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Temperature chart for the last 11,000 years

220 points by deusclovis 13y ago

exit 13y ago
googling "industrial revolution averted iceage" returns a few conservative blogs, smugly pleased with the possibility the only credible commentary i can find is in a nytimes article: "Scientists say that if natural factors were still governing the climate, the Northern Hemisphere would probably be destined to freeze over again in several thousand years. 'We were on this downward slope, presumably going back toward another ice age,' Dr. Marcott said." http://www.nytimes.com/2013/03/08/science/earth/global-temperatures-highest-in-4000-years-study-says.html http://www.nytimes.com/2013/03/08/science/earth/global-tempe...
- kaybe 13y ago
  I cannot cite the exact words, but in discussions professors have indeed expressed the opinion that a next ice age won't be of concern for us. Those charts, especially those going back further, are a good argument for why we will need to control the climate at some point in the future (but please not when we have not figured out how to without significant risk).
- deleted 13y ago
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  - mistercow 13y ago
    By "conservatives" exit means the American kind, who by and large deny the existence of AGW.
    - gwright 13y ago
      The dispute isn't about AGW, it is about CAGW. AGW: human activity increseas CO2 increased CO2 => increases temperature CAGW: Catastrophic Anthropogenic Global Warming human activity increases CO2 increased CO2 => increases temperature positive climate feedback mechanisms => magnified warming It is that last item where the controversy lies. Climate models all have a parameter that represents the climate sensitivity which predicts the way the climate responds to changes to input. If you believe that the sensitivity is high, then small changes to the input (via CO2 warming, for example) lead to large changes in the system and catastrophic results. If you believe the sensitivity is low, then small changes to the input do not have catastrophic outcomes. There has been considerable news of late that observations of temperature changes over the last 15-20 years do not match the predictions over the same time period of the models using a high climate sensitivity values. Edit: fixed formatting and spelling
      - anon1385 13y ago
        >The dispute isn't about AGW For most conservatives it is. Even in this thread we have people claiming it's all just a natural cycle. >There has been considerable news of late that observations of temperature changes over the last 15-20 years do not match the predictions over the same time period of the models using a high climate sensitivity values. New papers that suggested slightly lower sensitivity gave figures that were still within the range put forward in the last IPCC report, and still suggested sensitivities high enough to cause serious and damaging climate change unless emissions are reduced. Climate is a noisy system, you can't measure significant change in global surface temperature in only 15 years. You should take the time to go and look at the actual temperature data to get a feel for how noisy it is[1]. Short term cycles like ENSO -- that we currently have no real ability to predict -- have a far greater impact on surface temperatures over those time scales[2]. It just so happens that the last 15 years or so have seen a dominance of la Niña years (which correlate with cooler surface temperatures) for reasons we don't really understand; it could just be random or possibly ENSO could have been affected by climate change. There has been no "pause" at all in other measurements: 2012 was the lowest recorded extent and volume of arctic sea ice and the trend is clear: http://psc.apl.washington.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAnomalyCurrentV2.png http://psc.apl.washington.edu/wordpress/wp-content/uploads/s... Ocean heat has continued to rise: http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/ http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/ The only people talking about a "pause" are conservative pundits and climate change deniers. It shows weaknesses in the models, but nobody was claiming that the models were accurate for short timescales or that we have the complete picture a at all. There are still huge gaps in our understanding, but that is hardly a cause for celebration. [1] http://www.skepticalscience.com/pics/HadCRUT4vs3.jpg http://www.skepticalscience.com/pics/HadCRUT4vs3.jpg [2] https://tamino.wordpress.com/2013/09/02/el-nino-and-the-non-spherical-cow/ https://tamino.wordpress.com/2013/09/02/el-nino-and-the-non-...
      - asgard1024 13y ago
        So it's like if you're not disputing smoking is bad for health, but you're saying it's not "catastrophically" bad? It's like the sooner one stops smoking, the less chance he has for a "catastrophic" lung cancer; it's not like when you smoke 10K cigarettes you sure won't get cancer but if you smoke 20K you sure do. Of course, different people call "catastrophe" different things, but the analogy is quite apt here. There is no "catastrophe" coming, in the sense of a sudden disaster. We can stop any time, and the sooner we stop, the better overall result (and less costly) will be.
  - InclinedPlane 13y ago
    That's due to the little ice age (http://en.wikipedia.org/wiki/Little_Ice_Age http://en.wikipedia.org/wiki/Little_Ice_Age), which extended to the mid 19th century, not man-made climate change.
    - tehwalrus 13y ago
      apologies; I thought it was mainstream to believe that the "little ice age" would have continued into a proper one if not for the industrial revolution. This part of my comment remains relevant though: Conservatives have little to be smug about here - it shows that climate change is indeed anthropogenic, contrary to their narrative for the last 20 years - the red line, modern records, show a much faster rate of change than anything in the natural period.
      - kaybe 13y ago
        I think it is mainstream to acknowledge the possiblity of that, but not have a fixed believe. After all, it's climate science and we're only at the beginning, and who knows, there might have been another few thousand years of stable climate.
temphn 13y ago
This plot compares an inferred model to the instrumental record. Here is the study expressed in the words of Real Climate: http://www.realclimate.org/index.php/archives/2013/09/paleoclimate-the-end-of-the-holocene/ http://www.realclimate.org/index.php/archives/2013/09/paleoc... Over the last decades, numerous researchers have painstakingly collected, analyzed, dated, and calibrated many data series that allow us to reconstruct climate before the age of direct measurements. Such data come e.g. from sediment drilling in the deep sea, from corals, ice cores and other sources. Shaun Marcott and colleagues for the first time assembled 73 such data sets from around the world into a global temperature reconstruction for the Holocene, published in Science. Or strictly speaking, many such reconstructions: they have tried about twenty different averaging methods and also carried out 1,000 Monte Carlo simulations with random errors added to the dating of the individual data series to demonstrate the robustness of their results. Marcott et al.'s graphic states that their model reflects historical temperatures so accurately that it can measure the average temperature of the entire globe continuously back to 8000 years ago, to within a small fraction of 1 degree Celsius (i.e. the 1-sigma error bars). That is simply an extraordinary claim given: 1) The "divergence problem". The lack of correlation between model inputs like tree rings and the instrumental record over the last few decades is acknowledged by all; climate scientists generally state that it is due to anthropogenic factors, arguably assuming the consequent. http://www.skepticalscience.com/Tree-ring-proxies-divergence-problem.htm http://www.skepticalscience.com/Tree-ring-proxies-divergence... 2) Serious climate model prediction failures over the past 10 year period, as acknowledged in Nature: http://www.nature.com/news/climate-change-the-forecast-for-2018-is-cloudy-with-record-heat-1.13344 http://www.nature.com/news/climate-change-the-forecast-for-2... In other words, key model inputs used in climate reconstructions do not strongly correlate with the instrumental record over the last 30-40 years ("the divergence problem") and climate models have so far had a poor track record over the last 15 years, with average temperatures winding up below the envelope of model predictions. These predictive failures in the datasets we can check bode ill for the prospect of hindcasting global average temperatures to within 1 degree more than 8000 years ago.
