I think CO2 levels will be between 600 and 700 ppm as you said. From what I know, the predicted rise of 2 or 3 degrees celsius is based on conservative studies that assume we will all do something about fossil fuels soon. The less optimistic studies that assume we will keep burning fossil fuels predicts a global temperature rise of 5 to 6 degrees celsius within the next hundred years or so. Fun fact- scientists believe that a 5.5 degree increase in global temperature will be beyond human adaptability. So that's nice XD

But yeah, that's kinda my understanding of CO2 levels and global temperature. And as you say, climatic changes won't be our only problem- if we run out of fossil fuels and have no alternative sources of energy, we'll have no chance of surviving the conditions that we created.

Are you aware that CO2 levels were 7000ppm during the Cambrian period? That's ten times higher than they will be when we have burned all the fossil fuels.

In 1880, CO2 levels were at 280ppm, They are now 400ppm. If the entire increase in global mean surface temperature (1.1C) is due to that change in CO2, we get an increase of approximately 0.9C every time CO2 goes up by another 100ppm. So when we go from 400ppm to 600 or 700ppm, we are looking at another 1.8C to 2.7C increase in global mean surface temperature. All the crazy models that predicted that the polar ice caps would be gone by 2013, rely on a non-linear model. There is absolutely no evidence to support a non-linear model that "increases" the delta C/delta CO2 as CO2 levels go up. All the evidence supports a non-linear modal that "decreases" the Delta C/Delta ppm as CO2 levels go up. Even with a linear model, taking CO2 from 400ppm to Cambrian period levels of 7000ppm would give us 6600ppm * 0.9C/100ppm or an increase of 60C. That would have the earth's oceans sitting at a temperature right below the boiling point of water.

If you believe the scientists who say a 5.5C increase in global temperature will cause the end of the human race, you should start going to church. You are a good candidate to believe that a talking snake convinced a rib-woman to eat a magic apple.

Plots on this page show that global mean surface temperature has been more than 5.5C higher than it is today for hundreds of millions of years:

[en.wikipedia.org]

During those times, life on planet earth exploded. There was more vegetation, there were dragonflies with 2 to 3 foot wingspans. There was so much carbon life on this planet that when it died, and was compressed over time, and it became the majority of the fossil fuels we are burning today..

Oooh shit boy, you did NOT just compare me to a religious person...I've gotta do stuff with family right now, but I'll deal with you later.

Also if you look to wikipedia for advice and implying that I'M stupid, time to pull your head out of your ass.

Here are the references they used for the wikipedia article. Do you have something against Nature, Paleoceanography, Science, NOAA, Chemical Geology, Earth-Science Reviews, RealClimate, Journal of the American Chemical Society?

Sigman, D.M.; E.A. Boyle (October 2000). "Glacial/interglacial variations in atmospheric carbon dioxide" (PDF). Nature. 407 (6806): 859–869. doi:10.1038/35038000. PMID 11057657.
Jump up ^ Lisiecki, Lorraine E.; Raymo, Maureen E. (January 2005). "A Pliocene-Pleistocene stack of 57 globally distributed benthic d18O records" (PDF). Paleoceanography. 20: PA1003. BibcodPalOc..20.1003L. doi:10.1029/2004PA001071.
Supplement: Lisiecki, L. E.; Raymo, M. E. (2005). "Pliocene-Pleistocene stack of globally distributed benthic stable oxygen isotope records". Pangaea. doi:10.1594/PANGAEA.704257.
Lisiecki, L. E.; Raymo, M. E. (May 2005). "Correction to "A Pliocene-Pleistocene stack of 57 globally distributed benthic ?18O records"". Paleoceanography. 20 (2): PA2007. BibcodPalOc..20.2007L. doi:10.1029/2005PA001164.
data: doi:10.1594/PANGAEA.704257.
Jump up ^ Petit, J. R.; Jouzel, J.; Raynaud, D.; Barkov, N. I.; Barnola, J. M.; Basile, I.; Bender, M.; Chappellaz, J.; Davis, J.; Delaygue, G.; Delmotte, M.; Kotlyakov, V. M.; Legrand, M.; Lipenkov, V.; Lorius, C.; Pépin, L.; Ritz, C.; Saltzman, E.; Stievenard, M. (1999). "Climate and Atmospheric History of the Past 420,000 years from the Vostok Ice Core, Antarctica". Nature. 399: 429–436. doi:10.1038/20859.
Jump up ^ Zachos, J.; Pagani, M.; Sloan, L.; Thomas, E.; Billups, K. (2001). "Trends, rhythms, and aberrations in global climate 65 Ma to present". Science. 292 (5517): 686–693. BibcodSci...292..686Z. doi:10.1126/science.1059412. PMID 11326091.
Jump up ^ NOAA. "What's the hottest Earth's ever been?". climate.gov. National Oceanic and Atmospheric Administration. Retrieved 19 February 2015.
Jump up ^ Veizer, J. (1999). "87Sr/86Sr, ?13C and ?18O evolution of Phanerozoic seawater". Chemical Geology. 161: 59–88. doi:10.1016/S0009-2541(99)00081-9.
Jump up ^ Eyles, N.; Januszczak, N. (2004). "'Zipper-rift': A tectonic model for Neoproterozoic glaciations during the breakup of Rodinia after 750 Ma". Earth-Science Reviews. 65 (1–2): 1–73. BibcodESRv...65....1E. doi:10.1016/S0012-8252(03)00080-1.
Jump up ^ Royer, Dana (23 March 2014). "Dana Royer comment at RealClimate". RealClimate. Retrieved 26 March 2014.
Jump up ^ Knauth, L. Paul (2005). "Temperature and salinity history of the Precambrian ocean: implications for the course of microbial evolution". Palaeogeography, Palaeoclimatology, Palaeoecology. 219: 53–69. doi:10.1016/j.palaeo.2004.10.014.
Jump up ^ Shields, Graham A.; Kasting, James F. (2006). "A palaeotemperature curve for the Precambrian oceans based on silicon isotopes in cherts". Nature. 443: 969–972. doi:10.1038/nature05239.
Jump up ^ Gaucher, EA; Govindarajan, S; Ganesh, OK (2008). "Palaeotemperature trend for Precambrian life inferred from resurrected proteins". Nature. 451: 704–707. doi:10.1038/nature06510.
Jump up ^ Risso, VA; Gavira, JA; Mejia-Carmona, DF (2013). "Hyperstability and substrate promiscuity in laboratory resurrections of Precambrian b-lactamases". J Am Chem Soc. 135: 2899–2902. doi:10.1021/ja311630a.

