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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Recent Comments

Comments 22301 to 22350:

sauerj at 01:10 AM on 4 November 2016

Barack Obama is the first climate president

A little rain on the parade: I have trouble understanding how any carbon cessation strategy, other than a carbon tax (preferrably a revenue-neutral carbon fee & dividend, CFD as proposed by Citizen's Climate Lobby, CCL) is ever going to cut carbon emissions down to sustainable levels. So, I am perplexed why we are not unifying behind the simple logic of CFD, and make this the #1 focus. It may be hard to enact, but anything else, I feel, will ultimately be a waste of time. I believe the following data backs this up.

This LINK link (last chart) indicates that US energy efficiency (by unit GDP) has gone up 58% since 1990. Therefore, you'd expect carbon emissions would have gone down by 58% during that same time. Not so; this next LINK link (1st timeline chart) indicates that US carbon emissions have stayed flat-lined since 1990; this means that US consumes 58% more stuff than they did in 1990. Why did these conservation measure do nothing to reduce carbon emissions? My simple brain says, because of the flywheel inertia effect of supply vs demand economics keeping the fossil fuel demand up. Maybe I'm over simplifying, but I think I'm more right than wrong.

The following is what keeps ringing in my head: Anything but putting a price on carbon (which is a morally legitimate inclusion of their future external costs), no matter how "environmental" right these other efforts might seem, is a near-complete waste of time (other than for the message, and your own personal future adaptation to a carbon-free economy). You might have reduced your personal footprint, but all you really did was keep the cost of FF's down, and because of that somebody else or, more likely, some large-scale industry (which must operate on a least-cost, capitalistic basis to survive) will be more than glad to use the FF's that you so heroically tried to keep in the ground. In other words, you didn't accomplish a thing (other than broadcast a message and adapt only yourself to what will eventually be required). But, in terms of achieving real net change, you did nothing.

Now a counter argument would say that since renewable energy cost is falling below FF energy, then this will drive conversion. Yes, but not really! 1) What is missing in this argument, is that, because of the lowered FF cost, the demand per capita will simply go up. We will just "add on" the renewable energy onto the FF energy we were using before. I think the above data proves this. And, further more, 2) Electricity, even renewable electricity, will still cost ~4x more than gas, and ~2x more than oil (energies used for their high-temperature, thermal combustion potential, for example, drying). To replace this with electricity (using other high-temperature energies, i.e. hydrogen electrolysis or bio-diesel for example) will therefore cost ~3-5x today's FF costs. This is a near-impermissible hump of economic survival proportions for many status-quo, business as usual industries (all driven by US & OUR us & our market demands). Simply getting renewable electricity slightly more competitive over FF electricity (as FF prices will simply drop along side with renewable prices) will not be near enough to promote re-tooling industries that require these high-concentrated energy demands. Ultimately, CFD is required to overcome the flywheel effect of supply vs demand economics. I believe nothing short of this will be effective. ... And, the industries that do not survive the new economics will simply wither away, as they should for the sake of future generations.

Is not this cessation logic predominantly true? Or, is it too polarizing to be the primary battle cry? Why are not other groups (350, Climate Parents, Interfaith, Catholic Covenant, etc) not promoting this logical strategy? ... Likely Answer: Maybe these activist group leaders understand all of this, and they know they are seen as political adversaries by those we need to get on board (in congress). So, they purposely do not toot the CFD horn, as they know that will give a foothole for pundits to poison the political will that CCL is fragilely trying to build. Yes, that makes good sense. ... Wisdom! ... However, I do think SkS itself could toot the CFD horn a bit louder. Case in point, I knew about the power of CFD back in 2009 when reading Hansen's Storms (he probably mentions CCL in that book, but it didn't sink-in then) but I didn't know that the CCL organization even existed until 6 years after of reading SkS posts. And, I only heard about them when local chapter did a call-out in a local newspaper. That lack of attention by SkS is not good, sorry!

Moderator Response:

[JH] Post slightly edited per request of commenter.

Please note that the use of all caps is akin to shouting and is prohibited by the SkS Comments Policy.

Kirdee at 13:25 PM on 3 November 2016

Over 31,000 scientists signed the OISM Petition Project

Hi. I've been visiting SkS for some time now and generally find the explanations of the science of CC a useful balance of technical detail with layperson language. The filtering by knowledge level is a novel and useful tool (I usually read all levels!).

I've been exploring the topic of consensus and the flip-side, denial. So I've just read both Cook et al 2016 and the "petition paper" by Robinson et al (both of which are linked to in your article but at which I arrived quite indepently).

It is clear from reading Cook et al and your article above the value of understanding who is providing the opinions. Cook et al finds that the higher the level of expertise in climate science, the greater the level of consensus. Analogies of getting a heart condition checked out by a motor mechanic are relevant when comparing the findings of Cook et al (ie 97% of expert climate scientists agree that climate change is caused by human activity) versus the OISM petition, signed predominantly by non-climate, possibly non-practising, unpublished, general scientists.

So it is useful that you and other websites, notably the Huffington Post (http://www.huffingtonpost.com/kevin-grandia/the-30000-global-warming_b_243092.html) have tackled the credentials of both the signatories and the creators of the petition and Robinson et al paper. Thank you.

However, I think it would also be useful to tackle the paper itself. Climate change is bewildering to non-scientists, and when one comes across a paper as apparently credible-seeming as the Robinson et al paper, it is difficult for a non-scientist to sort the credible science from the rubbish. Robinson et al's theory about solar irradiance looks pretty good on the graphs, and the longer-term fluctuation in earth's temperature also makes our current increases look pretty modest.

