Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.


Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup


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.

Home Arguments Software Resources Comments The Consensus Project Translations About Support

Bluesky Facebook LinkedIn Mastodon MeWe

Twitter YouTube RSS Posts RSS Comments Email Subscribe

Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...

New? Register here
Forgot your password?

Latest Posts


More evidence than you can shake a hockey stick at

Posted on 6 August 2010 by John Cook

Last week, the NOAA published a must-read report outlining 10 climate indicators of global warming. A few days later, Dr James Powell published a must-watch YouTube video outlining many more lines of evidence for a warming world:

The video opens by listing the many groups that endorse the consensus that humans are causing global warming:

  • 33 national science academies
  • 68 national and international science organisations believe 
  • 97% of climate scientists

However, Dr Powell recommends you look at data and decide for yourself. At this point, he presents a whole bevy of climate indicators. Being a big fan of graphs, I'm going to have to delve into all his sources and publish some of these on Skeptical Science. Here's a taste of some of the evidence he presents:

  • The rise in temperature, along side CO2 concentrations and human CO2 emissions (a veritable cluster of hockey sticks)
  • Many different proxy records showing the unusual warming over the past century compared to previous centuries
  • The increase in the number of record high temperatures compared to record lows, both in the USA and Australia (but why hasn't this analysis been done in other countries?)
  • The growing season is lengthening
  • Nights have warmed more than days, ruling out the sun as the cause of recent global warming
  • The oceans have warmed steadily according to a number of independent ocean heat reconstructions
  • More wildfires
  • Snows are melting earlier in the year, sometimes as much as 20 days earlier in the spring
  • Fire seasons are starting earlier, last longer and are harder to control
  • The Northern Hemisphere is losing snow cover and permafrost
  • The world's glaciers are losing ice each year
  • Arctic sea ice extent and volume have both declined
  • Greenland is losing ice and the ice loss is steadily spreading north
  • Antarctica is losing ice
  • Sea levels are rising
  • Ocean acidity is increasing across the world's oceans
  • Northern Hemisphere plant species are moving up slopes
  • U.S. bird species are migrating further north to cooler temperatures
  • Biological events like timing of breeding, emerging of flowers and butterfly emergence are happening earlier in the year
  • Regions where climate is more favourable to plants are steadily migrating north

All this is presented in a short 10 minute YouTube video. You can also check out more form James Powell's website. Definitely worth watching and spreading around.

UPDATE: let me head off the "ah but what's causing the warming?" comments - that question is addressed in 10 Indicators of a Human Fingerprint on Climate Change.

0 0

Printable Version  |  Link to this page


Comments 1 to 34:

