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Man Made Climate Change

Discussion in 'Earth and Environmental Science' started by Yellow Fang, 21 Nov 2013.

  1. Yellow Fang

    Yellow Fang Veteran Geek

    Location:
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    One thing that has often puzzled me about climate change, is that while a 2°C rise in global temperature is considered safe, a 5°C rise is thought to be catastrophic. In addition, several books I have read have reported that earth temperature has not risen more than 6°C warmer than it has now for hundreds of millions of years. The last time the climate warmed 6°C warmer than now was at the End-Permian mass extinction event, when 90% of species perished. The only vertebrates that survived were ugly pig-like animals that sheltered in pools. However, I read in another book that at the start of the Eocene era, the average temperature in London was 25°C, and that England was covered in rainforest. I thought maybe that was because England was further south, but apparently we were at the same latitude. In addition, crocodiles were living 100 miles from the North Pole, which meant that the water temperature there could never have fallen below 10°C. That sounds like an average temperature rise of well over 5°C. I know the poles are expected to warm up more equatorial area, and that due to trigonometry the surface area of the planet between 45° and 90° latitude is much less than the between 0° and 45°, but still, it seems like a rise well above 5°C.
     
  2. amusicsite

    amusicsite dn ʎɐʍ sᴉɥ┴ Staff Member

    Location:
    UK
    Never confuse local climate change with a global one. There are many things that can change the local climate. Jet streams, volcanoes/ash clouds, earths tilt, strength of the sun, ocean currents, land cover...

    Global changes takes a lot more effort and changes to the whole system. For example the sun has been quite cool, relatively, yet the global temperatures have increased. Something other than the sun has caused this then. We know we don't really affect the strength of the sun, as far as we know. So the sun will probably have a hot period again sometime. Which could compound the effects of whatever is keeping the planet hot.

    The big problem with climate modeling is it's a very complex system. Which fluctuates over hundreds of thousands of years and we have only been accurately modeling it for a few decades. Yes there are some things we can deduce from things like yearly growth rings on trees, though we don't know things like how active the sun was then. Again we may be able to deduce an estimated model of the atmospheres chemical makeup but not to the accuracy we can now.

    So where does that leave us? Well I think you would have to be mad to think we have not changed the atmosphere, there are clouds of pollution that cover huge areas of the planet, millions of tons of chemicals pouring into the oceans and the like. It seems likely these will have an effect. Mostly from past records it seems that most of these warm up the planet, though some protect us from the sun and may do the reverse.
    I'm not sure on the 'disaster' temperature limit, though I believe it's the temperature increase which would trigger the melting of all ice in the summer. This would mean more of the sun's energy would be soaked up by the planet, further increasing the temperature of the planet and oceans. Which in turn and along with the ice melt will most likely cause sea levels to drastically raise....

    Or something like that.
     
  3. Yellow Fang

    Yellow Fang Veteran Geek

    Location:
    Reading
    Yes, but I still can't see how an average 5°C rise in average global temperature can produce a 15°C rise in temperature at a latitude of 51° (London) and all points north.

    Anyway, after a lot of struggling, I think I found the surface area of the Earth above a certain latitude.

    A = 2πR^2(1-sin(Θ))
    R= 6371 km
    29.3% of the Earth's surface is above 45° North and below 45° South. 11.1% of the Earth's surface is further north than London with another 11.1% on the other side of the planet. I suppose if you divide 5°C by 0.222 you get nearly 23°C, still it's a bit iffy. How much did it warm in the tropics?
     
  4. pipps

    pipps Regular Geek

    Wow, I didn't know any of this. Where did you learn that? If it's a book, I want to read it! It's weird to think there was crocodiles up there and London was a rain forest! When was this Eocene era? Sorry, I am pretty much clueless about these types of things.
     
  5. Yellow Fang

    Yellow Fang Veteran Geek

    Location:
    Reading
    These were two books. One was Six Degrees by Mark Lynas, which is enough to give you nightmares at night. I think the other was called something like Eocene: From Greenhouse to Icehouse. It was a geology text book, not really about man-made climate change. It's main controversy was the exact ending of the Eocene epoch. The bit about the rainforest and crocodiles was at the start of the book, but on the whole it was more interested in the other end of the timescale when things were cooling down. There was a lot of talk about foraminiferans, I remember, which are tiny plankton with shells. The Eocene started about 55 million years ago and ended about 30 million years ago.
     