- jdgiese 13y ago
  The plot does seem too precise to take seriously IMO, although I am an engineer, and not a climate scientist.
ctdonath 13y ago
Temperature chart for the last 425,000 years: http://ctdonath.blogspot.com/2012/02/global-climate-change-in-context.html?m=1 http://ctdonath.blogspot.com/2012/02/global-climate-change-i...
- davyjones 13y ago
  Wait...are we in "summer" on that time-scale now?!
  - ctdonath 13y ago
    Yup. At the end of the Dog Days of August, expecting an early hard frost. We'll be wishing for "warming" soon enough.
- kolbe 13y ago
  Do you know why the original 11,000 year chart doesn't look anything like the 10,000 year chart in your link?
  - wffurr 13y ago
    Different data set. The 10,000 year chart is only Antarctic ice cores. The 11,000 year chart is a composite of a number of temperature records - tree rings, etc.
    - ctdonath 13y ago
      The 11,000 year chart is a composite. Funny how the data takes a wild change right where a completely new data source is included.
      - anon1385 13y ago
        You realise that there is an entire paper in Science about how they synthesised the various temperature records? http://www.usu.edu/geo/physical/MarcottEtal_Science_2013.pdf http://www.usu.edu/geo/physical/MarcottEtal_Science_2013.pdf If you have something constructive to say about the methodology then let us know rather than making ignorant comments that tell us more about your political ideology than about the science.
_delirium 13y ago
Sources, The Science paper: http://www.usu.edu/geo/physical/MarcottEtal_Science_2013.pdf http://www.usu.edu/geo/physical/MarcottEtal_Science_2013.pdf Online supplemental material: http://www.sciencemag.org/content/suppl/2013/03/07/339.6124.1198.DC1/Marcott.SM.pdf http://www.sciencemag.org/content/suppl/2013/03/07/339.6124.... The figure itself is a new plot by Potsdam University researchers for realclimate.org, though, using the same dataset, but not a graphic taken directly from the paper (the paper's Fig. 1 has some alternate versions).
- throwaway_yy2Di 13y ago
  I think this stinks. The Science paper says their reconstruction is smoothed and has low time resolution. They say it preserves no variability at all on timescales <300 years, and attenuates even 1,000 year variations. Superimposing this with the 30-year Hadley data seems misleading, because it is on a very short timescale which is suppressed from the paleologic data. (edit): "Because the relatively low resolution and time uncertainty of our data sets should generally suppress higher-frequency temperature variability, an important question is whether the Holocene stack adequately represents centennial- or millennial scale variability. [...] The results suggest that at longer periods, more variability is preserved, with essentially no variability preserved at periods shorter than 300 years, ~50% preserved at 1000-year periods, and nearly all of the variability preserved for periods longer than 2000 years (figs. S17 and S18)."
  - _delirium 13y ago
    The realclimate.org post discusses that as a potential issue, yes. See the section following the sentence: Because the proxy data have only a coarse time resolution – would they have shown it if there had been a similarly rapid warming earlier in the Holocene?
    - deleted 13y ago
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    - throwaway_yy2Di 13y ago
brownbat 13y ago
Out of idle curiosity, can anyone tell me more about what a 0.4 (0.6, 1, 2...) °C anomaly feels like, maybe with reference to cities that have climates with differing annual averages? I mean, is it like shifting every city 5 ° in latitude closer to the equator, or what? (I know this wouldn't capture the whole story, I'm just curious.) EDIT: I guess the state of New York has a range of annual average temperatures from 4 °C to 12 °C, so maybe this isn't useful at all. http://en.wikipedia.org/wiki/Climate_of_New_York#Temperatures http://en.wikipedia.org/wiki/Climate_of_New_York#Temperature...
- pcrh 13y ago
  In the maps linked below, each isotherm represents a 2 C difference. So a global rise of 2 C would be equivalent to a 100-200 km or so shift towards the equator, for a given location. Or nearly equivalent to the temperature difference in the center of a major city compared to its suburbs. http://solargis.info/doc/_pics/SolarGIS-iMaps--World-air-temperature-map--Yearly-longterm-average.jpg http://solargis.info/doc/_pics/SolarGIS-iMaps--World-air-tem... http://solargis.info/doc/_pics/SolarGIS-iMaps--World-air-temperature-map--Yearly-longterm-average--detail2.jpg http://solargis.info/doc/_pics/SolarGIS-iMaps--World-air-tem...
- noiv 13y ago
  If the temperatures are be equally distributed plus 1°C feels like 1°C plus. But that's not the case neither in space nor time. I worry more about the peaks.
- sethrin 13y ago
  Think of it more as extra energy being imparted to the global weather system. This will have all sorts of fun and exciting effects, and as I understand the warming will be greatest at the poles. Alaska has warmed by about 1.6[0] in the last 60 years, and the interior of Alaska by 1.4° C in the last 100[1], compared to a global temperature rise of .8° C over the same period. This has resulted in the melting of thousands of cubic kilometers of glacial ice, with this study[2] suggesting that this is the largest glaciological factor in rising sea levels. To the eyes of the native inhabitant, the glacial retreat is shocking, with the lower altitude glaciers most affected. We've built glacier overlooks in some places, where once the glacier was a stone's throw away, and now it's barely visible, and in another few decades the only thing they'll be able to show anyone there are photos. I've seen photos from the early 1900s of glacial termini which towered over the masts of a sail-rigged steamer. Today there is a fjord there, and the glacier is more than 13km away. And you want to know what that feels like? How about instead you imagine how it feels to watch the Arctic melting around you, while an endless circus of millions deny that it's even happening. [0] http://climate.gi.alaska.edu/ClimTrends/Change/TempChange.html http://climate.gi.alaska.edu/ClimTrends/Change/TempChange.ht... [1] http://oldclimate.gi.alaska.edu/papers/Arctic62-3-295.pdf http://oldclimate.gi.alaska.edu/papers/Arctic62-3-295.pdf [2] http://glaciers.gi.alaska.edu/material/arendt_phd.pdf http://glaciers.gi.alaska.edu/material/arendt_phd.pdf
nhoss2 13y ago
Am I alone in finding the graph scary? This rate of change in temperature is probably not something that would be easy to slow down, yet it feels like not many people care about this.
- cubsink 13y ago
  I find it fucking depressing.
rjdagost 13y ago
