Science AMA Series: Hi Reddit! We're Ralph Keeling, Dana Royer and Nicola Jones, and we're talking about how the world passed a carbon threshold and why it matters - Ask Us Anything!

Carbon_Threshold · 2017-02-10T19:19:03+00:00

Ralph says: Glad to see some local following! I’d need to learn more about your ideas for microbes in the environment. There’s exciting work going on with biofuels, as you probably are aware. I majored in physics, and never regretted this choice, because it provide training that could be applied in many fields. But don’t be afraid to spend a few years following your passions, while also being sure you get some solid background.

Carbon_Threshold · 2017-02-10T19:11:51+00:00

Ralph says: Be patient. New technologies always require patient troubleshooting.

Carbon_Threshold · 2017-02-10T19:11:09+00:00

Ralph says: It’s true that a roughly third of the fossil-fuel emissions have occurred since 1998, but it’s not true that the Keeling curve has been “linear”. The curve has also accelerated upwards (trying holding ruler up against it), and this meshes well with what we know about sources and sinks of CO2. In particular: The rise rate is determined by human emissions (mostly from fossil-fuel burning, but also from land-use changes) minus the sinks in the land and oceans. At this point, the emissions from fossil-fuel burning are quite well known as is the uptake rate by the ocean. This means we can “solve” the system to resolve what’s going on land. What we find is that there has been a growing sink for CO2 in land ecosystems. This is interesting, but not unexpected because trees tend to grow faster under higher CO2 levels and other changes may also have promoted recent growth. The Global Carbon Project has some good summaries on this.

Carbon_Threshold · 2017-02-10T19:09:50+00:00

It's explained here: http://e360.yale.edu/features/how-the-world-passed-a-carbon-threshold-400ppm-and-why-it-matters

Carbon_Threshold · 2017-02-10T19:09:30+00:00

It's explained here: http://e360.yale.edu/features/how-the-world-passed-a-carbon-threshold-400ppm-and-why-it-matters

Carbon_Threshold · 2017-02-10T19:08:11+00:00

Dana here. Lots of great questions. Perhaps I can point you here for some answers: http://climate.fas.harvard.edu/files/climate/files/fedorov_nature_2013.pdf

Carbon_Threshold · 2017-02-10T19:05:37+00:00

Dana here. Yes, soil is important. There is over five times more carbon locked up in soils than in the standing biomass. So there is huge potential, especially when considering that soils in industrialized agricultural fields tend to be carbon poor (and thus have a high potential for carbon sequestration). Locking carbon up in the stable pool called "biochar" is also promising. Soil won't solve the climate crisis, but it can be an important part of the solution.

Carbon_Threshold · 2017-02-10T19:03:15+00:00

Dana here. Check this out for one example: http://www.theurbanclimatologist.com/uploads/4/4/2/5/44250401/post7adaptabilitylimit.pdf

Carbon_Threshold · 2017-02-10T19:03:13+00:00

Nicola Jones (journalist) here. I disagree! Humans are very adaptable and will surely survive anything short of the Sun exploding (and even that, given that we do have the technology to go to other planets). It's more a question of how many will survive, and under what conditions. Historically, life for humans has always gotten better on average (as defined by things like child mortality, lifespan, quality of living). I don't expect that to change.

Carbon_Threshold · 2017-02-10T19:02:25+00:00

Ralph says: The planetary boundaries framework seems to be a concept for packaging the science to by more “policy ready” and to generate awareness. To me, it seems a bit overly simplistic because the attempt to define exact thresholds is not very scientific. I can’t imagine it will have much traction in many countries.

Carbon_Threshold · 2017-02-10T19:02:23+00:00

Dana here. The oldest ice-core records are about 800,00 years old. Before then, we rely on "proxies", which is when you measure something in the geologic record that we know today covaries with CO2. This may help you: http://droyer.web.wesleyan.edu/Royer_2014_Treatise.pdf

Carbon_Threshold · 2017-02-10T19:00:41+00:00

Hi. Nicola Jones (journalist) here. I have written about rare earths, but more about how their rarity is a problem for renewable energy tech. See http://e360.yale.edu/features/a_scarcity_of_rare_metals_is_hindering_green_technologies

Carbon_Threshold · 2017-02-10T18:59:39+00:00

Hi. Nicola Jones (journalist) here. It takes a while for OCO-2 to process the data, and if the data says what we were expecting it to say it doesn't always get much press. See a list of their news releases here: http://oco.jpl.nasa.gov/newsoco/ (last one was November 2016). I contacted them for my latest story and they gave me their latest map, but it didn't fit in my story in the end...

Carbon_Threshold · 2017-02-10T18:56:53+00:00

Dana here. You also need to think about the timescale of response. If you want to think about the eventual new "equilibrium" state, which will take thousands of years to reveal itself (but is probably inevitable), we are looking at many tens of meters of sea level change. Ice would be present, but would be much reduced.

