Comments on the alleged megadrought

During the past few weeks, media have been hyping alarm about a new study  that claims that the Southwestern US is entering a megadrought and that the drought is made more severe by human-caused global warming. That claim is based on tree-ring analysis and computer modeling speculation.

Droughts have occurred due to natural cycles, but there is no physical evidence that carbon dioxide emissions play a significant role is controlling global temperature or precipitation. The new paper presents no evidence that alleged “human-caused” global warming is making the drought worse, it is just speculation. In fact, many droughts are associated with cooler periods.

Let’s put things in perspective. Here are the data for the past 1,200 years. It seems that “megadroughts” have occurred naturally, without any human influence.

These data show that the 20th century was wetter than normal. However, the next graph shows that there have been droughts. But, rather that entering a megadrought, we seem to be emerging from a dryer period according to NOAA.

The graph above comes from a 4-minute video posted by Tony Heller, on his “Real Climate Science” blog. This video destroys claims that the western United States is currently experiencing a nearly unprecedented megadrought. Video: https://youtu.be/W9xCWDZmUT4



Evidence that CO2 emissions do not intensify the greenhouse effect

The Broken Greenhouse – Why CO2 is a minor player in global climate

A Review of the state of Climate Science

Drought in the West

2015 was rainiest year at my house

Even though the southwest is experiencing drought conditions, 2015 was the rainiest year in the last nine years during which I recorded rainfall at my house.

Since mid-2007, I have been measuring and reporting daily rainfall at my house on the west side of Tucson, Arizona. This is part of the RainLog.org program run by SAHRA, “Sustainability of Semi-Arid Hydrology and Riparian Areas.”

Tucson has two rainy seasons: a winter season which may or may not have much rain, and the summer monsoon which gives us the majority of rainfall in the region. During the winter, our weather comes from the west and storms may be sucked dry as they pass over the Sierra Nevada of California. During the summer, our weather comes from the southeast with winds bearing moisture sucked out of the Gulf of Mexico and the Gulf of California.

See Anatomy of a Thunderstorm and The North American Monsoon

During the summer monsoon, desert heat and orographic uplift from mountain ranges turn that moist air into thunderstorms. In Tucson, much of the rain occurs on the east side of town because of the air flow direction and orographic uplift over the Catalina Mountains. We who live on the west side of town get what is left over.

Here are the numbers.

In 2015, I recorded 14.32 inches of rain. The next rainiest year was 2008 with 12.09 inches. The dryest year was 2013 with 7.95 inches. The graphs below from RainLong show how rain occurred during the year (there are two graphs because Rainlog can plot only five years at a time).

MyRain 2008-2010


Here is the total rainfall recorded in inches since 2008:
2008: 12.09
2009: 10.00
2010: 11.56
2011: 10.83
2012: 10.85
2013: 7.95
2014: 11.36
2015: 14.32

As I write this on January 2, 2016, El Nino driven rain is forecast for every day next week.


Drought and predictions of doom for the Southwest

Tony Davis has another climate scare story in the Arizona Daily Star: “Study: Worst SW drought in 1,000 years coming.” We should expect more stories like this because polling shows that “global warming” is not of great concern among the public, but many interests such as the money-grubbing IPCC, the EPA, and alternative energy companies depend on maintaining the myth of CO2-caused global warming. Tony writes: “Due to human-caused global warming, this region and the Great Plains are likely to experience droughts from 2050 to 2100 that are worse than the ‘megadroughts’ that lasted up to 60 years in the Southwest in pre-Medieval times, the study said.”

You can read the full study here. If you do, you will find that the study is based on failed computer models, statistical inference, and manipulation of data.

Bob Tisdale has some comments about this paper at the WattsUpWithThat blog. The thing about Bob is that he has this nasty habit of comparing computer model predictions against actual observational data.

Below, I show one of Bob’s graphs. This graph compares June-July-August precipitation data from 1979-2014 for both climate models (red) and observations (blue).

SW precipitation model data comparison

There are two things to notice about this graph. First, the models have always predicted that there would be twice as much precipitation than has actually occurred. Therefore a “modeled drought” might just be the model’s approach toward reality. Second, all the models show a slight decreasing trend in precipitation when in reality there has been a slight increasing trend in precipitation.

