenarios
) A couple of commentators (Pat Michaels, Roy Spencer) recently raised an issue about the standard scenarios used to compare climate models, in this case related to a study on the potential increase in hurricane activity.
The biggest uncertainty in what will happen to climate in the future (say 30 years or more) is the course that the global economy will take and the changes in technology that may accompany that. Since climate scientists certainly don’t have a crystal ball, we generally take a range of scenarios or projections of future emissions of CO2 and other important forcings such as methane and aerosols.
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Index
In addition to the category indexing on the side bar, we have set out a more thematic index here to help you find your way through the content on the site. [Note: this was kept up-to-date through about 2008. For more recent articles, please use the search function.]
Themes: Aerosols, Arctic and Antarctic climate, Atmospheric Science, Climate modelling, Climate sensitivity, Extreme events, Global warming, Greenhouse gases, Mitigation of Climate Change, Present-day observations, Oceans, Paleo-climate, Responses to common contrarian arguments, The Practice of Science, Solar forcing, Projections of future climate, Climate in the media, Meeting Reports, Miscellaneous.
If you are looking for introductions to the whole topic, start here.
Aerosols:
- “Global Dimming?“
- “Global Dimming II“
- “Pollution-Climate Connections“
- “Global Dimming may have a brighter future“
- “Climate sensitivity and aerosol forcings“
- “An Aerosol Tour de Forcing“
- “Global Dimming and climate models“
- “Current volcanic activity and climate?“
- “Aerosols: The Last Frontier?“
- “Ozone impacts on climate change“
- “Perspectives from China“
- “Global dimming and global warming“
- “Aerosols, Chemistry and Climate“
Arctic and Antarctic climate:
- “The Arctic Climate Impact Assessment“
- “The Arctic Climate Impact Assessment II“
- “The Arctic Climate Impact Assessment III“
- “Will spring 2005 be a bad one for Arctic ozone?“
- “2005 Record Arctic Ozone Loss“
- “Retreating Glacier Fronts on the Antarctic Peninsula over the Past Half-Century“
- “650,000 years of greenhouse gas concentrations“
- “Polar Amplification“
- “The Greenland Ice“
- “How much future sea level rise? More evidence from models and ice sheet observations.“
- “Significant Warming of the Antarctic Winter Troposphere“
- “More on the Arctic“
- “Sea level in the Arctic“
- “Ice Sheets and Sea Level Rise: Model Failure is the Key Issue“
- “The Copenhagen Consensus“
- “Is Antarctic climate changing?“
- “Historical climatology in Greenland“
- “Not just ice albedo“
- “Arctic Sea Ice decline in the 21st Century“
- “Making sense of Greenland’s ice“
- “Arctic sea ice watch“
- “New rule for high profile papers“
- “Antarctica is Cold? Yeah, We Knew That“
- “Moulins, Calving Fronts and Greenland Outlet Glacier Acceleration“
- “North Pole notes“
- “Ice Shelf Instability“
- “North Pole notes (continued)“
- “How much will sea level rise?“
- “On straw men and Greenland: Tad Pfeffer Responds“
- “What links the retreat of Jakobshavn Isbrae, Wilkins Ice Shelf and the Petermann Glacier?“
Atmospheric Science:
- “Water vapour: feedback or forcing?“
- “Et Tu LT?“
- “The tropical lapse rate quandary“
- “Busy Week for Water Vapor“
- “More satellite stuff“
- “Naturally trendy?“
- “Cloudy outlook for albedo?“
- “On a Weakening of the Walker Circulation“
- “The sky IS falling“
- “On Mid-latitude Storms“
- “Uncertainty in polar ozone depletion?“
- “Tropical tropospheric trends“
- “Butterflies, tornadoes and climate modelling“
- “Tropical tropospheric trends again“
