Paper finds droughts & floods due to natural variability, not man-made greenhouse gas

SSDD

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Nov 6, 2012
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In response to the barrage of recent posts by a certain member of this board, the vast majority of which reflect, and discuss nothing more than the output of computer models, I am going to post some recently published papers based on actual observation. The contrast is remarkable.

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This paper, recently published in the Journal of climate examined regional precipitation between 1979 and 2006 and found that the trends were related to the natural variability of sea surface temperatures, not a trace gas in the atmosphere.
 
Granny bought her a gas mask so the greenhouse gases don't get her...

Greenhouse gas levels rising at fastest rate since 1984
8 September 2014 ~ A surge in atmospheric CO2 saw levels of greenhouse gases reach record levels in 2013, according to new figures.
Concentrations of carbon dioxide in the atmosphere between 2012 and 2013 grew at their fastest rate since 1984. The World Meteorological Organisation (WMO) says that it highlights the need for a global climate treaty. But the UK's energy secretary Ed Davey said that any such agreement might not contain legally binding emissions cuts, as has been previously envisaged. The WMO's annual Greenhouse Gas Bulletin doesn't measure emissions from power station smokestacks but instead records how much of the warming gases remain in the atmosphere after the complex interactions that take place between the air, the land and the oceans.

_77461268_c0213150-sunset_at_11pm_in_antarctica-spl.jpg

Concentrations of CO2 in the atmosphere rose rapidly in 2013

About half of all emissions are taken up by the seas, trees and living things. According to the bulletin, the globally averaged amount of carbon dioxide in the atmosphere reached 396 parts per million (ppm) in 2013, an increase of almost 3ppm over the previous year. "The Greenhouse Gas Bulletin shows that, far from falling, the concentration of carbon dioxide in the atmosphere actually increased last year at the fastest rate for nearly 30 years," said Michel Jarraud, secretary general of the WMO. "We must reverse this trend by cutting emissions of CO2 and other greenhouse gases across the board," he said. "We are running out of time."

Atmospheric CO2 is now at 142% of the levels in 1750, before the start of the industrial revolution. However, global average temperatures have not risen in concert with the sustained growth in CO2, leading to many voices claiming that global warming has paused. "The climate system is not linear, it is not straightforward. It is not necessarily reflected in the temperature in the atmosphere, but if you look at the temperature profile in the ocean, the heat is going in the oceans," said Oksana Tarasova, chief of the atmospheric research division at the WM0O.

'More worrying'
 
Granny bought her a gas mask so the greenhouse gases don't get her...

Greenhouse gas levels rising at fastest rate since 1984
8 September 2014 ~ A surge in atmospheric CO2 saw levels of greenhouse gases reach record levels in 2013, according to new figures.
Concentrations of carbon dioxide in the atmosphere between 2012 and 2013 grew at their fastest rate since 1984. The World Meteorological Organisation (WMO) says that it highlights the need for a global climate treaty. But the UK's energy secretary Ed Davey said that any such agreement might not contain legally binding emissions cuts, as has been previously envisaged. The WMO's annual Greenhouse Gas Bulletin doesn't measure emissions from power station smokestacks but instead records how much of the warming gases remain in the atmosphere after the complex interactions that take place between the air, the land and the oceans.

_77461268_c0213150-sunset_at_11pm_in_antarctica-spl.jpg

Concentrations of CO2 in the atmosphere rose rapidly in 2013

About half of all emissions are taken up by the seas, trees and living things. According to the bulletin, the globally averaged amount of carbon dioxide in the atmosphere reached 396 parts per million (ppm) in 2013, an increase of almost 3ppm over the previous year. "The Greenhouse Gas Bulletin shows that, far from falling, the concentration of carbon dioxide in the atmosphere actually increased last year at the fastest rate for nearly 30 years," said Michel Jarraud, secretary general of the WMO. "We must reverse this trend by cutting emissions of CO2 and other greenhouse gases across the board," he said. "We are running out of time."