  6. amusicsite

    amusicsite dn ʎɐʍ sᴉɥ┴ Staff Member

    Location:
    UK
    So how much of the UK warming would be down to the La Niña and the Gulf Stream? I would imagine that an increase in ocean temperature could increase the amount energy in these systems.
     
  7. pipps

    pipps Regular Geek

    Oooh, wow. Now that you have said that books is enough to give you nightmares, I kind of want to read it haha. Going to have a look on Amazon for it. Sounds exciting. Will check out the other one too as I find this a really fascinating subject.

    Thank you for sharing!:)
     
  8. Yellow Fang

    Yellow Fang Veteran Geek

    Location:
    Reading
    The other book was called The Eocene-Oligocene Transition by Donald R. Prothero. I am not sure I would recommend buying it as it is quite expensive for a paperback. Also, it is a bit dull. If you really want to read it, I will send you my copy, so long as you promise to send it back when you've finished.
     
  9. amusicsite

    amusicsite dn ʎɐʍ sᴉɥ┴ Staff Member

    Location:
    UK
    [​IMG]

    :eek::eek::eek:
     
  10. amusicsite

    amusicsite dn ʎɐʍ sᴉɥ┴ Staff Member

    Location:
    UK
  11. Yellow Fang

    Yellow Fang Veteran Geek

    Location:
    Reading
    Yes, it is scary. However, there are geo-engineering techniques which we could resort to. Geo-engineering is very, very contentious. A lot of people (well Greens, but a fair few climate scientists too) think it is total insanity to consider it. Personally, I suspect we may not have an option.

    I have been reading Mark Lynas's latest book, The God Species. He discusses a number of environmental boundaries that he considers vital that we do not cross. These include greenhouse gases, freshwater, land use, biodiversity, toxins, aerosols, nitrogen fertilisers and ozone. Lynas is not really a Green. He thinks the Green movement has done a lot of damage to environmental causes by their opposition to technologies such as nuclear power, geo-engineering and GM crops. He also tends to think that the Green narrative of cutting back consumption and curtailing free-market economics has caused a political backlash. Ideology trumps science, incredibly enough. I am not sure I buy everything that Mark Lynas says, but he is right that pessimism is not an option. However difficult it is, we (well people with clout) have got to keep trying.
     
  12. pipps

    pipps Regular Geek

    Awh thank you for that offer, think I'm going to stick to The six degrees book for now though. I'm going on holiday soon and this book looks like some perfect holiday reading for me. I will be sat on the beach reading about all the devastation that will soon be! It really does look scary!
     
  13. amusicsite

    amusicsite dn ʎɐʍ sᴉɥ┴ Staff Member

    Location:
    UK
  14. amusicsite

    amusicsite dn ʎɐʍ sᴉɥ┴ Staff Member

    Location:
    UK
  15. amusicsite

    amusicsite dn ʎɐʍ sᴉɥ┴ Staff Member

    Location:
    UK
    http://phys.org/news/2016-02-greenland-ice-sheet-mississippi-river.html

    Will be interesting to see how this affects plankton in the Atlantic and I guess in the future if the ice reduces a lot then I guess this could drop below the levels that the sea around it is used to, which could be devastating to local marine life.
     
  16. Yellow Fang

    Yellow Fang Veteran Geek

    Location:
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    I read an article in a paper that suggested it could be a brake on climate change. The algal blooms that result from the nutrients released from melting ice die and drop to the bottom of the sea.
     
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  17. amusicsite

    amusicsite dn ʎɐʍ sᴉɥ┴ Staff Member

    Location:
    UK
    Indeed in the short term... What about the long term, if say for example most of the ice there does melt before the end of the century, or later. Then it could drastically reduce the algal around the island.
     
  18. amusicsite

    amusicsite dn ʎɐʍ sᴉɥ┴ Staff Member

    Location:
    UK
    Last edited: 9 Jul 2018
  19. amusicsite

    amusicsite dn ʎɐʍ sᴉɥ┴ Staff Member

    Location:
    UK
    http://www.flassbeck-economics.com/how-climate-change-is-rapidly-taking-the-planet-apart/

    Screenshot Editor.png

    So the next 10 years we get the full effects of the late 70s early 80s massive emissions increase. Along with all the feedback loops we have triggered. Could get hot and humid very quickly.
     
  20. amusicsite

    amusicsite dn ʎɐʍ sᴉɥ┴ Staff Member

    Location:
    UK