- “Tropical tropospheric trends again (again)“
- “Ozone holes and cosmic rays“
Climate modelling:
- “Is Climate Modelling Science?“
- “Planetary energy imbalance?“
- “Modeller vs. modeller“
- “Chaos and Climate“
- “Greenhouse gases help seasonal predictions“
- “Polar Amplification“
- “Climate Feedbacks“
- “Short and simple arguments for why climate can be predicted“
- “The Physics of Climate Modelling“
- “Hansen’s 1988 projections“
- “Why global climate models do not give a realistic description of the local climate“
- “Green and Armstrong’s scientific forecast“
- “Musings about models“
- “The IPCC model simulation archive“
- ““Hell train station”“
- “What the IPCC models really say“
- “Global Cooling-Wanna Bet?“
- “The Global Cooling Bet – Part 2“
- “Hypothesis testing and long range memory“
- “FAQ on climate models“
Climate sensitivity:
- “11ºC warming, climate crisis in 10 years?“
- “Climate sensitivity and aerosol forcings“
- “Natural Variability and Climate Sensitivity“
- “Richard Lindzen’s HoL testimony“
- “Climate sensitivity: Plus ça change…“
- “Runaway tipping points of no return“
- “Climate Feedbacks“
- “The CO2 problem in 6 easy steps“
- “Climate Insensitivity“
- “The certainty of uncertainty“
- “Target CO2“
- “Simple Question, Simple Answer… Not“
Extreme events:
- “Storms and Climate Change“
- “Storms & Global Warming II“
- “Hurricanes and Global Warming – Is There a Connection?“
- “On record-breaking events“
- “Reactions to tighter hurricane intensity/SST link“
- “Tropical Cyclones workshop“
- “Gray and Muddy Thinking about Global Warming“
- “NOAA: Hurricane forecasts“
- “Amazonian drought“
- “Fact, Fiction, and Friction in the Hurricane Debate“
- “Tropical SSTs: Natural variations or Global warming?“
- “On Mid-latitude Storms“
- “El Nino, Global Warming, and Anomalous U.S. Winter Warmth“
- “Hurricane Spin“
- “Storm World: A Review“
- “Tropical cyclone history – part I: How reliable are past hurricane records?“
- “Tropical cyclone history – part II: Paleotempestology still in its infancy“
- “Climate Change and Tropical Cyclones (Yet Again)“
Global warming:
- “Imprecision of the Phrase “Global Warming”“
- “Anomalous Recent Warmth in Europe“
- “Global temperatures continue to rise“
- “Update on 2005 temperatures“
- “2005 temperatures“
- “Global warming on Mars?“
- “Ozone depletion and global warming“
- “How long will global warming last?“
- “Betting on climate change“
- “Worldwide glacier retreat“
- “Why looking for global warming in the oceans is a good idea“
- “Planetary energy imbalance?“
- “Tropical Glacier Retreat“
- “Global warming on Earth“
- “Q & A: Global Warming“
- “Methane hydrates and global warming“
- “Can 2°C warming be avoided?“
- “Gray and Muddy Thinking about Global Warming“
- “El Niño and Global Warming“
- “Geo-engineering in vogue…“
- “‘The Discovery of Global Warming’ update“
- “Attribution of 20th Century climate change to CO2“
- “How much CO2 emission is too much?“
- “No man is an (Urban Heat) Island“
- “1934 and all that“
- “Friday roundup“
- “Six Degrees“
Greenhouse gases:
- “What does the lag of CO2 behind temperature in ice cores tell us about global warming?“
- “How do we know that recent CO2 increases are due to human activities?“
- “CO2 Fertilization“
- “Water vapour: feedback or forcing?“
- “The Acid Ocean – the Other Problem with CO2 Emission“
- “Busy Week for Water Vapor“
- “650,000 years of greenhouse gas concentrations“
- “Methane hydrates and global warming“
- “Calculating the greenhouse effect“
- “Methane hydrates and global warming“
- “Scientists baffled!“
- “Kristof on the Apocalypse“
- “Positive feedbacks from the carbon cycle“
- “Buying a stairway to heaven?“
- “Rasslin’ swamp gas“