Atmospheric CO2 is now at 142% of the levels in 1750, before the start of the industrial revolution. However, global average temperatures have not risen in concert with the sustained growth in CO2, leading to many voices claiming that global warming has paused. "The climate system is not linear, it is not straightforward. It is not necessarily reflected in the temperature in the atmosphere, but if you look at the temperature profile in the ocean, the heat is going in the oceans," said Oksana Tarasova, chief of the atmospheric research division at the WM0O.

'More worrying'

The BBC mangled the CO2 increase since 1750.. Technically correct, but misleading. CO2 levels are 42% higher than were in 1750. That's a TOTAL of 142% of the 1750 level. That's an old statistician trick to get a bigger number without being called a liar..

Good thing Grannie's wearing a mask -- because what she's breathing out is 6 times more toxic than the CO2 level in our fresh air !!!!

Good for Granny. Good for us.. More MASKS !! And don't look at the USA for that increase. OUR CO2 footprint has shrunk to 1990's levels.
 
Abstract from the OP's article

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. The intensity of regional trends simulated in climate models using observed time variability in greenhouse gases, tropospheric sulfate aerosol, and solar and volcanic aerosol forcing are appreciably weaker than those observed and also weaker than those simulated in atmospheric models using only observed SST forcing. The pattern of rainfall trends occurring in response to such external radiative forcing also departs significantly from observations, especially a simulated increase in rainfall over the tropical Pacific and southeastern Australia that are opposite in sign to the actual drying in these areas.

Additional experiments illustrate that the discrepancy between observed and GHG-forced rainfall changes during 1977–2006 results mostly from the differences between observed and externally forced SST trends. Only weak rainfall sensitivity is found to occur in response to the uniform distribution of SST warming that is induced by GHG and aerosol forcing, whereas the particular pattern of the observed SST change that includes an increased SST contrast between the east Pacific and the Indian Ocean, and strong regional warming of the North Atlantic Ocean, was a key driver of regional rainfall trends. The results of this attribution study on the causes for 1977–2006 regional rainfall changes are used to discuss prediction challenges including the likelihood that recent rainfall trends might persist
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No one has been contending that AGW is responsible for the link between ENSO-driven SST trends and droughts in the American southwest. The claim has been that AGW is driving ENSO changes which are resulting in those drought conditions.

My participation in this thread has only been concerned with whether or not a drought is taking place. I have posted nothing about links with AGW. So I assume SSDD was talking about someone else in the OP.

I have no serious disagreement with the findings of this paper. I don't know how accurate it is to say that AGW only creates uniformly distributed SST warming. The subduction of large amounts of heated surface water into the deep ocean has not led to a uniform distribution of that heat energy in the depths or at the surface. But that's all above my paygrade. I'll let the scientists figure it out and let us know.
 
But yet you've repeatedly alledged exactly that. That droughts and storms are TODAY enhanced or caused by GWarming.. Just nailed you last week on a DENIAL where you STATED THAT in the same thread..

Did ya notice the OP is over a year old?
 
But yet you've repeatedly alledged exactly that. That droughts and storms are TODAY enhanced or caused by GWarming.. Just nailed you last week on a DENIAL where you STATED THAT in the same thread..

Did ya notice the OP is over a year old?
Seems like he's doin some double talkin, eh?
 
But yet you've repeatedly alledged exactly that. That droughts and storms are TODAY enhanced or caused by GWarming.. Just nailed you last week on a DENIAL where you STATED THAT in the same thread..

Did ya notice the OP is over a year old?


I had not noticed its age.

You did not understand my statement. Let me repeat. Or you could scroll back up and read it again.

Paraphrased rom my previous post
No one has been contending that AGW is responsible for the link between ENSO-driven SST trends and droughts in the American southwest. The claim has been that AGW is driving ENSO changes and it is those changes which are resulting in those drought conditions.

So, a link exists between ENSO affects climate changes that produce droughts and flooding in different regions. The link was not created or altered by rising CO2 or the resultant AGW. Rising temperatures (from greenhouse warming or other sources) affect ENSO cycles and amplitudes. They thus, via the existing link, affect the occurrence and duration of the resultant floods and droughts.
 
But yet you've repeatedly alledged exactly that. That droughts and storms are TODAY enhanced or caused by GWarming.. Just nailed you last week on a DENIAL where you STATED THAT in the same thread..

Did ya notice the OP is over a year old?


