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Unforced variations: Mar 2020

Filed under: — group @ 1 March 2020

This month’s open thread for climate science topics.

151 Responses to “Unforced variations: Mar 2020”

  1. 101


    EGS asks MAR:

    Did you even look at your graphs?

    No exponential rise in global atmospheric N20 concentrations since 1965? No exponential rise in global atmospheric CH4 concentrations between 1915 and 2000? Both lines are nearly vertical!

    Per MAR’s graphs, the rise in NOX appears to be pretty much linear since 1952; the rise in SOX was most rapid from roughly 1980-85, and slowed drastically after the turn of the century. It’s hard to see anything in either graph that betrays an obvious relation to increased warming post-1970.

  2. 102

    #98, IG–

    The second of those two links appears to place EGS (see above comments) in a bit of an epistemological bind–or at least, to highlight said bind. EGS has been arguing about the GWP of various gases based, one presumes, on radiative physics, and various papers using estimates thereof.

    Yet he also rejects assessments of the GWP of CO2 as “warped” or “assumed.”

    We read in the second of IG’s links that:

    To determine the total radiative forcing of the greenhouse gases, we have used IPCC [Ramaswamy et al., 2001] recommended expressions to convert greenhouse gas global abundance changes, relative to 1750, to instantaneous radiative forcing (see Table 1). These empirical expressions are derived from atmospheric radiative transfer models and generally have an uncertainty of about 10%.

    How is it EGS accepts a methodology WRT non-CO2 GHGs, but rejects that same methodology when it comes to CO2?

  3. 103
    nigelj says:

    EGS @93

    Firstly read my comment @89 because it answers some of your questions.

    “But at lower concentrations CO2 accumulations are assumed to have more linear forcings that then become logarithmic as the concentrations build and the longwave bands saturate, so I presume the radiative forcing for each ppm increase + water amplification feedbacks would have been stronger in the 19th century than in the 20th century as concentrations began to approach 400 ppm, would they not?”

    No. The greenhouse effect doesn,t saturate. Refer below:

    And remember its about ‘cumulative’ concentrations of atmospheric CO2 not the rate at some point in time.

    “And what EVIDENCE is there that cooling anthropogenic aerosols suddenly cleared out of the atmosphere in the late 1970s and 1980s?”

    Because filters were fitted to coal fired power stations in the decade after 1978 (approximately), and the acid rain problem mostly disappeared. Particulates exit the atmospher quickly we know this from the results of volcanic actiivity. And other evidence.

    And CO2 concentrations had built up to a substantial level by the 1980’s and this tends to cancel some of the effect of coal based aerosols.

    “According to Leibesperger et al. (2012) SOX and NOX emissions peaked in the US in the 1980s and 1990s, not before.”

    Ok but Im not sure of your point. You said before you think SOX and NOX explain the warming surge after 1978 better than CO2 because there were high concentrations of these gases introduced at that point around 1980. But the reality is otherwise. These gases had been increasing gradually before then, but there was no huge sudden increase in the concentration of these oxides around the late 1970s that explain the rather abrupt warming spike after the late 1970s. Like a step change. So your “theory” doesn’t explain the reality, but the mainstream theory that CO2 is the main cause of the warming along with cooling effects of sulphate aerosols from coal describes the historical reality well, (see my comment @93)

    And please appreciate you need something MORE than a correlation. And you dont have anything. Nitrous oxides, methane, CFCs etcetera are indeed strong greenhouse gases as you mentioned, and their use has been increasing in some cases, but their total combined atmospheric concentrations is just not large enough to compare to the warming effect of CO2. Scientists have done the numbers. Read the IPCC reports etc.

    ” And these peaks and later declines(SOX and NOX emissions ) were counterbalanced by steady rises in these aerosols elsewhere on the globe up to 2000 and beyond. Primary organic aerosols began to rise in the US in the 1970s after declining since the 1950s, but elsewhere they were on a steady rise until peaking around the year 2000.”

    If SOX and NOX declined after the 1990s it is difficult to understand why you are arguing they are more responsible for warming than CO2. If they were counterbalanced by particulates this doesn’t change this fact. And you give no quantities to know whether things were “counterbalanced”. You give no quantitative comparisons to know if primary organic aerosols are significant.

    “Volcanos? The biggest volcanic eruptions of the 19th and 20th century were Tambora (1815)….This doesn’t support a narrative that warming could have been much suppressed over most of the 19th century. In the 20th century only the first 15 years, the early 1930s and early 1990s experienced significant volcanic cooling.”

