In 2017, Christy & McNider published a study where they estimated and removed the volcanic effects from our UAH lower tropospheric (LT) temperature record, finding that 38% of the post-1979 warming trend was due to volcanic cooling early in the record.
Yesterday in my blog post I showed results from a 1D 2-layer forcing-feedback ocean model of global-average SSTs and deep-ocean temperature variations up through 2019. The model is forced with (1) the RCP6 radiative forcings scenario (mostly increasing anthropogenic greenhouse gases and aerosols and volcanoes) and (2) the observed history of El Nino and La Nina activity as expressed in the Multivariate ENSO Index (MEI) dataset. The model was optimized with adjustable parameters, with two of the requirements being model agreement with the HadSST global temperature trend during 1979-2019, and with deep-ocean (0-2000m) warming since 1990.
Since the period since 1979 is of such interest, I re-ran the model with the RCP6 volcanic aerosol forcing estimates removed. The results are shown in Fig. 1.
Fig. 1. 1D model simulation of global (60N-60S) average sea surface temperature departures from assumed energy equilibrium (in 1765), with and without the RCP6 volcanic radiative forcings included.
The results show that 41% of the ocean warming in the model was simply due to the two major volcanoes early in the record. This is in good agreement with the 38% estimate from the Christy & McNider study.
It is interesting to see the “true” warming effects of the 1982-83 and 1991-1993 El Nino episodes, which were masked by the eruptions. The peak model temperatures in those events were only 0.1 C below the record-setting 1997-98 El Nino, and 0.2 C below the 2015-16 El Nino.
This is not a new issue, of course, as Christy & McNider also published a similar analysis in Nature in 1994.
These volcanic effects on the post-1979 warming trend should always be kept in mind when discussing the post-1979 temperature trends.
NOTE: In a previous version of this post I suggested that the Christy & McNider (1994) paper had been scrubbed from Google. It turns out that Google could not find it if the authors’ middle initials were included(but DuckDuckGo had no problem finding it).
The continuing global-average warmth over the last year has caused a few people to ask for my opinion regarding potential explanations. So, I updated the 1D energy budget model I described a couple years ago here with the most recent Multivariate ENSO Index (MEIv2) data. The model is initialized in the year 1765, has two ocean layers, and is forced with the RCP6 radiative forcing scenario and the history of El Nino and La Nina activity since the late 1800s.
The result shows that the global-average (60N-60S) ocean sea surface temperature (SST) data in recent months are well explained as a reflection of continuing weak El Nino conditions, on top of a long-term warming trend.
Fig. 1. 1D model of global ocean temperatures compared to observations. The model is forced with the RCP6 radiative forcing scenario (increasing CO2, volcanoes, anthropogenic aerosols, etc.) and the observed history of El Nino and La Nina since the late 1800s. The observations are monthly running 3-month averages and are offset with a single bias to match the model temperatures, which are departures from assumed energy equilibrium in 1765.
The model is described in more detail below, but here I have optimized the feedbacks and rate of deep ocean heat storage to match the 41-year warming trend during 1979-2019 and increase in 0-2000m ocean heat content during 1990-2017.
While the existence of a warming trend in the current model is due to increasing CO2 (I use the RCP6 radiative forcing scenario), I agree that natural climate variability is also a possibility, or (in my opinion) some combination of the two. The rate of deep-ocean heat storage since 1990 (see Fig. 3, below) represents only 1 part in 330 of global energy flows in and out of the climate system, and no one knows whether there exists a natural energy balance to that level of accuracy. The IPCC simply *assumes* it exists, and then concludes long-term warming must be due to increasing CO2. The year-to-year fluctuations are mostly the result of the El Nino/La Nina activity as reflected in the MEI index data, plus the 1982 (El Chichon) and 1991 (Pinatubo) major volcanic eruptions.
When I showed this to John Christy, he asked whether the land temperatures have been unusually warm compared to the ocean temperatures (the model only explains ocean temperatures). The following plot shows that for our UAH lower tropospheric (LT) temperature product, the last three months of 2019 are in pretty good agreement with the rest of the post-1979 record, with land typically warming (and cooling) more than the ocean, as would be expected for the difference in heat capacities, and recent months not falling outside that general envelope. The same is true of the surface data (not shown) which I have only through October 2019.
Fig. 2. UAH lower tropospheric temperature departures from the 1981-2010 average for land versus ocean, 1979 through 2019.