I had not noticed its age.

You did not understand my statement. Let me repeat. Or you could scroll back up and read it again.

Paraphrased rom my previous post
No one has been contending that AGW is responsible for the link between ENSO-driven SST trends and droughts in the American southwest. The claim has been that AGW is driving ENSO changes and it is those changes which are resulting in those drought conditions.

So, a link exists between ENSO affects climate changes that produce droughts and flooding in different regions. The link was not created or altered by rising CO2 or the resultant AGW. Rising temperatures (from greenhouse warming or other sources) affect ENSO cycles and amplitudes. They thus, via the existing link, affect the occurrence and duration of the resultant floods and droughts.

Nope.. No evidence that the 0.5degC change in Mean Global Temp in your lifetime is affecting floods and droughts. Natural cycles predominant. Otherwise -- you'd have to explain why the AMO has been CRUSHED in past years and Atlantic hurricanes have been virtually dormant. TEMPERATURE is one of nearly a dozen REQUIRED conditions for weather. Not sufficient to amplify weather by itself.
 
I, and several thousand atmospheric scientists, disagree.

Several thousand huh?? :lmao: Well go ask ONE of those several thousand what 0.5deg at the surface means to a SuperCell thunderstorm and get back to me. Chances of formation? Intensity of peak winds? Highest development height? Amount of hail? Formation of tornadoes?

You are full of shit.. NONE of that changes with JUST temperature alone. ESPECIALLY IF the warming is not JUST at the surface as in Global Warming heating..

Hansen showed his desperation and lack of humility with that one silly paper pushing temperature as a SUFFICIENT condition for extreme weather events. You notice that not a lot of real announcements coming in follow-up work on that farce. Probably heard those thousands of atmos scientists laughing behind his back..

In fact BullWink -- when's the last time you saw a scary exponential temperature projection come out in the press from your "consensus"? That's deader than the petrified forest son.. Your "thousands" have taken to hiding out and disguises for AT LEAST 2 years now..
 
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Meteorological drought in the Hadley Centre global climate model is assessed using the Palmer Drought Severity Index (PDSI), a commonly used drought index. At interannual time scales, for the majority of the land surface, the model captures the observed relationship between the El Niño–Southern Oscillation and regions of relative wetness and dryness represented by high and low values of the PDSI respectively. At decadal time scales, on a global basis, the model reproduces the observed drying trend (decreasing PDSI) since 1952. An optimal detection analysis shows that there is a significant influence of anthropogenic emissions of greenhouse gasses and sulphate aerosols in the production of this drying trend. On a regional basis, the specific regions of wetting and drying are not always accurately simulated. In this paper, present-day drought events are defined as continuous time periods where the PDSI is less than the 20th percentile of the PDSI distribution between 1952 and 1998 (i.e., on average 20% of the land surface is in drought at any one time). Overall, the model predicts slightly less frequent but longer events than are observed. Future projections of drought in the twenty-first century made using the Special Report on Emissions Scenarios (SRES) A2 emission scenario show regions of strong wetting and drying with a net overall global drying trend. For example, the proportion of the land surface in extreme drought is predicted to increase from 1% for the present day to 30% by the end of the twenty-first century.
 
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Global and regional trends in drought for 1950–2000 are analyzed using a soil moisture–based drought index over global terrestrial areas, excluding Greenland and Antarctica. The soil moisture fields are derived from a simulation of the terrestrial hydrologic cycle driven by a hybrid reanalysis–observation forcing dataset. Drought is described in terms of various statistics that summarize drought duration, intensity, and severity. There is an overall small wetting trend in global soil moisture, forced by increasing precipitation, which is weighted by positive soil moisture trends over the Western Hemisphere and especially in North America. Regional variation is nevertheless apparent, and significant drying over West Africa, as driven by decreasing Sahel precipitation, stands out. Elsewhere, Europe appears to have not experienced significant changes in soil moisture, a trait shared by Southeast and southern Asia. Trends in drought duration, intensity, and severity are predominantly decreasing, but statistically significant changes are limited in areal extent, of the order of 1.0%–7.0% globally, depending on the variable and drought threshold, and are generally less than 10% of continental areas. Concurrent changes in drought spatial extent are evident, with a global decreasing trend of between −0.021% and −0.035% yr−1. Regionally, drought spatial extent over Africa has increased and is dominated by large increases over West Africa. Northern and East Asia show positive trends, and central Asia and the Tibetan Plateau show decreasing trends. In South Asia all trends are insignificant. Drought extent over Australia has decreased. Over the Americas, trends are uniformly negative and mostly significant.

