California Wildfires, Climate Change, and the Hot-Dry-Windy Fire Weather Index

November 1st, 2019 by Roy W. Spencer, Ph. D.

Summer and early Fall are fire season in California. It has always been this way. Most summers experience virtually no precipitation over much of California, which means that the vegetation that grows during the cool, wet Winter becomes fuel for wildfires in Summer.

When you add the increasing population, risky forest management practices, and lack of maintenance of power lines, it should be little wonder that wildfire activity there has increased.

Few news reports of wildfires can avoid mentioning some nebulous connection of wildfires to human-caused climate change. This is a little odd from a meteorological perspective, however.

First of all, most of the historically significant wildfire events occur when COOL and DRY Canadian high pressure areas move south over the Great Basin region, causing strong downslope easterly winds (Santa Ana winds, Diablo winds). Global warming, in contrast, is supposed to result in WARMER and MOISTER air.

Secondly, the argument I’ve seen that excessive vegetation growth from a previous winter with abundant precipitation produces more fuel is opposite of the observation that fewer wildfires typically follow an unusually wet winter in California. They can’t have it both ways.

You might ask, why do SoCal temperatures sometimes rise so high before wildfire events if the source of the air is “cool” high pressure? It’s because the cooler high-altitude air over the Great Basin warms by compression as the air descends down the mountain slopes. Almost without exception (i.e., a super-adiabatic lapse rate), air at a higher altitude that is forced to descent to a low altitude will have a warmer temperature (and lower humidity) than the air it is displacing at low altitude. (While the warmth and dryness is widespread during these events, the high winds tend to be more localized to canyons and downslope areas.)

The dryness of this sinking air can be seen in this plot of the dewpoint temperature at LAX airport (Los Angeles) as dry air moved in from the east on December 4 with strong high pressure positioned over Nevada, and seven major wildfires developed and spread from the hot, dry, and locally windy conditions.

Hourly dewpoint temperatures at LAX airport from November 1 through December 31, 2017. Rapid drying is seen late on December 4, which is when the first of seven major wildfires (the Thomas fire) ignited.

But have such fire-enhancing weather events increased in, say, the last 50 years or more? And even if they have, was the cause due to greenhouse gas emissions from fossil fuels? While blaming some portion of recent global average warming on increasing CO2 is somewhat easier, blaming a change in regional or local weather patterns on it is much more difficult.

In the process of looking around for an answer to this question, I found some interesting recent work that would allow someone to analyze the appropriate meteorological station data, if it hasn’t already been done.

The Hot-Dry-Windy (HDW) Fire Weather Index

In 2018, a paper was published by a university research meteorologist and U.S. Forest Service (USFS) employees from three different USFS offices that describes a simple meteorological index related to wildfire risk. They call it the Hot-Dry-Windy (HDW) index, which is simply the product of (1) the surface wind speed times (2) the water vapor pressure deficit. The vapor pressure deficit uses the same information as relative humidity (temperature and dewpoint temperature), but it is a difference rather than a ratio, which better measures the potential of air to rapidly remove moisture from dead vegetation. For example a 10% relative humidity at 40 deg. F will have low drying potential, while 10% RH at 100 deg. F will have very high drying potential.

What is especially useful is that they used 30 years of weather forecast model (GFS) data to build a website that gives daily-updated forecasts of the HDW index across the United States. For example, here’s today’s forecast.

Importantly, the HDW index does not measure the actual fire danger, which must include how dry the vegetation currently is. It only shows whether the current weather will be conducive to the rapid spread of fire if a fire is started.

If you go to that website and click on a specific location, you get a time series plot of the HDW index values from 10 days ago up through the forecast for the coming days.

Unfortunately, the website does not provide any time series of the data over the last 30 years. But I can see the technique being applied to weather station data that goes back 50 years or more, for instance the formatted weather station data available here (which is where I got the Los Angeles airport data plotted above).

Until someone does this (if they haven’t already), I think it is a mistake to blame increased wildfire activity on “climate change”, when we don’t even know if there has been a change in the meteorological events most associated with major California wildfires: the intrusion of cool Canadian high pressure areas into the U.S. Southwest.

71 Responses to “California Wildfires, Climate Change, and the Hot-Dry-Windy Fire Weather Index”

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  1. Ray Ellis says:

    Dr Roy, sounds like a great retirement activity for you to take on.