The model performance since 1900 is shown next, along with the fit of the model deep-ocean temperatures to observations since 1990. Note that the warming leading up to the 1940s is captured, which in the model is due to stronger El Nino activity during that time.
Fig. 3. As in Fig. 1, but for the period 1900-2019. The inset show the model versus observations for the increase in 0-2000 m ocean temperatures since 1990.
The model equilibrium climate sensitivity which provides the best match to the observational data is only 1.54 deg. C, using HadSST1 data. If I use HadSST3 data, the ECS increases to 1.7 deg. C, but the model temperature trends 1880-2019 and 1979-2019 can no longer be made to closely approximate the observations. This suggests that the HadSST1 dataset might be a more accurate record than HadSST3 for multi-decadal temperature variability, although I’m sure other explanations could be envisioned (e.g. errors in the RCP6 radiative forcing, especially from aerosol pollution).
A Brief Review of the 1D Model
The model is not just a simple statistical fit of observed temperatures to RCP6 and El Nino/La Nina data. Instead, it uses the energy budget equation to compute the monthly change in temperature of ocean near-surface layer due to changes in radiative forcing, radiative feedback, and deep-ocean heat storage. As such, each model time step influences the next model time step, which means the model adjustable parameters cannot be optimized by simple statistical regression techniques. Instead, changes are manually made to the adjustable model parameters, the model is run, and then compared to a variety of observations (SST, deep ocean temperatures, and how CERES radiative fluxes vary with the MEI index). Many combinations of model adjustable parameters will give a reasonably good fit to the data, but only within certain bounds.
There are a total of seven adjustable parameters in the model, and five time-dependent datasets whose behavior is explained with various levels of success by the model (HadSST, NODC 0-2000m deep ocean temperature [1990-2017], and the lag-regression coefficients of MEI versus CERES satellite SW, LW, and Net radiative fluxes [March 2000 through April 2019]).
The model is initialized in 1765 (when the RCP6 radiative forcing dataset begins) which is also when the climate system is (for simplicity) assumed to be in energy balance. Given the existence of the Little Ice Age, I realize this is a dubious assumption.
The energy budget model computes the monthly change in temperature (dT/dt) due to the RCP6 radiative forcing scenario (which starts in 1765, W/m2) and the observed history of El Nino and La Nina activity (starting in 1880 from the extended MEI index, intercalibrated with and updated to the present with the newer MEIv2 dataset (W/m2 per MEI value, with a constant of proportionality that is consistent with CERES satellite observations since 2000). As I have discussed before, from CERES satellite radiative budget data we know that El Nino is preceded by energy accumulation in the climate system, mainly increasing solar input from reduced cloudiness, while La Nina experiences the opposite. I use the average of the MEI value in several months after current model time dT/dt computation, which seems to provide good time phasing of the model with the observations.
Also, an energy conserving non-radiative forcing term is included, proportional to MEI at zero time lag, which represents the change in upwelling during El Nino and La Nina, with (for example) top layer warming and deep ocean cooling during El Nino.
A top ocean layer assumed to represent SST is adjusted to maximize agreement with observations for short-term variability, and as the ocean warms above the assumed energy equilibrium value, heat is pumped into the deep ocean (2,000 m depth) at a rate that is adjusted to match recent warming of the deep ocean.
Empirically-adjusted longwave IR and shortwave solar feedback parameters represent how much extra energy is lost to outer space as the system warms. These are adjusted to provide reasonable agreement with CERES-vs.-MEI data during 2000-2019, which are a combination of both forcing and feedback related to El Nino and La Nina.
Generally speaking, changing any one of the adjustable parameters requires changes in one or more of the other parameters in order for the model to remain reasonably close to the variety of observations. There is no one “best” set of parameter choices which gives optimum agreement to the observations. All reasonable choices produce equilibrium climate sensitivities in the range of 1.4 to 1.7 deg. C.
The sudden eruption of Taal volcano south of Manila, Philippines began about 0630 UTC today, and the Himawari-8 satellite infrared imagery suggests that the plume might have penetrated the stratosphere, which is necessary for the volcano to have any measurable effect on global temperatures. The following link will take you to the recent satellite loop.
Smoke plumes from bushfires in southeast Australia on January 4, 2020, as seen by the MODIS imager on NASA’s Aqua satellite.
Summary Points
1) Global wildfire activity has decreased in recent decades, making any localized increase (or decrease) in wildfire activity difficult to attribute to ‘global climate change’.