    What? I never mentioned volcanoes. Concentrations of CO2 were far too low in the late 19th century to be hugely significant. Any warming effect would be easily swamped by the sunspot cycle and ocean cycles. We dont need to consider volanic activity in that period.

    Volcanic activity slowed a bit over the period 1910 – 1950 and this does help explain the warming over this period, in addition to increasing levels of CO2 and other mechanisms.

    “It’s doubtful that volcanic aerosols could have been much of a factor in the relatively cooler decades of the 1940s-70s.”

    Nobody claims they were. The main source of aerosols in this period was the acceleration of the use of coal after WW2. An issue easily googled.

    Your grand theory is incapable of explaining the reality.

  4. 104
    nigelj says:

    Nemesis @81

    ” EGS @64 packs every possible piece of denialist nonsense into one massive paragraph. Sounds like Victor version 2.0.”…..So why the hell waste time on that kinda shit again and again and again? Entertainment?”

    Yeah partly entertainment. Certainly better than “reality television”. Plus I find it clarifies my own thinking and understanding to tackle these issues, and write stuff down, and read other peoples rebuttals. And you might convince the occasional denialist, although probably only a few. We know the issue has become politicised especially with conservatives, so that makes people very stubborn, but hope springs eternal.

  5. 105
    nigelj says:

    EGS @92

    “Jumping to conclusions? Atmospheric CFC concentrations have barely fallen at all. CFC-12 concentrations only plateaued around 2000 and have barely fallen off since. Have a look at NOAA’s data”

    Ok, but the concentrations certainly plateaued from about 1995 -2010 in the graph (which stops at 2010) and so they don’t really explain the continuing increase in temperatures from 1995 – 2019. Zero correlation and no plausible mechanism given the total quantities of these gases in the atmosphere is too small to be a powerful factor in warming.

  6. 106
    MA Rodger says:

    EGS @97,
    I fear you need to start by learning the meaning of the word ‘exponential’. Note that if the rates of increase for CH4 & N2O were not becoming “quicker and quicker” (and thus not ‘exponential’), the resulting climate forcing from CH4 and N2O then would have been increasing at a similar rate after 1970 as they would have before. Given such a situation, how would such forcing agents suddenly be responsible for rapid increase in the rate of AGW after 1970?
    I’m not sure why you say one of the graphs I referenced is “misleading.” The rolling-5-year averages add to the clarity of the plot by smooting out the noise and annual incrimental values show far better the timing of contributions to climate forcing by the various gases than could be judged from any accumulative plot.
    The numbers plotted out in that graph you found “misleading” are sourced from the NOAA AGGI web page for the period since 1979. Prior to that, the source was IPCC AR5 WG1 Aii Table Aii.1.2. From those sources the post-1950 forcings you ask about can be assessed as something like:-

    Climate forcing 1950-2018
    . …. … …. …. W/m^2
    CO2 … …. …. 1.44 … …. …. 65%
    CH4 … …. …. 0.26 … …. …. 12%
    N2O … …. …. 0.16 … …. …… 7%
    CFC-12 …. …. 0.16 … …. …… 7%
    CFC-11 …. …. 0.06 … …. …… 3%
    Other minor .. …. 0.13 … …. …… 6%

  7. 107
    Al Bundy says:


    I bet your neighbor would be a GOPper if he lived in the USA. Humans are highly motivated by identity, by the axioms one’s group hold dear. Evidence contrary to said axioms causes cognitive dissonance, which is unpleasant. This can cause an individual to blame that which is causing discomfort, resulting not just in rejection of the factoid involved but in embracing everything contrary to said factoid regardless of believability. This can bring satisfaction because it often irritates the bearer of unwanted facts. The bearer’s irritation feels good, which reinforces the behavior. If one’s group’s members are similarly deriving pleasure via irritating bearers of inconvenient truths then facts lose their importance. Donald Trump junior exhorts GOPpers to swim in the sludge because pissing off liberals is the best game in town.

    Entire psycosystems of “alternative facts” result. Our best example could be mrkia. He’ll say whatever alternative fact is required to provoke a response, allowing himself to bask in the warmth of melting snowflakes.

    Remember, watching one’s opponent bleed is so satisfying that many people seek out opportunities to hurt their own fist.

    Perhaps you could comment on your neighbor’s heavy coat by asking him why he wasted money on such a useless item. After all, it never left the closet this past winter and all previous winters were similarly mild.