The drought scare seems to be a persistent theme. Back in August, Tony had another drought scare story featuring some of the same researchers (see: Megadrought and the Arizona Daily Star). In that previous story the researchers had this disclaimer:

“An obvious limitation of our work is that it is ‘blind’ to certain aspects of dynamically-driven changes in prolonged drought risk. For instance, changes in the magnitude, frequency, or teleconnection patterns of El Nino and La Nina (e.g., Coats et al. 2013) may alter the statistics of interannual variability in ways that are not captured by our simple models. Further, megadrought statistics over the last millennium may be forcing-dependent, as suggested by Cook et al. (2004), for instance, which shows that megadroughts were more common during the medieval climate era of 850-1200 CE. Another very serious limitation is imposed by the reliability of the models themselves to make realistic predictions of changes in climatological precipitation for the end of the 21st century.”

One other thing, both Tony Davis and the study authors claim “human-caused global warming.” Yet, to my knowledge, no one has presented any physical evidence to support the contention that our carbon dioxide emissions are a significant factor.

In a previous article, I show, with observational evidence, that the much touted enhanced greenhouse effect from our carbon dioxide emissions does not exist, see: Evidence that CO2 emissions do not intensify the greenhouse effect .

See also:

Carbon dioxide and the greenhouse effect

Climate change in perspective


Megadroughts and the Arizona Daily Star

In the Sunday edition of the Arizona Daily Star we were treated with a scare story about megadroughts titled, “S. Ariz. closer to an epic drought .” The sub-headline of the story by Tony Davis (seen only in the print edition) reads, “If emissions are unchecked, upper risk is 50%, study says.” Trouble is, the study itself, does not mention “emissions.”

The lead line of the story reads (my emphasis): “The odds of a potentially devastating Southwestern ‘megadrought’ due to human-caused climate change are as high as 50 percent in this century, a new study finds.” This lead line is contradicted by a line later in the story: Toby Ault, one of the study authors is quoted: “We’re not saying that what’s happening now (with drought) is because of climate change.” The study, itself, does not mention “human-cause” climate change.

It appears that the Star is fabricating data and promoting propaganda. You can read the full study here.

Just for the record, here is a scan of the Star headline and story beginning:

Star drought headline

The study “Assessing the risk of persistent drought using climate model simulations and paleoclimate data” is an exercise in statistical manipulation and computer modeling. It does imply that warming predicted by computer models could cause drought. But we have seen that computer models have failed spectacularly in prediction of temperature (see my article: Failure of climate models shows that carbon dioxide does not drive global temperature).

Here is what the study says:

“In the current generation of global climate models, the risk of a decade-scale drought occurring this century is at least 50% for most of the greater southwestern US and may indeed be closer to 80%… The probability of multidecadal megadrought is also high: the likelihood of a 35 year event is between 10% and 50% depending on how much climate change is realized during the coming century. The probability of even longer events (> 50 year, or “permanent” megadrought) is non-negligible (5-10%) for the most intense warming scenario.”


“An obvious limitation of our work is that it is ‘blind’ to certain aspects of dynamically-driven changes in prolonged drought risk. For instance, changes in the magnitude, frequency, or teleconnection patterns of El Nino and La Nina (e.g., Coats et al. 2013) may alter the statistics of interannual variability in ways that are not captured by our simple models. Further, megadrought statistics over the last millennium may be forcing-dependent, as suggested by Cook et al. (2004), for instance, which shows that megadroughts were more common during the medieval climate era of 850-1200 CE. Another very serious limitation is imposed by the reliability of the models themselves to make realistic predictions of changes in climatological precipitation for the end of the 21st century.”


“Our estimates of risk are consequently only as accurate as climate model projections of changes in precipitation.”

Has global warming caused any drought conditions in the western U.S.? Let’s look at the data of drought conditions since 1900:

Drought trend


Let’s take a longer perspective on drought:

Drought since 800AD

Is it still as scary as the Star alleges? The study authors are free to do their modeling and speculations. It seems to me, however, the Arizona Daily Star is making up data, perhaps to fit an agenda, and thereby doing a dis-service to readers.

“The greatest challenge facing mankind is the challenge of distinguishing reality from fantasy, truth from propaganda. Perceiving the truth has always been a challenge to mankind, but in the information age (or as I think of it, the disinformation age) it takes on a special urgency and importance.” Michael Crichton.