2) Like California, Australia is prone to bushfires every year during the dry season. Ample fuel and dry weather exists for devastating fires each year, even without excessive heat or drought, as illustrated by the record number of hectares burned (over 100 million) during 1974-75 when above-average precipitation and below-average temperatures existed.
3) Australian average temperatures in 2019 were well above what global warming theory can explain, illustrating the importance of natural year-to-year variability in weather patterns(e.g. drought and excessively high temperatures).
4) Australia precipitation was at a record low in 2019, but climate models predict no long-term trend in Australia precipitation, while the observed trend has been upward, not downward. This again highlights the importance of natural climate variability to fire weather conditions, as opposed to human-induced climate change.
5) While reductions in prescribed burning have probably contributed to the irregular increase in the number of years with large bush fires, a five-fold increase in population in the last 100 years has greatly increased potential ignition sources, both accidental and purposeful.
Historical Background
Australia has a long history of bush fires, with the Aborigines doing prescribed burns centuries (if not millennia) before European settlement. A good summary of the history of bushfires and their management was written by the CSIRO Division of Forestry twenty-five years ago, entitled Bushfires – An Integral Part of Australia’s Environment.
The current claim by many that human-caused climate change has made Australian bushfires worse is difficult to support, for a number of reasons. Bushfires (like wildfires elsewhere in the world) are a natural occurrence wherever there is strong seasonality in precipitation, with vegetation growing during the wet season and then becoming fuel for fire during the dry season.
All other factors being equal, wildfires (once ignited) will be made worse by higher temperatures, lower humidity, and stronger winds. But with the exception of dry lightning, the natural sources of fire ignition are pretty limited. High temperature and low humidity alone do not cause dead vegetation to spontaneously ignite.
As the human population increases, the potential ignition sources have increased rapidly. The population of Australia has increased five-fold in the last 100 years (from 5 million to 25 million). Discarded cigarettes and matches, vehicle catalytic converters, sparks from electrical equipment and transmission lines, campfires, prescribed burns going out of control, and arson are some of the more obvious source of human-caused ignition, and these can all be expected to increase with population.
Trends in Bushfire Activity
The following plot shows the major Australia bushfires over the same period of time (100 years) as the five-fold increase in the population of Australia. The data come from Wikipedia’s Bushfires in Australia.
Fig. 1. Yearly fire season (June through May) hectares burned by major bushfires in Australia since the 1919-20 season (2019-20 season total is as of January 7, 2020).
As can be seen, by far the largest area burned occurred during 1974-75, at over 100 million hectares (close to 15% of the total area of Australia). Curiously, though, according to Australia Bureau of Meteorology (BOM) data, the 1974-75 bushfires occurred during a year with above-average precipitation and below-average temperature. This is opposite to the narrative that major bushfires are a feature of just excessively hot and dry years.
Every dry season in Australia experiences excessive heat and low humidity.
Australia High Temperature Trends
The following plot (in red) shows the yearly average variations in daily high temperature for Australia, compared to the 40-year average during 1920-1959.
Fig. 2. Yearly average high temperatures in Australia as estimated from thermometer data (red) and as simulated by the average of 41 climate models (blue). (Source).
Also shown in Fig. 2 (in blue) is the average of 41 CMIP5 climate models daily high temperature for Australia (from the KNMI Climate Explorer website). There are a few important points to be made from this plot.
First, if we correlate the yearly temperatures in Fig. 2 with the bushfire land area burned in Fig. 1, there is essentially no correlation (-0.11), primarily because of the huge 1974-75 event. If that year is removed from the data, there is a weak positive correlation (+0.19, barely significant at the 2-sigma level). But having statistics depend so much on single events (in this case, their removal from the dataset) is precisely one of the reasons why we should not use the current (2019-2020) wildfire events as an indicator of long-term climate change.
Secondly, while it is well known that the CMIP5 models are producing too much warming in the tropics compared to observations, in Australia just the opposite is happening: the BOM temperatures are showing more rapid warming than the average of the climate models produces. This could be a spurious result of changes in Australian thermometer measurement technology and data processing as has been claimed by Jennifer Marohasy.
Or, maybe the discrepancy is from natural climate variability. Who knows?
Finally, note the huge amount of year-to-year temperature variability in Fig. 2. Clearly, 2019 was exceptionally warm, but a good part of that warmth was likely due to natural variations in the tropics and subtropics, due to persistent El Nino conditions and associated changes in where precipitation regions versus clear air regions tend to get established in the tropics and subtropics.