So I've done just enough preliminary digging into those aspects to convince myself that the Robinson et al paper is at best incomplete in its presentation of evidence (for instance, this webpage about solar irradiance http://solar-center.stanford.edu/sun-on-earth/glob-warm.html), and in reality, deliberately misleading.

Yes, go ahead and expose the poor credentials or vested interests of those with opinions that contrast the majority view or have a disporportionate influence, but we need to not simply write-off everything that those people say as rubbish simply because of those credentials or interests. The discrediting of those views should also be focused on the validity or otherwise of their scientific claims, backed up with credible science and analysis. I think it is far more powerful to expose the errors or holes in their arguments than to simply call them fraudulent.

You have all the relevant science within this site. I suggest that it would be a useful counter to the OISM petition and paper for you to list the scientific claims made in the paper and provide links to the relevant science or other references as you did with the list of studies on consensus. Then your debunking of the petition and paper would not need to rest on the absurdity of the perceived size of 31000 signatories as a representative sample.

Regards, Kirdee.

bozzza at 11:25 AM on 3 November 2016

Debunking climate myths with Leonardo DiCaprio's Before The Flood

As it is system that corrupts man of course regulated markets are responsible: what is representative democracy if not just another system waiting to game those who participate in it?

chriskoz at 07:48 AM on 3 November 2016

Barack Obama is the first climate president

...we transitioned from the worst climate president ever (Bush) to the best (Obama).

It goes without saying that with the next president, we must not go in a big time yo-yo to the dark ages & the worst imaginable fool (whose name is forbidden in my household, so I won't even mention it here) worse than Bush, who would destroy in no time, everything Obama has done.

As the election day nears and the absurdity of the fool having a real shot at the White House looms, I start to worry. Not really about the unusually low morale nor about total ignorance of reality by the fool: Congress, even Republican, would not easilly allow the foolishness to take over US politics. But at stake are the very things we're talking about here: there would be no opposition within the Republican Congress to destry all climate legacy Obama left, e.g. starting from KXL veto overturned.

But let's hope all my talk is just unnecessary scare and the next president Hillary Clinton will strive to at least match if not surpass Obama/s legacy.

chriskoz at 06:47 AM on 3 November 2016

Global weirding with Katharine Hayhoe: Episode 3

I raised the issue of Katharine's name few times here.

Now I started down-voting all posts where Katharine's name is mispeled. It'd be nice to have some bot to automatically send an email to the offending commenter reminding their mistake.

William@1 you have Katharine Hayhoe's name boldfaced at the title, how could you've missed it?

william5331 at 05:21 AM on 3 November 2016

Global weirding with Katharine Hayhoe: Episode 3

Kathaerine

Talk to us about how power companies are integrating privately owned renewable energy generating systems into their grids in such a way that it is worthwhile both for the power company and for the small investor in renewable energy. This is the barrier to greater uptake. The cost of equipment has reached the level of economic feasiblility. The power companies all over the world are dragging their feet. What models are there out there that we can point to. Power companies are like sheep. They need a leader.

Moderator Response:

[GT] Spelling corrected.

Rob Honeycutt at 00:44 AM on 3 November 2016

Debunking climate myths with Leonardo DiCaprio's Before The Flood

I think the difference is related to producer vs consumer, though.

Few consumers are going to make the effort to specifically demand sustainable foods in the volumes that would make a difference. People have to eat and they essentially eat what is available to purchase.

Careful and creative regulation could do a lot to shift the practices of producers in a manner that could have a significant effect much more quickly.

RedBaron at 11:43 AM on 2 November 2016

Debunking climate myths with Leonardo DiCaprio's Before The Flood

Rob,

Yes overall you can help by reducing the beef you eat, but you can help even more by simply chosing grass finished rather than corn finished. And we can help even more by not subsidizing the over production of commodity grains and converting that acreage back to grassland/savanna/forest depending on what the top successional biome is local to that region. And that strategy is the very best because grassland/savanna/forest all can support food and fiber production at the same time as supporting wildlife biodiversity. In most cases even more food and fiber per acre than commodity grains. Grasslands still support grazers and grain. Savannas still support both grazers and nuts, fruit, timber and omnivore species too. And forests can be managed as both timber and food forests. All it takes is good careful management and all 3 can become carbon sinks without disrupting the food supply or economies, actually improving both.

Rob Honeycutt at 10:28 AM on 2 November 2016

Debunking climate myths with Leonardo DiCaprio's Before The Flood

I was actually concerned they were going to overplay the beef thing much more. At least they didn't make the bogus claim that 51% of greenhouse emissions come from meat, like some do. They made the more rational and supportable claim that agriculture accounts for 18% of man-made CO2e (if I remember correctly).

Overall, yeah, you can help reduce your carbon footprint by limiting how much beef you consume.

(I was thinking the same thing about the Chik-fil-A connection when watching. :-)

I get my hackles up a bit when lifestyle changes get overplayed when the big nuts to crack are primarily systemic issues related to the sources of energy. It's terrible framing to say, essentially, "If you were to just behave as I'm saying you should behave then all will be well." It's a perfect way to get people to reject everything flat out.

In all that could have gone wrong, I think they did a really good job of sticking close to the science and projecting the incredible sense of urgency we face.

