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  • February « 2013 « RealClimate
    and Hansen et al 1988 simulations More Comments pop up 152 Unforced Variations Feb 2013 Filed under Climate Science Open thread group 4 February 2013 This month s open thread on climate science Comments pop up 421 Site Google Custom Search Recent Comments What is the best description of the greenhouse effect Jim Eager What is the best description of the greenhouse effect Patrick Eriksson What is the best description of the greenhouse effect Kevin McKinney Anti scientists Carbomontanus What is the best description of the greenhouse effect Spencer Marvel et al 2015 Part III Response to Nic Lewis SteveS What is the best description of the greenhouse effect Chris Colose Blizzard Jonas and the slowdown of the Gulf Stream System doiknow What is the best description of the greenhouse effect James Powell Unforced Variations Feb 2016 Jim Galasyn With Inline Responses Marvel et al 2015 Part III Response to Nic Lewis SteveS Marvel et al 2015 Part III Response to Nic Lewis steve s Marvel et al 2015 Part III Response to Nic Lewis Andrew Kerber Blizzard Jonas and the slowdown of the Gulf Stream System Hank Roberts Blizzard Jonas and the slowdown of the Gulf Stream System doiknow Marvel et al 2015 Part III Response to Nic Lewis MartinM Anti scientists Don McKenzie Marvel et al 2015 Part III Response to Nic Lewis Matt Skaggs Anti scientists mikeworst New On line Classes and Models Marcus Pages Acronym index Data Sources Categories Climate Science Aerosols Arctic and Antarctic Carbon cycle Climate impacts Climate modelling El Nino Geoengineering Greenhouse gases Hurricanes Instrumental Record IPCC Oceans Paleoclimate Sun earth connections Communicating Climate Reporting on climate skeptics Extras Attic Comment Policy Contributor Bio s FAQ Glossary In the News Reviews Supplemental data Tutorials hydrological cycle Open thread RC Forum Scientific practice statistics

    Original URL path: http://www.realclimate.org/index.php/archives/2013/02/ (2016-02-13)
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  • January « 2013 « RealClimate
    global mean temperature blue C GISS data and rate of sea level rise red cm year Church white data both detrended More References D P Chambers M A Merrifield and R S Nerem Is there a 60 year oscillation in global mean sea level Geophys Res Lett vol 39 pp n a n a 2012 http dx doi org 10 1029 2012GL052885 S Rahmstorf Response to Comments on A Semi Empirical Approach to Projecting Future Sea Level Rise Science vol 317 pp 1866d 1866d 2007 http dx doi org 10 1126 science 1141283 Comments pop up 31 Sea level rise Where we stand at the start of 2013 Filed under Climate Science Instrumental Record IPCC Oceans stefan 9 January 2013 Progress has been made in recent years in understanding the observed past sea level rise As a result process based projections of future sea level rise have become dramatically higher and are now closer to semi empirical projections However process based models still underestimate past sea level rise and they still project a smaller rise than semi empirical models Sea level projections were probably the most controversial aspect of the 4th IPCC report published in 2007 As an author of the paleoclimate chapter I was involved in some of the sea level discussions during preparation of the report but I was not part of the writing team for the projections At the core of the controversy were the IPCC projections which are based on process models i e models that aim to simulate individual processes like thermal expansion or glacier melt Many scientists felt that these models were not mature and understated the sea level rise to be expected in future and the IPCC report itself documented the fact that the models seriously underestimated past sea level rise See our in depth discussion published after the 4th IPCC report appeared That was confirmed again with the most recent data in Rahmstorf et al 2012 More References S Rahmstorf G Foster and A Cazenave Comparing climate projections to observations up to 2011 Environ Res Lett vol 7 pp 044035 2012 http dx doi org 10 1088 1748 9326 7 4 044035 Comments pop up 78 On Sensitivity Part II Constraining Cloud Feedback without Cloud Observations Filed under Climate modelling Climate Science group 4 January 2013 Guest Commentary by Karen M Shell Oregon State University Link to Part I Clouds are very pesky for climate scientists Due to their high spatial and temporal variability as well as the many processes involved in cloud droplet formation clouds are difficult to model Furthermore clouds have competing effects on solar and terrestrial radiation Increases in clouds increase reflected sunlight a cooling effect but also increase the greenhouse effect a warming effect The net effect of clouds at a given location depends the kind of clouds stratus cumulus etc their distribution in the vertical and on which radiative effect dominates Not only is it difficult to correctly represent clouds in climate models but estimating how clouds

    Original URL path: http://www.realclimate.org/index.php/archives/2013/01/ (2016-02-13)
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  • December « 2012 « RealClimate