Australia Precipitation Trends
To drive home the point that any given year should not be used as evidence of a long-term trend, Australia precipitation provides an excellent example. The following plot is like the temperature plot above (Fig. 2), but now for precipitation as reported by the BOM (data here).
Fig. 3. As in Fig. 2, but for annual precipitation totals.
We can see that 2019 was definitely a dry year in Australia, right? Possibly a record-setter. But the long-term trend has been upward (not downward), again illustrating the fact that any given year might not have anything to do with the long-term trend, let alone human-induced climate change.
And regarding the latter, the blue curve in Fig. 3 shows that the expectation of global warming theory as embodied by the average of 41 climate models is that there should have been no long-term trend in Australia precipitation, despite claims by the media, pseudo-experts, and Hollywood celebrities to the contrary.
It should be kept in mind that wildfire risk can actually increase with more precipitation during the growing season preceding fire season. More precipitation produces more fuel. In fact, there is a positive correlation between the precipitation data in Fig. 3 and bushfire hectares burned (+0.30, significant at the 3-sigma level). Now, I am not claiming that hot, dry conditions do not favor more bushfire activity. They indeed do (during fire season), everything else being the same. But the current 2019-2020 increase in bushfires would be difficult to tie to global warming theory based upon the evidence in the above three plots.
Global Wildfire Activity
If human-caused climate change (or even natural climate change) was causing wildfire activity to increase, it should show up much better in global statistics than in any specific region, like Australia. Of course any specific region can have an upward (or downward) trend in wildfire activity, simply because of the natural, chaotic variations in weather and climate.
But, contrary to popular perception, a global survey of wildfire activity has found that recent decades have actually experienced less fire activity (Doerr & Santin, 2016), not more. This means there are more areas experiencing a decrease in wildfire activity than there are areas experiencing more wildfires.
Why isn’t this decrease being attributed to human-caused climate change?
Concluding Comments
There are multiple reasons why people have the impression that wildfires are getting worse and human-caused climate change is to blame. First, the news tends to report only disasters… not a lack of disasters. The desire for more clicks means that headlines are increasingly sensationalized. The media can always find at least one expert to support the desired narrative.
Second, the spread of news is now rapid and it penetrates deeply, being spread through social media.
Third, an increasing number of environmental advocacy groups seize upon any natural disaster and declare it to be caused by increasing CO2 in the atmosphere. The hyperbolic and counter-factual claims of Extinction Rebellion is one of the best recent examples of this.
This is all against a backdrop of government funded science that receives funding in direct proportion to the threat to life and property that the researcher can claim exists if science answers are not found, and policy is not changed. So, it should come at no surprise that there is political influence on what research gets funding when the outcome of that research directly affects public policy.
My personal opinion, based upon the available evidence, is that any long-term increase in wildfire activity in any specific location like Australia (or California) is dominated by the increase in human-caused ignition events, whether they be accidental or purposeful. A related reason is the increasing pressure by the public to reduce prescribed burns, clearing of dead vegetation, and cutting of fire breaks, which the public believes to have short term benefits to beauty and wildlife preservation, but results in long term consequences that are just the opposite and much worse.
Recent news reports claim that dozens of people have been arrested in Australia on arson charges, a phenomenon which we must assume has also increased by at least five-fold (like population) in the last 100 years. Accidental sources of ignition also increase in lockstep with the increasing population and all of the infrastructure that comes along with more people (vehicles, power lines, campfires, discarded matches and cigarettes, etc.)
So, to automatically blame the Australian bushfires on human-caused climate change is mostly alarmist nonsense, with virtually no basis in fact.
2019 was the third warmest year (+0.44 deg. C) in the 41 year satellite record, after 2016 (+0.52 deg. C) and 1998 (+0.48 deg. C).
The Version 6.0 global average lower tropospheric temperature (LT) anomaly for December, 2019 was +0.56 deg. C, statistically unchanged from the November value of +0.55 deg. C.
The yearly rankings over the 41-year satellite-based temperature record shows 2019 as the third warmest, behind 2016 and 1998.
The linear warming trend since January, 1979 remains at +0.13 C/decade (+0.11 C/decade over the global-averaged oceans, and +0.18 C/decade over global-averaged land).
Various regional LT departures from the 30-year (1981-2010) average for the last 24 months are:
The UAH LT global anomaly image for December, 2019 should be available in the next few days here.