RedBaron at 08:01 AM on 2 November 2016

Debunking climate myths with Leonardo DiCaprio's Before The Flood

Starting at 51:00 all that is misleading regarding agriculture. I did find some other flaws, but I'll let others discuss the parts that were misleading in their fields of expertise. My field of expertise is agriculture. Yes agriculture is a big problem, but it certainly isn't the cow to blame, it's the feedlots and the vast acreage of corn and soy grown to supply feedlots and biofuel industries. Feedlots and all factory farming is a emissions source for both CO2 and CH4, properly managed grasslands are a net sink for both. So why would they blame the cows unless rather than actually stick to the science, it was rather spun to fit a certain dogma?

Some people might be swayed by spin, but when science is spun, it generally has a backlash later when people realise they were played for the fool. I would be much happier if they actually addressed the root of the problem than give ridiculous advise like just eat more chicken. LOLZ like a silly Chick-fil-A advertisement. :D

nigelj at 05:38 AM on 2 November 2016

Climate change could push risk of ‘megadrought’ to 99% in American southwest

Swampfoxh @ 8, sounds like an interesting book. Any clues in the book why we would have a regular drought cycle like this?

I'm curious what would happen every thousand years to trigger this, as its such a long cycle.

Rob Honeycutt at 04:53 AM on 2 November 2016

Debunking climate myths with Leonardo DiCaprio's Before The Flood

RedBaron... Would you care to expand on what science you think the movie got wrong?

John Hartz at 02:22 AM on 2 November 2016

Coal doesn’t help the poor; it makes them poorer

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Cedders at 07:32 AM on 31 October 2016

Extreme weather isn't caused by global warming

Some non-expert comments to Giancarlo and Terry, in lieu of a more informed response.

Giancarlo - yes, it'd surprise me a litle if increased drought hasn't been unambiguously detected, although it has been unambiguously projected. Would be interested to take that figure 5 in Hao up to present and see if the trend is positive yet. I find examples of projections in the USA in the National Climate Assessment, and in Cook, B. I., Ault, T. R. & Smerdon, J. E. Sci. Adv. 1, e1400082 (2015) covered here and here. Cook also detects extreme drought in the Levant. It does seem there has been differences of emphasis in the literature recently. Sheffield et al 'Little change in global drought over the past 60 years' seems like a downward estimate compared to the usual measure (PDSI) of past drought, and is put in context by John Holdren in an article reproduced on this site. He also refers to a summary in research by Schwalm et al that 'severity and incidence of climatic extremes, including drought, have increased'. Spinoni et al (2013) finds a small increase in each of global drought frequency, duration and severity from 1951-2010, but big regional variations that are disruptive.

Responding to Terry's graph, this is nice work, but I'm sure someone must looking at this professionally, who you may be able to contact. The increase in thunderstorms you show is so dramatic it must surely be an artefact, maybe of increased reporting? Secondly, a correlation between two time series each of which are increasing may well come to >90% (even more so if smoothed), but be misleading since both are dependent on time.

It strikes me that new measures may be useful for examining trends in 'extreme' weather rather than total weather, for example, maximum hourly rainfall, variance of rainfall, or collating data on water tables and aquifers. Not sure how realistic or expensive that would be.

Tom Curtis at 05:50 AM on 31 October 2016

Welcome to Skeptical Science

curiousd@31, apparently Chris Colose joined NASA GISS just this month, and consequently has a new email address. For that he deserves congratulations. For the rest, I am not a correspondent with any of the people listed, and am finding the email addresses by google search. If I were you, and if the email address you have is current, I would make Dr Pierrehumbert the first point of contact. My experience in contacting scientists is that so long as you remember that any help they provide you is a courtesy by them, not a right of yours; they tend to bend over backwards to help honest enquirers. Given that all three of the people I recommended, and SOD, have a history of trying to help explain AGW, I very much doubt that they would be different in this regard; and Dr Pierrehumbert would be acknowledged by the three others as the most expert on this topic, not to mention best informed about what he meant when he wrote his text book. Here is a more recent email address for him.

ubrew12 at 02:55 AM on 31 October 2016

Climate change could push risk of ‘megadrought’ to 99% in American southwest

LaughingMan@4: Unless the beavers have a wicked 'rain dance', I don't think they're going to be as helpful as you imagine in many places.

ubrew12 at 02:52 AM on 31 October 2016

Climate change could push risk of ‘megadrought’ to 99% in American southwest

bjchip@1: Maybe one form of how Earth will 'Ring' was anticipated in the 1972 film 'Silent Running'. Bruce Dern plays a biologist who maintains a spaceship filled with the last natural plants from Earth, and responds with rebellion when he's asked to clear them out for cargo. I don't think many natural ecosystems can respond quickly enough to avoid catastrophe; for them, 'Ringing' brings fracture. I think humans can respond more rapidly (but probably after much difficulty), and may have to act forcefully to prevent species extinction in a few decades or so.

ELIofVA at 00:11 AM on 31 October 2016

Global weirding with Katharine Hayhoe: Episode 2

I asked a few weeks ago after Katharine Hayoe's earlier videos featured on this web site how as a Evangelico Christian she resolves the contradictions between the Bibilical version of creation and the physical evidence of much longer time frame. In this video, when she speaks of much longer time frames than the Bible, she is siding the the physical evidence. I presume that many Christains take the Bible as a metaphor more than a historical document. I hope she can speak to these Christian believers to support Climate Change believers so that we can work together to solve the problem.