    by simply analyzing a single infrared or visible satellite image which is almost always available Velden et al 2006 The technique calls for the analyst to determine the center location of the system the cloud pattern type the degree of organization of the pattern and the intensity trend A maximum surface wind speed is determined after the application of a number of rules and constraints The Dvorak Technique has been used for many years at all global tropical cyclone forecast centers and has been shown in many cases to yield a good estimate of maximum TC wind speed when applied properly Knaff et al 2010 However there is a level of analyst subjectivity inherent in the procedure the cloud patterns are not always clear it is sometimes difficult to accurately determine the storm center and the rules and constraints have been interpreted and applied differently across agencies This introduces heterogeneity in the global TC record since the Dvorak Technique is usually the only available tool for assessing the maximum wind speed There has been recent work to eliminate the human element in the Dvorak Technique by automating the procedure The Advanced Dvorak Technique ADT uses objective storm center and cloud pattern schemes to remove the subjectivity Olander and Velden 2007 All other classification rules and constraints are then applied and combined with additional statistical information to produce automated intensity estimates Although the ADT skill is comparable to experienced human Dvorak analysts large errors can occur if the scene type is not identified properly A new crowd sourcing project called Cyclone Center embraces the human element by enabling the public to perform a simplified version of the Dvorak Technique to analyze historical global tropical cyclone TC intensities Hennon 2012 Cyclone Center s primary goal is to resolve discrepancies in the recent global TC record arising principally from inconsistent development of tropical cyclone intensity data The Cyclone Center technique standardizes the classification procedure by condensing the Dvorak Technique to a few simple questions that can be answered by global nonprofessional users One of the main advantages of this approach is the inclusion of thousands of users instead of the 1 3 who would normally classify a TC image This allows the computation of measures of uncertainty in addition to a mean intensity Nearly 300 000 images encompassing all global TCs that formed from 1978 2009 will be classified 30 times each a feat that would take a dedicated team of twenty Dvorak trained experts about 12 years to complete Citizen scientists have already performed over 100 000 classifications since the project launch in September Once the project is complete a new dataset of global TC tracks and intensities will be made available to the community to contribute to our efforts to provide the best possible TC data record Interested readers are encouraged to learn more about and participate in the project at the cyclonecenter org website there are some FAQ on the project blog The CycloneCenter project is a collaboration between the

    Original URL path: http://www.realclimate.org/index.php/archives/2012/12/ (2016-02-13)
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  • November « 2012 « RealClimate
    a quadratic Filed under Climate Science Oceans skeptics statistics stefan 20 November 2012 if your data do not look like a quadratic This is a post about global sea level rise but I put that message up front so that you ve got it even if you don t read any further The reputable climate statistics blogger Tamino who is a professional statistician in real life and has published a couple of posts on this topic puts it bluntly Fitting a quadratic to test for change in the rate of sea level rise is a fool s errand I d like to explain why with the help of a simple example Imagine your rate of sea level rise changes over 100 years in the following way More Comments pop up 44 Stronger regional differences due to large scale atmospheric flow Filed under Climate impacts Climate modelling Climate Science Communicating Climate Reporting on climate statistics rasmus 20 November 2012 A new paper by Deser et al 2012 free access is likely to have repercussions on discussions of local climate change adaptation I think it caught some people by surprise even if the results perhaps should not be so surprising The range of possible local and regional climate outcomes may turn out to be larger than expected for regions such as North America and Europe Deser et al imply that information about the future regional climate is more blurred than previously anticipated because of large scale atmospheric flow responsible for variations in regional climates They found that regional temperatures and precipitation for the next 50 years may be less predictable due to the chaotic nature of the large scale atmospheric flow This has implications for climate change downscaling and climate change adaptation and suggests a need to anticipate a wider range of situations in climate risk analyses Although it has long been recognised that large scale circulation regimes affect seasonal inter annual climate and decadal variations the expectations have been that anthropogenic climate changes will dominate on time scales longer than 50 years For instance an influential analysis by Hawking Sutton 2009 link to figures has suggested that internal climate variability account for only about 20 of the variance over the British isles on a 50 year time scale More References C Deser R Knutti S Solomon and A S Phillips Communication of the role of natural variability in future North American climate Nature Climate