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Thread: Five Climate Change Science Misconceptions - Debunked

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    Five Climate Change Science Misconceptions - Debunked

    Five climate change science misconceptions – debunked


    Mark Maslin, Professor of Earth System Science, UCL, The ConversationSeptember 15, 2019


    http://theconversation.com/five-clim...ebunked-122570


    The science of climate change is more than 150 years old and it is probably the most tested area of modern science. However the energy industry, political lobbyists and others have spent the last 30 years sowing doubt about the science where none really exists. The latest estimate is that the world’s five largest publicly-owned oil and gas companies spend about US$200m each year on lobbying to control, delay or block binding climate-motivated policy.
    This organised and orchestrated climate change science denial has contributed to the lack of progress in reducing global green house gas (GHG) emissions - to the point that we are facing a global climate emergency. And when climate change deniers use certain myths – at best fake news and at worse straight lies – to undermine the science of climate change, ordinary people can find it hard to see through the fog. Here are five commonly used myths and the real science that debunks them.

    1) Climate change is just part of a natural cycle

    2) Changes are due to sunspots/galactic cosmic rays

    3) CO2 is a small part of the atmosphere - it can't have a large heating effect

    4) Scientists manipulate all data sets to show a warming trend

    5) Climate models are unreliable and too sensitive to carbon dioxide

    See the link for details. I would also add another myth that wasn't mentioned: 6) Future projections rely entirely on climate models - It is possible to estimate the future climate based on multiplying

    the climate sensitivity (which can be derived from the paleoclimate ice core data) times the projected climate forcings at some future time (example 2100).

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    Climate sensitivity refers to the amount of global surface warming that will occur for a doubling of CO2 levels above pre-industrial levels. An immediate doubling of CO2 results in a decrease of

    3.7 watts per square meter of energy being radiated from earth to space. The earth's surface would warm by 1.2 degrees C. in order to restore the energy the energy balance. This can be

    calculated from Planck's law.

    climate sensitivity (CS) = the change in mean global temp. (delta T) divided by the change in radiation forcings (deltaF).

    CS=1.2degrees C/ 3.7 = 0.32 (no feedback climate sensitivity)

    Since there are feedbacks in the climates system the no feedback climate sensitivity will not tell us how the global mean temp. (GMT) will change over time. Water vapor is the most important

    climate feedback because as the atmospheric temperature rises, the atmosphere's absolute humidity rises with the relative humidity staying approximately constant, and water vapor is a

    powerful greenhouse gas. The water vapor feedbback is therefore a positive feedback and may add around 1.0 watts/square meter of additional radiation equivalent forcing. The earth becomes

    less reflective as ice melts in response to warmer temperatures and the change in reflectivity (albedo) from 1979 to 2011 corresponded to +0.3 watts/square meter of additional forcing. Other

    feedbacks include lapse rate, clouds changes, and changing winds). The cloud feedback is not well known but the evidence points to it being weakly positive. These are all fast feedbacks with

    the water vapor feedback being almost instantaneous and the response time is limited to 50 years for all feedbacks.



    Paleoclimate studies have determined a climate sensitivity close to 3.0 degrees C. per doubling of CO2 or 3.0/3.7 = 0.81 degrees C./watts per square meter.

    If we want to find out how much the RCP 4.5 ( the 4.5 is the equivalent radiation forcing number) scenario will warm the planet by 2100 we can multiply 0.81 times 4.5 = 3.6 degrees C above

    pre-industrial levels. This assumes that the planetary energy will be balanced in 2100. If not, then the GMT will be a little less than 3.6 degrees C. How does this compare with the IPPC AR5

    report? It is high by about 1 degree C.

    The IPCC report projects a mode of 2.4 degrees C. in the 2081-2100 time frame relative to pre-industrial levels. This discrepancy bothers me and seems to indicate a climate sensitivity that

    could be 25% less than 3.0 degrees C. per CO2 doubling. This is inconsistent with previous studies by the IPCC and inconsistent with what I have read elsewhere.