For a little while I was interested in paleoclimatology and I started studying how researchers developed these historical temperature reconstruction curves. Basically you take “proxies” for temperature, things like tree rings, coral growth, sediment layer thickness, etc. and you posit a relationship between the proxy measurements and temperature. Measurements that better fit the hypothesized model get more weight in the temperature reconstruction. The main problem is that no one knows if the hypothesized models (temperature vs. tree ring thickness, sediment layer thickness, etc.) have any validity. Why should tree rings grow linearly with temperature- what about a huge number of other variables? The temperature “signal” is at best very weak. Decoupling the temperature signal from other variables (humidity, elevation, tree species, CO2 concentration, etc.) is a hugely difficult multivariate statistics problem and most of the researchers I've corresponded with do not seem to appreciate this fact. Another major problem is that proxies get weighted in the temperature reconstruction based on how well they fit the hypothesized temperature model. The weighting is where things get really shaky. Right away, you have biased your results in such a way that that nonconforming data is discarded / de-weighted. Note that there is not anything wrong with these nonconforming samples that invalidates them; they just don't fit the proposed models very well. Typically researchers develop their own methods for weighting samples in the temperature reconstructions and many of these methods would make a statistician cringe. Often during the weighting phase you find that a handful of proxy samples (out of a sample size of hundreds) get the vast majority of the weight in the temperature reconstructions. Sometimes the weight of a temperature reconstruction in a location is almost completely computed from a few proxy samples taken halfway around the world at a completely different elevation. If you try to discuss these fundamental problems with climate scientists you'll typically get told that you're not a scientist (not true) or that you're a "denialist" being paid by big oil (not true). I am convinced that these temperature reconstructions are useless at best.
- _delirium 13y ago
  It's definitely not the case that climate scientists are uninterested in discussing methodological problems with paleoclimate proxies. A considerable amount of the literature is taken up with doing precisely that, and it takes up a good portion of the Paleoclimatology section of the IPCC report: http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter6.pdf http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-cha...
crazy1van 13y ago
My skepticism in climate change is based on a long history of censuses in the scientific community that later proved to be completely wrong. I'm not saying we should not try to understand the world. I'm saying we should realize we have limits. The more complex the system we seek to understand, the more we should be skeptical. The climate of the entire planet and to the degree one particular species impacts it seems extremely complex to me. Hence, I am highly skeptical.
- bjz_ 13y ago
  http://www.skepticalscience.com/its-not-us.htm http://www.skepticalscience.com/its-not-us.htm http://www.skepticalscience.com/settled-science.htm http://www.skepticalscience.com/settled-science.htm
- leot 13y ago
  No one is saying that we should devote 100% of GDP to mitigating global warming. Go ahead, factor in the uncertainty. What % of GDP should we spend to avert the very real possibility catastrophic warning occurs? What % are we spending?
  - crazy1van 13y ago
    If it were left up to me, I would say we should have zero forced spending and an unlimited amount of voluntary spending to avert a potential global warming catastrophe. Let me remind you, that at any time you are free to donate any amount of your own money to thwart global warming. That's not what some people really want though. They don't want to spend their own money on the problem. They want to spend other people's money on the problem. And I contend we don't know nearly enough about the issue to cross that line.
    - nknighthb 13y ago
      I'll be happy to agree not to force anyone else to spend their money to avert global warming. But there is one additional provision I'll require: I must be free to shoot anyone harming me by contributing to global warming. Deal?
deleted 13y ago
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moe 13y ago
World population chart for the same timeframe: http://upload.wikimedia.org/wikipedia/commons/b/b7/Population_curve.svg http://upload.wikimedia.org/wikipedia/commons/b/b7/Populatio...
rmrfrmrf 13y ago
Throwing my hat into the ring here: 1) I think that we, as the human population, should actively move toward more efficient, less destructive industry on principle, not just because of the threat of climate change. I think making it about climate change gives too many opportunities for argument derailment. Think about when "tree hugger" was a pejorative term; i mean, who DOESN'T want to hug a tree? I think it's a lot harder for people to argue against the idea of "leave a place as you found it" than to find flaws a data set. It also allows for much broader regulation. For example, we could then start focusing on legislation against pharm manufacturers allowing meds to seep into the water supply rather than just the air pollution they're producing. 2) I'm starting to wonder why we're not focusing more on adaptation to than prevention of climate change. I've been watching a lot of TED talks lately (thanks, Netflix!) about the impact of climate change, and the one that I'm thinking of was a researcher who spent time in the arctic studying the wildlife there, and made the case that we should prevent climate change so that we can save arctic wildlife. But I wonder, if we were alive in the age of dinosaurs, would we be saying that we need to clean up the atmosphere to prevent the impact winter that would inevitably kill them? While I love wildlife, I almost feel like it's not our responsibility as humans to tamper with natural processes like extinction. In our prevention efforts, we may also be preventing natural selection and, by extension, adaptation. It could be a reality that we'll face an extinction event that wipes out all other non-domesticated mammalian life. While we can all agree that an Earth like that would suck, we know that, 600 million years from now, EVERYTHING will be wiped out. People speculate that, at this time, humans themselves will either become extinct or will have migrated off the planet. So, my question is, are we prepared to jump ship if Earth becomes uninhabitable? Is it realistic to try to change all 5,000,000,000,000,000,000 kilograms of atmosphere, or should we starting thinking about building habitats for space living?
- asgard1024 13y ago
  > why we're not focusing more on adaptation to than prevention of climate change The reality is that prevention is cheaper (there is also an issue of distribution of the cost, though). Prevention of climate change effectively means not using energy from fossil fuels, while adaptation means paying extra energy cost for each unit of energy you get from fossil fuels. This extra cost is actually greater than extra cost that would be incurred if you used non-fossil fuel source. So if you decide to continue to use fossil fuel sources at all, the total cost (savings due to cheap fuel + mitigation costs) will always be higher than the non-fossil energy sources (higher cost to get the energy but savings on mitigation).
kjackson2012 13y ago