Aaaaand you checked those sources to make sure they match what you read on Wikipedia? I'll look up those sources myself, of course, but just because a site claims to use another source doesn't mean that they took the data in context.

Please do. I'm going to sleep right now. I look forward to reading your response tomorrow morning. You can also google "Global mean surface temperature during Cambrian period" or "Global mean surface temperature during Eocene period" and you will find the following text: "Early Eocene Period – 54 to 48 Million Years Ago. ... Temperatures during the Eocene can be reconstructed from geochemical measurements of ocean sediments and from vegetation types preserved on land. The reconstructed global mean surface temperature for the Early Eocene is 9 to 14°C higher than today."

[skepticalscience.com] This article contradicts your argument that there is a linear relationship between rise and CO2 and rise in temperature. As far as the greater amount of CO2 and temperature during the Cambrian and other eras of the Earth goes, it's not just the amount of CO2 and temperature increase that's a problem. It's the rate of increase. The fluctuations of CO2 and temperature throughout history have happened at relatively slow, steady rates. However, since the industrial revolution, we've witnessed a huge spike in CO2. Organisms are used to evolving and adapting to relatively gradual changes, but this is a rate of change that- as far as I know- has not been seen in Earth's history. If this is true, then your logic that CO2 and global temperatures have been much higher, therefore we'll be fine, are flawed. It wouldn't be so flawed if these changes happening at slow, easy to adapt to rates, but that does not appear to be the case.

I don't know if I'll post anything more on here tonight, but I've just got to clear things up about one thing- I don't tolerate being treated like an idiot. Your little comment back there comparing me to a fundie religious believer pissed me the fuck off. Insults to my intelligence are border line fighting words for me.

Now I don't mind being contradicted or proven wrong. That's perfectly fine. But I draw the line at insults and snide comments. That's when I get angry. I'd love to continue the conversation civilly and respectfully, but I just needed to get that off my chest and let you know where I draw the line. So let's start off on a clean slate. I'm willing to be more patient and respectful if you are.

Agreed. Overpopulation is certainly a factor. However, allow me to posit this- let's say that as of tomorrow, our birth rate and death rate equaled out so that our population no longer rises. Or perhaps our population begins to drop. This still won't solve the problem of over consumptiom and CO2 emissions. Non renewables will remain non renewable, and CO2 will still be pumped out, albeit at a slower rate. Solving the overpopulation problem will certainly alleviate the problem, but I don't think that it's the be all end all.

Agreed, but easier said than done, right? The reason is because of different economic and political situations around the world. In developing nations, many people have lots of kids because they need the extra help to do work around the home. Lack of sex education, contraception, and women's rights to choose further exacerbate the problem. In industrial nations, the opposite is true. People in developed nations have less need and desire for kids, so they don't have as many. Of course, developed nations are also the biggest emitters of greenhouse gases. This goes to show that overpopulation is far from the only prevalent problem.

Oh yeah, we definitely need the worlds' governments to get behind solving these problems. However, I think that change on a government level has to start and be moved by popular support on an individual level. This means being more vocal and informed about environmental issues so that we are spreading reliable information. Oddly enough, it's not so much world governments so much as the US government that's the problem. We're the biggest CO2 emitters and resource depleters, yet we're doing the least about it. Most governments around the world at least acknowledge the validity of climate change as a real problem.