  1. But but but but ... I can hear the chorus now, trying to separately attack each point. Your question about record highs is a good one. Surely this is a simple enough figure to be readily available from most European countries, Canada, at least some South American countries, China and Japan? It is an important piece of analysis because it gets away from the denier cry that "High temps are just weather, we've always had them". Yes indeed, but the point of records is that you haven't had them.
    0 0
  2. I did a little exercise with European highs and lows - up to 1990, there was a median of 1.5 record highs and 3 record lows set per decade. Then in the 1990s, there were 5 record highs and 2 records lows. In the 2000s, there were 9 record highs and 1 record low. I think more record highs are being set this summer - while last January's cold snap produced no record lows as far as I am aware.
    0 0
  3. Poast #2 is by country - data taken from Wikipedia. List of Weather Records Record Highs in the 1990s - Croatia, Estonia, Lithuania, Spain, Macedonia Record Highs in the 2000s - UK, Switzerland, Serbia, Slovakia, Portugal, Moldova, Italy, Iceland, France
    0 0
  4. In my post yesterday, I reported that fourteen countries had set their all-time hottest temperature record this year. I neglected to mention that one country has also set its coldest temperature in recorded history mark in 2010. Guinea had its coldest temperature in its history on January 9, 2010, when the mercury hit 1.4°C (34.5°F) at Mali-ville in the Labe region. Of the 229 countries with extreme coldest temperature records, 14 of these records have occurred in the past ten years (6% of all countries). There have been five times as many (74) extreme hottest temperature records in the past ten years (33% of all countries.) My source for extreme weather records is Chris Burt, author of Extreme Weather.
    0 0
  5. What about global trends in the frequency of extreme precipitation events?. I'm aware of a number of regional analyses, that show an increasing frequency of these, but globally?.
    0 0
  6. "Fire seasons are starting earlier, last longer and are harder to control" This year's fire season is already ugly. Alaska Siberia Canada And there's satellite evidence that an NWP is soon to open up ... despite the good "news" reported by Watts and co.
    0 0
  7. Of course, weather events should be treated as data points and not proof, but here are some spooky data-points! -- Projected daytime highs for Moscow, RU: 6-8-2010: 40C (104F) 7-8-2010: 40C (104F) 8-8-2010: 38C (100F) 9-8-2020: 39C (102F) That's Moscow, not Cairo -- Moscow, not New Delhi. MOSCOW, not Riyadh!
    0 0
  8. Moscow's been like that for weeks, too. Conditions at 22:00 Moscow time: 81 °F Smoke. Interesting analysis of the Russia phenomenon here by Wunderground's Rob Carver. Jeff Masters has an update here.
    0 0
  9. Thanks for this posting, John. The sources of the slides, the script, and a PowerPoint set for the video can be found at my website. As John anticipated, several commenters on ClimateProgress and YouTube noted that I did not spend much time, or any time, or the evidence that humans have caused global warming. But I did cover that in the slide that starts at 1:27 of the video with the chart of carbon emissions, CO2 concentrations, and global temperatures from the Arctic Climate Impact Assessment. I also discuss the significance of that chart on my website.
    0 0
  10. Line 4 should read "...on the evidence..."
    0 0
  11. James, that's excellent. The powerpoint slides will come in handy, too, thanks.
    0 0
  12. James - Fantastic. I get tired of the "buried in bull" arguments, great to see such a large collection of actual data, with sources no less. Sometimes, when I'm feeling masochistic, I post something about actual data on JoNova's site. Then I go hide until the spittle level dies down...
    0 0
  13. This is an excellent presentation. Well done. I will add it to my Youtube favourites (my channel is - I've collected a decent selection of the best videos about climate change). I have many 'discussions' with people on Youtube - I'll be very interested to see what comments this presentation attracts.
    0 0
  14. Dr. Powell, My favorite part is where you summarize observed warming by stating if increases in CO2 are not causing modern day global warming then two things must be true: 1) Something unknown is suppressing the well-understood greenhouse effect (and doing so during massive increases in GHGs). 2) Something unknown is causing the warming that mirrors the GHE. So we can accept what we know to be true (AGW) or we accept two unknowns. A pretty simple and straightforward defense of the science. Thank you.
    0 0
  15. Dear Prof. Mandia, Thanks for your comments. The deniers ask us to believe a third claim in addition to the two you cite: carbon emissions and atmospheric CO2 concentrations can continue to rise, but global temperatures will not continue to rise. This claim goes against all scientific knowledge; to support it they have not a shred of evidence.
    0 0
  16. Your question about record highs is a good one. Surely this is a simple enough figure to be readily available from most European countries
    Since 2002, when the website below was born, there have been more record-breaking hot days than cold each year for the list of cities, towns and airports around the world. The record-breakers for the current year are here. That page also includes a list of 1600 or so (from memory) of the cities and towns in the database with there min/max temps (but no dates).
    0 0
  17. Does anyone know the cause of the dip in CO2 concentrations on the slide featured in post 15, the dip being about 1500 AD.
    0 0
  18. The record low in Guinea is interesting. I was a Peace Corps volunteer in neighboring Sierra Leone in the late 70s. Several of my students were from Guinea and had seen ice form on open water during the Harmattan.
    0 0
  19. A plethora of data to explore: Dynamic climate indicators visualization via NCDC. Speaking of the humidity data available from NCDC, Tamino notices something begging a question: Not only is global humidity rising with the warming trend as expected, even its year-to-year fluctuations match well with those of global temperature. This is extremely strong evidence that, just as expected both from computer models and from basic physics, the dominant factor in global humidity is global temperature. It also raises a question for those who doubt the correctness of observed global temperature increase: if (as so many denialists claim) the globe isn’t warming because the global temperature estimates are wrong, then why does the specific humidity track it so well? Any bets on how long it takes someone to suggest that the increase in global humidity isn’t real — that the data are wrong and the apparent increase is only due to the “urban wet island” effect?