Global temperatures are basically flat for the last 17 years, and below every single computer model of climate change. This is even more stark given the fact that the most co2 has been produced in the last 17 years. I think the theory is pretty much broken and they need to figure a better model. http://www.dailymail.co.uk/news/article-2420783/Worlds-climate-scientists-confess-Global-warming-just-QUARTER-thought--computers-got-effects-greenhouse-gases-wrong.html http://www.dailymail.co.uk/news/article-2420783/Worlds-clima...
- ronaldx 13y ago
  Please, you need to study statistics again. Check the graph in the parent article. Zoom into any 17 year period between -3000 and 1900 and it will "look flat", and during many 17 year periods the temperature temporarily went up, but nonetheless you can see there's a clear downward trend throughout that period. It's impossible to deny that this trend has been sharply reversed. A 17 year period is normally supposed to tell you nothing interesting - but the 17 year period up to 1996 clearly indicates something quite disturbing is going on. Climate change is not negated by a temporary plateau.
- bjz_ 13y ago
  http://www.skepticalscience.com/global-warming-stopped-in-1998-intermediate.htm http://www.skepticalscience.com/global-warming-stopped-in-19... The Daily Mail? Really?
  - kjackson2012 13y ago
    That's comparing apples to oranges. All the other data used to create the original graph o calculate temperature such as tree rings, etc do not take into account the temperature of the oceans, etc. There may be perfectly good explanations as to why the temperature may be flat, but those same explanations are not being fed into the graph that the OP posted.
    - anon1385 13y ago
      >All the other data used to create the original graph o calculate temperature such as tree rings, etc do not take into account the temperature of the oceans, etc https://en.wikipedia.org/wiki/Proxy_(climate)#Corals https://en.wikipedia.org/wiki/Proxy_(climate)#Corals
clubhi 13y ago
Start burning tires folks. We need to save ourselves from an ice age.
serichsen 13y ago
It seems that the uncertainty is much higher at the end of the blue curve. I wonder why. It also seems that the red curve has no uncertainty data. I would not dare draw any conclusion from these curves before I have satisfying explanations for these two questions.
- jellicle 13y ago
  It's probably because all the climate scientists in the world are trying to trick you.
- erikb 13y ago
  Yes, and it is not clear on the diagram, if the red curve is actually inside the uncertainty range. At least on my screen I really can't tell.
jokoon 13y ago
Sorry but I hear a lot of speculation, not real reports of hard actual life threatening changes. Maybe soft ones like the sea temperature and acidity, but most people can still go out and food still grows.
callmeed 13y ago
Can someone please explain how we're able to know the temperature in 4,000 BC with an accuracy of +/- .2° C?
codex 13y ago
I don't think this chart comes close to proving that Obama was born in the United States.
microcolonel 13y ago
Of note is that the chart's error bars fill the entire scale near the end, so the measurements could really be anywhere there. It's anyone's guess whether or not temperatures have somehow mysteriously skyrocketed or not. My personal inkling is that the alarmist reports are wrong, and the changes aren't as drastic as reported; since the same people publish results from proprietary, rigged climate models.
JulianMorrison 13y ago
Well, the upside is, we fixed the ice age that was trying to happen.
beloch 13y ago
The cyclical recurrence of interglacial and glacial periods (we're technically still in one of these) can theoretically be explained by cyclically evolving properties of the Earth's orbit around the sun such as the precession of the Earth's ratational axis (google Milankovitch cycles). This theory is consistent with the gradual cooling trend observed thus far into the Holocene epoch, and predicts it will continue for tens of thousands of years. The linked graph shows this very nicely. A sudden, full-blown glacial period would be far more disastrous for human civilization than significant global warming. The latter would submerge densely populated coastal areas and force humans to move to the new coastlines, but the overall capacity of the Earth to support life would increase, just as it did at the start of the Holocene. The former would result in a large reduction in the Earth's carrying capacity and global famine. Any change in the Earth's temperature is going to be disruptive to both human civilization and the existence of other species on Earth. We have reversed the effects of several thousand years of cooling in just a couple of centuries and, assuming we are able to continue extracting and burning hydrocarbons at an unabated pace indefinitely (dubious) we could significantly change the face of the world, but it will still support our civilization, just in a very changed state. Avoiding the pain of this change is ample incentive to curb the use of hydrocarbons. (Edit: It has taken centuries and a significant portion of the world's hydrocarbon reserves to produce less than a degree of warming. At this rate, even if we evaded peak-oil for another thousand years the Earth will still be in a glacial period.) However, we should be much more aware of events that could trigger another glacial period. Megaeruptions or large meteor impacts could plunge global temperatures suddenly and catastrophically. These are far greater threats to our species, but we are both incapable of adequately predicting them or preventing them if we do predict them. The probability of this sort of event happening in a single human lifespan is remote, while global warming is a certainty, but these events will eventually occur with certainty. Managing global warming is certainly a good idea for the comfort of our civilization, but we should have more eyes on the bigger threats. (Edit: Even if we tried, we would be unable to maintain global warming indefinitely simply by burning hydrocarbons. In the ten-thousand year time-frame we will need to find other ways to combat gradual cooling.)
- novalis78 13y ago
  thanks for adding "the bigger picture" into the mix.
Gravityloss 13y ago
"Worry about global warming impacts in the next 100 years, not an ice age in over 10,000 years. " http://www.skepticalscience.com/heading-into-new-little-ice-age.htm http://www.skepticalscience.com/heading-into-new-little-ice-... Basically none of these memes are new. They often rely on misunderstanding of context. (For those who didn't know, skeptical science rebuts these commonly found arguments against global warming.)
crististm 13y ago
Until you were there to measure the temperature, all you have is just the output of a model. The model is not the world.
dghughes 13y ago
How much do we humans contribute to the heating of the world? The heat we output from our bodies and population increases must mean more heat. I say this because a friend has a small barn and in it two horses, two pigs and some chickens. He said the barn doesn't use any heat source because the heat from the two horses is enough to warm the barn. Even a bucket of water in the barn won't freeze.
- mturmon 13y ago
  A human uses about 100W. I don't know about horses, but depending on how well-insulated the barn is, a few hundred watts would make a significant difference. About those humans heating the Earth -- the effect of the GHG's we emit is tapping into solar insolation, which is huge, so it probably dwarfs the above figures (see next paragraph). Also, the energy that powers us (food) would be turned into heat by other processes anyway. Order of magnitude: population of 7 billion * 100W/person = 9.7TW. Solar insolation 1361 W/m^2, over the projected area of the earth, which totals 175,000,000 TW. I just throw that figure (100W) as a useful order of magnitude estimate.