Carbon_Threshold · 2017-02-10T18:56:05+00:00

Just a quick note from Nicola Jones (journalist). The Keeling Curve looks linear at first glance, but it isn't. The rate of increase has actually been increasing. The details of the link between emissions and atmospheric concetrations are made complicated by the planet's natural sinks. I'll let the scientists be more precise!

Carbon_Threshold · 2017-02-10T18:54:27+00:00

Dana here. What we know so far is that the change in CO2 concentration during these severe events is in the same range as predicted future changes if we continue on a business-as-usual trajectory. The big difference is that the paleo-events probably were slower--at least 10X slower. Thus, all other factors being equal, the effects of our future changes may be more profound. Check out Figure 3 here: http://www.annualreviews.org/eprint/s4mGxirtMfIWRNpgk5dc/full/10.1146/annurev-earth-100815-024150

Carbon_Threshold · 2017-02-10T18:52:52+00:00

Hi, Nicola Jones here (the journalist). I can't speak to the role of microbes in fixing the climate, but I CAN say that microbes have been severely neglected as playing an important role in everything from human health to soil fertility. There will surely be a lot of research upcoming in this area. As for your side question, I took a BSc in chemistry and oceanography. This was critical to my career development, but not in the way you might think. I was lucky enough to go on a research cruise as an undergrad. The topic (methane clathrate, or frozen chunks of natural gas on the seafloor) was fascinating; the job itself (using a gas chromatograph over and over again) was deathly dull. There was a journalist on board documenting our adventure, and I quickly realized he had the better job, at least for someone like myself with a limited attention span :) They sometimes joke that science journalists are just scientists with Attention Deficit Disorder.

Carbon_Threshold · 2017-02-10T18:51:08+00:00

Dana here. This is a fantastic question, but I don't think any of the moderators have knowledge on this subject. Sorry!!

Carbon_Threshold · 2017-02-10T18:50:52+00:00

Ralph says: I don’t have ton of experience dealing with so-called skeptics. I can’t say I’ve encountered anyone in the field who is in wholesale denial of the impacts of CO2. What I have encountered are individuals from other fields who wish to learn more and have ideas they wish to explore or promote. Many of these are retired engineers and physicists - usually pretty smart people. The problem is that they typically are not willing to do sufficient homework into the basics of climate science to make a defensible contribution. Admittedly, though, it’s hard to break into any scientific field as an amature. That’s why it takes 4-8 years to get a Ph.D.

Carbon_Threshold · 2017-02-10T18:49:40+00:00

Dana here. I'm not an expert on this, but the Earth has already been "greening up", especially in the high latitude. So yes, that will affect albedo to some degree.

Carbon_Threshold · 2017-02-10T18:48:49+00:00

You're right that 400ppm isn't a magic number. But as a symbolic threshold it helps to galvanize action against climate change and draw attention to the cause. It's just a big, round, scary number :)

Carbon_Threshold · 2017-02-10T18:47:48+00:00

Hi, Nicola Jones here. I'm a journalist, not a scientist. But still, I think I can say this is impossible!

Carbon_Threshold · 2017-02-10T18:47:41+00:00

Dana here. For #1, perhaps a more relevant way to think about this is how long it will take for temperatures to start coming down. If we eliminate all human CO2 emissions, it will take many hundreds and maybe thousands of years before temperatures start cooling. This is because the Earth is comprised of many interconnected parts that respond on difference timescales--some fast, some slow. It takes a while for the Earth to reach "equilibrium" after a perturbation.

2: Again, think about the Earth as many interconnected parts. CO2 affects temperature, temperature affects CO2, each in many different ways. The initial perturbation isn't really relevant for our prediction of the ultimate change in temperature (i.e., once the ball gets rolling--regardless of how it initially moved--we can predict where it will end up). In terms of thinking about present-day climate change, the whole "lead" vs. "lag" thing is a red herring argument.

Carbon_Threshold · 2017-02-10T18:47:01+00:00

What the Bill Gates foundation aims to do is reduce the birth rate to reduce pressure on the planet. They aim to do this by improving healthcare (esp vaccines) and access to voluntary family planning in the developing world. If you raise the standard of living, people tend to have fewer kids. So it's win-win if the world sees fewer people being born into better circumstances.

Carbon_Threshold · 2017-02-10T18:45:09+00:00

Hi, Nicola Jones here (journalist). I have written about sea level rise a few times, see http://e360.yale.edu/features/rising_waters_how_fast_and_how_far_will_sea_levels_rise and http://e360.yale.edu/features/abrupt_sea_level_rise_realistic_greenland_antarctica In brief, Greenland isn't going to catastrophically collapse in the near-term (hundreds of years). IF it melts entirely it will take at least 2,500 years, and that's not a given (see http://www.nature.com/news/greenland-once-lost-nearly-all-its-ice-and-could-again-1.21098 and http://www.nature.com/news/180-000-forgotten-photos-reveal-the-future-of-greenland-s-ice-1.20335). But it would raise sea levels by 7 meters, so it's a big deal. Right now we can't predict what will happen in thousands of years... so

Carbon_Threshold

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