  8. 108
    Nemesis says:

    Btw, Stefan Rahmstorf and his family’s life is threatened by deniers:

    This makes me real sick. THIS is the UGLY world we live in and this will not change. Those who enter abandon all hope.

  9. 109
    EGS says:

    The main reason I became so alarmed by the Polvani et al. Nature paper and wrote on this blog was that the paper originally claimed that their model runs showed that one-third of all global warming and fully half of all arctic warming between 1955-2005 had been caused by ODCs. The press release still claims that.

    This wasn’t from some crackpot corner of the warming denialist blogosphere but from scientists based at Columbia University’s School of Engineering and Applied Science and the Lamont-Doherty Earth Observatory. I took note.

    And I had read over several years that halocarbons, tropospheric O3, and especially CH4 and N2O deserve much greater policy attention because they resonate on the rapidly rising parts of the the absorption curve of the infrared wave band, so as their atmospheric concentrations rise in a linear and even exponential manner, they would be contributing relatively more to global warming than CO2 as the CO2 absorption band curve saturated along its logarithmic curve.

    That seemed to have also been confirmed in the atmosphere by the tropical upper tropospheric temperature and specific humidity measurements by satellite and balloons, suggesting a lower climate sensitivity to CO2 than had been believed in the past.

    That’s what made it so exasperating to me that CO2 seemed to suck all of the air out of the climate change room (couldn’t resist that metaphor).

    If I understand the comments above, this is not what the field believes. There is, in fact, high climate sensitive to CO2 and relatively low sensitivity to the other GHGs and black carbon. And yes, I do understand the concept variance.

    I jumped to some conclusions and made some arrogant and needlessly abrasive statements in my sense of urgency. Sincere apologies for that. I hope that you understand it came from a place of genuine concern about AGW.

  10. 110
    Dan Miller says:

    #54 Al: Yes, I believe that COVID-19 is providing a “natural” experiment to evaluate the role that aerosols play in hiding the impact of manmade GHGs.

    While the global reduction in emissions will be good for the planet in the long term, the reduction in manmade aerosols should result in an almost immediate increase in global temperatures.

    My understanding is that manmade aerosols hide about half of the impact of manmade GHGs. And while increased CO2 levels last for hundreds or thousands of years, manmade aerosols last in the atmosphere for weeks.

    So, we should see a jump in global average surface temperatures starting about now… after adjusting for factors such as El Nino, etc.

    Is anyone working on this?

  11. 111
    EGS says:

    MA Rodger@106
    EGS @97,
    “I fear you need to start by learning the meaning of the word ‘exponential’. Note that if the rates of increase for CH4 & N2O were not becoming “quicker and quicker” (and thus not ‘exponential’),”

    Really? No need to fear, MA Rodger. The data from your graph for CH4:

    1850: 774 ppb

    1900: 865 ppb

    1950: 1116 ppb

    2000: 1773 ppb

    It’s one thing to try to score points by insulting people (as you have a habit of doing) and quite another to try to do so with deliberate falsehoods. Shame on you.

  12. 112
    Nemesis says:

    @Al Bundy, #170

    ” After all, it never left the closet this past winter and all previous winters were similarly mild.”

    Fact is this:

    ” The 2019/2020 winter has been the warmest on record for Europe, with average temperatures 1.4C above the previous high of 2015/2016…”

    I tell you:

    Hell is real and it’s a real Madhouse :)) Want to hear some bloody shit about the near term future of “human society”?^^ The animal world will look like kindergarden compared to crumblin “human society”.

  13. 113
    Al Bundy says:

    Nigelj: The greenhouse effect doesn,t saturate.

    AB: If it did then Venus would be relatively habitable.

  14. 114
    Nemesis says:

    @nigelj, #104

    “… but hope springs eternal.”

    Uh uh, funny “hope” is kids stuff^^, you are talking to someone who grew up and is still living in the ghetto^^, you still haven’t arrived at bloody reality yet^^ But you will soon enough.

    ” Spitting blood clears up dream and reality alike.”

    – Sunao

  15. 115
    nigelj says:

    “Multi-agency report highlights increasing signs and impacts of climate change in atmosphere, land and oceans. Published 10 March 2020.”

  16. 116
    Mr. Know It All says:

    108 – Nemesis
    “Btw, Stefan Rahmstorf and his family’s life is threatened by deniers:
    This makes me real sick. THIS is the UGLY world we live in and this will not change. Those who enter abandon all hope.”