Within the long-term trends there are considerable interannual and decadal variations in soil moisture and drought characteristics for most regions, which impact the robustness of the trends. Analysis of detrended and smoothed soil moisture time series reveals that the leading modes of variability are associated with sea surface temperatures, primarily in the equatorial Pacific and secondarily in the North Atlantic. Despite the overall wetting trend there is a switch since the 1970s to a drying trend, globally and in many regions, especially in high northern latitudes. This is shown to be caused, in part, by concurrent increasing temperatures. Although drought is driven primarily by variability in precipitation, projected continuation of temperature increases during the twenty-first century indicate the potential for enhanced drought occurrence.
 
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A monthly dataset of Palmer Drought Severity Index (PDSI) from 1870 to 2002 is derived using historical precipitation and temperature data for global land areas on a 2.5° grid. Over Illinois, Mongolia, and parts of China and the former Soviet Union, where soil moisture data are available, the PDSI is significantly correlated (r = 0.5 to 0.7) with observed soil moisture content within the top 1-m depth during warm-season months. The strongest correlation is in late summer and autumn, and the weakest correlation is in spring, when snowmelt plays an important role. Basin-averaged annual PDSI covary closely (r = 0.6 to 0.8) with streamflow for seven of world's largest rivers and several smaller rivers examined. The results suggest that the PDSI is a good proxy of both surface moisture conditions and streamflow. An empirical orthogonal function (EOF) analysis of the PDSI reveals a fairly linear trend resulting from trends in precipitation and surface temperature and an El Niño– Southern Oscillation (ENSO)-induced mode of mostly interannual variations as the two leading patterns. The global very dry areas, defined as PDSI < −3.0, have more than doubled since the 1970s, with a large jump in the early 1980s due to an ENSO-induced precipitation decrease and a subsequent expansion primarily due to surface warming, while global very wet areas (PDSI > +3.0) declined slightly during the 1980s. Together, the global land areas in either very dry or very wet conditions have increased from ∼20% to 38% since 1972, with surface warming as the primary cause after the mid-1980s. These results provide observational evidence for the increasing risk of droughts as anthropogenic global warming progresses and produces both increased temperatures and increased drying.
 
Drought under global warming a review - Dai - 2010 - Wiley Interdisciplinary Reviews Climate Change - Wiley Online Library

This article reviews recent literature on drought of the last millennium, followed by an update on global aridity changes from 1950 to 2008. Projected future aridity is presented based on recent studies and our analysis of model simulations. Dry periods lasting for years to decades have occurred many times during the last millennium over, for example, North America, West Africa, and East Asia. These droughts were likely triggered by anomalous tropical sea surface temperatures (SSTs), with La Niña-like SST anomalies leading to drought in North America, and El-Niño-like SSTs causing drought in East China. Over Africa, the southward shift of the warmest SSTs in the Atlantic and warming in the Indian Ocean are responsible for the recent Sahel droughts. Local feedbacks may enhance and prolong drought. Global aridity has increased substantially since the 1970s due to recent drying over Africa, southern Europe, East and South Asia, and eastern Australia. Although El Niño-Southern Oscillation (ENSO), tropical Atlantic SSTs, and Asian monsoons have played a large role in the recent drying, recent warming has increased atmospheric moisture demand and likely altered atmospheric circulation patterns, both contributing to the drying. Climate models project increased aridity in the 21st century over most of Africa, southern Europe and the Middle East, most of the Americas, Australia, and Southeast Asia. Regions like the United States have avoided prolonged droughts during the last 50 years due to natural climate variations, but might see persistent droughts in the next 20–50 years. Future efforts to predict drought will depend on models' ability to predict tropical SSTs. WIREs Clim Change 2011 2 45–65 DOI: 10.1002/wcc.81
 

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