    • Roy W. Spencer says:

      I’ve been told by my supporters I’m not allowed to retire. Or die.

    • Fred M Cain says:

      Dear Dr. Spencer,

      Thank you for a good, concise explanation of California’s unique climate and the Santa Ana winds.

      Just last week I read an editorial in our local newspaper blaming “climate change” for these disastrous fires. To me that is so stupid that it’s beyond belief. I had a notion to write a letter to the editor about it but I doubt it would do any good.

      There are times where I feel like the news media are winning the propaganda war on climate change.

      I wish everyone would read the book “Blunder” which I’m just finishing now. Trouble is, so many Americans are either too lazy or too busy to sit down and read something like that. We ignore your studies at our own peril.

      Best Regards,
      Fred M Cain,
      Topeka, IN

      • Lee Blair Nicholson says:

        Do you have a link to your book? The title was messed up in your reply. Also, what are your qualifications?

  2. Christopher Game says:

    I am not familiar with the history of care of wildernesses in America, and know little about it in Australia. But I can add a comment here.

    For tens of thousands of years, Australian aborigines used fire as a traditional hunting method. In suitable seasons, they set off a bushfire (that’s what we call them here) so as to drive the wild animals into the open and be easily hunted. This was done often enough to keep the fire fuel down, so that the fires were small, localised, and not too hot. The animals that were not hunted escaped, and later re-populated the refreshed fire zone.

    The genus of tree that best survives a fire that is not too severe is Eucalyptus. The result has been that the trees that dominated the land before the use of that hunting method were replaced mostly by Eucalyptus species.

    After the arrival of the British, that habit of fire moderation was partly continued.

    But it has now been largely blocked by environmentalists, bureaucrats, politicians, political activists, and virtue signallers, who live in cities, safe from the dangers of the wilderness, and ignorant of nature. The result is great accumulation of fuel for bushfires so that now we have less frequent but very much more fierce and destructive bushfires. All the animals are killed, and the Eucalyptus species cannot survive, and people are killed. The land is denuded, so that soil is washed into water storages.

    Then the virtue signallers blame the destruction on man-made CO2-emissions global warming. And many people believe them.

    • pochas94 says:

      I recently had occasion to do some hiking in the hills above Malibu. They had been recently burned over. Then, a particularly wet season, so that the underbrush had regrown with a vengeance. Now, more wildfires. Wash rinse repeat. Californians will just have to watch where they build their mansions.

  3. Thom says:

    They can’t have it both ways Doc? They do it just about every day. My most favorite is that low water levels and high water levels in the Great Lakes are blamed on climate change.

  4. Mark Wapples says:

    I keep getting told if it proves AGW its climate, if it dissproves it, it is a weather event.

    I assume that a similar concept applies to forest fires.

  5. Aaron S says:

    Increasing CO2 in the atmosphere could directly increase fires by increasing fuel.

    • Midas says:

      Huh??? Do you actually believe that CO2 burns in air?

      • Jon says:

        He means that more CO2 will create more greening, this more fuel for the burning..

        • Midas says:

          And would this increase the number of fires, or just their strength.

          • Aaron S says:

            I dont know. Fire frequency is highly variable in nearly all lakes I have seen evaluated. So this new phase of very rapid CO2 increase and associated greening would need to be carefully studied. It would be minor compared to precipitation and temperature or wind etc. So I imagine not easy to isolate. This sort of reseach is an opportunity. For example what plants are even increasing? I imagine C3 plants more than C4 because the C3 metabolic pathway is favorable in elevated CO2 conditions. Would be a cool phd or nsf project.

    • coturnix says:

      Yes! Well, not excactly..

      Although it can be argued so, in mediterranean climates extra co2 is not likely to make much difference since most plant growth there happens during the cold/moist season when VPD is very low. In fact, while extra co2 might extend the growth season into summer drought, it will also make plants during summer more moist, thus making summer fires less likely. In fact, it can be argued that ideally in a very high co2 climate, where plants waste very little water per absorbed co2, the plants would not even dry out at all during summer, preventing most fires.