BaerbelW at 23:02 PM on 30 October 2016

Over 31,000 scientists signed the OISM Petition Project

Just found a new entry on Snopes about this:

Not All Climatologists

Acouphène at 22:29 PM on 30 October 2016

CERN CLOUD experiment proved cosmic rays are causing global warming

New paper from CERN experiment : "A significant fraction of nucleation involves ions, but the relatively weak dependence on ion concentrations indicates that for the processes studied variations in cosmic ray intensity do not significantly affect climate via nucleation in the present-day atmosphere."

http://science.sciencemag.org/content/early/2016/10/26/science.aaf2649

curiousd at 16:44 PM on 30 October 2016

Welcome to Skeptical Science

Hi Tom Curtis,

I have attempted to contact everyone on your list except Dr. Pierrehumbert and either get no response or find that the listed e mail address does not work. I am not on Facebook nor Twitter! Do you know of a more recent e mail address for Gavin Schmidt? I would prefer to check with another expert before contacting Dr. Pierrehumbert.

Sincerely,

Curiousd

RedBaron at 10:50 AM on 30 October 2016

Climate change could push risk of ‘megadrought’ to 99% in American southwest

It is a pity that LaughingMans post was so inflamatory. Because that is in fact one leg of a 3 pronged approach, ecosystem restoration. And none better than keystone and engineer species like beaver to start restoring vast areas and using them as carbon sinks, as well as mitigating drought. Beavers are the stereotypical ecosystem engineer because of the effects their dams have on channel flow, geomorphology, and ecology. The ecological cascade that follows is profound and spreads far beyond the beavers' habitat.

Unlike LaughingMan, I don't see this as a stand alone solution. But it certainly can be a significant part of the solution.

ed leaver at 09:11 AM on 30 October 2016

Debunking climate myths with Leonardo DiCaprio's Before The Flood

Hi John, your contributions are appreciated. Could you possibly attribute the concluding figure of your last "We have all the technology..." bullet? It appears to be Figure 2 from The Solutions Project's: 100% Clean and Renewable Wind, Water, and Sunlight (WWS) AllSector Energy Roadmaps for 139 Countries of the World Jacobsen, Deluchi, et al. 24 October 2016.

Thanks!

LaughingMan at 03:30 AM on 30 October 2016

Climate change could push risk of ‘megadrought’ to 99% in American southwest

I would argue that the occurrence is normal as well.

The likelihood of climate change itself having the effect its always had vs. Human influence is illogical. A permanent drought has been effect in Western US since the 1930s, the Grapes of Wrath even addresses this issue with no recourse. The water wars are in full effect and the EPA made it illegal for water conservation to occur. So if water management has been outlawed by Obama, then the only conclusion will be no water for consumption later.

I have a solution though! While the EPA might regulate human use to exhaust what watersheds might be left, it would be advantageous to farmers and land owners to bring in beavers from Canada to restore the watersheds.

The beaver has proven its ability in Texas and is the ultimate watershed manager. It can engineer the development of green savannah if allowed to carry out its functions.

Obama tried really hard to exterminate the US population in a quiet unobvious way. First he stripped people of their rights, then he stripped them of their jobs, then he quietly took away their access to water and food.

If the watershed in your area is under threat of drying up, you need beavers now to fix it. Beavers, often thought to be a nuisance, a pest, a horrible animal to have near you is actually a clever watershed engineer. They can be effectively communicated with, they can be an effective ally.

The key is the research conducted in Gatineau Quebec Canada by the Government of Canada.

The beaver was interfering with run off, road construction, and was deemed a pest. When the lead researcher used tape recorders with tapes playing running water sound, the beaver started to build dams near the sound. The effect was mind blowing. The beaver started to build where the tape recorders were.

Thus saving the government millions in road construction costs. Plus, the ability to get the beaver to perform vital construction better than any human construct in water was amazing too! Overall, the Canadian watersheds depend on beavers to manage a lot of it. We didn't know until about 5 years ago. Now we rely on beavers to help keep watersheds managed effectively.

This will work in California and the western US as well. But first, the farmers need to tell the EPA to get lost, collect rain water without penalty, stop exhausting or taxing ground water and ease up on archaic farming principles.

If all the areas are properly addressed the solution to the problem should fix itself.

We cannot hope for better outcomes without addressing best practices.

That includes watershed management, responsible use, responsible legislation, policy and procedure, as well as due diligence.

To simply blame climate change is a cop out. Its easier to blame stupidity and ignorance and greed. If I take a five hour shower every day, flush the toilet 50 times a day, open a fire hydrant and flood a street every other day, and generally waste water that's on me. But if the EPA says you can't legally collect rainwater, you have to use your water allotments from the watershed or lose them, and make water management impossible, that's on the government.

This isn't about climate change. The climate always changes. This is about stupidity. If you still think the climate change is at fault, you should also blame the rain spirits for not showing mercy. And the water elves for not bringing moisture and the Eskimos for not bringing ice. Yeah, blame everything else first, shake fingers and further the problem. Or find a trickle of a stream, two inches wide, 1 inch deep, order some beavers, and quietly correct the problem! Within two years you will have your watershed back.

Moderator Response:

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Ger at 23:10 PM on 29 October 2016

Climate change could push risk of ‘megadrought’ to 99% in American southwest

Sauerj@2: 'ringing' or Gibbs phenomenon: https://en.wikipedia.org/wiki/Gibbs_phenomenon. The result from a step function/pulse on a second (or higher) order system

sauerj at 20:06 PM on 29 October 2016

Climate change could push risk of ‘megadrought’ to 99% in American southwest

Nice comment. Curious, could you explain a bit more the concept of "ringing". That is one I haven't heard before. Thanks!

dred at 13:36 PM on 29 October 2016

So what's really happening in Antarctica?