Change vol 2 pp 775 779 2012 http dx doi org 10 1038 nclimate1562 E Hawkins and R Sutton The Potential to Narrow Uncertainty in Regional Climate Predictions Bull Amer Meteor Soc vol 90 pp 1095 1107 2009 http dx doi org 10 1175 2009BAMS2607 1 Comments pop up 59 ClimateDialogue Exploring different views on climate change Filed under Climate Science Communicating Climate skeptics group 15 November 2012 This is a guest posting from some Dutch colleagues on a new online experiment in fostering dialogue on climate change Bart Verheggen has asked us to host this quick introduction We are interested to hear if you think this is a good idea Guest Commentary by Bart Strengers PBL ClimateDialogue org offers a platform for discussions between invited climate scientists on important climate topics that have been subject to scientific and public debate The goal of the platform is to explore the full range of views currently held by scientists by inviting experts with different views on the topic of discussion We encourage the invited scientists to formulate their own personal scientific views they are not asked to act as representatives for any particular group in the climate debate Obviously there are many excellent blogs that facilitate discussions between climate experts but as the climate debate is highly polarized and politicized blog discussions between experts with opposing views are rare Background The discovery early 2010 of a number of errors in the Fourth IPCC Assessment Report on climate impacts Working Group II led to a review of the processes and procedures of the IPCC by the InterAcademy Council IAC The IAC report triggered a debate in the Dutch Parliament about the reliability of climate science in general Based on the IAC recommendation that the full range of views should be covered in the IPCC reports Parliament asked the Dutch government to also involve climate skeptics in future studies on climate change In response the Ministry of Infrastructure and the Environment announced a number of projects that are aimed to increase this involvement ClimateDialogue org is one of these projects We are starting ClimateDialogue with a discussion on the causes of the decline of Arctic Sea Ice and the question to what extent this decline can be explained by global warming Also the projected timing of the first year that the Arctic will be ice free will be discussed With respect to the latter in its Fourth Assessment Report in 2007 IPCC anticipated that near ice free conditions might occur by the end of this century Since then several studies have indicated this could be between 2030 2050 or even earlier We invited three experts to take part in the discussion Judith Curry chair of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology Walt Meier research scientist at the National Snow Ice Data Center NSIDC in Boulder Colorado and Ron Lindsay Senior Principal Physicist at the Polar Science Center of the University of Washington in Seattle Future topics that will be discussed include climate sensitivity sea level rise urban heat island effects the value of comprehensive climate models ocean heat storage and the warming trend over the past few decades Our format Each discussion will be kicked off by a short introduction written by the editorial staff followed by a guest blog by two or more invited scientists The scientists will start the discussion by responding to each other s arguments It is not the goal of ClimateDialogue to reach a consensus but to stimulate the discussion and to make clear what the discussants agree

    Original URL path: http://www.realclimate.org/index.php/archives/2012/11/ (2016-02-13)
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  • October « 2012 « RealClimate
    to get the answer they want and then stop monitoring if it doesn t happen This only happens in the fevered imaginations of conspiracy theorists So I was intrigued enough to investigate what this actually referred to More Comments pop up 251 Climate Change videos Part I Filed under Climate Science Communicating Climate group 9 October 2012 The US National Research Council has been doing a lot recently to expand background knowledge of the climate system and of climate change In tandem with a new report discussing strategies for advancing climate modeling they have put up a an introductory web site on climate models including some interviews with some actual climate modelers More comprehensively they have helped put together a series of videos discussing everything from the definition of climate to attribution of climate changes and future projections The series is in seven parts viewable here There are additional resources here We thought it would be interesting to have a separate post on each of the seven videos so that discussions on the videos themselves or the topics covered or not could be more focused So with no further ado here is part I What is Climate Comments pop up 96 Unforced variations Oct 2012 Filed under Climate Science Open thread group 1 October 2012 This month s open thread Try to keep it at least vaguely focused on climate science Comments pop up 782 Site Google Custom Search Recent Comments What is the best description of the greenhouse effect Jim Eager What is the best description of the greenhouse effect Patrick Eriksson What is the best description of the greenhouse effect Kevin McKinney Anti scientists Carbomontanus What is the best description of the greenhouse effect