      • Aaron S says:


        I like the alternative hypothesis. The situation is indeed complex. I would counter that perhaps the plants would not always become fuel as you say, but I think in stressed climates wet phases increase flora volume then dry phases convert to fuel. So the interannual cycle would produce the extra fuel even if some years your hypothesis was correct. Then during the 1 in 10 or even 1 in 100 yr dry event the intensity of fire would increase. So likely during a major ENSO dry phase the fuel would clear. That is how many fire frequency studies work. So it is complicated.

  6. Aaron S says:

    Burnt macerals are common in pollen samples from lakes. They can be C dated to show trends in fire frequency. Variability is large in the many proxy records.50yrs is not enough time to evaluate if the period of the variability is century to milenial scale. Need to look at valid data to asses this.

  7. Norilsk says:

    Russia Today nails it showing the record of negligence by the utility PG&E.

  8. Norilsk says:

    Tony Heller demonstrates that CO2 has virtually done all it can do. CO2 is very limited to a narrow band of the infrared spectrum that is being reflected upward from the Earth.

    Why is the notion that as CO2 increases the temperature increases still being pushed? It defies the physics of CO2 capabilities.

    • Midas says:

      Why do you people keep referring to someone with no qualifications or experience in the field. He is just a random guy off the street.

      • Norilsk says:

        Midas,If you are referring to Tony Heller, he has a masters degree in electrical engineering and an undergraduate degree in geology (the science that deals with the earth’s physical structure and substance, its history, and the processes that act on it.)He is more than suited to understand and do the research. What makes you an authority? Are you challenging his CO2 premise?

        • gallopingcamel says:

          “Climate Science” is squishy and corrupt.

          Midas should pay attention to people like me who are trained in hard sciences such as physics, chemistry, geology and engineering.

          In academia there are no penalties for being wrong unless you are an engineer.

  9. Art Groot says:

    Williams et al (2019) have done the research on VPD-area burned relationships in California. “Robust interannual relationships between VPD and summer forest‐fire area strongly suggest that nearly all of the increase in summer forest‐fire area during 19722018 was driven by increased VPD”.

  10. DocSiders says:

    Um….CO2 doesn’t burn at any temperature or at any oxygen levels. CO2 is used in fire EXTINGUISHERS (those are things that put out fires).

    CO2 is oxidized (i.e. burned) carbon.

    You don’t get to comment on anything relating to anything above 2nd grade science from now on.

    • Darcy says:

      Calm down there, Doc. Nobody in this thread said that CO2 burns.

    • Ken says:

      Fire needs heat energy, oxygen, and ignition source. Take away one and you have no fire.

      CO2 extinguisher does two things. When the compressed CO2 is released it expands as a cold cloud … removing heat energy. The cloud of CO2 also displaces any oxygen that might be feeding the fire.

      Atmospheric CO2 does neither.

  11. Tom Dayton says:

    Following up on Art Groots comment: Tamino has written a simpler version of some of what Williams et al. (2019) did. Both Tamino and Williams rigorously showed that this post by Spencer is wrong.

  12. Aaron S says:

    Yes more CO2, more plants, more fuel, more fire during dry net dry Evapotranspiration intervals. Confused what midas is implying. Please explain?

  13. According to my calculations, which must remain secret until copyrighted, an increase of +0.1 degrees C. of the average California temperature will cause a 15.6743% increase in the number of wildfires.

    A decline of -2.953 degrees C. would result in virtually no CA wildfires at all,

    Wildfires have nothing to do with the lack of tree maintenance around transmission lines, and the lack of forest management.

    PG&E can’t afford to maintain their transmission lines because they are spending all their spare cash installing windmills and solar panels, as required by the CA politicians.

    All bad news is caused by climate change,
    or President Trump.

    And don’t you forget it

  14. Tom Dayton says:

    PG&E for decades has been secretly refraining from doing maintenance it knew needed to be done. While falsifying records. And using that money instead to pay executives and shareholders. But probably Richard Greene wont believe that, because the Wall Street Journal is controlled by communists…

    • Stephen P Anderson says:

      A lot of companies are do that. Most hospitals in the US spend less on maintenance than they used to. Go to any flourishing hospital and walk around and observe all the dollars spent on the asthetics then go behind the scenes and see what they’re spending on maintenance and maintenance personnel. Gap is widening.

  15. Tom Dayton says:

    The Wall Street Journal investigated specifically PG&Es maintenance of electrical systems

  16. Darcy says:

    Roy correctly points out that vapor pressure deficit (VPD) is a critical factor in the expansion rate of a wildfire.

