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View Diary: You Think It's Hot Now? Wait for Thermogeddon (218 comments)

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  •  Okay, this stuff confues me....Now what is the (0+ / 0-)

    story with the reduced solar activity and how does that fit into the analysis?

    •  Think of the Sun as a stove burner (1+ / 0-)
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      While human activities generate heat, volcanos erupt, hot springs steam, etc. it is the Sun shining on the Earth that is the biggest factor in how much heat the Earth gets every day.

      If you stand in front of a fireplace with a fire burning in it, you can feel the heat. Put a container of water in front of the fireplace, it will begin to warm up just from absorbing that heat being radiated from the fire. (And the side of the container away from the fire will radiate that heat away into the room.) What the Earth picks up on the side facing the sun, it can radiate away as it rotates, into the night sky away from the Sun.

      Now think about a pot of water on a stove burner. You can warm it by turning on the burner underneath, even boil it if you turn up the heat high enough. The water will warm to whatever temperature balances the heat coming in from the burner, against the heat radiating away up from the pot, plus heat used up turning water into vapor.

      Put a lid on the pot to block that heat and vapor steaming away, a simmering pot will get hotter, maybe even hot enough to boil. That's what greenhouse gasses do in the atmosphere - they act like a lid to keep heat from escaping as quickly as it would otherwise, so things get hotter and stay hotter.

      Now if you put the lid on the pot, but also turn down the burner, heat will still be trapped by the lid, but since there's less coming in, it won't get hot as quickly as it would if the burner hadn't been turned down.

      Well, it happens that the Sun turns itself up and down on a regular cycle, stretching over years. Here's a NASA site with info about it, and Wikipedia. Like a pot on a stove under a lid, the Earth is still getting hotter, but not as fast because the Sun isn't putting out as much heat and other kinds of radiation. On the scale of the Solar System, even minor changes (by percentage) still add up to a huge amount.

      It gets more complicated than just heat too. The shifts in the kinds and amounts of radiation reaching the Earth have other effects on the weather than just heat. Heating the upper atmosphere so it expands, interactions with solar plasma and magnetic storms - all of this can affect the weather around the globe in ways we still don't fully understand - but a more active Sun and Greenhouse gasses mean warming will likely accelerate.

      Now the Sun has actually been cranked down farther and longer than had been expected for roughly the past ten years or so. That meant global warming trends seemed to slow down. (Plus air pollution from China actually had the effect of reflecting more heat back into space than had been allowed for.) The upshot was, climate models that didn't allow for the Sun running cooler and China putting up a temporary sunshade, were predicting a faster temperature rise than was actually seen - so there was a huge "I told you so" from the climate change denial industry.

      BUt, it looks like the Sun may be cranking up again, so our brief respite may be ending.

      "No special skill, no standard attitude, no technology, and no organization - no matter how valuable - can safely replace thought itself."

      by xaxnar on Sat Jul 23, 2011 at 11:20:56 AM PDT

      [ Parent ]

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