How the ice age commencing ~3 million years ago may have been caused (several angles follow:)

a) There are different hypothesis that have been tested in global cooling model simulation to check their potential importance in the glacial inception of the Northern Hemisphere. One of the major hypotheses is the closure of both the Indonesian (~3-5 Ma, Cane and Molnar, 2001) and Panama seaways (~3 Ma, Bartoli et al, 2005). The closure of the Panama isthmus, which began 13 Ma, was very slow. When the connection between the Pacific and the Atlantic Oceans closed, it intensified the thermohaline circulation in the Atlantic intensifying the heat transport from the equator toward high latitudes. Such hypotheses tested in GCMs circulation show that, even if a larger heat export could bring more precipitation and lead to the built of an ice sheet, the difference in ice sheet volume accumulated between an “open” or “closed” isthmus is small (Klocker et al., 2005; Lunt et al., 2008). On the contrary, the closure of the Indonesian seaway stopped the warm waters from the South Pacific from flowing into the Indian Ocean. This increased the amount of the North Pacific cold waters involved in circulation into the Indian Ocean and thus reduced the heat transport from the tropics toward the higher latitudes, finally triggering a global cooling (Cane and Molnar, 2001). http://www.climatescienceandpolicy.eu/2011/01/the-three-million-years-ago-dilemma-the-beginning-of-the-ice-ages/

……………………………………..

b) The collision of India and southern Asia began between 50 million and 40 million years ago, during the Eocene Epoch, and continues today. The collision produced two main geologic results. First, it began to block the westward-flowing Tethys seaway near the Equator, a process completed with the junction of Africa and Asia near present-day Iran roughly 16 million to 14 million years ago. Second, the creation of the Himalayas and the Plateau of Tibet, which resulted from the collision, altered global climates by changing patterns of weathering (and thus the transfer rate of carbon to the atmosphere) as well as wind circulation. India’s collision with southern Asia also altered patterns of oceanic productivity by increasing erosion and thus nutrient runoff to the Indian Ocean.

Principal Cenozoic faunal migration routes and barriers.
Encyclopædia Britannica, Inc.
The present-day Mediterranean Sea is a geologically recent descendant of a portion of the Tethys seaway. About six million years ago, during the Messinian Age, the western remnant of the Tethys seaway was subject to a brief paroxysm, known as the Messinian salinity crisis, that lasted approximately 270,000 years and saw the entire basin virtually isolated from the wrld ocean. The basin experienced severe desiccation and the precipitation of vast deposits of evaporites (such as salt and gypsum) up to several kilometres in thickness. The Atlantic Ocean subsequently refilled the basin from the west at the beginning of the Zanclean Age. Geologic evidence suggests that water rushing through a channel cut near Gibraltar filled some 90 percent of the Mediterranean Sea within two years. Some scientists contend that sea levels may have risen 10 metres (about 33 feet) per day within the basin during the period of peak flow. The Mediterranean basin has undergone significant geologic evolution during the most recent five million years. About one million years ago this part of the Tethys was transformed into the Mediterranean Sea by the elevation of the Gibraltar sill. Consequently, the Mediterranean basin became isolated from deep oceanic bottom waters, and the present-day pattern of circulation developed. …

The Bering land bridge which united Siberia and Alaska served as a second connection between Eurasia and North America. This link seems to have been breached by the Arctic and Pacific oceans between five and seven million years ago, allowing the transit of cold water currents and marine faunas between the Pacific and Atlantic oceans. The Atlantic and Pacific were also linked by the Central American seaway in the area of present-day Costa Rica and Panama. This seaway, extant since the first half of the Cretaceous Period, prevented the interchange of terrestrial fauna between North and South America; however, for a brief interlude during the Paleocene, a land connection may have existed between North and South America across the volcanic archipelago of the Greater Antillean arc, and some scholars have argued that land bridges between the two continents may have existed for short periods during the Late Cretaceous and again during the late Miocene. The seaway was closed by the elevation of the Central American isthmus between 5.5 million and 3 million years ago. This event had two significant geologic results. … Second, the emergence of the isthmus deflected the westward-flowing North Equatorial Current toward the north and enhanced the northward-flowing Gulf Stream. This newly invigorated current carried warm, salty waters into high northern latitudes, which contributed to increased rates of evaporation over the oceans and greater precipitation over the region of eastern Canada and Greenland. This pattern eventually led to the formation and development of the polar ice cap in the Northern Hemisphere between 4 million and 2.5 million years ago. https://www.britannica.com/science/Tertiary-Period

………………………………………………..

More angles: ("Ice age" is differentiated from "periodic glaciation".)

c) For several million years the Earth has experienced regular galciations followed by shorter warmer periods roughly every 100,000 years. What causes this seemingly regular climate oscillation ? The textbook answer is that they are initiated by changes in the Earth’s orbit and axis tilt called Milankowitch cycles and are then enhanced by a CO2 feedback effect. However the details are complex. For the last 1 million years Ice ages have occurred more or less every 100,000 years which corresponds to the change in eccentricity of the Earth’s orbit around the sun. Looking at the detailed effects on changes to incident solar radiation we find:

1. A 41,000 year variation in the tilt of the Earth’s axis to the sun. This effects the severity of winters and summers during the year.

2. A 23,000 year precession of the same axis of rotation which changes the season within the year. 13,000 years ago Winter in the Northern hemispheer was in June.

