Is there any credible scientific evidence that droughts and floods have increased in the last 50 years?
No alarmist gibberish, please provide links. Peer reviewed journal articles preferred.
Update 1: Dook: I must say I am impressed by your answer- peer reviewed articles and an admission that the evidence is, as you say, tentative.
I wonder what effect destroying watersheds by clear cutting forests has, paving over hundreds of square miles of grassland, and building in flood plains.
Update 2: Apparently there is considerable debate over droughts and floods, just like there is debate over the MWP and even whether or not the temperature has risen in the last ten years. We really don't know what's happening today but we know for sure what is will happen in 50 years. Thank you all for proving my point.
- Hey DookLv 76 years agoFavorite Answer
It is indeed advisable to disregard alarmist conspiracy theory claptrap about hundreds of Nobel Prize winning scientists being part of a century-long Marxist / environmentalist hoax (see National Academy of Sciences summaries below).
The scientific evidence on AGW and droughts and floods is still tentative because the noise-to-signal ratio is high. IPCC has focused lately on paleoclimate reconstructions (to better establish what natural variation might be expected absent human influences). The evidence so far suggests an increasing trend (more and more records broken). A different issue, but: climate models fairly consistently indicate much greater increases in both frequency and severity of extreme weather in the future.
Peer reviewed publications include:
P. Berg, C. Moseley, and J.O. Haerter, "Strong increase in convective precipitation in response to higher temperatures", Nature Geosci, vol. 6, (2013) pp. 181-185, 2013.
D. Coumou, and S. Rahmstorf, "A decade of weather extremes", Nature Climate change (2012)
Ingo Richter and Shang-Ping Xie “Muted precipitation increase in global warming simulations: A surface evaporation perspective.” Journal of Geophysical Research published online: 31 DEC 2008.
Mantua, N.J.: "La Niña impacts on the Pacific Northwest," in La Niña and its impacts: facts and speculation, 102-114, edited by Michael Glantz. Tokyo, Japan (2002).
RE NAS (U.S. National Academy of Sciences, 2010):
“Climate change is occurring, is caused largely by human activities, and poses significant risks for a broad range of human and natural systems.”
“Choices made now about carbon dioxide emissions reductions will affect climate change impacts experienced not just over the next few decades but also in coming centuries and millennia…Because CO2 in the atmosphere is long lived, it can effectively lock the Earth and future generations into a range of impacts, some of which could become very severe.”
“The Academy membership is composed of approximately 2,100 members and 380 foreign associates, of whom nearly 200 have won Nobel Prizes.
Members and foreign associates of the Academy are elected in recognition of their distinguished and continuing achievements in original research; election to the Academy is considered one of the highest honors that can be accorded a scientist or engineer.”
Edit to science denier Raisin Cain: "My evidence" is NOT climate models. Which part "A DIFFERENT ISSUE" (above) did you not understand?
- SagebrushLv 76 years ago
Quote by Will Happer, Princeton University physicist, former Director of Energy Research at the Department of Energy: “I had the privilege of being fired by Al Gore, since I refused to go along with his alarmism....I have spent a long research career studying physics that is closely related to the greenhouse effect....Fears about man-made global warming are unwarranted and are not based on good science. The earth's climate is changing now, as it always has. There is no evidence that the changes differ in any qualitative way from those of the past.”
I think I will stick with Happer.
- Ottawa MikeLv 66 years ago
Apparently not according to the most recent IPCC report:
“In summary, there continues to be a lack of evidence and thus low confidence regarding the sign of trend in the magnitude and/or frequency of floods on a global scale”
"In summary, the current assessment concludes that there is not enough evidence at present to suggest more than low confidence in a global-scale observed trend in drought or dryness (lack of rainfall) since the middle of the 20th century due to lack of direct observations, geographical inconsistencies in the trends, and dependencies of inferred trends on the index choice. Based on updated studies, AR4 conclusions regarding global increasing trends in drought since the 1970s were probably overstated." http://www.ipcc.ch/report/ar5/wg1/
- Anonymous6 years ago
This is an interesting study. It makes it obvious that their current measurements are not sufficient for this determination. Note that this study suggests that the PDSI is not an accurate measurement. One thing to also note is their discussion.
"In particular, calculations of the Palmer Drought Severity Index (PDSI) show a decrease in moisture globally since the 1970s with a commensurate increase in the area in drought that is attributed, in part, to global warming"
Note that this measurement is discussing an overall decrease in moisture globally. Clearly this creates a problem in looking at the "extremes" increasing by sheer virtue of what they are calculating. If one were to say that the droughts AND floods are increasing, then using if this measure indicated an increase in droughts, it would inherently be used to prove a DECREASE in floods. In other words, the measure could never be used to show BOTH an increase in flooding and an increase in droughts. And this article seems to indicate that the measure used is not sufficient for showing either.
