What is global dimming?

I just read an article (see link below) that discusses about global dimming. Its a new term to me and I wanted to share. Global dimming is the reduction of heat reaching the earth. Normally, clouds are white, shinny and reflective and they help to reflect the sun’s heat energy back to the space. Green house gases, fossil fuel and other emissions change the formation of the clouds and increases reflection of heat energy. The overall lowers the amount if heat reaching the earth’s surface. SO GLOBAL WARMING IS NOT ALL THAT BAD!



7 responses to “What is global dimming?

  1. nkya246776,
    I read the article about global dimming but I honestly do not know how to interpret that information. I have been researching in many websites, newspapers, books and magazines about global warming for my paper. I have learned that when we start the process of extracting oil from fossil fuels and we initiate the burning of oil (the black smoke that arises) all of those are black particles know as “black carbon” go into the atmosphere. According to The College of Arts and Sciences in Boulder Colorado, a research study has shown that “Black carbon, whose primary component is often called soot, is known to degrade air quality and contribute to warming of the Earth’s atmosphere.” They also found that “Black carbon can also cause warming of the atmosphere by absorbing light. Prolonged exposure to breathing black carbon particles from human and natural burning sources is known to cause human health effects.” Not only that but NASA has reported that “NASA Earth Observatory and NASA’s Goddard Institute for Space Studies (GISS) the average global temperature on Earth has increased 0.8°Celsius (1.4°Fahrenheit) since 1880.” Think about it, since we started the industrial revolution (when we found fossil fuels) the temperature of the Earth has increased since then. So in my opinion, global warming is actually getting bad for the planet and it is only getting worse. Climate change is closer than we think. I hope this information helps. Thank you for your sharing though.

  2. I feel you read the link that I provided in my post you will get more info for your research on global warming. The article did not go too deep on global diming but the interpretation I got was fossil fuel gases change the formation of clouds and that increases the reflective capabilities of the clouds to heat waves. More heat is reflected back to the space and lowers heat on the earth’s surface. As far as destruction to ozone layer by fossil fuel gases that is up to discussion.

  3. nkya246776,
    I read everything from that link that you posted before. I am not a science major nor a scientist, which means that I can only speak for the things that I have researched, and the destruction of the ozone layer is not up to discussion, it is actually a fact. It just does not make sense that ¨heat is reflected back to the space and lowers heat on Earth´s surface.¨ The Earth´s surface has increased over the past 200 years. If you want to know more about this check this links please:
    I hope that helps.

  4. I thought I’d weigh in here, because this exchange is a good example of one of the ways I hope this course proves helpful. First of all, the page Alvin linked to does not seem to be a highly authoritative or current source — it’s filled with typos, it lacks documentation, and in general it reads like a lay person’s summary of a BBC documentary from over 8 years ago. Nevertheless, the phenomenon it describes — global dimming — makes some sense. The “seeding” of clouds by aerosols was mentioned by Emanuel as one of the primary “geoengineering” approaches currently being researched. The idea that clouds have reflective properties that prevent some solar energy from reaching the earth’s surface seems to be uncontroversial. The concept of surface reflectivity also comes up in discussions of glacier melt, since snow and ice cover is also highly reflective (the degree of reflectivity is also known as “albedo”) and thus prevents solar energy from being absorbed by the earth and converted to the lower frequency infrared radiation that is absorbed by greenhouse gases. Instead the solar energy stays in the form of visible and UV light that are not absorbed by greenhouse gases and is reflected back into space. (Recall Emanuel’s discussion of the “snowball earth,” which came about due to a runaway feedback mechanism involving this sort of albedo effect: more ice -> more cooling -> more ice -> more cooling.)
    Beyond this, however, there are layers of complexity that I can’t really address. For instance, if the increase in cloud cover that results from fossil-fuel pollution coincides with an increase in atmospheric carbon dioxide from the burning of those fuels, would the cooling effect of the clouds be outweighed by the warming effect of the added greenhouse gases? (This is why current geoengineering proposals to increase cloud cover generally talk about using water vapor, not pollution, to “seed” the clouds.) And, setting aside the issue of temperature altogether, what about other impacts of “global dimming” such as (according to the article) decreased rainfall? These are the sorts of questions that researchers continue to investigate.
    The real takeaway here, I think, is to begin to understand the complexity of these issues, learn to critically assess the quality of research and reporting, and resolve to be cautious and deliberate in forming one’s own judgments. What I want to emphasize is that being “literate” in this area does not mean that you have to be a scientist or an expert in the field. But it does mean being able to read critically and form reasonable judgments about who, and what information, to trust — which is one of the main things I hope you take away from this course.

  5. Luis,
    I am not denying the fact that destruction of ozone layer has a pretty significant link to the rising in temperatures. In fact, i have supported that fact in my previous posts. My point in this discussion is that greenhouse gases do reflect UV rays back to the space but this is not significant enough to outweigh the amount of rays allowed to reach earth’s surface through the ozone layer.Plus, clouds are not formed all over the space so the reflection of UV rays would only occur in certain areas where clouds are formed. So, if I was doing a math problem, the amount of UV rays (heat energy) allowed through the ozone layer minus amount of UV rays reflected by polluted clouds equals to the net amount of rays reaching the earth’s surface. This net amount is still pretty significant and that is why the temperature on earths surface keeps on rising. Let me know if you need more explanation.

  6. nkya246776,
    Now I understand more about the global dimming effect, but my argument was not against that. I was trying to argue what you said in the first post “SO GLOBAL WARMING IS NOT ALL THAT BAD!” because as I mentioned before, there is enough evidence that the global warming effect is taking action. Nevertheless, thank you for sharing the global dimming information, I made a mistake when I said “It just does not make sense that heat is reflected back to the space and lowers heat on Earth´s surface.” I was trying to interpret what you posted but I was confused. Everything seems more clear after Dr. Findling’s post and your answer. I also read an article from Bill McKibben “The Arctic Ice Crisis” that I think should check, it is very interesting and it talks about the UV light reflected back into the space.
    Link: http://www.rollingstone.com/politics/news/the-arctic-ice-crisis-20120816

  7. Luis,
    I read the Rollingstone article and I am glad we are on the same page now. The future doesnt look so bright for us and the next generations. Rising tempreatures and sea levels, severe weather changes, ice melting at a rapid rate in Greenland and other areas all signify the uncontrollable effects of global warming. As we have previosly discussed in this course, president Obama’s speech on climate change and global warming brings more awareness to this critical issue. Even vice president Al Gore, when he retired he dedicated himself to advocate the issues of climate change and global warming and as I recall he won a Nobel peace prize. It takes more than one or two political leaders to pass laws that limits greenhouse gas emissions. Global warming is still a political agenda and not many leaders want to bring this issue on the table. Plus industries and corporations have a such a high influence on our leaders and decisions they make. So it am guessing it will take a long time before all political leaders get into an agreement on what to do to intervene.

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