- “How much CO2 emission is too much?“
- “The sky IS falling“
- “Learning from a simple model“
- “The lag between temperature and CO2. (Gore’s got it right.)“
- “Beck to the future“
- “Thin Soup and a Thin Story“
- “Part II: What Ångström didn’t know“
- “A Saturated Gassy Argument“
- “The CO2 problem in 6 easy steps“
- “My model, used for deception“
- “CO2 equivalents“
- “Is the ocean carbon sink sinking?“
- “Hot off the projector #3: Atmospheric CO2 to 800 kyr ago“
- “Venus Unveiled“
- “CO2 is not the only greenhouse gas, and greenhouse effects are not the only CO2 problem“
Mitigation of Climate Change:
- “Geo-engineering in vogue…“
- “Air Capture“
- “Climate change methadone?“
- “The mpg confusion“
- “Tropical tropospheric trends again (again)“
Oceans:
- “Gulf Stream slowdown?“
- “Saltier or not?“
- “Decrease in Atlantic circulation?“
- “The Acid Ocean – the Other Problem with CO2 Emission“
- “Atlantic circulation change summary“
- “El Niño and Global Warming“
- “Ocean heat content: latest numbers“
- “Why greenhouse gases heat the ocean“
- “Tropical SSTs: Natural variations or Global warming?“
- “Carl Wunsch, The Economist and the Gulf Stream“
- “Ocean Circulation: New evidence (Yes), slowdown (No)“
- “Revealed: Secrets of Abrupt Climate Shifts“
- “A Linkage Between the LIA and Gulf Stream?“
- “The IPCC sea level numbers“
- “Ocean Cooling. Not.“
- “Thin Soup and a Thin Story“
- “Who ya gonna call?“
- “Of buckets and blogs“
- “Ocean heat content revisions“
Paleo-climate:
- “Temperature Variations in Past Centuries and the so-called "Hockey Stick"“
- “False Claims by McIntyre and McKitrick regarding the Mann et al. (1998) reconstruction“
- “Myth vs. Fact Regarding the "Hockey Stick"“
- “Weren’t temperatures warmer than today during the “Medieval Warm Period”?“
- “OK, But we do know it was warmer than present 6000 years ago, don’t we?“
- “On Yet Another False Claim by McIntyre and McKitrick“
- “What If … the “Hockey Stick” Were Wrong?“
- “Dummies guide to the latest “Hockey Stick” controversy“
- “Moberg et al: Highly variable Northern Hemisphere temperatures?“
- ““New Analysis Reproduces Graph of Late 20th Century Temperature Rise”“
- “Hockey sticks: Round 27“
- “Debate over the Early Anthropogenic Hypothesis“
- “A New Take on an Old Millennium“
- “Sir Nicholas Shackleton“
- “A Mistake with Repercussions“
- “Art and climate“
- “Addendum to “A Mistake with Repercussions”“
- “How Red are my Proxies?“
- “National Academies Synthesis Report“
- “Medieval warmth and English wine“
- “The missing piece at the Wegman hearing“
- “Followup to the ‘Hockeystick’ Hearings“
- “Revealed: Secrets of Abrupt Climate Shifts“
- “Broadly Misleading“
- “A Linkage Between the LIA and Gulf Stream?“
- “When the mites go up…“
- “What triggers ice ages?“
- “Cold Case vs. CSI“
- “The lag between temperature and CO2. (Gore’s got it right.)“
- “The weirdest millennium“
- “Curve manipulation: lesson 2“
- “Younger Dry-as dust?“
- “Past reconstructions: problems, pitfalls and progress“
- “The debate is just beginning — on the Cretaceous!“
- “Tropical cyclone history – part I: How reliable are past hurricane records?“
- “Tropical cyclone history – part II: Paleotempestology still in its infancy“
- “536 AD and all that“
- “Progress in reconstructing climate in recent millennia“
Present-day observations:
- “Et Tu LT?“
- “The tropical lapse rate quandary“
- “Gulf Stream slowdown?“
- “What is a first-order climate forcing?“
- “The Surface Temperature Record and the Urban Heat Island“
- “Groundhog Day“
- “Cloudy outlook for albedo?“
- “More on the Arctic“
- “Historical climatology in Greenland“
- “Has Pacific Northwest snowpack declined? Yes.“
