Climate Activists Switch From Blaming Humans For Too Little And Now Too Much Rainfall…And Call It ‘Science’

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Modern ‘Science’ Blames Humans

For California Weather…If It’s Bad

Image Source: Cook et al., 2010

In the present era of agenda-driven journalism, major news outlets often attempt to persuade readers that weather events occurring now have never happened before…and they are worsened by human-caused climate change.

In 2015, Humans Caused Drought, Too Little Rainfall In California

Global Warming Brought on California’s Severe Drought

Humans to Blame for Catastrophic Drought in California, Scientists Say

Study: Human-caused global warming behind Calif. drought

Long-suffering California can blame drought on global warming, experts say

“Scientists predict that “enhanced drought” will continue in California throughout this century because global warming has ‘substantially increased’ the likelihood of extreme droughts in the state.”

In 2017, Humans Causing Floods, Too Much Rainfall In California

Heavy California rains par for the course for climate change

With Climate Change, California Is Likely To See More Extreme Flooding

GLOBAL WARMING MEANS CALIFORNIA WILL SEE A LOT MORE ‘PINEAPPLE EXPRESS’ [RAIN]STORMS

Bill Nye Blames Global Warming For Devastating Floods In Northern Cali

New York Times, 1992

“BEGINNING about 1,100 years ago, what is now California baked in two droughts, the first lasting 220 years and the second 140 years. Each was much more intense than the mere six-year dry spells that afflict modern California from time to time, new studies of past climates show. The findings suggest, in fact, that relatively wet periods like the 20th century have been the exception rather than the rule in California for at least the last 3,500 years, and that mega-droughts are likely to recur.”

“Dr. Scott Stine, a paleoclimatologist at California State University at Hayward, used radiocarbon dating techniques to determine the age of the trees’ outermost annual growth rings, thereby establishing the ends of drought periods. He then calculated the lengths of the preceding dry spells by counting the rings in each stump. This method identified droughts lasting from A.D. 892 to A.D. 1112 and from A.D. 1209 to A.D. 1350. Judging by how far the water levels dropped during these periods — as much as 50 feet in some cases — Dr. Stine concluded that the [Medieval-era] droughts were not only much longer, they were far more severe than either the drought of 1928 to 1934, California’s worst in modern times, or the more recent severe dry spell of 1987 to 1992.”

The Historical Southwest U.S. Climate: 3.2°C Warmer During Medieval Times

Millar et al., 2006

“The paleoclimate modeled for Whitewing [Sierra Nevada, CA] during the Medieval period was significantly warmer and slightly drier than present . Medieval mean annual minimum temperature was warmer than current by 3.2°C, with large differences in winter (+3.5°C, January) and summer (+4.0°C, July). Mean annual maximum temperature was also greater in the Medieval period (+2.3°C), with greater differences in winter (+3.2°C, January) than summer (+2.6°C, July). Annual precipitation was less by 24 mm.”

Scuderi, 1993

“Long-term trends in the temperature reconstruction are indicative of a 125-year periodicity that may be linked to solar activity as reflected in radiocarbon and auroral records. The results indicate that both the warm intervals during the Medieval Warm Epoch (A.D. 800 to 1200) and the cold intervals during the Little Ice Age (A.D. 1200 to 1900) are closely associated with the 125-year [solar activity] period.”

Medieval Drought Lasted Hundreds Of Years And Was Much More Severe

Whitehouse et al., 2010

“Paleoclimatic and model data indicate increased temperatures in western North America [∼AD 900–1300] 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.”

Kirby et al., 2014

Cook et al., 2010

Scientists: Natural Variability Dominates In Southwestern U.S. Drought

Cheng et al., 2016

“The current California drought has cast a heavy burden on statewide agriculture and water resources, further exacerbated by concurrent extreme high temperatures. Furthermore, industrial-era global radiative forcing brings into question the role of long-term climate change on CA drought. How has human-induced climate change affected California drought risk?  … The results thus indicate the net effect of climate change has made agricultural drought less likely, and that the current severe impacts of drought on California’s agriculture has not been substantially caused by long-term climate changes.”

Prein et al., 2016

“Projected changes of a poleward extension of the subtropical dry zones simulated by climate models and the corresponding decrease of precipitation in the U.S. Southwest have not been found in observations to date because of the large natural climate variability.”

Seager et al., 2015

“The causes of the California drought during November to April winters of 2011/12 to 2013/14 are analyzed using observations and ensemble simulations with seven atmosphere models forced by observed SSTs. …[T]he precipitation deficit during the drought was dominated by natural variability, a conclusion framed by discussion of differences between observed and modeled tropical SST trends.”

Diaz and Wahl, 2015

“An analysis of the October 2013–September 2014 precipitation in the western United States and in particular over the California–Nevada region suggests this anomalously dry season, while extreme, is not unprecedented in comparison with the approximately 120-yr-long instrumental record of water year (WY; October–September) totals and in comparison with a 407-yr WY precipitation reconstruction dating back to 1571. Over this longer period, nine other years are known or estimated to have been nearly as dry or drier than WY 2014. The 3-yr deficit for WYs 2012–14, which in California exceeded the annual mean precipitation, is more extreme but also not unprecedented, occurring three other times over the past approximate 440 years in the reconstruction.”

