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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Climate Hustle

What does past climate change tell us about global warming?

What the science says...

Select a level... Basic Intermediate

Greenhouse gasses, principally CO2, have controlled most ancient climate changes. This time around humans are the cause, mainly by our CO2 emissions.

Climate Myth...

Climate's changed before
Climate is always changing. We have had ice ages and warmer periods when alligators were found in Spitzbergen. Ice ages have occurred in a hundred thousand year cycle for the last 700 thousand years, and there have been previous periods that appear to have been warmer than the present despite CO2 levels being lower than they are now. More recently, we have had the medieval warm period and the little ice age. (Richard Lindzen)

Greenhouse gasses – mainly CO2, but also methane – were involved in most of the climate changes in Earth’s past. When they were reduced, the global climate became colder. When they were increased, the global climate became warmer. When CO2 levels jumped rapidly, the global warming that resulted was highly disruptive and sometimes caused mass extinctions. Humans today are emitting prodigious quantities of CO2, at a rate faster than even the most destructive climate changes in earth's past.

Abrupt vs slow change.

Life flourished in the Eocene, the Cretaceous and other times of high COin the atmosphere because the greenhouse gasses were in balance with the carbon in the oceans and the weathering of rocks. Life, ocean chemistry, and atmospheric gasses had millions of years to adjust to those levels.

Lush Eocene Arctic 50 million years ago

Lush life in the Arctic during the Eocene, 50 million years ago (original art - Stephen C. Quinn, The American Museum of Natural History, N.Y.C)

But there have been several times in Earth’s past when Earth's temperature jumped abruptly, in much the same way as they are doing today. Those times were caused by large and rapid greenhouse gas emissions, just like humans are causing today.

Those abrupt global warming events were almost always highly destructive for life, causing mass extinctions such as at the end of the PermianTriassic, or even mid-Cambrian periods. The symptoms from those events (a big, rapid jump in global temperatures, rising sea levels, and ocean acidification) are all happening today with human-caused climate change.

So yes, the climate has changed before humans, and in most cases scientists know why. In all cases we see the same association between CO2 levels and global temperatures. And past examples of rapid carbon emissions (just like today) were generally highly destructive to life on Earth.

Basic rebuttal written by howardlee

Update July 2015:

Here is a related lecture-video from Denial101x - Making Sense of Climate Science Denial

Last updated on 6 August 2015 by pattimer. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Related Arguments


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Comments 701 to 710 out of 710:

  1. @ 699 MA Rodger,

    What is a discal projection?

  2. Hi MA Rodgers,

    Why would the denialist consider that just 5% of atmospheric CO2 is down to anthropogenic causes? That would be just 20ppm. Where did the other 110ppm come from? That's 860Gt of CO2 so the source should be quite evident.

    I'm a bit confused. What do you mean by where did the other 110ppm come from?

  3. TVC15 @700. Re. CO2 levels in the distant past, see this rebuttal: Do high levels of CO2 in the past contradict the warming effect of CO2?

  4. I need your help again guys!  I posted this statement: In July 2007, a survey of hurricanes in the North Atlantic over the past century noted an increase in the number of observed...

    A denier who many on the sidelines thinks is brilliant and who I suspect is being paid to spout what he spouts responded with this.

    "The operand is "observed."

    You have the technology to observe both tornadoes and hurricanes that you were never able to observe in the past.

    And that's the recent past, outside of the last 50 years.

    There's no science behind "climate change." It's all political and socio-economic-based:

    German economist and Intergovernmental Panel on Climate Change (IPCC) official Ottmar Eddenhofer, explained prior to the Cancun conference in an interview with the Global Warming Policy Foundation (Potter 2010): First of all, developed countries have basically expropriated the atmosphere of the world community. But one must say clearly that we redistribute de facto the world's wealth by climate policy. Obviously, the owners of coal and oil will not be enthusiastic about this. One has to free oneself from the illusion that international climate policy is environmental policy. This has almost nothing to do with environmental policy anymore, with problems such as deforestation or the ozone hole...Basically it's a big mistake to discuss climate policy separately from the major themes of globalization.

    In a paper prepared for the Cancun conference Professor Kevin Anderson, Director of the Tyndall Centre for Climate Change Research, said the only way to reduce global emissions enough, while allowing the poor nations to continue to grow, is to halt economic growth in the rich world over the next twenty years.He called for World War II-type rationing of electricity in order to force people to conserve (Gray 2010)



  5. @703 David Kirtley thank you so much. Odd that did not come up when I searched for Ordovician-Silurian.