    0 0
  20. doug_bostrom at 08:32 AM, regarding "Not only is global humidity rising with the warming trend as expected, even its year-to-year fluctuations match well with those of global temperature." The question I think it raises is "Is specific humidity tracking temperature, or is it instead temperature that is tracking specific humidity?" If the heat resident within the water vapour as a result of it's change of state on the earth's surface was to be removed from the equation, how much heat would be be left in the other components that comprise the atmosphere and how well would temperature track it?
    0 0
  21. I'm not quite getting the point of your question/remark, JohnD. Maybe not enough coffee here yet.
    0 0
  22. Actually, johnd @#20, the phase transition from liquid H2O to vapour, or solid to vapour, absorbs energy (as I believe you understand). Thus, when water evaporates, it cools it lowers the temperature. This quantity of heat (latent heat of vapourization) would need to be ADDED to the atmosphere, not subtracted, from the standpoint of energy balance. Without doing any calculations, considering that water vapor represents at most a few mole-% of the atmosphere, and we're only dealing with about the incremental amount of water vapour that would be added as a result of a very slight increase in temperature, the amount would be very small. The key point here is that water vapor pressure increases as a function of temperature (Clausius-Clapeyron relationship). So far as I'm aware, this is the effect we're seeing in the increasing moisture content of the atmosphere with warming. It's just another independent "thermometer" for skeptics who don't trust HadCRUT, GISS, etc.
    0 0
  23. CoalGeologist at 06:50 AM, the heat energy absorbed by phase transition extracts heat energy from the surface waters and transfers it into water vapour which then transports it aloft through the atmosphere. Thus that heat energy is then contained in the water vapour component of the atmosphere (until it is given up as the vapour reforms back to water) and as such becomes part of the total heat energy measured as air temperature. Your comment about water vapour % being small, whilst it may be in regards to the atmosphere as a whole, it is THE major component of all those that the heat energy of the atmosphere resides in. Perhaps if you could go back to the basics and quantify how much heat energy resides in each of the individual components that comprise the atmosphere, that would bring the role that the heat energy resident in water vapour has in measured temperatures into perspective. Perhaps a dreaded analogy can help. As steam from a pot of water, being heated by whatever means, circulates within a room, the air temperature of the room rises quite quickly due to the circulation of the heat energy that is contained in the steam. Take away the pot of water, and any moisture content of the air within the room, what components of the air remaining would absorb the heat that continues to be released from the source and would that make any difference to the temperatures measured in the room?
    0 0
  24. JohnD I'm so accustomed to folks arguing against data here that I'm actually struggling to understand what you're saying, trying to interpret your remarks as not somehow being an argument -against- there being more latent heat residing in the atmosphere as a result of it including increased water vapor content. Put more simply, you're not trying to say that -more- water vapor in the air is -not- evidence of increased latent heat in the air, are you?
    0 0
  25. #23: "quantify how much heat energy resides in each of the individual components that comprise the atmosphere, that would bring the role that the heat energy resident in water vapour has in measured temperatures into perspective." Why is this distinction necessary? Whether the heat is in the water vapor or the air, the measured temperature is higher. For some fun and instructive graphics in this regard, try the NOAA climate indicators. For some not-so-much-fun, yet still instructive results, try searching google news for "record heat and record high humidity".
    0 0
  26. The cyclicity of H2O evaporating or sublimating into the atmosphere, then recondensing as liquid or solid is why water is not regarded as a forcing in climate warming. The time period for this cycle is measured in terms of days and the net energy balance is zero. To my understanding enhanced greenhouse warming is driven primarily by the enhanced absorption of IR radiation by the increasing quantities of GHGs in the atmosphere, especially CO2 & CH4, plus the additional water vapor content due to warming (i.e. the notorious, and still disputed, water vapor "feedback"). Water vapor feedback is complicated by the fact that water vapor can condense to solid or liquid to form clouds, which have their own characteristics in terms of absorption or reflection of incident radiation. It was my impression that the water vapor you were discussing is the incremental quantity that has been added to the atmosphere (on average) due to net warming of the atmosphere due to higher concentration of GHGs, which I still believe is negligible. Perhaps you could offer some quantitative support for whatever is your position on this. Better yet would be to cite a source in the peer-reviewed literature.
    0 0
  27. CoalGeologist at 03:34 AM, the basis of the greenhouse theory is that the heat content of the atmosphere is absorbed and then carried by those gases that have been identified as greenhouse gases. Water vapour is the primary and majority greenhouse gas and it only becomes a gas, and thus a greenhouse gas upon absorbing heat energy at the earths surface, which it then transports aloft where it is gradually dispersed, finally giving up all the heat where the highest clouds are formed. The heat content of the atmosphere, primarily carried by the greenhouse gases, is measured as a temperature, thus rather than considering rising humidity as confirmation of warming, they must be considered as one and the same, the temperature being merely a measure of the heat content residing primarily within the water vapour. How much water vapour is moves into the atmosphere at any time is dependent on what conditions prevail on the earths surface where the atmosphere and the surface waters interact and not the temperature of the atmosphere, because it is the water vapour itself that primarily determines the temperature of the atmosphere. Much like those who struggle with their coffee each morning. By whatever means they measure the sweetness of the coffee, there will be a correlation found between the measure of sweetness and the amount of sweetener being added to the coffee. For rising humidity to be used as proof of rising temperatures, so too could rising sweetener levels be used as proof of a rising measure of sweetness. That seems rather confused to me. It is not the rising measure of sweetness that causes the rising level of sweetener, but that is what has been suggested regarding the atmosphere.