    Welcome to the world of those who wear MAGA hats – few do so because they will get a beat down, not just threats, from the lunatic left. ;)
    PS Did not read your linked article – was written in Chinese. :)

    Back to climate science. Here is the latest Climate news from Down Under. Of special interest to many here, at 3:00 they discuss whether the wildfires in Australia were attributable to climate change – the answer given by the gubmint: “no”.

    Possible snow this weekend in Portland, Oregon:

  17. 117
    MA Rodger says:

    NOAA have also reported for February with an anomaly of +1.17ºC, up from January’s +1.14ºC. The increase in anomaly was due entirely to rising NH Land temperatures with SSTs showing a dip in the anomaly. (This Land-up, Ocean-down is not dissimilar to the start of 2016, so might fit in with Roy Spencer’s grand pronouncement that the “continuing weak El Nino conditions are also likely responsible for the current up-tick in temperature.” But it’s a mighty big “up-tick” given the weakness of the “responsible” El Niño.)

    As with the TLT anomalies and GISTEMP, NOAA’s Feb 2020 is the second-warmest February on record, and this without any significant El-Niño-boost (although the boost is usually less in surface records).
    NOAA’s Feb 2020 sits 3rd in the NOAA all-month anomaly record behind the El-Niño-boosted months Feb & Mar 2016 (as per GISS, UAH & RSS) while the start to 2020 in NOAA is the 2nd warmest on record after the El-Niño-boosted 2016 (as per GISS, UAH & RSS).

  18. 118
    Nemesis says:

    @KIA Ignoramus, #116

    I am not left, I am a nasty Anarchist, I trust in the cooking pot of Nature exclusively and I tell you the real bloody beauty of The Lovely Cooking Pot Of Nature:

    You and your beloved ones and alike are in it as well and, man, muhahaha, I LOVE that bloody fact, sweetheart.

    Eating and beeing eaten 38) See you there quickly I swear,

  19. 119
    Al Bundy says:

    EGS: I jumped to some conclusions and made some arrogant and needlessly abrasive statements in my sense of urgency.

    AB: I salute you. When the stakes are this high most folks, including me, blow a gasket periodically. Only the best both feel shame and man up.

  20. 120
    Dan says:

    re: 116. “Possible snow this weekend in Portland, Oregon:

    Yet another of your non sequiturs that have nothing to do with climate. Because you fail to try to learn the difference between climate and weather. Stop flaunting your ignorance.

  21. 121

    EGS, #109–

    If I understand the comments above, this is not what the field believes. There is, in fact, high climate sensitive to CO2 and relatively low sensitivity to the other GHGs and black carbon.

    At the risk of being overly pedantic–OMG, what am I saying?

    Anyway, as I understand it, it’s not only a matter of sensitivity. That varies among the various GHGs–and it’s perfectly true that CH4, N2O, and chlorofluorocarbons have higher, or much higher, values than does CO2:

    But note this bit:

    Another alternate metric is the Global Temperature Potential (GTP). While the GWP is a measure of the heat absorbed over a given time period due to emissions of a gas, the GTP is a measure of the temperature change at the end of that time period (again, relative to CO2). The calculation of the GTP is more complicated than that for the GWP, as it requires modeling how much the climate system responds to increased concentrations of GHGs (the climate sensitivity) and how quickly the system responds (based in part on how the ocean absorbs heat).

    Elsewhere on the same site:

    Each gas’s effect on climate change depends on three main factors:

    How much is in the atmosphere? [snip]
    How long do they stay in the atmosphere? [snip]
    How strongly do they impact the atmosphere? [snip]

    A big piece of it, naturally, is the first. How much is in the atmosphere? Well, we saw that in those graphs just discussed in the comments above. But for convenience:

    CO2: ~412 ppm (but the data in the source has it ~400 because it’s data from 2016)

    CH4: ~1.8 ppm (~1800 ppb)

    N2O: ~300 ppb

    Chlorofluorocarbons: OK, it’s complicated, but except for a couple, less than 100 parts per trillion

    Putting it together, the atmospheric abundances relative to CO2 (assuming I haven’t dropped a decimal or two somewhere):

    CO2: 1, natch

    CH4: ~0.5%

    N2O: ~0.03%

    Chlorofluorocarbons: ~0.00004% or less

    Hope that’s helpful.