Spencer Marvel et al 2015 Part III Response to Nic Lewis SteveS What is the best description of the greenhouse effect Chris Colose Blizzard Jonas and the slowdown of the Gulf Stream System doiknow What is the best description of the greenhouse effect James Powell Unforced Variations Feb 2016 Jim Galasyn With Inline Responses Marvel et al 2015 Part III Response to Nic Lewis SteveS Marvel et al 2015 Part III Response to Nic Lewis steve s Marvel et al 2015 Part III Response to Nic Lewis Andrew Kerber Blizzard Jonas and the slowdown of the Gulf Stream System Hank Roberts Blizzard Jonas and the slowdown of the Gulf Stream System doiknow Marvel et al 2015 Part III Response to Nic Lewis MartinM Anti scientists Don McKenzie Marvel et al 2015 Part III Response to Nic Lewis Matt Skaggs Anti scientists mikeworst New On line Classes and Models Marcus Pages Acronym index Data Sources Categories Climate Science Aerosols Arctic and Antarctic Carbon cycle Climate impacts Climate modelling El Nino Geoengineering Greenhouse gases Hurricanes Instrumental Record IPCC Oceans Paleoclimate Sun earth connections Communicating Climate Reporting on climate skeptics Extras Attic Comment Policy Contributor Bio s FAQ Glossary In the News Reviews Supplemental data Tutorials hydrological cycle Open thread RC Forum Scientific practice statistics The Bore

    Original URL path: http://www.realclimate.org/index.php/archives/2012/10/ (2016-02-13)
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  • September « 2012 « RealClimate
    RETRACTED Long term toxicity of a Roundup herbicide and a Roundup tolerant genetically modified maize Food and Chemical Toxicology vol 50 pp 4221 4231 2012 http dx doi org 10 1016 j fct 2012 08 005 Comments pop up 65 Why bother trying to attribute extreme events Filed under Climate modelling Climate Science gavin 20 September 2012 Nature has an interesting editorial this week on the state of the science for attributing extreme events This was prompted by a workshop in Oxford last week where presumably strategies observations and results were discussed by a collection of scientists interested in the topic including Myles Allen Peter Stott and other familiar names Rather less usual was a discussion referred to in the Nature piece on whether the whole endeavour was scientifically worthwhile and even if it was whether it was of any use to anyone The proponents of the unscientific and pointless school of thought were not named and so one can t immediately engage with them directly but nonetheless the question is worthy of a discussion More Comments pop up 153 El Nino s effect on CO2 causes confusion about CO2 s role for climate change Filed under Carbon cycle Climate impacts Climate Science Greenhouse gases statistics rasmus 11 September 2012 Are the rising atmospheric CO 2 levels a result of oceans warming up And does that mean that CO 2 has little role in the global warming Moreover are the rising levels of CO 2 at all related to human activity These are claims made in a fresh publication by Humlum et al 2012 However when seeing them in the context of their analysis they seem to be on par with the misguided notion that the rain from clouds cannot come from the oceans because the clouds are intermittent and highly variable whereas the oceans are just there all the time I think that the analysis presented in Humlum et al 2012 is weak on four important accounts the analysis the physics reviewing past literature and logic More References O Humlum K Stordahl and J Solheim The phase relation between atmospheric carbon dioxide and global temperature Global and Planetary Change vol 100 pp 51 69 2013 http dx doi org 10 1016 j gloplacha 2012 08 008 Comments pop up 66 Unforced variations Sep 2012 Filed under Climate Science Open thread group 5 September 2012 Open thread a little late because of the holiday But everyone can get back to work now Comments pop up 591 Site Google Custom Search Recent Comments What is the best description of the greenhouse effect Jim Eager What is the best description of the greenhouse effect Patrick Eriksson What is the best description of the greenhouse effect Kevin McKinney Anti scientists Carbomontanus What is the best description of the greenhouse effect Spencer Marvel et al 2015 Part III Response to Nic Lewis SteveS What is the best description of the greenhouse effect Chris Colose Blizzard Jonas and the slowdown of the Gulf Stream System

    Original URL path: http://www.realclimate.org/index.php/archives/2012/09/ (2016-02-13)
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  • August « 2012 « RealClimate
    the Antarctic Peninsula is one of the most rapidly warming places on earth But like everywhere else in Antarctica the length of available temperature data is short most records begin in 1957 when stations were put in place during the International Geophysical Year a few start in the late 1940s This makes the recent rapid warming difficult to evaluate in general what s interesting is how the trend compares with the underlying variability As anyone who s been there can tell you the weather on the Antarctic Peninsula is pretty wild and this applies to the climate as well year to year variability is very large Put another way the noise level is high and discerning the signal requires more data than is available from the instrumental temperature record This is where ice cores come in handy they provide a much longer record and allow us to evaluate the recent