Scientists: Natural Variability Dominates In Continental U.S. Drought

Seager et al., 2009   (Southeastern U.S.)

“Tree-ring records show that the twentieth century has been moist from the perspective of the last millennium and free of long and severe droughts that were abundant in previous centuries.  The recent drought, forced by reduced precipitation and with reduced evaporation, has no signature of model-projected anthropogenic climate change.”

Stambaugh et al., 2011 (Midwestern U.S.)

“[D]rought conditions over the period of instrumental records (since 1895) do not exhibit the full range of variability, severity, or duration of droughts during the last millennium.  Thirteen decadal to multidecadal droughts (i.e., ≥10 years) occurred during the last millennium – the longest lasting sixty-one years and centered on the late twelfth century.”

Andreadis and Lettenmaier, 2006 (Continental U.S.)

“Droughts have, for the most part, become shorter, less frequent, and cover a smaller portion of the country over the last century.”

Scientists: Natural Variability Dominates In Global-Scale Drought

Cook et al., 2015

“Megadroughts reconstructed over north-central Europe in the 11th and mid-15th centuries reinforce other evidence from North America and Asia that droughts were more severe, extensive, and prolonged over Northern Hemisphere land areas before the 20th century, with an inadequate understanding of their causes.”

Hoerling et al., 2010 

“In this study, the nature and causes for observed regional precipitation trends during 1977–2006 are diagnosed. It is found that major features of regional trends in annual precipitation during 1977–2006 are consistent with an atmospheric response to observed sea surface temperature (SST) variability. This includes drying over the eastern Pacific Ocean that extends into western portions of the Americas related to a cooling of eastern Pacific SSTs, and broad increases in rainfall over the tropical Eastern Hemisphere, including a Sahelian rainfall recovery and increased wetness over the Indo–West Pacific related to North Atlantic and Indo–West Pacific ocean warming. It is further determined that these relationships between SST and rainfall change are generally not symptomatic of human-induced emissions of greenhouse gases (GHGs) and aerosols.”

Sheffield et al., 2012

Little change in global drought over the past 60 years

“Here we show that the previously reported increase in global drought is overestimated because the PDSI uses a simplified model of potential evaporation that responds only to changes in temperature and thus responds incorrectly to global warming in recent decades. More realistic calculations, based on the underlying physical principles that take into account changes in available energy, humidity and wind speed, suggest that there has been little change in drought over the past 60 years.”

Cai et al., 2014

“Recent drought in 1993–2008 was still within the frame of natural climate variability based on the 306 yr PDSI reconstruction.    The dry and wet phases of Lingkong Mountain were in accordance with changes in the summer Asian-Pacific oscillation and sunspot numbers, they also showed strong similarity to other tree-ring based moisture indexes in large areas in and around the CLP, indicating the moisture variability in the CLP [Chinese Loess Plateau] was almost synchronous and closely related with large-scale land–ocean–atmospheric circulation and solar activity.”

McCabe and Wolock, 2015

“Monthly precipitation (P) and potential evapotranspiration (PET) from the CRUTS3.1 data set are used to compute monthly P minus PET (PMPE) for the land areas of the globe. The percent of the global land area with annual sums of PMPE less than zero are used as an index of global drought (%drought) for 1901 through 2009. Results indicate that for the past century %drought has not changed, even though global PET and temperature (T) have increased.”

Roderick and Farquhar, 2004

“Contrary to expectations, measurements of pan evaporation show decreases in many parts of the Northern Hemisphere over the last 50 years. When combined with rainfall measurements, these data show that much of the Northern Hemisphere’s terrestrial surface has become less arid over the last 50 years. However, whether the decrease in pan evaporation is a phenomenon limited to the Northern Hemisphere has until now been unknown because there have been no reports from the Southern Hemisphere. Here, we report a decrease in pan evaporation rate over the last 30 years across Australia of the same magnitude as the Northern Hemisphere trends (approximately −4 mm a−2). The results show that the terrestrial surface in Australia has, on average, become less arid over the recent past, just like much of the Northern Hemisphere.”

IPCC, 2007 (AR4):

“Warming the troposphere enhances the cooling rate, thereby increasing precipitation, but this may be partly offset by a decrease in the efficiency of radiative cooling due to an increase in atmospheric CO₂ (Allen and Ingram, 2002; Yang et al., 2003; Lambert et al., 2004; Sugi and Yoshimura, 2004). This suggests that global mean precipitation should respond more to changes in shortwave forcing than CO₂ forcing, since shortwave forcings, such as volcanic aerosol, alter the temperature of the troposphere without affecting the efficiency of radiative cooling. This is consistent with a simulated decrease in precipitation following large volcanic eruptions [which cause cooling] (Robock and Liu, 1994; Broccoli et al., 2003), and may explain why anthropogenic influence has not been detected in measurements of global land mean precipitation (Ziegler et al., 2003; Gillett et al., 2004b), although Lambert et al. (2004) urge caution in applying the energy budget argument to land-only data.”

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July 6, 2017 at 04:58AM