  22. 122
    mike says:

    at MAR/AL: I think Covid 19 is going to create an interesting real world experiment with abrupt reduction of emissions and aerosol particles. I think we should see a fall in yoy increase of CO2 in atmosphere rather quickly. I have read that the expected fall in aerosols should produce an almost immediate bump in global temps. We live in interesting times, do we not?


  23. 123
    jb says:

    Knumbskull in America (KIA) at 116:

    Welcome to the world of those who wear MAGA hats – few do so because they will get a beat down, not just threats, from the lunatic left. ;)

    Well, what do you know – another piece of righty PC. Looking askance at an idiot in a MAGA hat is a “beat down.” Asking a person why they would vote for a sociopath, a criminal, an incompetent moron and frankly, an elitist snob, is a “beat down.” Confronting a person with his bad choices for our common public life (or for that matter, any inconvenient truth) is a “beat down.” Violently, aggressively and proudly ignorant, yet willing to do anything to avoid having to justify their idiocy to the rest of the world. Welcome to the world of MAGA.

  24. 124
  25. 125

    KIA 116: Welcome to the world of those who wear MAGA hats – few do so because they will get a beat down, not just threats, from the lunatic left. ;)

    BPL: KIA knows that nobody is more persecuted than white heterosexual Christian men.

  26. 126
    William B Jackson says:

    No 116 as you have been told before local weather is weather not climate! Even you should know that the gubmint down other is a denier controlled organ, it would only be a surprise if they said otherwise. Mr KIA proving the falsity of his nom de plume yet again!

  27. 127
    William B Jackson says:

    Sorry “down under” sheesh!!

  28. 128
    nigelj says:

    EGS @109

    “If I understand the comments above, this is not what the field believes. There is, in fact, high climate sensitive to CO2 and relatively low sensitivity to the other GHGs and black carbon.”

    No not really. It’s accepted that the ‘other’ greenhouse gases (NO2, methane, CFCs etc) are potent greenhouses gases more so than CO2 in many cases, but the quantities we are adding to the atmosphere are very small compared to the quantities of CO2 we are adding, (as others have tabulated) so even although CO2 is less potent than these gases, it overwhelms the effect of the other gases combined.

    There was nothing abrasive in your comments.

  29. 129
    MA Rodger says:

    mike @122,
    With a nod to this being more Climate Solutions than Climate Science, I would suggest that COVID-19 >> Reduced ΔCO2/yr is missing a step. It is surely COVID-19 >> Reduced CO2 emissions >> Reduced ΔCO2/yr.
    So how big a change should we expect in CO2 emissions from COVID-19? I see a quoted monthly value for China’s reduced oil use of 25% which is presumably a short-lived drop and resulting from the shut-down of very large parts of the economy at the height of the crisis there. But on a global scale for a significant period? Remember the financial crash of 2009 was an insignificant blip on the emissions curve measuring -3% within the otherwise rising trend (so resulting in a reduced atmospheric CO2 level of 0.06ppm). With Europe now badly gripped, CORVID-19 is likely to be worse for the world economy than 2009. But I would suggest it would have to bring the world economy to its knees to be more than a slightly bigger insignificant blip.

    “But if history is any guide, reductions in greenhouse gas emissions may not last. The 1918 Spanish influenza outbreak, oil shocks of the 1970s, and the 2008 financial crisis caused ephemeral drops in polluting activities – before the economy fell back into high-emissions mode.”
    [From Aljazeera OP here]

    There are others who are more optimistic and who set out reason to brand COVID-19 as “just another nail in the coffin” of the FF industry.

    Slightly more ‘sciency’, you will gather that I don’t see CORVID-19 having anything at all to do with the recent MLO CO2 numbers which have been showing low ΔCO2/yr values over recent weeks.

  30. 130
    Al Bundy says:

    jb: Asking a person why they would vote for a sociopath, a criminal, an incompetent moron and frankly, an elitist snob, is a “beat down.”

    AB: Yeah, but I find the term “elitist” objectionable. There’s nothing elite about mrkia, drumpf, or the GOPpish leeches who own our world.

  31. 131

    A professor who appears to be a global warming denier has posted a series of no fewer than 61 videos on Youtube. Worse, these are college lectures about the atmosphere. Michel van Biezen appears to be an academic, a physicist at Loyola Marymount University. Here’s a sample:

    He claims he examined the NASA temperature data for a year and adjustments were being made “for other than scientific reasons.” So a conspiracy theorist as well as a denier.