North American wildfires and global warming

Almost every time we have a major wildfire, alarmists blame global warming and claim that such warming will increase the incidence of wildfires. They also often claim that the number of wildfires is increasing. Their argument seems logical at first, higher temperatures and less precipitation will dry out forests making them more susceptible to wildfire.

The graph below compiled by C3Headlines using data from the National Interagency Fire Center in the U.S. and the National Forestry Database in Canada shows that the number of wildfires has decreased dramatically since 1970 and has remained relatively constant since the mid 1980s. The number of acres burned, however, has slightly increased and that may have to do with wildfire fighting decisions.


These numbers suggest some possible conclusions: either global warming does not have much influence on the number of wildfires, in contrast to alarmist claims, or there has not been sufficient warming since 1970 to test the hypothesis. Fire incidence could also reflect the time and severity of cyclic drought.

I’ve also included below the UAH lower tropospheric temperature record since 1979 when satellites began measuring global temperature.


Meanwhile, NASA says “Climate Models Project Increase in U.S. Wildfire Risk” The analysis was based on current fire trends and predicted greenhouse gas emissions. Time will tell if this is just another “garbage in, garbage out” computer simulation.

See also:

Mega-fires in Southwest due to forest mismanagement

Drought in the West

Droughts in the Southwest put in perspective

USDA says carbon dioxide can reverse effects of drought

Scaremongering from the University of Nebraska

A press release from the University of Nebraska-Lincoln proclaims “U.S. Drought Monitor shows record-breaking expanse of drought.” It goes on to say “More of the United States is in moderate drought or worse than at any other time in the 12-year history of the U.S. Drought Monitor, officials from the National Drought Mitigation Center at the University of Nebraska-Lincoln said today.” Twelve year history? I suppose the headline is correct for their tiny data set (barely however, 2002 and 2003 were nearly as dry as 2012). The headline is very misleading.

Too bad they didn’t check with the now 112-year record at the National Climate Data Center (NCDC) here to get a longer historical perspective. The graphs below from NCDC show that drought was more widespread and more severe in 1934.


US-drought-June-1934-300x272This looks like an example of deliberate cherry-picking of drought history data with the goal of grabbing headlines and perhaps funding.

See more here.

See more about droughts here:

Drought in the West

Droughts in the Southwest put in perspective

El Niño, bristlecone pines, and drought in the Southwest

University of Arizona Scientists Find Evidence of Roman Period Megadrought

Weather extremes not increasing with warming

Extreme weather makes news.  It is a tenet of catastrophic anthropogenic global warming adherents (CAGWs) that extreme weather events have become and will become ever more common as the planet warms.  However, new research in Europe, based on historical records and tree-rings, covering the period AD 962–2007, shows no trend in extreme weather events. In fact, the researchers found “A fairly uniform distribution of hydroclimatic extremes throughout the Medieval Climate Anomaly, Little Ice Age and Recent Global Warming…”

 The paper is Buntgen, U.et al., 2011. Combined dendro-documentary evidence of Central European hydroclimatic springtime extremes over the last millennium. Quaternary Science Reviews 30: 3947-3959..(Link to abstract, the full paper is behind a pay wall.)

The abstract reads:

A predicted rise in anthropogenic greenhouse gas emissions and associated effects on the Earth’s climate system likely imply more frequent and severe weather extremes with alternations in hydroclimatic parameters expected to be most critical for ecosystem functioning, agricultural yield, and human health. Evaluating the return period and amplitude of modern climatic extremes in light of pre-industrial natural changes is, however, limited by generally too short instrumental meteorological observations. Here we introduce and analyze 11,873 annually resolved and absolutely dated ring width measurement series from living and historical fir (Abies alba Mill.) trees sampled across France, Switzerland, Germany, and the Czech Republic, which continuously span the AD 962–2007 period. Even though a dominant climatic driver of European fir growth was not found, ring width extremes were evidently triggered by anomalous variations in Central European April–June precipitation. Wet conditions were associated with dynamic low-pressure cells, whereas continental-scale droughts coincided with persistent high-pressure between 35 and 55°N. Documentary evidence independently confirms many of the dendro signals over the past millennium, and further provides insight on causes and consequences of ambient weather conditions related to the reconstructed extremes. A fairly uniform distribution of hydroclimatic extremes throughout the Medieval Climate Anomaly, Little Ice Age and Recent Global Warming may question the common believe that frequency and severity of such events closely relates to climate mean stages. This joint dendro-documentary approach not only allows extreme climate conditions of the industrial era to be placed against the backdrop of natural variations, but also probably helps to constrain climate model simulations over exceptional long timescales.