220 points by deusclovis 13y ago

exit 13y ago

googling "industrial revolution averted iceage" returns a few conservative blogs, smugly pleased with the possibility the only credible commentary i can find is in a nytimes article: "Scientists say that if natural factors were still governing the climate, the Northern Hemisphere would probably be destined to freeze over again in several thousand years. 'We were on this downward slope, presumably going back toward another ice age,' Dr. Marcott said." http://www.nytimes.com/2013/03/08/science/earth/global-temperatures-highest-in-4000-years-study-says.html http://www.nytimes.com/2013/03/08/science/earth/global-tempe...

kaybe 13y ago
I cannot cite the exact words, but in discussions professors have indeed expressed the opinion that a next ice age won't be of concern for us. Those charts, especially those going back further, are a good argument for why we will need to control the climate at some point in the future (but please not when we have not figured out how to without significant risk).
deleted 13y ago
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- mistercow 13y ago
  By "conservatives" exit means the American kind, who by and large deny the existence of AGW.
  - gwright 13y ago
    The dispute isn't about AGW, it is about CAGW. AGW: human activity increseas CO2 increased CO2 => increases temperature CAGW: Catastrophic Anthropogenic Global Warming human activity increases CO2 increased CO2 => increases temperature positive climate feedback mechanisms => magnified warming It is that last item where the controversy lies. Climate models all have a parameter that represents the climate sensitivity which predicts the way the climate responds to changes to input. If you believe that the sensitivity is high, then small changes to the input (via CO2 warming, for example) lead to large changes in the system and catastrophic results. If you believe the sensitivity is low, then small changes to the input do not have catastrophic outcomes. There has been considerable news of late that observations of temperature changes over the last 15-20 years do not match the predictions over the same time period of the models using a high climate sensitivity values. Edit: fixed formatting and spelling
    - anon1385 13y ago
      >The dispute isn't about AGW For most conservatives it is. Even in this thread we have people claiming it's all just a natural cycle. >There has been considerable news of late that observations of temperature changes over the last 15-20 years do not match the predictions over the same time period of the models using a high climate sensitivity values. New papers that suggested slightly lower sensitivity gave figures that were still within the range put forward in the last IPCC report, and still suggested sensitivities high enough to cause serious and damaging climate change unless emissions are reduced. Climate is a noisy system, you can't measure significant change in global surface temperature in only 15 years. You should take the time to go and look at the actual temperature data to get a feel for how noisy it is[1]. Short term cycles like ENSO -- that we currently have no real ability to predict -- have a far greater impact on surface temperatures over those time scales[2]. It just so happens that the last 15 years or so have seen a dominance of la Niña years (which correlate with cooler surface temperatures) for reasons we don't really understand; it could just be random or possibly ENSO could have been affected by climate change. There has been no "pause" at all in other measurements: 2012 was the lowest recorded extent and volume of arctic sea ice and the trend is clear: http://psc.apl.washington.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAnomalyCurrentV2.png http://psc.apl.washington.edu/wordpress/wp-content/uploads/s... Ocean heat has continued to rise: http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/ http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/ The only people talking about a "pause" are conservative pundits and climate change deniers. It shows weaknesses in the models, but nobody was claiming that the models were accurate for short timescales or that we have the complete picture a at all. There are still huge gaps in our understanding, but that is hardly a cause for celebration. [1] http://www.skepticalscience.com/pics/HadCRUT4vs3.jpg http://www.skepticalscience.com/pics/HadCRUT4vs3.jpg [2] https://tamino.wordpress.com/2013/09/02/el-nino-and-the-non-spherical-cow/ https://tamino.wordpress.com/2013/09/02/el-nino-and-the-non-...
    - asgard1024 13y ago
      So it's like if you're not disputing smoking is bad for health, but you're saying it's not "catastrophically" bad? It's like the sooner one stops smoking, the less chance he has for a "catastrophic" lung cancer; it's not like when you smoke 10K cigarettes you sure won't get cancer but if you smoke 20K you sure do. Of course, different people call "catastrophe" different things, but the analogy is quite apt here. There is no "catastrophe" coming, in the sense of a sudden disaster. We can stop any time, and the sooner we stop, the better overall result (and less costly) will be.
- InclinedPlane 13y ago
  That's due to the little ice age (http://en.wikipedia.org/wiki/Little_Ice_Age http://en.wikipedia.org/wiki/Little_Ice_Age), which extended to the mid 19th century, not man-made climate change.
  - tehwalrus 13y ago
    apologies; I thought it was mainstream to believe that the "little ice age" would have continued into a proper one if not for the industrial revolution. This part of my comment remains relevant though: Conservatives have little to be smug about here - it shows that climate change is indeed anthropogenic, contrary to their narrative for the last 20 years - the red line, modern records, show a much faster rate of change than anything in the natural period.
    - kaybe 13y ago
      I think it is mainstream to acknowledge the possiblity of that, but not have a fixed believe. After all, it's climate science and we're only at the beginning, and who knows, there might have been another few thousand years of stable climate.

temphn 13y ago

This plot compares an inferred model to the instrumental record. Here is the study expressed in the words of Real Climate: http://www.realclimate.org/index.php/archives/2013/09/paleoclimate-the-end-of-the-holocene/ http://www.realclimate.org/index.php/archives/2013/09/paleoc... Over the last decades, numerous researchers have painstakingly collected, analyzed, dated, and calibrated many data series that allow us to reconstruct climate before the age of direct measurements. Such data come e.g. from sediment drilling in the deep sea, from corals, ice cores and other sources. Shaun Marcott and colleagues for the first time assembled 73 such data sets from around the world into a global temperature reconstruction for the Holocene, published in Science. Or strictly speaking, many such reconstructions: they have tried about twenty different averaging methods and also carried out 1,000 Monte Carlo simulations with random errors added to the dating of the individual data series to demonstrate the robustness of their results. Marcott et al.'s graphic states that their model reflects historical temperatures so accurately that it can measure the average temperature of the entire globe continuously back to 8000 years ago, to within a small fraction of 1 degree Celsius (i.e. the 1-sigma error bars). That is simply an extraordinary claim given: 1) The "divergence problem". The lack of correlation between model inputs like tree rings and the instrumental record over the last few decades is acknowledged by all; climate scientists generally state that it is due to anthropogenic factors, arguably assuming the consequent. http://www.skepticalscience.com/Tree-ring-proxies-divergence-problem.htm http://www.skepticalscience.com/Tree-ring-proxies-divergence... 2) Serious climate model prediction failures over the past 10 year period, as acknowledged in Nature: http://www.nature.com/news/climate-change-the-forecast-for-2018-is-cloudy-with-record-heat-1.13344 http://www.nature.com/news/climate-change-the-forecast-for-2... In other words, key model inputs used in climate reconstructions do not strongly correlate with the instrumental record over the last 30-40 years ("the divergence problem") and climate models have so far had a poor track record over the last 15 years, with average temperatures winding up below the envelope of model predictions. These predictive failures in the datasets we can check bode ill for the prospect of hindcasting global average temperatures to within 1 degree more than 8000 years ago.