The global and regional monthly anomalies for the various atmospheric layers we monitor should be available in the next few days at the following locations:
Polar Stratospheric Cloud display (smartphone photo posted by Reddit user Breuuan on Dec. 31, 2019.)
Increasing carbon dioxide in the atmosphere will continue to cause upper atmospheric cooling in the 2020s, which will lead to some of the most beautiful cloud displays ever witnessed by human eyes.
Along with the warming in the lower atmosphere that more CO2 is theoretically expected to produce, the upper atmosphere is supposed to cool even more strongly. For example, in our satellite observations since 1979, we have observed about 3-4 times as much cooling in the middle stratosphere as warming in the troposphere over the last four decades. This cooling is expected to exist even higher up, into the upper mesosphere and beyond, which is at the edge of outer space and where meteors burn up. The current record solar minimum conditions are probably also contributing to this cooling.
Polar Stratospheric Clouds and Noctilucent Clouds are Increasing
As 2019 came to a close, reports of some of the most vivid opalescent displays of wintertime polar stratospheric clouds (PSCs) in memory have been coming in from Northern Europe. These clouds require very cold temperatures in the stratosphere (-80 deg. C or colder). They show up shortly after sunset or before sunrise when the sun is still shining at that high altitude (15-25 km), while the usual weather-related clouds in the troposphere are no longer illuminated by the sun.
Wintertime polar stratospheric clouds in Sweden, Dec 30, 2019 (by Patricia Cowern Israelsson).
In the summertime in the polar regions, electric-blue noctilucent clouds (NLCs) are sometimes seen in the upper mesosphere (80-85 km) where temperatures plunge to the coldest anywhere on Earth, -100 deg. C. Like PSCs, they are seen after sunset or before sunrise, but due to their great altitude occur when the sun is well below the horizon and some brighter stars are beginning to shine. These clouds exist at literally the edge of space, above 99.999% of the mass of the atmosphere, and are believed to be seeded by meteoric dust.
These clouds have a rippled appearance, and time lapse photography has revealed an amazing variety of undulations, like waves from multiple pebbles thrown in a pond interacting. The following 4K time lapse video shows cloud behavior unlike any you have seen before, and is well worth the 2 minutes it takes to watch (go full-screen):
Last year (2019) NLCs were observed well outside the polar regions for the first time in recorded history, as far south as southern California and Nevada. This is due to some combination of colder temperatures and higher water vapor amounts (methane is converted to water vapor at these altitudes, and increasing atmospheric methane could be causing higher humidity up there).
I keep getting asked about our charts comparing the CMIP5 models to observations, old versions of which are still circulating, so it could be I have not been proactive enough at providing updates to those. Since I presented some charts at the Heartland conference in D.C. in July summarizing the latest results we had as of that time, I thought I would reproduce those here.
The following comparisons are for the lower tropospheric (LT) temperature product, with separate results for global and tropical (20N-20S). I also provide trend ranking “bar plots” so you can get a better idea of how the warming trends all quantitatively compare to one another (and since it is the trends that, arguably, matter the most when discussing “global warming”).
From what I understand, the new CMIP6 models are exhibiting even more warming than the CMIP5 models, so it sounds like when we have sufficient model comparisons to produce CMIP6 plots, the discrepancies seen below will be increasing.
Global Comparisons
First is the plot of global LT anomaly time series, where I have averaged 4 reanalysis datasets together, but kept the RSS and UAH versions of the satellite-only datasets separate. (Click on images to get full-resolution versions).
The ranking of the trends in that figure shows that only the Russian model has a lower trend than UAH, with the average of the 4 reanalysis datasets not far behind. I categorically deny any Russian involvement in the resulting agreement between the UAH trend and the Russian model trend, no matter what dossier might come to light.
Tropical Comparisons
Next is the tropical (20N-20S) comparisons, where we now see closer agreement between the UAH and RSS satellite-only datasets, as well as the reanalyses.
I still believe that the primary cause of the discrepancies between models and observations is that the feedbacks in the models are too strongly positive. The biggest problem most likely resides in how the models handle moist convection and precipitation efficiency, which in turn affects how upper tropospheric cloud amounts and water vapor respond to warming. This is related to Richard Lindzen’s “Infrared Iris” effect, which has not been widely accepted by the mainstream climate research community.