    The climate sensitivity calculation is only an estimate and the standard deviation range is from 2.0 to 4.5 degrees C per doubling of CO2. The simple calculation plus

    the theoretical considerations on climate feedbacks gives me confidence that the RCP scenario will result in at least a 2.5 degree C. increase in GMT by 2100 and that

    will likely be catastrophic for much of the world.
    Last edited by skepticalmike; 09-16-2019 at 03:25 AM.

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    As a skeptical luke-warmist, I pay about as much attention to denier BS as I do alarmist BS.
    Edmund Burke: "In vain you tell me that Artificial Government is good, but that I fall out only with the Abuse. The Thing! the Thing itself is the Abuse!"

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    The graph below is an estimate of the human influence on climate for 4 different scenarios that does not rely on computer climate models. The method uses only human perturbations (forcings) to the climate system

    and multiplies that by climate sensitivity. As we can see from the graphs below, the global mean temperature continues to rise beyond 2150 for all but the most benign scenario, RCP3-PD. Under the RCP4.5 scenario

    the GMT rises to 2.7 degrees C. by 2100 and to 3.25 degrees C. by 2150. I am focusing on the most likely scenario and the most likely climate sensitivity value.

    Everything below is from skepticalscience.com, "A Glimpse at Our Possible Future Climate, Best to Worst Case Scenarios".


    Caveats: The following graphs do not include natural influences on global surface temperatures, or internal variability, but they do include all human forcings. Note that while we focus on the equilibrium climate sensitivity in this post, short-term temperature responses are dictated by the transient climate response. The graphs below primarily show this transient short-term response, and some additional warming that will continue to occur until the planet reaches a new energy equilibrium state. This does not account for possible changes in the carbon cycle, like reduced ocean carbon absorption or releases from melting permafrost, for example. These graphs only consider human emissions, and they're simple approximations (temperature = sensitivity x forcing), not climate model runs.






    Figure 5: Estimated expected warming for each RCP scenario in a most likely case world with 3°C equilibrium climate sensitivity.





    Figure 3: RCP scenario atmospheric CO2 concentrations through 2100




    Figure 2: RCP fossil fuel CO2 emissions scenarios through 2100. Emissions estimates from the International Energy Agency (IEA) through 2011 in black.



    Some adverse impacts are expected by the time we reach 1.5°C surface warming above pre-industrial temperatures. For example, widespread coral mortality, hundreds of millions of people at risk of increased water stress, more damage from droughts and heat waves and floods, and increased species extinction rates. However, by and large these are impacts which we should be able to adapt to, at a cost, but without disastrous consequences.Once we surpass 2°C (which is internationally considered the "danger limit" beyond which we should not pass), the impacts listed above are exacerbated, and some new impacts will occur. Coastal flooding will impact millions of people. Coral bleaching will be widespread (exacerbated by ocean acidification), most coral reefs may not survive (Frieler et al. 2012, Kiessling et al. 2012), global food crop production will decline, and sea levels will rise by close to 1 meter by 2100. Up to 30% of global species will be at risk for extinction.At 3–4°C warming, widespread coral mortality will occur (at this point corals are basically toast), and 40–70% of global species are at risk as we continue on the path toward the Earth's sixth mass extinction. Glacier retreats will threaten water supplies in Central Asia and South America. The possibility of significant releases of CO2 and methane from ocean hydrates and permafrost could amplify global warming even further beyond our control. Sea level rise of 1 meter or more would be expected by 2100, with the possibility of destabilization of the Greenland and West Antarctic ice sheets, which would cause much more sea level rise and flooding of coastal communities.

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    SkepicalMike, please explain "climate sensitivity." What is it, how is it determined/derived?
    Edmund Burke: "In vain you tell me that Artificial Government is good, but that I fall out only with the Abuse. The Thing! the Thing itself is the Abuse!"

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    Quote Originally Posted by Chris View Post
    SkepicalMike, please explain "climate sensitivity." What is it, how is it determined/derived?
    The climate sensitivity is a way to estimate the global mean temperature (GMT) change from one equilibrium state to another equilibrium state given changes in climate "forcings". Climate

    forcings can be natural or anthropogenic perturbations to the climate system such as changes in: greenhouse gases, atmospheric aerosols, land surface albedo (reflectivity), or solar irradiance.