jdgiese 13y ago
The plot does seem too precise to take seriously IMO, although I am an engineer, and not a climate scientist.

ctdonath 13y ago

Temperature chart for the last 425,000 years: http://ctdonath.blogspot.com/2012/02/global-climate-change-in-context.html?m=1 http://ctdonath.blogspot.com/2012/02/global-climate-change-i...

davyjones 13y ago
Wait...are we in "summer" on that time-scale now?!
- ctdonath 13y ago
  Yup. At the end of the Dog Days of August, expecting an early hard frost. We'll be wishing for "warming" soon enough.
kolbe 13y ago
Do you know why the original 11,000 year chart doesn't look anything like the 10,000 year chart in your link?
- wffurr 13y ago
  Different data set. The 10,000 year chart is only Antarctic ice cores. The 11,000 year chart is a composite of a number of temperature records - tree rings, etc.
  - ctdonath 13y ago
    The 11,000 year chart is a composite. Funny how the data takes a wild change right where a completely new data source is included.
    - anon1385 13y ago
      You realise that there is an entire paper in Science about how they synthesised the various temperature records? http://www.usu.edu/geo/physical/MarcottEtal_Science_2013.pdf http://www.usu.edu/geo/physical/MarcottEtal_Science_2013.pdf If you have something constructive to say about the methodology then let us know rather than making ignorant comments that tell us more about your political ideology than about the science.

_delirium 13y ago

Sources, The Science paper: http://www.usu.edu/geo/physical/MarcottEtal_Science_2013.pdf http://www.usu.edu/geo/physical/MarcottEtal_Science_2013.pdf Online supplemental material: http://www.sciencemag.org/content/suppl/2013/03/07/339.6124.1198.DC1/Marcott.SM.pdf http://www.sciencemag.org/content/suppl/2013/03/07/339.6124.... The figure itself is a new plot by Potsdam University researchers for realclimate.org, though, using the same dataset, but not a graphic taken directly from the paper (the paper's Fig. 1 has some alternate versions).

throwaway_yy2Di 13y ago
I think this stinks. The Science paper says their reconstruction is smoothed and has low time resolution. They say it preserves no variability at all on timescales <300 years, and attenuates even 1,000 year variations. Superimposing this with the 30-year Hadley data seems misleading, because it is on a very short timescale which is suppressed from the paleologic data. (edit): "Because the relatively low resolution and time uncertainty of our data sets should generally suppress higher-frequency temperature variability, an important question is whether the Holocene stack adequately represents centennial- or millennial scale variability. [...] The results suggest that at longer periods, more variability is preserved, with essentially no variability preserved at periods shorter than 300 years, ~50% preserved at 1000-year periods, and nearly all of the variability preserved for periods longer than 2000 years (figs. S17 and S18)."
- _delirium 13y ago
  The realclimate.org post discusses that as a potential issue, yes. See the section following the sentence: Because the proxy data have only a coarse time resolution – would they have shown it if there had been a similarly rapid warming earlier in the Holocene?
  - deleted 13y ago
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  - throwaway_yy2Di 13y ago

brownbat 13y ago

Out of idle curiosity, can anyone tell me more about what a 0.4 (0.6, 1, 2...) °C anomaly feels like, maybe with reference to cities that have climates with differing annual averages? I mean, is it like shifting every city 5 ° in latitude closer to the equator, or what? (I know this wouldn't capture the whole story, I'm just curious.) EDIT: I guess the state of New York has a range of annual average temperatures from 4 °C to 12 °C, so maybe this isn't useful at all. http://en.wikipedia.org/wiki/Climate_of_New_York#Temperatures http://en.wikipedia.org/wiki/Climate_of_New_York#Temperature...

pcrh 13y ago
In the maps linked below, each isotherm represents a 2 C difference. So a global rise of 2 C would be equivalent to a 100-200 km or so shift towards the equator, for a given location. Or nearly equivalent to the temperature difference in the center of a major city compared to its suburbs. http://solargis.info/doc/_pics/SolarGIS-iMaps--World-air-temperature-map--Yearly-longterm-average.jpg http://solargis.info/doc/_pics/SolarGIS-iMaps--World-air-tem... http://solargis.info/doc/_pics/SolarGIS-iMaps--World-air-temperature-map--Yearly-longterm-average--detail2.jpg http://solargis.info/doc/_pics/SolarGIS-iMaps--World-air-tem...
noiv 13y ago
If the temperatures are be equally distributed plus 1°C feels like 1°C plus. But that's not the case neither in space nor time. I worry more about the peaks.
sethrin 13y ago
Think of it more as extra energy being imparted to the global weather system. This will have all sorts of fun and exciting effects, and as I understand the warming will be greatest at the poles. Alaska has warmed by about 1.6[0] in the last 60 years, and the interior of Alaska by 1.4° C in the last 100[1], compared to a global temperature rise of .8° C over the same period. This has resulted in the melting of thousands of cubic kilometers of glacial ice, with this study[2] suggesting that this is the largest glaciological factor in rising sea levels. To the eyes of the native inhabitant, the glacial retreat is shocking, with the lower altitude glaciers most affected. We've built glacier overlooks in some places, where once the glacier was a stone's throw away, and now it's barely visible, and in another few decades the only thing they'll be able to show anyone there are photos. I've seen photos from the early 1900s of glacial termini which towered over the masts of a sail-rigged steamer. Today there is a fjord there, and the glacier is more than 13km away. And you want to know what that feels like? How about instead you imagine how it feels to watch the Arctic melting around you, while an endless circus of millions deny that it's even happening. [0] http://climate.gi.alaska.edu/ClimTrends/Change/TempChange.html http://climate.gi.alaska.edu/ClimTrends/Change/TempChange.ht... [1] http://oldclimate.gi.alaska.edu/papers/Arctic62-3-295.pdf http://oldclimate.gi.alaska.edu/papers/Arctic62-3-295.pdf [2] http://glaciers.gi.alaska.edu/material/arendt_phd.pdf http://glaciers.gi.alaska.edu/material/arendt_phd.pdf

nhoss2 13y ago

Am I alone in finding the graph scary? This rate of change in temperature is probably not something that would be easy to slow down, yet it feels like not many people care about this.

