/sci/ - Science & Math

>>8938515
>>8938636

The graph itself is based on two real datasets, but without sourcing we can't tell what's what. This version of of it tends to be reposted as a skeptic meme, which leads us to think it may be inappropriately splicing the two things that aren't comparable. If you talk an actual paleoclimate expert who deals in these extremely long time scales, they'd actually disagree that there is no correlation between temperature and CO2. Indeed, CO2 is probably the main deciding factor on why our planet looks the way it looks today, and how some of the large-scale shifts occurred in the distant past. Leaving out CO2 as a factor means we can't account for shit and nothing makes sense; factoring it in puts the puzzle pieces together:

http://www.nature.com/nature/journal/v446/n7135/abs/nature05699.html

http://onlinelibrary.wiley.com/doi/10.1002/2014GL060457/full

http://science.sciencemag.org/content/330/6002/356

http://www.tandfonline.com/doi/full/10.3402/tellusb.v65i0.19734

And of course, I'm sure you've all seen graphs very similar to this before. (source: https://www.ipcc.ch/publications_and_data/ar4/wg1/en/figure-6-3.html))

1/2

>>4369909

>IT'S TOO SHORT DURRRR

Yes, I suppose you could take the entire 4.5 billion year history of the Earth and say that we are experiencing horrific global cooling. Except humans don't live for millions of years and talking about dinosaurs and shit really isn't relevant to our current situation.

However, even if we take into account very long timescales, the changes that are now underway are extraordinarily rapid and cannot be explained by natural factors alone.

>>3811794

>CO2 has had a minor influence on climate in the past as indicated by ice core records, however it has never been the primary driving force of a climatic change.

That's not what I gathered from the literature.

http://www.sciencemag.org/content/330/6002/356

>Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature

http://www.agu.org/meetings/fm09/lectures/lecture_videos/A23A.shtml

>The Biggest Control Knob: Carbon Dioxide in Earth's Climate History

http://droyer.web.wesleyan.edu/climate_sensitivity.pdf

>Climate sensitivity constrained by CO2 concentrations over the past 420 million years

Etc.

>>3611765

So those measurements can tell us how much global warming is currently realized at a given point of time. But how much global warming is there to come, at a given level of greenhouse gas emissions? There's a lot of inertia in the system and a lot of complicated feedbacks. So there's sorting-out to do.

There are three broad categories of such methods: empirical/laboratory observations, paleoclimate records, and GCMs. When you combine all these methods you get an average of 3 degrees increase in temperature for every doubling of CO2 concentration, with a "fat tail distribution" on higher temperatures. i.e. higher temperature increases are more likely than lower ones.

Assuming we make no changes in policy, we will hit 1000 ppm CO2 by the end of 2100. This will be the highest concentration of CO2 since the dinosaurs died out, and CO2 would have doubled more than twice. At this level of warming, we would eventually return to an ice-free state with sea levels perhaps 80 meters higher than it is now. Perhaps only 1 or 2 metres by the end of the century, but this places a huge amount of infrastructure at risk: nuclear power plants, naval bases, gas terminals, ports, sewage treatment plants, and so on. Large warmings under geologically-speaking extremely fast (but still 10 times slower than today) conditions have historically led to mass extinctions.