It seems clear to me that we are either not collecting the data necessary to make this determination OR we have not been collecting the data long enough to make any long-term claims.
Rememebr that droughts and floods are one of the MAIN arguments of the catastrophic nature of AGW. In fact, it is the only one that would lead to worldwide concern. Consider. The rise in the ocean level is slow enough to ensure that the people are not really in danger with even a moderate amount of precauions. The hurricanes and such relatively cause little loss of life. The only ReAL concern is the ability to feed ourselves. Lack of food on a large scale would cause massive deaths. Lack of food comes from increases in droughts and/or flooding to the point of affecting large sections of farmland.
Recognize, when I say hurricanes cause relative little loss of life, we must recognize that we are talking about AGW measures that will cost in the trillions. The assinine principle of being worth a trillion if it saves one person is STUPID. That money being spent is being redirected from something else. In order to justify trillions spent you need to show either more money saved OR loss of life in the millions, because a million dollars spent towards other means can certainly save more than one life.
So your evidence is climate models? LOL. Do you want to discuss these climate models.
You have climate models to model the paleoclimate data and determine temperature, CO2 content etc. of the distant past. You have lciamte model to determine the current temperature and the temperature of the more recent past. You ahve cliamte model to determine the climate sensitivity based upopn the result of the paleoclimate models. You have climate models to determine the future predicted temperatures based upon the results of the cliamte modesl previously discussed. Then to get to the climate models you are talking about, you have climate mdoels using the results of the temp predictions to determine other climate affects like floods and droughts.
So you have models of models of models of models. ALL of this is without having evidence of increases in drought or floods over the past 50 years. And YOUR CASE is that it is advisable to mock those who are skeptical of these models of models of models of models.
Sure, why not. I just made a model showing that the heat is hiding in chinese rice. Afterall, the price of rice in China has been increasing. This is a model, not a model of a model of a model of a model. Do you accept that the missing heat is hiding in Chinese rice or do you hate science???
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- Jeff MLv 76 years ago
The number of droughts is similar. The extremes of droughts are increasing.
The following is an excerpt from the paper above regarding the paper posted by Raisin Caine
"Two recent papers looked at the question of whether large-scale drought has been increasing under climate change. A study in Nature by Sheffield et al.20 entitled ‘Little change in global drought over the past 60 years’ was published at almost the same time that ‘Increasing drought under global warming in observations and models’ by Dai5 appeared in Nature Climate Change (published online in August 2012). How can two research groups arrive at such seemingly contradictory conclusions?"
The following is the full paper Raisin Caine posted: http://www.environmentportal.in/files/file/global%...
The following is the full paper spoken of in the quote above: http://storm.colorado.edu//~whan/ATOC4800_5000/Mat...
There are other papers dealing with the occurrence of drought as well.
This paper states that there has been no change in the occurrence of drought in the northern hemisphere while the southern hemisphere has undergone a drying trend. It goes on to state that parts of the northern hemisphere have undergone significant drying, though. From what I have read the areas mentioned are consistent with a warming atmosphere.
Global trends and patterns of drought from space (Damberg, 2013):- http://amir.eng.uci.edu/publications/13_Drought_Tr...
Characteristics and trends in various forms of the Palmer Drought Severity Index during 1900–2008 (Dai, 2011) - http://onlinelibrary.wiley.com/doi/10.1029/2010JD0...
A Global Dataset of Palmer Drought Severity Index for 1870–2002: Relationship with
Soil Moisture and Effects of Surface Warming (Dai et al, 2004) - http://www.cgd.ucar.edu/cas/adai/papers/Dai_pdsi_p...
Basically, there are different versions of the PDSI. There are some flaws in it that have attempted to be fixed with each subsequent release. Note that one of the papers I provided above, from 2013, takes measurements from satellite not from models. These show, as stated, that drought has not changed in one of the hemisphere but increased drying has occurred in areas that are expected to dry in a warming environment.
Raisin Caines statements concerning how hurricanes have caused little loss of life is a non-argument. Hurricanes not only cause loss of life, they also cause storm surges, economic damage, and so on. These more intense storm surges have caused people to be forcibly migrated. They have cost economic loss to affected countries and decreases in fresh water supplies.
Access to clean drinking water is a problem in areas such as Tuvalu, Kiribati and other low lying islands. This is why the governance of these some of these island nations give credits to people that install composting toilets. The following is the IPCC AR4 report on small islands.
These nations will be the ones most affected by rising seas, increased storm surges, and so on.
- Anonymous6 years ago
I don't have any specific data about droughts, but cloud cover is decreasing.
- rrLv 46 years ago
i dont think so