3. A 100,000 year oscillaton in the elipticity of the Earth’s orbit around the sun. Most important is the change in elipticity of the Earth’s orbit which changes the distance from the Sun during the year. So when winter in the northern hemisheper corresponds to a large distince from the sun we can expect more severe cold winters. http://clivebest.com/blog/?p=2732

…….

antarctica: 40 million years ago to present

How Antarctica got its ice sheets–In the continual movement of Earth’s tectonic plates, Antarctica was severed from the southern tip of South America about 34 million years ago, creating the Drake Passage. Antarctica became completely surrounded by ocean. The powerful Antarctic Circumpolar Current began to sweep around the continent, isolating Antarctica from the warmth of the global oceans and provoking large-scale cooling. Illustration by Jack Cook. http://www.whoi.edu/services/communications/oceanusmag.050826/v42n2/haug-en1.html
…………

e) 3-22-04 How could the Gulf Stream–which transports not only moisture but also heat to the North Atlantic–lead to major Northern Hemisphere cooling and the formation of ice?
Neal Driscoll and Gerald Haug proposed one solution. They postulated that moisture carried northward by the Gulf Stream was transported by prevailing westerly winds to Eurasia. It fell as rain or snow, eventually depositing more fresh water into the Arctic Ocean–either directly, or via the great Siberian rivers that empty into the Arctic Ocean.

The added fresh water would have facilitated the formation of sea ice, which would reflect sunlight and heat back into space. It would also act as a barrier blocking heat stored in the ocean from escaping to the atmosphere above the Arctic. Both these phenomena would further cool the high latitudes. In addition, Arctic waters flowing back into the North Atlantic would have become less cold and salty–short-circuiting the efficiency of the Ocean Conveyor belt as a global heat pump to North Atlantic regions.

These preconditions–moisture plus an Arctic nucleus for cooling–would have made the climate system highly susceptible to ice sheet growth. Even modest changes in the global environment would have been sufficient to tip the scales and lead to the onset of major Northern Hemisphere glaciation.

Just such a change occurred between 3.1 and 2.5 million years ago, as Earth’s axis fluctuated so that the planet’s tilt toward the sun was less than today’s angle of 23.45 degrees. Less tilt to the Earth would have reduced the amount and intensity of solar radiation hitting the Northern Hemisphere, leading to colder summers and less melting of winter snows.

The onset of Northern Hemisphere glaciation also affected the Subarctic Pacific. It led to the formation about 2.7 million years ago of a freshwater lid at the surface of the ocean, called a halocline. This Arctic halocline would have created a barrier to upwelling, which blocked deep carbon-dioxide-rich deep waters from rising to the surface. The “leak” of heat-trapping carbon dioxide into the atmosphere was stemmed, further cooling the planet.

Many other ocean-atmosphere feedback mechanisms, resulting from the opening and closing of oceanic gateways, remain imperfectly understood. http://www.whoi.edu/services/communications/oceanusmag.050826/v42n2/haug.html

………..

f) Their case rests on temporal correlations between tectonic and climatic phenomena. Particularly impressive is the correlation at 50 Ma of the Indian–Asian collision and the consequent shutdown of what they call the “carbon factory” during the climate optimum, which is immediately followed by the temperature decline of the Middle and Late Eocene and the transition to a glacial state. Correlations do not necessarily imply causation, but they are strongly suggestive when linked in the manner that Kent and Muttoni (1) do. http://www.pnas.org/content/105/42/16061.full

………..

III. The mechanisms behind sudden climate transitions.

It is still unclear how the climate on a regional or even global scale can change as rapidly as present evidence suggests. It appears that the climate system is more delicately balanced than had previously been thought, linked by a cascade of powerful mechanisms that can amplify a small initial change into a much larger shift in temperature and aridity (e.g., Rind and Overpeck, 1993). At present, the thinking of climatologists tends to emphasize several key components:

III.1. North Atlantic circulation as a trigger or an amplifier in rapid climate changes.

The circulation of the north Atlantic Ocean probably plays a major role in either triggering or amplifying rapid climate changes in the historical and recent geological record (Broecker 1995, Keigwin et al., 1994, Jones et al., 1996; Rahmstorf et al., 1996).

II.2 Carbon dioxide and methane concentration as a feedback in sudden changes.

Analysis of bubbles in ice cores shows that at the peak of glacial phases, CO2 was about 30% lower than during interglacial conditions (e.g., Jouzel et al., 1993). We do not at present know whether the lower glacial CO2 levels were a cause or merely an effect of the ice ages.

III.3 Surface reflectivity (albedo) of ice, snow and vegetation.

The intensely white surface of sea ice and snow reflects back much of the sun’s heat, hence keeping the surface cool. Presently, about a third of the heat received from the sun is reflected back into space, and changes in this proportion thus have the potential to strongly influence global climate (e.g., Crowley and North, 1991). In general the ice cover on the sea, and the snow cover on the land, have the potential to set off rapid climate changes because they can either appear or disappear rapidly given the right circumstances.

III.4 Water vapour as a feedback in sudden changes.

Water vapour is a more important greenhouse gas than carbon dioxide, and as its atmospheric concentration can vary rapidly, it could have been a major trigger or amplifier in many sudden climate changes.

III.5. Dust and particulates as a feedback in sudden changes.

Particles of mineral dust, plus the aerosols formed from fires and from chemicals evaporating out of vegetation and the oceans, may also be a major feedback in co-ordinating and amplifying sudden large climate fluctuations.