    The climate sensitivity includes the effects all of the climate feedbacks and how they may amplify or attenuate the GMT over time. It allows us to estimate the change in GMT without having to

    know exactly what the feedbacks are and how they effect the climate.


    Climate sensitivity can be derived from climate models or from analyzing physical evidence from past changes in climate. The end of the Last Glacial period is often used to estimate climate

    sensitivity. Using ice core data the climate forcing caused by changing levels of CO2, methane, and nitrous oxide was 3.0 watts per square meter. The climate forcing caused by the Earth's

    surface change in albedo was 3.5 watts/square meter. The temperature change was 5 degrees C. The climate sensitivity can be calculated by dividing the temperature change by the climate

    forcings, 5/6.5 = 0.77 degrees C/watt/square meter. It is important to do the analysis when the climate is in equilibrium at each state and this is confirmed by noting no change in sea levels.

    A doubling of CO2 results in 3.7 watts/square meter less energy radiated to space and the GMT change resulting from this can be found by multiplying 3.7 times 0.77 = 2.85 degrees C. This

    formula works not just for CO2 but for all radiation forcings.
    Last edited by skepticalmike; 09-17-2019 at 02:37 AM.

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    OMG

    This is like hinduism of climate science or something.
    Last edited by Lummy; 09-18-2019 at 09:41 PM.
    Congratulations to our President Trump on taking out top ISIS terrorist Abu Bakr al-Baghdadi!

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    Quote Originally Posted by skepticalmike View Post
    The climate sensitivity is a way to estimate the global mean temperature (GMT) change from one equilibrium state to another equilibrium state given changes in climate "forcings". Climate

    forcings can be natural or anthropogenic perturbations to the climate system such as changes in: greenhouse gases, atmospheric aerosols, land surface albedo (reflectivity), or solar irradiance.

    The climate sensitivity includes the effects all of the climate feedbacks and how they may amplify or attenuate the GMT over time. It allows us to estimate the change in GMT without having to

    know exactly what the feedbacks are and how they effect the climate.


    Climate sensitivity can be derived from climate models or from analyzing physical evidence from past changes in climate. The end of the Last Glacial period is often used to estimate climate

    sensitivity. Using ice core data the climate forcing caused by changing levels of CO2, methane, and nitrous oxide was 3.0 watts per square meter. The climate forcing caused by the Earth's

    surface change in albedo was 3.5 watts/square meter. The temperature change was 5 degrees C. The climate sensitivity can be calculated by dividing the temperature change by the climate

    forcings, 5/6.5 = 0.77 degrees C/watt/square meter. It is important to do the analysis when the climate is in equilibrium at each state and this is confirmed by noting no change in sea levels.

    A doubling of CO2 results in 3.7 watts/square meter less energy radiated to space and the GMT change resulting from this can be found by multiplying 3.7 times 0.77 = 2.85 degrees C. This

    formula works not just for CO2 but for all radiation forcings.
    https://wattsupwiththat.com/2016/03/...uggeddaboutit/

    the reason I wrote this post. This year, the atmospheric CO2 level is right around four hundred ppmv. So to double, it would have to go to eight hundred ppmv … and even assuming we could maintain exponential growth for the next eight decades and we burned every drop of the two thousand gigatonne high-end estimate of the fossil reserves, CO2 levels would still not be double those of today.

    And in fact, ......more at link
    Last edited by Cotton1; 09-19-2019 at 01:27 AM.
    when the mind is thinking it is talking to itself...Plato

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    Quote Originally Posted by Cotton1 View Post
    https://wattsupwiththat.com/2016/03/...uggeddaboutit/

    the reason I wrote this post. This year, the atmospheric CO2 level is right around four hundred ppmv. So to double, it would have to go to eight hundred ppmv … and even assuming we could maintain exponential growth for the next eight decades and we burned every drop of the two thousand gigatonne high-end estimate of the fossil reserves, CO2 levels would still not be double those of today.