    [Response: Classic example of taking something real, belaboring it, and totally mangling the implications without any quantification. Pretty contemptible. – gavin]

  32. 132
    Nemesis says:

    mike, #122

    ” I think Covid 19 is going to create an interesting real world experiment with abrupt reduction of emissions and aerosol particles…”

    Welcome to the beautiful faustian bargain:

    That’s the bloody beauty of criminal deniers:

    THEY take care of my old ass by blowing as much aerosols as possible into the atmosphere… at the cost of their children and grandchildren, harr harr^^ Uhm, no, I did not procreate as I’ve seen shit comin decades ago, lucky me^^ So:

    THANK YOU very much mr KIA, EGS, mr Drumpf et al !!!


  33. 133
    MA Rodger says:

    There is a new paper Brennan et al (2020) ‘Arctic sea ice variability during the Instrumental Era’ creating an Arctic Sea Ice record from 1850-2018 and giving a bigger 1940s SIE dip than did Walsh et al (2017), the comparison between the two illustrated in Brennan et al’s Fig 3:

    I note the last two sentences of the Brennan et al Abstract may attract some attention from denialist hoping for some choice words to lessen the perceived importance of recent Arctic SIE declines.

    “The 25‐year trends [in Arctic SIE] during this period are ∼33–38% smaller than the satellite era (1979–2018) but almost twice as large as previous estimates. Additionally we find that variability of SIE on decadal timescales prior to satellite era is ∼40% greater than previously estimated.

  34. 134
    jb says:

    AB at 130:

    AB: Yeah, but I find the term “elitist” objectionable. There’s nothing elite about mrkia, drumpf, or the GOPpish leeches who own our world.

    Clearly you are correct, there is nothing elite about Trump (and I was talking specifically about him.) But, he is elitist.

    To be elitist, you must either 1) believe that society should be led by an elite, or 2) believe that you are elite. Trump qualifies under both counts. He believes himself to be an elite businessman, even though his fortune is inherited, and he ran largely on the idea that a businessman such as he has the skills to run a country.

    I think it is necessary to make this point, because righty PC holds that elites are trying to take over our country – when in fact, righty voters are playing into the hands of another (de facto if not in fact) elite – the fabulously wealthy.

  35. 135
    nigelj says:

    Oh the horrible irony. New research paper:

    “Changing rapid weather variability increases influenza epidemic risk in a warming climate.”

  36. 136
    nigelj says:

    jb and Al Bundy. Trump is a waste of space. Lets not waste space by talking about him too much.

  37. 137
    Joseph Zorzin says:

    Michael Mann’s letter to the editor in today’s Boston Globe (3-19-2020)

    “I am relieved to see policy makers treating the coronavirus threat with the urgency it deserves. They need to do the same when it comes to an even greater underlying threat: human-caused climate change.
    In a recent column (“I’m skeptical about climate alarmism, but I take coronavirus fears seriously,” Ideas, March 15), Jeff Jacoby sought to reconcile his longstanding rejection of the wisdom of scientific expertise when it comes to climate with his embrace of such expertise when it comes to the coronavirus.
    In so doing, Jacoby took my words out of context, mischaracterizing my criticisms of those who overstate the climate threat “in a way that presents the problem as unsolvable, and feeds a sense of doom, inevitability, and hopelessness.”
    As I have pointed out in past commentaries, the truth is bad enough when it comes to the devastating impacts of climate change, which include unprecedented floods, heat waves, drought, and wildfires that are now unfolding around the world, including the United States and Australia, where I am on sabbatical.
    The evidence is clear that climate change is a serious challenge we must tackle now. There’s no need to exaggerate it, particularly when it feeds a paralyzing narrative of doom and hopelessness.
    There is still time to avoid the worst outcomes, if we act boldly now, not out of fear, but out of confidence that the future is still largely in our hands. That sentiment hardly supports Jacoby’s narrative of climate change as an overblown problem or one that lacks urgency.
    While we have only days to flatten the curve of the coronavirus, we’ve had years to flatten the curve of CO2 emissions. Unfortunately, thanks in part to people like Jacoby, we’re still currently on the climate pandemic path.
    Michael E. Mann
    State College, Pa.
    The writer is a professor at Penn State University, where he is director of the Earth System Science Center.”

    [Response: I’m going to boost this to a main post. Thanks for highlighting. – gavin]

  38. 138
    Oxyaena says:

    There exist entire countries that will literally cease to exist in the next few decades as a result of unmitigated climate change; climate change denialism is irresponsible and frankly immoral. How many people must die before you deniers realize the error of your ways?

