Two years ago I made a post that featured a dozen or so maps and graphs that lended insight into global warming. It turned out to be one of the most read pages on my site. I now want to update that page with even better and a larger number images which are relevant to climate change. They will feature only very brief explanations. Most of what is being shown is self-evident, but if you have questions, feel free to ask them. Hopefully this can serve as a good reference for those who want some images relevant to global warming. I also recommend the site http://www.globalwarmingart.com. These images can all be clicked on for enhanced view. I am also happy to take further suggestions and them.
Every once in a while it is worth reviewing the basic physics behind the greenhouse effect and global warming. Sometimes all the debate about global warming in the media loses focus of the fact that the world really is governed by the laws of physics. Unfortunately, many internet explanations get dumbed down to the point of having an atmosphere that serves as a single “slab” between the ground and space, and has a bunch of colorful arrows coming out of it and bouncing off it, etc. This is a useless explanation, and gives no justice to understanding what is happening. Two encounters in the outside world recently prompted me to do another post just to have a reference handy, and I’m using this to replace an older post which I entitled “just a few more molecules.” There’s also been an interesting episode with Dr. Andy Lacis from NASA GISS over at Dot Earth which I’d like to elaborate on.
The webcast for Dr. Alley’s presentation is now up, so I recommend watching the video. It is concerning the role of CO2 on climate over geologic time.
As my own side note, Alley is one of my favorite scientists…he’s pretty much “the guy” when it comes to ice core work and has done a lot with paleoclimate (over the ice core record especially), abrupt climate change, glaciology, and sea level rise. He’s a very interesting character who always puts things in a nice perspective, and often humorous ways of teaching (e.g., his Johnny Cash geology lesson).
Professor Galen McKinley at the University of Wisconsin-Madison has recently put up a web page which discusses the global carbon cycle and its connection to climate change. Within, is an applet in which the user can play around with various inputs of carbon sources and sinks, and see how this determines future CO2 concentration and global mean temperature. It might be worth playing around with for a while to see how various future scenarios might look.
I haven’t been able to post much lately, so I just want to put in this post which outlines some of the basic radiative forcing and feedback physics which climatologists use to assess climate change. This is fairly standard material which should be understood by anyone with a deep interest in climate. This article is a bit lengthy so hopefully you have the patience to go through it (or put it on your favorites and come back). Also, a lot of discussion has come up recently over Richard Lindzen’s ERBE analysis in which he purports to show that global climate sensitivity is small, and that the net effect of climate feedbacks is to dampen the so-called Planck response. That basically provoked this post. I’m going to define all these terms below, so don’t worry if I’ve already lost you, and while I am going to do some math in this post, it should be accessible to most people who know a bit of algebra. Skipping over a few calculus steps won’t be detrimental and I’ve tried not to assume much climate background (although I do link to some side references for clarification on some matters). My focus is not on Lindzen’s analysis here, which I don’t feel to be robust at all, but rather building up simple mathematical models for understanding climate change. This will not be new to anyone who has followed the climate literature or discussions for some time, but hopefully it can be helpful to some, or at the very least, serve as a useful reference.
A fundamental issue with changes in atmospheric chemistry is that there may be multiple, and potentially competing effects in terms of problems caused to ecosystems or human welfare. For instance, aerosol declines in developed nations since the middle of the century result in less health and pollution issues, but also lead to global brightening which makes the more of the greenhouse gas influence show up.
First off, I apologize for my lack of posts recently… I’ve been busy and haven’t had much interesting to talk about. A hot topic this week has been the release of the Synthesis report from the discussions at the Copenhagen conference earlier this year. This report, in part, is to take off where the IPCC AR4 left off in discussing key developments that occurred after the deadline for AR4 references.
Most people spending much time on the blogosphere are well aware of claims that “Global Warming stopped in 1998” or similar-style remarks. Even though the 1998-2008 period contains most of the warmest years on the instrumental record (something that is very unusual), and all the years are well above the traditional 1951-1980 (or 1961-90) climatologies, a key focus for skeptics has been the lack of upward slope in a linear regression over the 1998-2008 period.
It has also been emphasized by many that a traditionally defined climatology involves roughly 30 years of data, and so at least a few decades are needed to say much about the underlying trends in climate. However, there is not much in the peer-reviewed literature regarding the probability (or significance) of decadal flatlines, or coolings, when the climate regime is superimposed on a long-term warming trend due to radiative forcing. This is the subject of an upcoming paper in Geophysical Research Letters by David Easterling and Michael Wehner in Is the Climate Warming or Cooling? (subscription required, abstract not available since the paper has not been formally published yet). Their conclusion is that these kind of decadal time-frames can yield slopes of either warming or cooling in a warming world, even in the later 21st century, and nothing is odd about the 1998-2008 trend.
Update- Some changes over the last few hours
Update2- Anthony Watts has contacted Lindzen for clarification
Update 3 on bottom
Science is an evolving process. Data, models, and methods all evolve in time, correcting errors along the way, and building more questions or robust conclusions in the process. It is necessary for people with expertise in a particular area to keep up with the data and any changes that may be made to it, as well as the underlying problems that may exist within the data. In some unfortunate cases, people lose objectivity and will use only a particular dataset (or version of that dataset) that re-inforced some point they are trying to make. In presenting information, not telling people outside of their field what the possible caveats are in a dataset, or explaining revisions that were made to data they show is not generally taken well in academic setting. So it is with a recent example. Continue reading
The idea that methane is a more ‘potent’ greenhouse gas than carbon dioxide is a popular notion. There’s an interesting discussion going on in Bad Astronomy by Phil Plait. Plait says,
Methane is in fact a more efficient greenhouse gas than CO2, but there’s so much less of it that the overall effect is much lower. Methane’s contribution to the greenhouse effect is only about half or less that of carbon dioxide.