    0 0
  28. ...the basis of the greenhouse theory is that the heat content of the atmosphere is absorbed and then carried by those gases that have been identified as greenhouse gases. Stopped me in my tracks, that did. The heat content of the atmosphere, primarily carried by the greenhouse gases, is measured as a temperature... And again. Bruising, really. Letting aside those problems and ignoring the flawed analogy between the taste of coffee versus phase changes in water and what causes and maintains them, the reason why the atmosphere is more humid is because the atmosphere is capable of carrying more water vapor before it condenses. In other words, atmospheric humidity is increasing because an increase in temperature allows it to do so. This is not even slightly complicated and it just boggles my mind to see the gymnastics some of us will go through to avoid looking at a graph and dealing with a conclusion. Or do we believe in an alternate explanation for why precipitation frequently happens as moist air is driven up and over mountains, experiencing adiabatic cooling and thus following the prediction that water will precipitate as the atmosphere approaches saturation? And of course, it's worth noting this increasing humidity is following the simple prediction that a given amount of C02 forcing will be followed by amplification by increased water vapor in the atmosphere.
    0 0
  29. doug_bostrom at 09:18 AM, doug, I take it then that you do not accept that the atmosphere could be warmer because of the increase in heat content bought about by an increase in water vapour. What carries the heat content that determines the measured temperature of the atmosphere if not primarily water vapour?
    0 0
  30. JohnD, water vapor can store heat in both latent and sensible forms. Latent heat is not what's measured w/a thermometer. What's the capacity for sensible heat of water vapor in comparison w/the rest of the gases in the atmosphere? Water vapor in our temperature realm has a specific heat capacity of ~1.8kJ/kg K versus dry air at ~1.0 kJ/kg K. The mean mass of water vapor in the atmosphere is something like 1.27 × 10^16 kg, the dry air mass 5.13 × 10^18 kg. We don't need to work the arithmetic to see that water vapor is not the dominant reservoir of sensible heat in the atmosphere.
    0 0
  31. doug_bostrom at 10:27 AM, when considering the heat energy being carried by water vapour we should confuse the heat content itself with how it may manifest itself. Latent heat and sensible heat are not two different types of heat but rather the means of describing different conditions involving the transfer of heat energy. What is relevant to the subject of how the weather, and thus the climate varies, is how the heat content of the atmosphere may vary. With weather and climate both being subject to the balancing of various forces, any factor does not have to be the dominant reservoir, but rather the one most sensitive to any underlying changes, and this is the function of water vapour. This subject is leading I believe into the recent argument, put I think by RSVP, who IIRC, argued that all the gases in the atmosphere could be considered greenhouse gases if they absorbed IR, against much opposition, again IIRC.
    0 0
  32. New paper on the Mann temperature proxy reconstruction: to be published in the Annals of Applied Statistics . A Statistical Analysis of Multiple Temperature Proxies: Are Reconstructions of Surface Temperatures Over the Last 1000 Years Reliable? Abstract. Predicting historic temperatures based on tree rings, ice cores, and other natural proxies is a difficult endeavor. The relationship between proxies and temperature is weak and the number of proxies is far larger than the number of target data points. Furthermore, the data contain complex spatial and temporal dependence structures which are not easily captured with simple models. In this paper, we assess the reliability of such reconstructions and their statistical significance against various null models. We find that the proxies do not predict temperature significantly better than randomseries generated independently of temperature. Furthermore, various model specifications that perform similarly at predicting temperature produce extremely different historical backcasts. Finally, the proxies seem unable to forecast the high levels of and sharp run-up in temperature in the 1990s either in-sample or from contiguous holdout blocks, thus casting doubt on their ability to predict such phenomena if in fact they occurred several hundred years ago. We propose our own reconstruction of Northern Hemisphere average annual land temperature over the last millenium, assess its reliability, and compare it to those from the climate science literature. Our model provides a similar reconstruction but has much wider standard errors, reflecting the weak signal and large uncertainty encountered in this setting
    0 0
    Moderator Response: A perfect topic to take to the "How reliable are climate models" thread. Please continue discussion of this paper at that thread.
  33. Johnd: "The heat content of the atmosphere, primarily carried by the greenhouse gases" was discussed at great length here: waste heat thread. This is a misconception that you and RSVP share. Absorbed heat is carried by all molecules in the atmosphere and not just by a select few. The heat absorbed by CO2 (and H2O) is shared to the rest of the N2 and O2. This is very basic, long well understood, physics and chemistry. AGW theory will not make sense until you understand heat transfer in the atmosphere. I suggest you review the waste heat thread.
    0 0
    Moderator Response: I second that suggestion to take further discussion of that particular topic to that other thread.
  34. I disagree with the moderator response in #32. The new statistics paper is about statistical models (which test statistical hypotheses), not climate models.
    0 0

You need to be logged in to post a comment. Login via the left margin or if you're new, register here.

The Consensus Project Website


(free to republish)

© Copyright 2024 John Cook
Home | Translations | About Us | Privacy | Contact Us