Another possibility, which Will Happer and others have been exploring, is that the radiative forcing from CO2 is not as strong as is assumed in the models.
Finally, one should keep in mind that individual climate models still have their warming rates adjusted in a rather ad hoc fashion through their assumed history of anthropogenic aerosol forcing, which is very uncertain and potentially large OR small.
First, I did an update of all the WordPress plugins a couple days ago, and I immediately became locked out of the website. I could not even ftp in to disable the plugins. The web hosting company had to restore my access.
Secondly, some people have noted that their comments are held for moderation for no apparent reason. This has been a continuing problem for a long time. I have a limited number of key words and people I automatically screen out, but there are many more cases where there is no apparent reason for the comment to be rejected.
If you have the latter problem, try posting your comment in parts (Part 1 of 3, Part 2 of 3…). Let me know by email when you have a small section of comment that will not post so I can see what might be tripping the filter. (I see a LOT of actual spam that has as little as one sentence of irrelevant content, and I have no idea how the algorithm flagged it.) Anthony Watts once told me he has similar problems.
People’s Climate March in Denver, CO on April 29, 2017 (CNN).
It’s that time of year again, when we are subjected to exaggerated climate claims such as in this Forbes article, 2019 Wraps Up The Hottest Decade In Recorded Human History. Given that the global average surface temperature is about 60 deg. F, and most of the climate protesters we see in the news are wearing more clothing than the average Key West bar patron, I would think that journalists striving for accuracy would use a more accurate term than “hottest”.
So, I am announcing that in our 41-year record of global satellite measurements of the lower atmosphere, 2019 will come in as 3rd least-chilly.
For the decade 2010-2019, the satellite temperatures averaged only 0.15 C higher than in the previous decade (2000-2009). That’s less than a third of a degree F, which no one would even notice over 10 years.
If you are wondering how your neck of the woods has fared this year, the latest year-to-date plot of 2019 temperature departures from the 30-year average (1981-2010) shows the usual pattern of above- and below-normal, with little visual indication that the global average for 2019 is now running 0.36 deg. C above normal.
Latest 2019 year-to-date average surface temperature departures from the 1981-2010 average from the NCEP CFSv2 global data assimilation system (graphic courtesy of Weatherbell.com).
The use of the term “hottest” to describe recent warming belies the fact that the rate of warming we have experienced in recent decades is minuscule compared to the several tens of degrees of temperature change most people experience throughout the year — and sometimes from one week to the next.
So, how are we supposed to react when the arithmetically-averaged temperature, across all extremes, goes up by only a small fraction of a degree in ten years? With horror? Outrage? Is the term “hottest” in a headline supposed to move us? Seriously?
Should we all get someone to fly across the Atlantic so they can transport us to Europe on a luxury yacht to help Save the Earth™ on our next European vacation?
The click-bait journalism typified by terms like “hottest”, “climate emergency”, and now “climate catastrophe” helps explain why the public is largely indifferent to the global warming issue, at least if we are asked to spend more than a few dollars to fix it.
This is why the alarmist narrative has moved on from temperature, and now focuses on wildfires, droughts, floods, hurricanes, snowstorms, and sea level rise. Yet, none of these have worsened in the last 100 years, with the exception of global sea level rise which has been occurring at a rate of about 1 inch per decade for as long as it has been monitored (since the 1850s, well before humans could be blamed).
And, just in case some new visitors to my blog are reading this, let me clarify that I am not a denier of human-caused climate change. I believe at least some of the warming we have experienced in the last 50 years has been due to increasing carbon dioxide. I just consider the fraction of warming attributable to humans to be uncertain, and probably largely benign.
This is fully consistent with the science, since the global energy imbalance necessary to explain recent warming (about 1 part in 250 of the natural energy flows in and out of the climate system) is much smaller than our knowledge of those flows, either from either theoretical first principles or from observations.
In other words, recent warming might well be mostly natural.
The Version 6.0 global average lower tropospheric temperature (LT) anomaly for November, 2019 was +0.55 deg. C, up from the October value of +0.46 deg. C.
The linear warming trend since January, 1979 remains at +0.13 C/decade (+0.11 C/decade over the global-averaged oceans, and +0.18 C/decade over global-averaged land).
Various regional LT departures from the 30-year (1981-2010) average for the last 23 months are:
The UAH LT global anomaly image for November, 2019 should be available in the next few days here.
The global and regional monthly anomalies for the various atmospheric layers we monitor should be available in the next few days at the following locations:
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