    Ficklin and Novick (2017) in JGR-Atm reported that warming and decreased RH has produced a dramatic increase in VPD in California (and the US southwest in general), especially in the summer and fall.

    This is an obvious and (I believe) non-controversial link between climate change, VPD, and wildfires.

    Ficklin, D.L. and Novick, K.A., 2017. Historic and projected changes in vapor pressure deficit suggest a continental‐scale drying of the United States atmosphere. Journal of Geophysical Research: Atmospheres, 122(4), pp.2061-2079.

    See Figure 1 for maps.

    From the conclusion: “We find significant increases in VPD for nearly all seasons in the recent past from diverging trends in e(s) owing to increases in air temperature and decreases in e(a) from decreases in relative humidity. These trends are especially apparent in the southwestern United States, which has shown to be especially sensitive to forest mortality from increases in temperature …”

  17. ren says:

    Anyways, as the Santa Ana winds push over the mountains and move downslope into the valleys, the air compresses. That causes it to heat up and dry out, which by extension dries out any vegetation in the way, priming it to explode if theres a spark.

    Canyons funnel the winds even more, causing them to accelerate further, which is how you end up with winds gusting 50 mph or higher by the time they reach Southern California.

  18. Entropic man says:

    From a biologist’s viewpoint, one indication that the climate is changing is that the burned forests are regenerating as scrub.

  19. Once again Dr. Roy is right. The rising trend of wildfires has nothing to do with carbon dioxide given that the acreage burned has fallen by a factor of four over the last 75 years.

    If you don’t believe me, take a look at the 4th “National Climate Assessment” published last year. Here is a link to a brief version (196 pages):

    On pages 29 you will find “Chart k” that shows wild fires trending upwards since 1980. While the chart is correct it is highly misleading since records show 52 million acres burned in 1930 compared to only five million in 1980.

    You can find the full data set here:

    For me the interesting question is why the NCA4 highlights deceptive information. The report plays similar tricks with heat waves, US heavy precipitation, sea ice extent, sea level and ocean acidity.

    Michael Mann’s “Nature Trick” was intended to hide the decline in temperatures. It seem to me that the NCA4 is an even more blatant attempt to mislead the public.

    • Darcy says:

      You missed this at the top of the page you linked to:

      “Prior to 1983, sources of these figures are not known, or cannot be confirmed, and were not derived from the current situation reporting process. As a result the figures prior to 1983 should not be compared to later data.”

      You’re not even comparing apples vs oranges. You’re comparing apples vs mystery fruit of unknown provenance.

      • gallopingcamel says:

        When it comes to wildfires we have records going back to 1926 by the National Interagency Fire Service that compares oranges to oranges.

        Stop trying to muddy the waters.

  20. Fred M. Cain says:

    Dear Dr. Spencer,

    As long as we are on the subject of fires, I have often seen it presented in the press and news media that the fires are due to a prolonged, 20-year drought which is (naturally) the direct result of “climate change”.

    I agree completely that since the year 2000 especially, there has been an abundance of dry years. But, is this so-called 20-year “drought” historically unprecedented? I, for one, can’t see that it is. I have looked at some rainfall stats in the Southwest and I’m just not seeing it. What is your take on this?

    What disturbs me the most is that I have found some forestry reports and papers which stated that following a catastrophic, high-intensity fire, the old forest will not be able to regenerate (due to climate change, of course) and the recommendation is for forest managers to plant or encourage the growth of something else. (i.e. scrub pinyon pines and juniper instead of ponderosa pines).

    So there you have it. There are actually plans that have been put forth to change the forest ecosystem structure due to a change of climate that might not even have happened yet.
    I wrote to a couple of people about this and, of course, I too was ignored.

    Best Regards,
    Fred M. Cain,
    Topeka, IN

  21. gallopingcamel says:


    During the 1930s summers were hot and dry in the USA which caused the “Dust Bowl” and wildfires that were an order of magnitude larger than today. Nobody has an explanation for this but it is safe to say that the burning of fossil fuels had nothing to do with it.

    John Steinbeck published his “Grapes of Wrath” novel that describes how this affected us “little people”.