- “Glacier Mass Balance: equilibrium or disequilibrium response?“
- “No man is an (Urban Heat) Island“
- “1934 and all that“
- “Sweatin’ the Mediterranean Heat“
- “Are Temperature Trends affected by Economic Activity (II)?“
- “A barrier to understanding?“
- “Uncertainty, noise and the art of model-data comparison“
- “Model-data-comparison, Lesson 2“
- “Global trends and ENSO“
- “Mind the Gap!“
- “Mountains and molehills“
- “2008 temperature summaries and spin“
Projections of future climate:
- “Climate model scenarios“
- “Make your own forecasts of future energy, carbon emissions, and climate“
- “Lawson vs. the IPCC“
- “Can 2°C warming be avoided?“
- “James Lovelock’s Gloomy Vision“
- “Kristof on the Apocalypse“
- “Stern Science“
- “Hansen’s 1988 projections“
- “Green and Armstrong’s scientific forecast“
- “Regional Climate Projections“
- “The Forecast in the Streets“
- ““Hell train station”“
Responses to common contrarian arguments:
- “Michaels misquotes Hansen“
- “Antarctic cooling, global warming?“
- “What does the lag of CO2 behind temperature in ice cores tell us about global warming?“
- “Are Temperature Trends affected by Economic Activity?“
- “Fox News gets it wrong“
- “Michael Crichton’s State of Confusion“
- “Michael Crichton’s State of Confusion II: Return of the Science“
- “Climate Change Disinformation“
- “Will-full ignorance“
- “George Will-misled and misleading“
- “The global cooling myth“
- “Strange Bedfellows“
- “Myth vs. Fact Regarding the "Hockey Stick"“
- “What If … the “Hockey Stick” Were Wrong?“
- “Water vapour: feedback or forcing?“
- “How much of the recent CO2 increase is due to human activities?“
- “Inhofe and Crichton: Together at Last!“
- “How to be a real sceptic“
- “The Wall Street Journal vs. The Scientific Consensus“
- “Senator Inhofe on Climate Change“
- “CO2 Fertilization“
- “Calculating the greenhouse effect“
- “Good climate debate FAQ“
- “Bush on “The Fundamental Debate”“
- “Incurious George“
- “Heat Rising at the Washington Post“
- “Open Thread on Lindzen Op-Ed in WSJ“
- “Lindzen: point by point“
- “Thank you for emitting“
- “Global cooling, again“
- “Cuckoo Science“
- “English vineyards again….“
- “Avery and Singer: Unstoppable hot air“
- “Inhofe’s last stand“
- “Swindled!“
- “Swindled: Carl Wunsch responds“
- “Does a Global Temperature Exist?“
- “Lindzen in Newsweek“
- “The lag between temperature and CO2. (Gore’s got it right.)“
- “Beck to the future“
- “The weirdest millennium“
- “Curve manipulation: lesson 2“
- “Oregon Institute of Science and Malarkey“
- “BBC contrarian top 10“
- “Les Chevaliers de l’Ordre de la Terre Plate, Part I: Allègre and Courtillot“
- “Les Chevaliers de l’Ordre de la Terre Plate, Part II: Courtillot’s Geomagnetic Excursion“
- “The global cooling mole“
- “Impressions from the European Geophysical Union conference 2008“
- “Freeman Dyson’s selective vision“
- “Once more unto the bray“
- “Not the IPCC (“NIPCC”) Report“
Scientific Practice:
- “Statistical analysis of consensus“
- “Just what is this Consensus anyway?“
- “Exeter conference: Avoiding Dangerous Climate Change“
- “Is Climate Modelling Science?“
- “IPCC in action: Part I“
- “IPCC in action: Part II“
- “Peer Review: A Necessary But Not Sufficient Condition“
- “Peer Review: A Necessary But Not Sufficient Condition II“
- “Lawson vs. the IPCC“
- “How to be a real sceptic“
- “Hansen in the New York Times“
- “Happy Birthday, Charles Darwin!“
- “A Mistake with Repercussions“
- “How not to write a press release“
- “Communicating Science & Technology“
- “The Copenhagen Consensus“
- “Nature’s press advisories“
- “Chinese whispers in Australia“
- “AGU, AAPG and AMQUA“
- “Supreme Court Amicus Curiae from scientists“
- “Further comment on the Supreme Court briefs“