cubsink 13y ago
I find it fucking depressing.

rjdagost 13y ago

For a little while I was interested in paleoclimatology and I started studying how researchers developed these historical temperature reconstruction curves. Basically you take “proxies” for temperature, things like tree rings, coral growth, sediment layer thickness, etc. and you posit a relationship between the proxy measurements and temperature. Measurements that better fit the hypothesized model get more weight in the temperature reconstruction. The main problem is that no one knows if the hypothesized models (temperature vs. tree ring thickness, sediment layer thickness, etc.) have any validity. Why should tree rings grow linearly with temperature- what about a huge number of other variables? The temperature “signal” is at best very weak. Decoupling the temperature signal from other variables (humidity, elevation, tree species, CO2 concentration, etc.) is a hugely difficult multivariate statistics problem and most of the researchers I've corresponded with do not seem to appreciate this fact. Another major problem is that proxies get weighted in the temperature reconstruction based on how well they fit the hypothesized temperature model. The weighting is where things get really shaky. Right away, you have biased your results in such a way that that nonconforming data is discarded / de-weighted. Note that there is not anything wrong with these nonconforming samples that invalidates them; they just don't fit the proposed models very well. Typically researchers develop their own methods for weighting samples in the temperature reconstructions and many of these methods would make a statistician cringe. Often during the weighting phase you find that a handful of proxy samples (out of a sample size of hundreds) get the vast majority of the weight in the temperature reconstructions. Sometimes the weight of a temperature reconstruction in a location is almost completely computed from a few proxy samples taken halfway around the world at a completely different elevation. If you try to discuss these fundamental problems with climate scientists you'll typically get told that you're not a scientist (not true) or that you're a "denialist" being paid by big oil (not true). I am convinced that these temperature reconstructions are useless at best.

_delirium 13y ago
It's definitely not the case that climate scientists are uninterested in discussing methodological problems with paleoclimate proxies. A considerable amount of the literature is taken up with doing precisely that, and it takes up a good portion of the Paleoclimatology section of the IPCC report: http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter6.pdf http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-cha...

crazy1van 13y ago

My skepticism in climate change is based on a long history of censuses in the scientific community that later proved to be completely wrong. I'm not saying we should not try to understand the world. I'm saying we should realize we have limits. The more complex the system we seek to understand, the more we should be skeptical. The climate of the entire planet and to the degree one particular species impacts it seems extremely complex to me. Hence, I am highly skeptical.

bjz_ 13y ago
http://www.skepticalscience.com/its-not-us.htm http://www.skepticalscience.com/its-not-us.htm http://www.skepticalscience.com/settled-science.htm http://www.skepticalscience.com/settled-science.htm
leot 13y ago
No one is saying that we should devote 100% of GDP to mitigating global warming. Go ahead, factor in the uncertainty. What % of GDP should we spend to avert the very real possibility catastrophic warning occurs? What % are we spending?
- crazy1van 13y ago
  If it were left up to me, I would say we should have zero forced spending and an unlimited amount of voluntary spending to avert a potential global warming catastrophe. Let me remind you, that at any time you are free to donate any amount of your own money to thwart global warming. That's not what some people really want though. They don't want to spend their own money on the problem. They want to spend other people's money on the problem. And I contend we don't know nearly enough about the issue to cross that line.
  - nknighthb 13y ago
    I'll be happy to agree not to force anyone else to spend their money to avert global warming. But there is one additional provision I'll require: I must be free to shoot anyone harming me by contributing to global warming. Deal?

deleted 13y ago

[deleted]

moe 13y ago

World population chart for the same timeframe: http://upload.wikimedia.org/wikipedia/commons/b/b7/Population_curve.svg http://upload.wikimedia.org/wikipedia/commons/b/b7/Populatio...

rmrfrmrf 13y ago

Throwing my hat into the ring here: 1) I think that we, as the human population, should actively move toward more efficient, less destructive industry on principle, not just because of the threat of climate change. I think making it about climate change gives too many opportunities for argument derailment. Think about when "tree hugger" was a pejorative term; i mean, who DOESN'T want to hug a tree? I think it's a lot harder for people to argue against the idea of "leave a place as you found it" than to find flaws a data set. It also allows for much broader regulation. For example, we could then start focusing on legislation against pharm manufacturers allowing meds to seep into the water supply rather than just the air pollution they're producing. 2) I'm starting to wonder why we're not focusing more on adaptation to than prevention of climate change. I've been watching a lot of TED talks lately (thanks, Netflix!) about the impact of climate change, and the one that I'm thinking of was a researcher who spent time in the arctic studying the wildlife there, and made the case that we should prevent climate change so that we can save arctic wildlife. But I wonder, if we were alive in the age of dinosaurs, would we be saying that we need to clean up the atmosphere to prevent the impact winter that would inevitably kill them? While I love wildlife, I almost feel like it's not our responsibility as humans to tamper with natural processes like extinction. In our prevention efforts, we may also be preventing natural selection and, by extension, adaptation. It could be a reality that we'll face an extinction event that wipes out all other non-domesticated mammalian life. While we can all agree that an Earth like that would suck, we know that, 600 million years from now, EVERYTHING will be wiped out. People speculate that, at this time, humans themselves will either become extinct or will have migrated off the planet. So, my question is, are we prepared to jump ship if Earth becomes uninhabitable? Is it realistic to try to change all 5,000,000,000,000,000,000 kilograms of atmosphere, or should we starting thinking about building habitats for space living?

asgard1024 13y ago
> why we're not focusing more on adaptation to than prevention of climate change The reality is that prevention is cheaper (there is also an issue of distribution of the cost, though). Prevention of climate change effectively means not using energy from fossil fuels, while adaptation means paying extra energy cost for each unit of energy you get from fossil fuels. This extra cost is actually greater than extra cost that would be incurred if you used non-fossil fuel source. So if you decide to continue to use fossil fuel sources at all, the total cost (savings due to cheap fuel + mitigation costs) will always be higher than the non-fossil energy sources (higher cost to get the energy but savings on mitigation).