    While Kansas, Nebraska, Texas and nearby states were suffering “Dust Bowl” conditions other states were experiencing wildfires that destroyed as much as 50 million acres in a single year compared to 9 million acres in 2018.

  22. Fred M. Cain says:

    Dear “Galloping Camel”,

    I think that’s an excellent point! I, too, have wondered about the devastating drought and heat wave in the 1930s. The state of Indiana recorded its all-time record high of 112F in ’34, I think it was.

    But no one wants to look at this because it’s not consistent with the IPCC’s agenda.

    What the news media has been reporting is that the ten worst forest fires in history have all occurred since the year 2000. This so-called “fact” has also been repeated over and over in forestry literature.

    There are two points that need to be brought out here. Number one, is that statement even true at all? What you posted suggests that it might not be.

    And number two is the assumption that these recent forest fires simply must be the direct result of climate change. This assumption rests entirely on the belief that they simply cannot think of anything else that it could be. This is the same logic that Spencer talks about in “Blunder”. Global warming simply has to be the result of anthropogenic greenhouse gasses because “they cannot think of what else could cause it”.

    My own personal, honest and humble opinion is that both the recent fires along with global warming are almost certainly being caused by something else.

    Best Regards,
    Fred M. Cain,
    Topeka, IN

  23. gallopingcamel says:

    Fred said:

    “What the news media has been reporting is that the ten worst forest fires in history have all occurred since the year 2000. This so-called “fact” has also been repeated over and over in forestry literature.”

    According to the National Interagency Fire Center the “Media” are right since the NIFC data on “Wildfires Greater Than 100,000 Acres” starts in 1997:

    Even so I don’t find it plausible that the largest US wildfire was the 2004 “Taylor Complex” fire that consumed 1,305,592 acres in Alaska, since the total acreage was so much higher in the 1930s:

    It did not take long to find much larger wildfires including a 8.1 million acre burn in Manitoba. Ooops, that is in Canada so here are a few from the USA:

    1845 1.5 Mega-acres in Oregon
    1871 2.5 Mega-acres in Michigan
    1898 2.5 Mega-acres in South Carolina
    1910 3.0 Mega-acres in Idaho & Montana

    I got the above information from Wikipedia so it probably can’t be relied on. For example I find it suspicious that according to Wikipedia, the largest wildfire in the 1930s was the 220,000 acre Matilija Fire in California.

    Dr. Roy is right when he says wildfires correlate with hot dry weather. However there is not a hint of correlation between that and the Keeling curve. In other words CO2 has nothing to do with wildfires no matter what governor Gavin Newsome may say to divert attention from his incompetence.

    • Norman says:


      Roy is almost right. Wildfires do correlate with hot dry weather (which is logical) but they need fuel.

      In this longer term graph of Wildfires covering multiple states they so show that in the early 1930’s there were considerable land area burned by wildfires (units in hectares).

      Hectares equal to 2.47 acres.

      In this study they also found you need to have a wet moist year to build the fuel to burn. You have the deserts that are very hot and dry but they have no fuel to burn.

      I think it is false to start any fire study at 1970 or so. There are longer records available that show this is a poor starting point to form any conclusion on climate and fire.

      • gallopingcamel says:

        That 2009 study agrees with the NIFC data that shows wildfires peaking in the 1930s.

        The 1930s were hot and dry in much of the USA and that helped to increase the acreage burnt. Today, poor forest management practices are a problem, especially in California.

  24. Steve Kerckhoff says:

    Dr. Roy, how does AGW cause the homeless and illegal aliens to start reckless campfires that start wild fires in California?

  25. Fred M. Cain says:

    First of all, I want to say how glad I am to have found this forum or blog or whatever we might call it. Having just read “Blunder” for the first time, I have been turned in to quite a follower of Dr. Roy. It is most refreshing to hear from the other people on this forum as well who seem to know what they’re talking about – free from hype.

    I think all your comments about fire are good ones including Dr. Roy’s about hot, windy conditions.

    I believe there are two sensible explanations for some of these horrific fires that have been brought forth. One is excessive fuels build up {in forested areas that is} and the other is the huge expansion in the West of what has been called the urban/wildlands interface. The above comment about the homeless starting fires might fall into that category.

    Both these explanations, however, are considered secondary to the REAL culprit: “Climate Change”. Of course it’s climate change at least according to the news media.