- “Fall AGU“
- “AGU Hangover“
- “The IPCC Fourth Assessment SPM“
- “Fraser Institute fires off a damp squib“
- “Ozone Hole Leaks and Other Tales“
- “Full IPCC AR4 report now available“
- “Transparency of the IPCC process“
- “Perspectives from China“
- “Spanish perspectives“
- “What if you held a conference, and no (real) scientists came?“
- “Blogs and peer-review“
- “Bridging the divides“
- “Are geologists different?“
- “A new survey of scientists“
- “Greenspan, Einstein and Reich“
- “Contrarians and consensus: The case of the midwife toad“
Solar forcing:
- “Recent Warming But No Trend in Galactic Cosmic Rays“
- “A critique on Veizer’s Celestial Climate Driver“
- “The lure of solar forcing“
- “Did the Sun hit record highs over the last few decades?“
- “Another study on solar influence“
- “The trouble with sunspots“
- “How not to attribute climate change“
- “Taking Cosmic Rays for a spin“
- “Nigel Calder in the Times“
- “‘Cosmoclimatology’ – tired old arguments in new clothes“
- “Cosmic rays don’t die so easily“
Climate in the Media:
- “The False Objectivity of “Balance”“
- “Getting the balance right…“
- “Al Gore’s movie“
- “Disinformation? You want it, IREA’s got it“
- “Peter Doran and how misleading talking points propagate“
- “The missing repertoire“
- “Sachs’ WSJ Challenge“
- “Consensus as the New Heresy“
- “The Human Hand in Climate Change“
- “WSJ Editorial Board: Head Still Buried in the Sand“
- “Climate Reporting in Physics World“
- “Broad Irony“
- “A Tale of Three Interviews“
- “Cockburn’s form“
- “Global Warming Delusions at the Wall Street Journal“
- “A phenomenological sequel“
- “Find the error“
- “A day when Hell was frozen“
- “Wired Magazine’s Incoherent Truths“
- “More PR related confusion“
- “Journalistic whiplash“
- “Palin on Global Warming“
- “Why don’t op-eds get fact checked?“
Meeting Reports:
- “Live (almost) from AGU–Dispatch #1“
- “Live (almost) from AGU–Dispatch #2“
- “Hot off the projector #3: Atmospheric CO2 to 800 kyr ago“
- “Live (almost) from AGU–Dispatch #4“
- “Notes from The Gathering #5: Arctic sea ice: is it tipped yet?“
- “Live (almost) from AGU–Dispatch #6“
- “Rolling up the circus tent: Dispatch #7“
- “Impressions from the European Geophysical Union conference 2008“
- “Field notes from a Nature Conservancy meeting“
Miscellaneous:
- “Welcome to RealClimate“
- “A disclaimer“
- “RealClimate In the News“
- “Doubts about the Advent of Spring“
- “Scientists respond to Barton“
- “Framing of climate science“
- “Books books books“
- “One year on…“
- “Hansen in the New York Times“
- “Those pesky scientific facts…“
- “Meteors, Nuclear Tests and Global Warming“
- “Pielke père et fils in Nature“
- “Washington Post Cartoon“
- “IPCC draft: No comment.“
- “MY Review of Books“
- “Introducing RC forum“
- “It’s different in Europe“
- “The Copenhagen Consensus“
- “New public opinion poll on global warming“
- “New Google search function“
- “2006 Year in review“
- “Calling All Science Teachers“
- “Save the World! Earn $25 million!“
- “Global Warming debate“
- “Adventures on the East Side“
- “The Sheep Albedo Feedback“
- “Fun with correlations!“
- “A bit of philosophy“
- “G8 summit declaration“
- “Convenient Untruths“
- “The “Have you stopped beating your wife yet (yes/no)” questionnaire“
- “Sustainability: A Nobel Cause“
- “Did we call it or what“
- “Books ’07“
- “Our Books“
- “Comprehensive climate glossary“
- “Books ’08“
- “2008 Year in review“
Antarctic Oscillation (“AAO”)
) Measure of the pressure gradient between the polar and subpolar regions of the Southern Hemisphere. Term was introduced by Thompson and Wallace (2000). More information on the AAO can be found here. See also Arctic Oscillation (“AO”).