In a previous post, Media pawns in IPCC extreme weather hype, I present research and graphics that show there have been no upward trends in droughts, wet weather, or hurricanes as the world warmed from the “little ice age.”

In spite of science to the contrary, CAGWs and the IPCC must continue to present their scary stories to secure funding to fight their imagined hobgoblins and gain power.  And such stories sell newspapers.

See also:

Pained Earth’s summer to forget: the rest of the story

Book Review: The Delinquent Teenager Who Was Mistaken for the World’s Top Climate Expert, an IPCC Exposé

Droughts in the Southwest put in perspective

The severe drought in Texas this year has fueled speculation that alleged human-caused global warming has somehow caused “unprecedented” conditions. But real research data show that the current drought is not unprecedented and is part of a natural cycle. There have been much more severe and persistent droughts in the past before humans began emitting signification amounts of carbon dioxide into the atmosphere. This post focuses on research from the University of Arizona and the Lamont-Doherty Earth Observatory of Columbia University.

From the University of Arizona and Arizona State University we have “A 1,200-year perspective of 21st century drought in southwestern North America.”

The Abstract reads in part:

A key feature of anticipated 21st century droughts in Southwest North America is the concurrence of elevated temperatures and increased aridity. Instrumental records and paleoclimatic evidence for past prolonged drought in the Southwest that coincide with elevated temperatures can be assessed to provide insights on temperature-drought relations and to develop worst-case scenarios for the future. In particular, during the medieval period, AD 900–1300, the Northern Hemisphere experienced temperatures warmer than all but the most recent decades. Paleoclimatic and model data indicate increased temperatures in western North America of approximately 1 °C over the long-term mean. This was a period of extensive and persistent aridity over western North America. Paleoclimatic evidence suggests drought in the mid-12th century far exceeded the severity, duration, and extent of subsequent droughts. The driest decade of this drought was anomalously warm, though not as warm as the late 20th and early 21st centuries. The convergence of prolonged warming and arid conditions suggests the mid-12th century may serve as a conservative analogue for severe droughts that might occur in the future. The severity, extent, and persistence of the 12th century drought that occurred under natural climate variability, have important implications for water resource management. The causes of past and future drought will not be identical but warm droughts, inferred from paleoclimatic records, demonstrate the plausibility of extensive, severe droughts, provide a long-term perspective on the ongoing drought conditions in the Southwest, and suggest the need for regional sustainability planning for the future.

This paper goes on to discuss the role of El Niño-La Niña cycles and sea-surface temperature, but the paper does not really address cause of the droughts. The theme of this paper is that past droughts are associated with warm periods and that continued warming may portend more severe droughts in our future. However, the authors partly contradict themselves by saying that the more severe droughts of the Medieval period occurred when the temperatures were cooler than the current warm period.

It seems we have a complex interplay of natural cycles which are not completely understood.

From Cornell, we have “The characteristics and likely causes of the Medieval megadroughts in North America.” and a very interesting graph:

Droughts in the west

  This graph shows that while the current drought is severe, it is much less severe than droughts during the Medieval Warm Period, a time before humans were emitting much carbon dioxide into the atmosphere.

The paper presents three conclusions:

1) The similarity of the spatial patterns suggests that the physical processes that caused the modern droughts also caused the medieval megadroughts.

2) The global atmosphere ocean conditions that currently cause modern droughts for a few years at a time were the prevailing ocean climate during the medieval period.

2) Despite the shift in the mean tropical ocean climate ENSO variability continued as now but oscillating about a colder mean state.

The authors also present an archaeological speculation:

The medieval megadroughts may also have left their signature on the human environment of the West. The great cliff cities in the four corners region of the West such as at Chaco Canyon and Mesa Verde were all abandoned towards the end of the drought. These societies were based on irrigated agriculture. Although there remains much debate about why these highly organized Indian societies collapsed, archaeologists are revisiting the idea that decades of dry conditions were part of the reason.