    And in fact, ......more at link
    I read the article. I don't have any confidence in the models used to produce the results, especially the one relying on a single exponential decay model. The carbon cycle is extremely

    complex and any carbon model is going to be very complicated. This type of analysis needs to be done by experts and go through a peer review process. This article was written by

    someone with no academic credentials and it would never be published in a scientific journal. We have to know the details of the Bern model, which were not given, and the results don't

    look reasonable to me. The CO2 levels from the graphs using the Bern model appear to low.

    The proven reserves of fossil fuel carbon are 746 Gtons (G=giga = 1x10 exp9) = 2740 Gtons CO2. The actual fossil fuel reservoir of carbon is 5000 Gtons of which 80% is in coal, 10% in

    oil and 10% in natural gas.


    Fate of fossil fuel CO2 in geologic timeDavid ArcherDepartment of the Geophysical Sciences, University of Chicago, Chicago, Illinois, USA

    ] The idea that anthropogenic CO2 release may affect
    the climate of the earth for hundreds of thousands of years has not reached general public awareness. Goodstein [2004]reports that fossil fuel CO2 will disappear after a millennium.This misconception is widespread in scientific and public discussion. It certainly makes sense to focus our attention on the century timescale within which we live out our lives, and within which most of the CO2 will be absorbed by the natural carbon cycle[3]
    Potential sources of new CO2 to the ocean/atmosphere carbon pools include fossil fuel carbon, changes in the sizeof the terrestrial biosphere including soil organic carbon,and changes in the amount of methane sequestered in frozen clathrate deposits in terrestrial permafrost and ocean margin sediments. The amount of fossil fuel carbon available for energy use is generally considered to total about 5000 G ton of carbon, dominated by coal. Ultimately extractable oil resources are thought to be about 250 Gton C, potentially expanding several fold if unconventional oil sources such a soil sands are considered. Traditional natural gas reserves represent about 200 Gton C, again with the potential to expand several fold with future exploration and technological advances [Rogner, 1997; Sundquist, 1985]. Humankind has already released about 300 Gton C from fossil fuels and deforestation, and the IPCC business-as-usual scenario(IS92a) projects about 1600 Gton of carbon released from a combination of fossil fuels and terrestrial fluxes, with emissions beyond 2100 unspecified. The maximum amount
    of fossil fuel carbon that could ultimately be released would seem to be about 5000 Gton C, on a timescale of several centuries.


    Everything below is from yaleclimateconnections.org.


    https://www.yaleclimateconnections.o...arbon-dioxide/


    Using a combination of various methods, researchers have estimated that about 50 percent of the net anthropogenic pulse would be absorbed in the first 50 years, and about 70 percent in the first 100 years. Absorption by sinks slows dramatically after that, with an additional 10 percent or so being removed after 300 years and the remaining 20 percent lasting tens if not hundreds of thousands of years before being removed.
    As University of Washington scientist David Archer explains, this “long tail” of absorption means that the mean lifetime of the pulse attributable to anthropogenic emissions is around 30,000 to 35,000 years.


    Last edited by skepticalmike; 09-20-2019 at 04:57 PM.

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    This article briefly discusses the latest climate models which will likely increase the projections of the global mean temperature rise for all scenarios.

    Earth warming more quickly than thought, new climate models show

    https://phys.org/news/2019-09-earth-quickly-climate.htm


    A new generation of 30-odd climate models known collectively as CMIP6—including the two unveiled Tuesday—will underpin the IPCC's next major report in 2021.
    "CMIP6 clearly includes the latest modelling improvements," even as important uncertainties remain, Joeri Rogelj, an associate professor at Imperial College London and an IPCC lead author, told AFP.
    These include increased supercomputing power and sharper representations of weather systems, natural and man-made particles, and how clouds evolve in a warming world.
    "We have better models now," said Boucher. "They have better resolution, and they represent current climate trends more accurately."
    'Tipping points'
    A core finding of the new models is that increased levels of CO2 in the atmosphere will warm Earth's surface more—and more easily—than earlier calculations had suggested.
    If confirmed, this higher "equilibrium climate sensitivity", or ECS, means humanity's carbon budget—our total emissions allowance—is likely to shrink.





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