III.6. Seasonal sunlight intensity as a background to sudden changes.

A major background factor in pacing climate switches on timescales of tens of thousands of years seems to have been the set of ‘Milankovitch’ rhythms in seasonal sunlight distribution or insolation (Imbrie and Imbrie, 1992; Imbrie et al., 1992, 1993). Although the insolation values change gradually over thousands of years, they may take the earth’s climate to a ‘break point’ at which other factors will begin to amplify change into a sudden transition. http://www.esd.ornl.gov/projects/qen/transit.html

…………

h) Last but certainly not least in this list of factors causing the last ice age is that the continent of Antarctica moved to its locale near the South Polar Axis, via continental plate drift.

8-27-09 According to calculations by geologist Professor Christopher Scotese of the University of Texas, Antarctica could
move significantly away from its current location and become at least partially ice-free again within the next 50 million years. http://www.sciencefocus.com/qa/antarctica-moving-away-south-pole

bjchip at 05:44 AM on 29 October 2016

Climate change could push risk of ‘megadrought’ to 99% in American southwest

It is often a point claimed by some who are uninterested in actually reasoning clearly, that thousands of years ago California and its environs experienced droughts that spanned centuries.

Their illogical point is that because the droughts before there was a CO2 issue the CO2 cannot be the cause of droughts.

That was in the period closest to the holocene optimum. It was then as warm as it is currently (though we have raised temperatures more suddenly).

It is, I always point out, utterly illogical to expect a different result from the same temperatures. We are returning (briefly, as it appears we are merely passing through them on the way to something much warmer) to the conditions of the climate optimum.

There are two questions only. The first one is how high will it finally go, as it is clear that we're aimed for something significantly in excess of anything our civilization evolved in.

The second is the effect of the rate of change. It is a complex system and we hit it with a step function change of input. Will it "Ring"? What would ringing look like?

Keep up the good work.

curiousd at 15:38 PM on 28 October 2016

Welcome to Skeptical Science

Thank you Tom,

Attempting to contact Chris Colose.

Curiousd

Rob Honeycutt at 13:28 PM on 28 October 2016

Tracking the 2°C Limit - September 2016

It's a little challenging to get statistical significance with 10 years of data. The point is, the trend over the past decade is running warmer than the long term trend.

denisaf... This is an ongoing series I've been doing posting this chart showing where we are relative to the 2C limit. And no, the 2C limit dates back to the original UNFCCC in Rio and that doesn't state "2C by 2100." The idea is that we need to limit global temperature to 2C, period. And now there are even more aggressive proposals to limit warming to 1.5C.

Harry Twinotter at 13:20 PM on 28 October 2016

Tracking the 2°C Limit - September 2016

It is clear the data shows that there is a good chance the decadal warming trend is accelarating. But the trend is only borderline statistically significant, to 2-sigma anyway? That is Steve L's point?

I am just playing contrarian here.

denisaf at 09:08 AM on 28 October 2016

Tracking the 2°C Limit - September 2016

Why calling it 'Tracking the 2 C Limit' when the discussion is about the various measures of the rising temperature. The 2 C Limit discussed at the Paris Conference is a hypothetical value when in actual fact the temperature will continue to rise although the rate trend will depend on how rapidly the global rate of greenhouse gas emissions decreases. The original referral was to '2 C by 2100' not to '2 C Limit'

bjchip at 08:03 AM on 28 October 2016

Global weirding with Katharine Hayhoe: Episode 2

http://qz.com/817354/scientists-have-been-forecasting-that-burning-fossil-fuels-will-cause-climate-change-as-early-as-1882/

Those darned Chinese have been trying to hoax us for a longgg time...

...or someone isn't competent to be a dog-catcher.

:-)

Moderator Response:

[PS] Fixed link and excess white space

ubrew12 at 01:30 AM on 28 October 2016

Global weirding with Katharine Hayhoe: Episode 2

Excellent video! I like the way she anticipates denier arguments and innoculates her listeners with the truth before the 'doubt is our product' crew can infect them. I just found out about Eunice Foote yesterday: amazing bit of history.

Tom Curtis at 15:50 PM on 27 October 2016

Welcome to Skeptical Science

curiousd @27 and 28, I am fairly sure the formula you are using is incorrect. Unfortunately I am not sure as to the correct formula. The HITRAN database gives S_ij and γ_air for each line, where S_ij and γ_air are illustrated by this diagram:

The values given are for a reference temperature of 296 K, and 1 atmosphere pressure. S varies based on temperature, and γ based on temperature and pressure. As a result both Pierrehumbert in Principles of Planetary Climate (PoPC) and HITRAN give formulas for making the appropriate adjustment. For adjusting γ you use PoPC formula 4.61 and HITRAN formula 6. For adjusting S you use PoPC formula 4.62 and HITRAN formula 4. At least, that is as best I understand it. However, these formulas differ, probably based on assumptions about the shape of absorption pattern (shaded area above), which is not strictly known. There is a brief discussion of this in PoPC pages 227 and 228.

The actual absorption coefficient in each spectral line is not determined by S alone, but by S and γ as per formula 4.63 (PoPC) and HITRAN formula 10.

Even if I have misunderstood this, I am certain your formula is incorrect in not taking account of doppler and pressure broadening, which I understand to be very important.

At this stage I am again going to recommend you consult somebody with significant experience with these formulas.