  39. 139
    Keith Woollard says:

    I have hinted at this issue a few times in the past but I have only just got around to actually writing it down. My question is, why isn’t relative humidity higher than it is? If you take any point on the ocean sufficiently far from any land, then during the day water will evaporate. At night the air will cool and therefore can hold less moisture. When dew point is reached some water will condense. And the next day the cycle will start again. The base limit is determined always by the overnight temperature, but during the day the absolute humidity will rise from this level. So in general, for an area with no influence of land, the diurnal minimum should be equal to the dew point. However this is mostly not the case. I have just looked at 6 places with at least 2200km (up to 5400km) of water around them. Here is a table of the difference between dew point and min temp:-

    South Pole 5
    Tristan Da Cunha 2
    Pitcairn I 3
    Kiribati 3
    Laysan I 6
    Ascension I 4

    Why isn’t the air saturated at the coldest point of the day? I think this is an important question if we hope to understand the water vapour feedback

  40. 140

    KW, #139–

    Good question. But “when dew point is reached some water will condense” should actually be “IF dew point is reached…” AFAIK, there’s no guarantee that will be the case, even over the ocean. After all, temperature trends are not uniquely determined by the diurnal cycle.

    Also is “South Pole” an error of some sort? Clearly, it is not a place with “2200km (up to 5400km) of water around..” At least, not liquid water…

  41. 141
    MA Rodger says:

    Keith Woollard @139,

    I think you will find if you look that, while the air sitting at the ocean/atmosphere boundary layer is saturated with RH=1, it is the transport of this air away from the ocean/atmosphere boundary layer that determines the rate of ocean evaporation into the atmosphere. As I remember, the general rule of thumb is that at a reference height of 2m (and I assume you are looking at met data which is recorded at 2m above island surface eg this for Pitcairn showing a night temperature of 24°C and night ‘dew point’ temperature of 21°C thus a difference of 3°C); at 2m the average RH=~0.8 this being a major variable that determines levels of ocean evaportion. (The Pitcairn met data shows RH=0.84 for the night.) Because of this required ‘drop in humidity between boundary layer air and near-surface air’ to allow ocean evaporation, rain is not so much a night-time phenomenon in the Tropics (caused by the cool night-time tempertures) but rather an afternoon phenomenon (when the air is heated in thermals and thus rises and cools significantly enough to reach RH=1).

  42. 142
    Keith Woollard says:

    Thanks MAR@141.

    I suspect you are probably correct. Although it does seem a fair bit of difference given that the pre-dawn will have a number of hours close to MinTemp and even the slightest breeze will mix the near surface.

  43. 143
    Al Bundy says:

    NigelJ: Trump is a waste of space. Lets not waste space by talking about him too much.

    AB: I remember getting upset at drivers who queue for fifteen minutes in traffic and then rubberneck at the causal accident, thus aggravating the delay.

    We know. But we’re human and that Drumpfs logic.

  44. 144
    John Pollack says:

    Keith @ 139 You don’t specify if the min T and dew point T differences are averages (if so, for what period?) or individual days, which makes a difference. Of course, the dew point T cannot exceed the air T, so there is an inherent condition where the difference can go to zero, but not below zero, which would show up in any average.

    Any weather condition that would mix drier air in from some other source, whether aloft, or horizontally, could result in a dew point depression. MAR’s explanation @141 holds. In addition, moisture can condense at the surface, which may be cooler than at 2m due to radiation.

    There are also instrumental considerations. Automated humidity equipment overall tends to be more finicky than temperature sensors, and can drift out of adjustment. If the sensor is too moist, the observations will either be thrown out or corrected to the air temperature. If too dry, it might not get caught for a while. Even if there is a manual check, you can imagine how long it might take for humidity equipment to get repaired on a remote island. If the even if humidity readings are all manual, the observer probably takes them hourly, which might not correspond to the time of minimum temperature.

    The South Pole is a special case. Water vapor is inherently difficult to measure accurately at very low temperatures. Consider that for much of the year, there is more carbon dioxide in the atmosphere than water vapor at the South Pole. In addition, ice is an excellent heat radiator, and the snow/ice surface can easily be colder than the air at 2 meters, causing additional water vapor to freeze at the surface.