With both papers we see that data collection is one thing, interpretations are another.

See also:

Drought in the West

El Niño, bristlecone pines, and drought in the Southwest

EL NINO behavior, climate models predict opposite of what really happens

USDA says carbon dioxide can reverse effects of drought

Results of a four-year field study conducted by the U.S. Department of Agriculture found that “Rising carbon dioxide (CO2) levels can reverse the drying effects of predicted higher temperatures on semi-arid rangelands.”

Warmer temperatures increase water loss to the atmosphere, leading to drier soils. In contrast, higher CO2 levels cause leaf stomatal pores to partly close, lessening the amount of water vapor that escapes and the amount of water plants draw from soil. This new study finds that CO2 does more to counterbalance warming-induced water loss than previously expected. In fact, simulations of levels of warming and CO2 predicted for later this century demonstrated no net change in soil water, and actually increased levels of plant growth for warm-season grasses.

See the USDA news release here.

This result should not be surprising to anyone except climate alarmists who have long predicted global warming will increase evapotranspiration and decrease soil moisture. However many laboratory and field studies found that rising carbon dioxide reduces evapotranspiration and leads to higher soil moisture content, results similar to the USDA study. The USDA study was conducted on warm-season grasses. Other studies were conducted on a wide range of grasses, beans, sorghum, scrub oak, forbs, and food crops.


See also:

Drought in the West

Water Supply and Demand in Tucson


El Niño, bristlecone pines, and drought in the Southwest

While the Southwest is experiencing drought conditions, unusual flooding is occurring along the Mississippi River.  This is part of the natural La Niña cycle.

Research from the University of Hawaii’s International Pacific Research Center  has found an 1100-year correlation between El Niño-La Niña cycles and tree rings in bristlecone pines in the American Southwest.  This may allow better prediction of the cycles and a better understanding of past cycles and their implications.

El Niño and its partner La Niña, the warm and cold phases in the eastern half of the tropical Pacific,  play havoc with  climate worldwide. Predicting El Niño events more than several months ahead is now routine, but predicting how it will change  in a warming world has been hampered by the short instrumental record. An international team of climate scientists has now shown that annually resolved tree-ring records from North America, particularly  from  the US Southwest, give a continuous representation of the intensity of El Niño events over the past 1100 years and can be used to improve El Niño prediction.

Tree rings in the US Southwest, the team found, agree well with the 150-year instrumental sea surface temperature records in the tropical Pacific. During El Niño, the unusually warm surface temperatures in the eastern Pacific lead to changes in the atmospheric circulation, causing unusually wetter winters in the US Southwest, and thus wider tree rings; unusually cold eastern Pacific temperatures during La Niña lead to drought and narrower rings. The tree-ring records, furthermore, match well existing reconstructions of the El Niño-Southern Oscillation and correlate highly, for instance, with [oxygen 18] isotope concentrations of both living corals and corals that lived hundreds of years ago around Palmyra in the central Pacific.

The graph below shows the correlation.

El nino amplitude from tree rings

The tree rings reveal that the intensity of El Niño has been highly variable, with decades of strong El Niño events and decades of little activity. The weakest El Niño activity happened during the Medieval Climate Anomaly in the 11th  century, whereas the strongest activity has been since the 18th  century.

These different periods of El Niño activity are related to long-term changes in Pacific climate. Cores taken from lake sediments in the Galapagos, northern Yucatan, and the Pacific Northwest reveal that the eastern–central tropical Pacific climate swings between warm and cool phases, each lasting from 50 to 90 years. During warm phases, El Niño and La Niña events were more intense than usual. During cool phases, they deviated little from the long-term average as, for instance, during the Medieval Climate Anomaly when the eastern tropical Pacific was cool.

While correlation does not necessarily prove causation, these results are compelling.  Many factors such as temperature and amount of precipitation affect the width of tree rings.  The researchers say in this case, that precipitation is the controlling factor.  They rely on Liebig’s Law  which states that yield is proportional to the amount of the most limiting nutrient, and in the desert southwest, water is the limiting factor.

We are currently experiencing the La Niña phase which means a dry southwest and colder, wetter conditions in the north and mid-west.

For more background on drought see: Drought in the West.