Rob Honeycutt at 14:33 PM on 27 October 2016

Tracking the 2°C Limit - September 2016

Tom, My sense of the TLT data is that it's sort of a worst of all worlds. While you're right, it is probably the satellite product most similar to the surface data, the channel still peaks well above the surface, plus is measuring a significant portion of the upper troposphere.

It seems to me it's probably better to look at satellite data and surface data as apples and oranges, and use them to communicate the different aspects of the climate system each is measuring. And for that, TTT is probably the superior channel over TMT or TLT.

Rob Honeycutt at 14:15 PM on 27 October 2016

Tracking the 2°C Limit - September 2016

Fixed. Thanks for pointing that out, Bob.

Rob Honeycutt at 14:05 PM on 27 October 2016

Tracking the 2°C Limit - September 2016

I suspect you're right, Bob. Not sure what I did there.

Will do an update. Thx!

Bob Tisdale at 09:08 AM on 27 October 2016

Tracking the 2°C Limit - September 2016

Hi Rob. You may want to check your decadal trends. Based on the raw GISS LOTI, HADCRUT4 and Berkeley Earth (land+ocean) data, they appear to be too high for the last 120 months. As determined by EXCEL, for the past 120 months of data, the raw data present the trends of:

0.312 deg C/decade for Berkeley

0.314 deg C/decade for GISS

0.306 deg C/decade for HADCRUT4

I suspect you're presenting 9-year (108-month) trends.

Cheers

curiousd at 08:47 AM on 27 October 2016

Welcome to Skeptical Science

I believe I am correct with the above expression for SMASS, but that somehow the data published in Fig. 4.7 of P-H is as if it were at higher resolution than what I get from the Spectral Calc version of HITRAN. Except for the sharp fundamental around 670 wn, the other features I get agree with P-H pretty well, agreement which yields a check on my expression for SMASS.

A few years back, someone on this site told me how to make graphs and publish them cheaply or maybe free with an associated URL. There is some website that does this. Could someone remind me how this works?

Tom Curtis at 06:44 AM on 27 October 2016

Tracking the 2°C Limit - September 2016

While the RSS TTT may be more representative of the troposphere as a whole, the TLT channel remains the best (though far from perfect) comparison with surface temperatures. Unfortunately it has not been updated in line with the new method for determining the TMT (from which it is derived).

Dcrickett at 06:27 AM on 27 October 2016

'The atmosphere is being radicalized' by climate change

I do not agree 100% with the essay or any of the comments. I loved them all; this is a necessary conversation. Thanks, everybody!

scaddenp at 06:19 AM on 27 October 2016

The True Cost of Coal Power

If you are using up a finite resource, then you dont have "sustainable farming" without using a definition of "sustainable" that would differ a long way from any conventional usage. Why is solar not an option? What part of the world is this?

LaughingMan at 05:53 AM on 27 October 2016

The True Cost of Coal Power

Now that this is real, the co op rural movement is where I'm at. Sustainable farming is the name of the game. How do we power a sustainable farming indoor vertical growing system? We have no coal power come next month. Our only means of power generation is oil, natural gas, and gasoline. Air power and solar are not options. We don't have hydrogen systems and the Nitinol engine doesn't exist here yet. We have no rivers so to speak, and no alternatives that will provide the megawatts we need for our communities. I'm tempted to go back to coal or using biomass burnable products that are comparable. Anyone have a suggestion? Oil is abundant. We can burn crude oil by the thousands of barrels and not put a ding into production one bit.

Thanks!

Laughing Man

Steve L at 03:32 AM on 27 October 2016

Tracking the 2°C Limit - September 2016

La Niña comment is out of date. Good for you for printing the error along with your 2 sigma errors along with the midpoint trend estimate. By this you can see that the RSS trend isn't statistically different from zero. Some of the others aren't highly significant and may become insignificant with 11 years of data (depending on the strength of the coming La Niña).

Glenn Tamblyn at 20:35 PM on 26 October 2016

'The atmosphere is being radicalized' by climate change

denisaf

"They cannot provide the liquid fuels required by most forms of transport. "

Where liquid fuels are not required:

Electric cars can currently meet daily commuting type range, which is the vast majority of personal car usage.
Electric trucks, buses etc can similarly do daily delivery range tasks now.
Electric heavy gauge rail does not need liquid fuels.
Light Rail/Trams can currently operate electrically and do not need liquid fuels.
Similarly, electric trolley buses are common in Eastern Europe - no liquid fuel required.
Stand-alone electric buses that us inductive or overhead charging at stops are being trialled in Europe - no liquid fuels.
Short range aviation with batteries is possible.

Where liquid fuel might be required:

Longer range aviation. Hard to see an alternative.
Shipping. Solar and wind can contribute to reducing the energy demands of a ship, but unlikely to supply more than a modest fraction
Long distance personal car use. Battery recharge en route can meet this need but requires longer 'recharge stops'. Liquid fuels only needed if we want fast turn-around time at 'refueling stops'
Long distance road transport. Similar. Time vs convenience/cost trade off.

So aviation and shipping need something like liquid fuels Long distance land trasnport only needs it if we value time more highly than other factors.

So if we are willing to wear longer long distance land journeys, we only need liquid (or compressed gas) fuels for aviation and shipping. And we can source those from renewables via electrolosys, chemical synthesis, biofuels etc.

nigelj at 10:36 AM on 26 October 2016

'The atmosphere is being radicalized' by climate change

I just think radicalising the atmosphere is a bit sensationalist. Maybe restructuring the atmosphere has the right sound. And we all know how restructuring ends, not always very well.

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