    This brings me back to my real question: Has the climate in much of the West REALLY changed? I, for one, remain unconvinced. I’d love to hear from some of you on this subject. The West has a long, long record of erratic and extreme weather. Is what we’ve seen the last ten or 20 years really a “new normal” like they say? Again, I am unconvinced.

    There are two really fun reads that I can suggest: The novels “Storm” and “Fire” by George R. Stewart. Both were written about 70-80 years ago and in spite of the fact that they are just story books, Stewart succeeds in painting a good picture of the weather in California in the 1930s and ’40s. After reading them I was hit with the realization, what has really changed here? Probably nothing.

    Best Regards,
    Fred M. Cain,
    Topeka, IN

    • gallopingcamel says:

      You are skeptical of “Climate Science” and that shows you have resisted brainwashing by the Alarmists.

      While I can’t tell you why global temperatures have “Flatlined” since 1998 I can tell you CO2 has no measurable effect on global tempetarures.

      • Mick says:

        It certainly does on the isolated lab bench. Trouble is, they used that to extrapolate to the very dynamic natural earth system. In that context Its pseudoscience

  26. Nate says:


    One thing to consider is that it takes a long time, months, for the moisture content of wood to decrease to the level where it burns easily.

    Thus a day of warm dry air is not sufficient.

  27. Fred M. Cain says:


    One thing I haven’t seen mentioned on this thread yet unless I missed it, is the dramatic differences in elevation.

    During a wet California winter, a huge amount of dense brush and herbaceous plants spring up which in turn desiccate over the long, dry, hot summer.

    In the higher elevation fir zones in the Sierra and Transverse ranges, there are times when the very last of the snow might not be gone until mid or late June. In those high elevation forests, the ground and forest litter can still be quite damp by the time the Santa Ana winds arrive.

    This would appear to be the case this year as some of the very worst fires have been restricted to the lower elevations.

    Best Regards,
    Fred M. Cain

  28. Ken says:

    Physics of LEDs: LED exists at zero and one state. It requires an electric current to energize the LED so it goes from zero to one state and emits energy as visible light.

    Ohms law says if you hook up a bunch of LEDs in parallel to a fixed battery source the amount of current drops across each LED. So at a certain saturation point of too many LEDS there is not going to be enough energy to power any of the LEDs from zero to one.

    What happens if you increase the amount of CO2 in the atmosphere to the point where there is not enough IR energy to excite CO2 from its zero to one state … particularly given its emissivity means the state change is very slow. Does that mean the Greenhouse effect is stopped because there is no IR returning to earth? Does this mean cooling of the climate if there is too much CO2 in the atmosphere?

    • Norman says:


      You don’t need IR to excite a CO2 molecule to a higher vibrational energy state. Kinetic energy from collisions is just as effective.

      If you view each CO2 molecule as a radiator of IR then if you have more of these radiators you have more kinetic energy from the non radiating gases (N2 and O2) being converted to IR which then some of this energy will be returned to the surface via IR emitted by the CO2.

      The more CO2 the higher its emissivity for a given path-length.

      It has actually been experimentally tested years ago.

    • Dr Roys Emergency Moderation Team says:

      OK, Norman.

  29. Aaron S says:

    120k yr ago sea level rose 10 m above today and rates climbed 3m per century. Yet CO2 was 290ppm. Hmm almost like CO2 was not the driver and suggests that we are perhaps in the middle of another natural climate excursion. How to differentiate natural climate warming then from supposed CO2 forcing now?

    If you say orbital forcing, well maybe but not exactly because the orbital forcing does not equal the climate response. So there is something else going on.

    • gallopingcamel says:

      The something else that is going on is orchestrated by Mother Nature.

      You can safely ignore the effects of CO2 on climate as Mother Nature does.

  30. Aaron S says:

    I am shocked the climate reviewers published this. This Reality will muddy the waters on climate certainty and open the door for natural components to be considered.

    For example, there is an obvious inconsistency presented in the article below.

    They claim more extreme climate change today than natural:
    “The Earth is presently in an interglacial period which began about 10,000 years ago. But greenhouse gas emissions over the past 200 years have caused climate changes that are faster and more extreme than experienced during the last interglacial.”