  6. This is more motivated reasoning. Well obviously there is science behind it - the whole IPCC WG1 is nothing but science. However, solving it is political and economic and the argument he is trying is that there is a nefarious plot by scientists who want everyone including themselves to suffer massive economic damage for no good reason except... But people which view the world through ideological glasses seem to believe this.

    There is also the IPCC WG3 on ... solutions. In there you can see the published opinion from the many that have studied the issue instead of the opinions (misrepresented at that) of carefully chosen few.  I wonder how well Ottmar Eddenhofer feels his views were represented by the Global Warming Policy Foundation.

  7. I would also say this is totally off-topic. PLease put your comments in an appropriate thread.

  8. TVC15 @701,

    The sun illuminated the disc of the Earth with an intensity measured by TSI. The disc has an area of πr^2. But this energy is spread out, not over a disc but over a globe with area 4πr^2. So TSI requires dividing by 4 to give the average solar climatic impact.

    TVC15 @702,

    The denialist is quoted @695 saying "Is man made CO2 not 5% of atmospheric CO2?" With 410ppm CO2 in the atmosphere, 5% would be 20ppm. But since pre-industrial times CO2 has rise from 280ppm, a rise of 130ppm. If mankind is responsible for only 20ppm of this, where did the other 110ppm come from? Perhaps the denialist is believing that this extra 110ppm is down to the shape-shifting lizards, or perhaps all the unicorns he sees inhabiting the world.

  9. MA Rodger @708

    Thank you for the clarifications! 

    scaddenp @ 706,707

    Ops sorry to step off topic but I appreciate the insights. I read some interesting information about Eddenhofer on Desmog.

  10. Hi Again,

    I'm not sure how to respond to these types of denalist claims.

    So how does one parse out the individual influences of the sun, CO2, water, and now "sulphate aerosols"?

  11. The assertion of the author can be countered with many examples. The subject of longterm climate patterns is so complex and beyond current human understanding that any assertions are highly suspect.


    [PS] Argument from personal incredularity. I suggest you take time to inform yourself of the science and respond with research to back your assertion.

  12. Warend @711 ,

    over less than one hour, you have made 4 comments in 4 separate threads here at SkS.   Each comment was distinctly fatuous.   So the readers can only draw the conclusion you are not a bot.    ;-)

    Warend, you are posting on the wrong website.   This website here is for rational skeptics.   Your comments would have a much better fit at WhatsUpWithThat ~ a website where misery loves company.    ;-)   

  13. All these arguments are irrelevant as mankind is destroying the wildlife and environments of earth.

    Unless mankind changes immediately Man will be extinct before 2400

    The earth does not need mankind!

    Stop polluting the land and seas, stop cutting down the trees, and stop and feed the poor!

    Educate the population so that the population falls. 

    You don't have a choice!


  14. "Unless mankind changes immediately Man will be extinct before 2400"

    Probably earlier?

    “The IPCC report that the Paris agreement based its projections on considered over 1,000 possible scenarios. Of those, only 116 (about 10%) limited warming below 2C. Of those, only 6 kept global warming below 2C without using negative emissions. So roughly 1% of the IPCC’s projected scenarios kept warming below 2C without using negative emissions technology like BECCS. And Kevin Anderson, former head of the Tyndall Centre for Climate Change Research, has pointed out that those 6 lone scenarios showed global carbon emissions peaking in 2010. Which obviously hasn’t happened.
    So from the IPCC’s own report in 2014, we basically have a 1% chance of staying below 2C global warming if we now invent time travel and go back to 2010 to peak our global emissions. And again, you have to stop all growth and go into decline to do that. And long term feedbacks the IPCC largely blows off were ongoing back then too.”

    “ The level of fossil fuel consumption globally is now roughly five times higher than in the 1950s, and one-and-half times higher than in the 1980s, when the science of global warming was confirmed and governments accepted the need to act on it. This is a central feature of the “great acceleration” of human impacts on the natural world. . . .
    CO2 emissions are 55% higher today than in 1990. Despite 20 international conferences on fossil fuel use reduction and an international treaty that entered into force in 1994, man made greenhouse gases have risen inexorably.”

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