  45. 145
    MA Rodger says:

    HadCRUT have reported for February with an anomaly of +1.00ºC, a small rise on January’s +0.98ºC anomaly.
    As with the TLT anomalies and GISTEMP & NOAA, HadCRUT’s Feb 2020 is convincingly the second-warmest February on record, and this without any significant El-Niño-boost (although the boost is usually less in surface records than TLT records). The warmest Febs run 2016 (+1.11ºC), 2020 (+1.00ºC), 2017 (+0.85ºC), 1998 (+0.76ºC), 2002 (+0.70ºC), 2015 (+0.69ºC), 2019 (+0.66ºC), 2004 (+0.61ºC), 1995 (+0.60ºC), 2010 (+0.59ºC), 1999 (+0.58ºC), 2006 (+0.57ºC), 2007 (+0.57ºC), 2018 (+0.53ºC).
    HadCRUT’s Feb 2020 sits 4th in the HadCRUT all-month anomaly record behind the El-Niño-boosted months Dec 2015, Feb & Mar 2016 (3rd in NOAA, GISS, UAH & RSS) while the start to 2020 in NOAA is the 2nd warmest on record after the El-Niño-boosted 2016 (as per NOAA, GISS, UAH & RSS)

  46. 146
    MA Rodger says:

    I’ve not seen the likes of this message on ESRL’s Mauna Loa CO2 web pages before:-

    “The Mauna Loa analyzer is currently down. No new data will be available until further notice.”

    It appeared after three consecutive days of “Unavailable” daily readings. If it keeps up I shall have to consider using Scripps Inst data for comparison with my grand MLO CO2 predictions. Yet the next few days CO2 levels coincide with some pretty low CO2 levels from last year (thus expect some big daily increases on last year), low enough to significantly bump up the present month-to-date’s 2.0ppm/yr value before the full March annual CO2 increase is complete. And for a significant part of this ‘low-level’ period last year Scripps wasn’t getting data.

    Meanwhile the ESRL Global CO2 numbers continue to add data. While the latest numbers are subject to significant revision, the daily trend numbers show the annual CO2 increase running at about 2.9ppm/yr but the upward trend has greatly slowed and is now looking very likely to peak soon and begin a new downward wobble (this the light blue trace on this graphic [usually 2 clicks to ‘download yor attachment’]. It will have peaked when the black acceleration trace goes negative. But do bear in mind that there can be revisions within this data stretching back three months-or-so which can be quite radical.)

  47. 147
    Chuck says:

    Now that the world is facing a real immediate crisis (Covid-19) can realclimate finally dispose of the moronic stylings of serial posters like KIA and Weaktor? It is really tiring to have to continually scroll beyond these trolls…

    KIA 4: many are concerned with equity, social justice, and other leftist PC frivolous malarkey.

  48. 148
    William B Jackson says:

    #147 You ever notice that leftest PC malarkey is almost always about things that are good for all, while KIA’s rightist PC malarkey tends to be about meanness and grasping behavior!

  49. 149
    MA Rodger says:

    A few days back NSIDC reported that the 2020 maximum daily Sea Ice Extent was reached on March 5th, the 11th lowest on record and the highest maximum since 2013. The JAXA record puts it very slightly different but, for the JAXA SIE record for 2020-to-date (28 March) it gives that same NSIDC result – average JAXA SIE for years-to-28Mar shows 2020 11th lowest and the highest since 2013. Relative to recent years, 2020-so-far has been an icy year averaging 11th spot and the highest average since 2013.

    Yet March 28 also saw the JAXA SIE hit a record daily low. So far this isn’t massively impressive (see SIE anomaly graph here – usually 2 clicks to ‘download your attachment’), just a single 2020 day squeezed in between record melty periods set in 2017 & 2019 but enough to show that 2020 can easily add another Arctic suprise to those of recent years.

    As of today, the number of record low SIE days that each year holds runs as follows:-

    2020 … 1 (to date)
    2019 … 64
    2018 … 57
    2017 … 25
    2016 … 128
    2015 … 8
    2014 … 0
    2013 … 0
    2012 … 68
    2011 … 9
    2010 … 6

  50. 150

    #149, MAR–

    Thanks for the update, and the list of record low SIE days by year. That’s an interesting way to sample the variability year-round. It also indicates the trend in a way, in that since there are 366 possible calendar dates, and per your list, all possible ‘slots’ are filled by years no later than 2010.

    FWIW,I’m pretty sure 2020 will clock up some more record days before it’s done.