changes in a more complete context A new paper in Nature this week presents results from an ice core drilled by the British Antarctic Survey BAS at James Ross Island on the Antarctic Peninsula More Comments pop up 24 Language Intelligence Lessons on persuasion from Jesus Shakespeare Lincoln and Lady Gaga A Review Filed under Communicating Climate Reviews mike 20 August 2012 Any book that manages to link together the lessons of the Bible Shakespeare Abraham Lincoln and Lady Gaga not to mention Martin Luther King Winston Churchill Bob Dylan and Jerry Seinfeld can t be all bad With Joe Romm s new book Language Intelligence it is in fact ALL good There are lessons galore for the scientists among us who value public outreach and communication The book is a de facto field guide for recognizing and assimilating many of the key tools of persuasive language and speech something that is ever more important to science communicators who face the daunting challenge of having to communicate technical and nuanced material to an audience largely unfamiliar with the lexicon of science sometimes agnostic or even unreceptive to its message and in the case of contentious areas like climate change and evolution already subject to a concerted campaign to misinform and confuse them More Comments pop up 171 Extreme metrics Filed under Climate impacts Climate Science statistics gavin 18 August 2012 There has been a lot of discussion related to the Hansen et al 2012 PNAS paper and the accompanying op ed in the Washington Post last week But in this post I ll try and make the case that most of the discussion has not related to the actual analysis described in the paper but rather to proxy arguments for what people think is important More References J Hansen M Sato and R Ruedy Perception of climate change Proceedings of the National Academy of Sciences vol 109 pp E2415 E2423 2012 http dx doi org 10 1073 pnas 1205276109 Comments pop up 158 Older Entries Site Google Custom Search Recent Comments What is the best description of the greenhouse effect

    Original URL path: http://www.realclimate.org/index.php/archives/2012/08/ (2016-02-13)
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  • July « 2012 « RealClimate
    latest misrepresentations of the Esper et al study discussed in our article Surprise Fox News Fails Paleoclimatology Update 7 13 12 Further comment from Bob Ward of the Grantham Institute in Huffington Post UK The World s Most Visited Newspaper Website Continues to Regurgitate Nonsense from Climate Change Sceptics Update 7 14 12 Some additional context provided by this LiveScience article It s been a tough few months for tree rings perhaps unfairly Back in April we commented on a study that one of us Mike was involved in that focused on the possibility that there is a threshold on the cooling recorded by tree ring composites that could limit their ability to capture the short term cooling signal associated with larger volcanic eruptions Mostly lost in the discussion however was the fact emphasized in the paper that the trees appeared to be doing a remarkably good job in capturing the long term temperature signal the aspect of greatest relevance in discussions of climate change This week there have been two additional studies published raising questions about the interpretation of tree ring based climate reconstructions More Comments pop up 79 Unforced Variations July 2012 Filed under Climate Science Open thread group 3 July 2012 Have at it Comments pop up 561 Site Google Custom Search Recent Comments What is the best description of the greenhouse effect Jim Eager What is the best description of the greenhouse effect Patrick Eriksson What is the best description of the greenhouse effect Kevin McKinney Anti scientists Carbomontanus What is the best description of the greenhouse effect Spencer Marvel et al 2015 Part III Response to Nic Lewis SteveS What is the best description of the greenhouse effect Chris Colose Blizzard Jonas and the slowdown of the Gulf Stream System doiknow What is the best description of the greenhouse effect James Powell Unforced Variations Feb 2016 Jim Galasyn With Inline Responses Marvel et al 2015 Part III Response to Nic Lewis SteveS Marvel et al 2015 Part III Response to Nic Lewis steve s Marvel et al 2015 Part III Response to Nic Lewis Andrew Kerber Blizzard Jonas and the slowdown of the Gulf Stream System Hank Roberts Blizzard Jonas and the slowdown of the Gulf Stream System doiknow Marvel et al 2015 Part III Response to Nic Lewis MartinM Anti scientists Don McKenzie Marvel et al 2015 Part III Response to Nic Lewis Matt Skaggs Anti scientists mikeworst New On line Classes and Models Marcus Pages Acronym index Data Sources Categories Climate Science Aerosols Arctic and Antarctic Carbon cycle Climate impacts Climate modelling El Nino Geoengineering Greenhouse gases Hurricanes Instrumental Record IPCC Oceans Paleoclimate Sun earth connections Communicating Climate Reporting on climate skeptics Extras Attic Comment Policy Contributor Bio s FAQ Glossary In the News Reviews Supplemental data Tutorials hydrological cycle Open thread RC Forum Scientific practice statistics The Bore Hole Books Contributors Highlights Dummies Guide to the latest Hockey Stick controversy El Nino Global Warming and Anomalous U S Winter Warmth Hurricanes and

    Original URL path: http://www.realclimate.org/index.php/archives/2012/07/ (2016-02-13)
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