    But point out the risk that natural systems can be so much more extreme then we have considered:

    “We examined data from the last interglacial, which occurred 125,000 to 118,000 years ago. Temperatures were up to 1℃ higher than today – similar to those projected for the near future.
    Our research reveals that ice melt in the last interglacial period caused global seas to rise about 10 metres above the present level. The ice melted first in Antarctica, then a few thousand years later in Greenland.
    Sea levels rose at up to 3 metres per century, far exceeding the roughly 0.3-metre rise observed over the past 150 years.”

    You can not make this stuff up!!! Like maybe someone can clarify what I am missing? As I see it empirical data from 120kyr ago strongly supports natural climate is more varied than anything we have seen. Thus, this 1C could be mostly natural?

    Again, orbital parameters are poorly constrained and there is literature for that also so their blanket statement it is insulation form Milankovitch is based on weak foundations. 1 step closer to an accurate view.

    This is why I love science it is self correcting in time.

  31. gallopingcamel says:

    Over the last 850,000 years CO2 and temperature have correlated closely according to the EPICA and Vostok ice core records.

    Given that [CO2] followed temperature by hundreds of years we can be sure that CO2 is not the “Control Knob” for climate.

  32. Fred M. Cain says:

    “You are skeptical of ‘Climate Science’ and that shows you have resisted brainwashing by the Alarmists.”

    Galloping Camel,

    Yeah, I guess what it is, I’ve been fascinated by the weather since my youth. I’ve been watching the weather closely now for nearly 50 years both in Arizona and in the Midwest. So, when they keep talking about “climate change” well, yes, I’m just not seeing it.

    Back in the 1970s in Arizona, it was also really dry about that time and there were several huge and catastrophic forest fires. I came to believe that the climate was changing back then. But it really wasn’t. It was only another one of the Southwest’s long-term droughts which mostly ended around 1978.

    Right now there is something very strange going on and it would be neat if Professor Roy could comment on this. There is an unusually strong upper level trough that has formed off the Baja California coast, what I like to think of as a “cut off low”.

    This has forced the southern extremity of the southern jet stream clear down into the tropics. I think this is very unusual for early to mid-November. This development is simply not consistent with global warming. In fact, the prevailing westerly winds aloft failed to move very far north over the summer which caused the Southwest’s “summer monsoon” to largely fail. This event is also not consistent with the global warming theory.

    Best Regards,
    Fred M. Cain

    • Mick says:

      Ive lived in the PNW all my life. It still rains for 9 months a year. I grow apples. I still cant grow oranges. The whole CC is pseudoscience. Not changing where I live. The only thing that changes is the weather.

  33. Fred M. Cain says:

    At the risk of beating my subject and interest to death, here is another article I found online that discusses a massive tree die off in the Sierra Nevada Mountains.

    If you read the entire article, forest management practices are mentioned as a possible cause.

    However, the primary focus is on global warming. As I stated (above), there was also a severe drought in the 1970s. I think I can recall reading that there was a massive tree die-off in the 1970s as well although that might’ve been more in the Transverse Range above Los Angeles.

    Did higher temperatures in California really make this most recent event so much worse?

    Another assumption that I have trouble with is that a warmer planet will automatically make climates so much dryer. I don’t know if that’s really the case or not. Does anybody know?

    Martin seems to think things will get wetter – not dryer but I don’t know how much of an expert he really is. His book “Therophobia” may have done us skeptics more harm than good. It really doesn’t read very well nor make a good case. I finally stopped reading about half way through it.

    Best Regards,
    Fred M. Cain

    • gallopingcamel says:

      Fred said:
      “Another assumption that I have trouble with is that a warmer planet will automatically make climates so much dryer. I don’t know if that’s really the case or not. Does anybody know?”

      Simple physics says that the saturation vapor pressure of water rises with temperature:

      At 0 Centigrade the saturation pressure of water is 600 Pascals whereas at 20 Centigrade it is more than three times higher and six times higher at 30 Centigrade.

      This explains why snowfall is lower during glaciations than during inter-glacials. You can confirm this by studying the EPICA and Vostok ice core records.

      In a nutshell, a warm planet is wetter than a cool one.

    • Mick says:

      California has recently had good rain and snow. I think ecoterrorism is the culprit.

  34. Snape says:

    The climate change connection is simple: summers out West are getting hotter, but not wetter. Hotter but not wetter equals drier fuel. Drier fuel will exacerbate whatever else is contributing to the fire.

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