kjackson2012 13y ago

Global temperatures are basically flat for the last 17 years, and below every single computer model of climate change. This is even more stark given the fact that the most co2 has been produced in the last 17 years. I think the theory is pretty much broken and they need to figure a better model. http://www.dailymail.co.uk/news/article-2420783/Worlds-climate-scientists-confess-Global-warming-just-QUARTER-thought--computers-got-effects-greenhouse-gases-wrong.html http://www.dailymail.co.uk/news/article-2420783/Worlds-clima...

ronaldx 13y ago
Please, you need to study statistics again. Check the graph in the parent article. Zoom into any 17 year period between -3000 and 1900 and it will "look flat", and during many 17 year periods the temperature temporarily went up, but nonetheless you can see there's a clear downward trend throughout that period. It's impossible to deny that this trend has been sharply reversed. A 17 year period is normally supposed to tell you nothing interesting - but the 17 year period up to 1996 clearly indicates something quite disturbing is going on. Climate change is not negated by a temporary plateau.
bjz_ 13y ago
http://www.skepticalscience.com/global-warming-stopped-in-1998-intermediate.htm http://www.skepticalscience.com/global-warming-stopped-in-19... The Daily Mail? Really?
- kjackson2012 13y ago
  That's comparing apples to oranges. All the other data used to create the original graph o calculate temperature such as tree rings, etc do not take into account the temperature of the oceans, etc. There may be perfectly good explanations as to why the temperature may be flat, but those same explanations are not being fed into the graph that the OP posted.
  - anon1385 13y ago
    >All the other data used to create the original graph o calculate temperature such as tree rings, etc do not take into account the temperature of the oceans, etc https://en.wikipedia.org/wiki/Proxy_(climate)#Corals https://en.wikipedia.org/wiki/Proxy_(climate)#Corals

clubhi 13y ago

Start burning tires folks. We need to save ourselves from an ice age.

serichsen 13y ago

It seems that the uncertainty is much higher at the end of the blue curve. I wonder why. It also seems that the red curve has no uncertainty data. I would not dare draw any conclusion from these curves before I have satisfying explanations for these two questions.

jellicle 13y ago
It's probably because all the climate scientists in the world are trying to trick you.
erikb 13y ago
Yes, and it is not clear on the diagram, if the red curve is actually inside the uncertainty range. At least on my screen I really can't tell.

jokoon 13y ago

Sorry but I hear a lot of speculation, not real reports of hard actual life threatening changes. Maybe soft ones like the sea temperature and acidity, but most people can still go out and food still grows.

callmeed 13y ago

Can someone please explain how we're able to know the temperature in 4,000 BC with an accuracy of +/- .2° C?

codex 13y ago

I don't think this chart comes close to proving that Obama was born in the United States.

microcolonel 13y ago

Of note is that the chart's error bars fill the entire scale near the end, so the measurements could really be anywhere there. It's anyone's guess whether or not temperatures have somehow mysteriously skyrocketed or not. My personal inkling is that the alarmist reports are wrong, and the changes aren't as drastic as reported; since the same people publish results from proprietary, rigged climate models.

JulianMorrison 13y ago

Well, the upside is, we fixed the ice age that was trying to happen.

beloch 13y ago

The cyclical recurrence of interglacial and glacial periods (we're technically still in one of these) can theoretically be explained by cyclically evolving properties of the Earth's orbit around the sun such as the precession of the Earth's ratational axis (google Milankovitch cycles). This theory is consistent with the gradual cooling trend observed thus far into the Holocene epoch, and predicts it will continue for tens of thousands of years. The linked graph shows this very nicely. A sudden, full-blown glacial period would be far more disastrous for human civilization than significant global warming. The latter would submerge densely populated coastal areas and force humans to move to the new coastlines, but the overall capacity of the Earth to support life would increase, just as it did at the start of the Holocene. The former would result in a large reduction in the Earth's carrying capacity and global famine. Any change in the Earth's temperature is going to be disruptive to both human civilization and the existence of other species on Earth. We have reversed the effects of several thousand years of cooling in just a couple of centuries and, assuming we are able to continue extracting and burning hydrocarbons at an unabated pace indefinitely (dubious) we could significantly change the face of the world, but it will still support our civilization, just in a very changed state. Avoiding the pain of this change is ample incentive to curb the use of hydrocarbons. (Edit: It has taken centuries and a significant portion of the world's hydrocarbon reserves to produce less than a degree of warming. At this rate, even if we evaded peak-oil for another thousand years the Earth will still be in a glacial period.) However, we should be much more aware of events that could trigger another glacial period. Megaeruptions or large meteor impacts could plunge global temperatures suddenly and catastrophically. These are far greater threats to our species, but we are both incapable of adequately predicting them or preventing them if we do predict them. The probability of this sort of event happening in a single human lifespan is remote, while global warming is a certainty, but these events will eventually occur with certainty. Managing global warming is certainly a good idea for the comfort of our civilization, but we should have more eyes on the bigger threats. (Edit: Even if we tried, we would be unable to maintain global warming indefinitely simply by burning hydrocarbons. In the ten-thousand year time-frame we will need to find other ways to combat gradual cooling.)

novalis78 13y ago
thanks for adding "the bigger picture" into the mix.

Gravityloss 13y ago

"Worry about global warming impacts in the next 100 years, not an ice age in over 10,000 years. " http://www.skepticalscience.com/heading-into-new-little-ice-age.htm http://www.skepticalscience.com/heading-into-new-little-ice-... Basically none of these memes are new. They often rely on misunderstanding of context. (For those who didn't know, skeptical science rebuts these commonly found arguments against global warming.)

crististm 13y ago

Until you were there to measure the temperature, all you have is just the output of a model. The model is not the world.

dghughes 13y ago

How much do we humans contribute to the heating of the world? The heat we output from our bodies and population increases must mean more heat. I say this because a friend has a small barn and in it two horses, two pigs and some chickens. He said the barn doesn't use any heat source because the heat from the two horses is enough to warm the barn. Even a bucket of water in the barn won't freeze.

mturmon 13y ago
A human uses about 100W. I don't know about horses, but depending on how well-insulated the barn is, a few hundred watts would make a significant difference. About those humans heating the Earth -- the effect of the GHG's we emit is tapping into solar insolation, which is huge, so it probably dwarfs the above figures (see next paragraph). Also, the energy that powers us (food) would be turned into heat by other processes anyway. Order of magnitude: population of 7 billion * 100W/person = 9.7TW. Solar insolation 1361 W/m^2, over the projected area of the earth, which totals 175,000,000 TW. I just throw that figure (100W) as a useful order of magnitude estimate.