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Droughts:


SREX (Seneviratne et al., 2012) assessed that there was medium confidence that anthropogenic influence has contributed to some changes in the drought patterns observed in the second half of the 20th century based on attributed impact of anthropogenic forcing on precipitation and temperature changes, and that there was low confidence in the assessment of changes in drought at the level of single regions.

...

There is not enough evidence to support medium or high confidence of attribution of increasing trends to anthropogenic forcings as a result of observational uncertainties and variable results from region to region (Section 2.6.2.2). Combined with difficulties described above in distinguishing decadal scale variability in drought from long-term climate change we conclude consistent with SREX that there is low confidence in detection and attribution of changes in drought over global land areas since the mid-20th century.

Tropical cyclones:


There is low confidence in basin-scale projections of changes in intensity and frequency of tropical cyclones in all basins to the mid-21st century

On floods, the AR5 confirms the conclusions of the SREX report, which concluded:

there is limited to medium evidence available to assess climate-driven observed changes in the magnitude and frequency of floods at a regional scale because the available instrumental records of floods at gauge stations are limited in space and time, and because of confounding effects of changes in land use and engineering. Furthermore, there is low agreement in this evidence, and thus overall low confidence at the global scale regarding even the sign of these changes.
by Bjinse on Fri Oct 4th, 2013 at 12:09:24 PM EST
[ Parent ]
The above quote on tropical cyclones taken from AR5 was on projections. However, there is no divergence on regional or global analysis on tropical cyclones:


There is low confidence in long-term (centennial) changes in tropical cyclone activity, after accounting for past changes in observing capabilities.


Current datasets indicate no significant
observed trends in global tropical cyclone frequency over the past century and it remains uncertain whether any reported long-term increases in tropical cyclone frequency are robust, after accounting for past changes in observing capabilities (Knutson et al., 2010).
by Bjinse on Fri Oct 4th, 2013 at 01:56:07 PM EST
[ Parent ]
You underline, for cyclones, the question of frequency, while sidestepping the stated clear evidence on intensity :
However over the satellite era, increases in the intensity of the strongest storms in the Atlantic appear robust (Kossin et al., 2007; Elsner et al., 2008) but there is limited evidence for other regions and the globe.

 (Obviously, there is a time lag: AR5 cannot take into account the devastating cyclones hitting Asia in the last couple of years. It would be surprising if a trend were not noted in the next round.

It is rightly acknowledged that people of faith have no monopoly of virtue - Queen Elizabeth II
by eurogreen on Sun Oct 6th, 2013 at 07:16:33 AM EST
[ Parent ]
My diary noted the observed intensity in hurricanes for the Atlantic basin since 1970s, so I fail to see where I would 'sidestep'.

Considering the subject of hurricane intensity, the following remark from the AR5 should suffice:

Time series of cyclone indices such as power dissipation, an aggregate compound of tropical cyclone frequency, duration, and intensity that measures total wind energy by tropical cyclones, show upward trends in the North Atlantic and weaker upward trends in the western North Pacific since the late 1970s (Emanuel, 2007), but interpretation of longer-term trends is again constrained by data quality
concerns (Landsea et al., 2011).

...

In summary, this assessment does not revise the SREX conclusion of low confidence that any reported longterm (centennial) increases in tropical cyclone activity are robust, after accounting for past changes in observing capabilities.

SREX's conclusion :


Based on research subsequent to the AR4 and Kunkel et al. (2008), which further elucidated the scope of uncertainties in the historical tropical cyclone data, the most recent assessment by the World Meteorological Organization (WMO) Expert Team on Climate Change Impacts on Tropical Cyclones (Knutson et al., 2010) concluded that it remains uncertain whether past changes in any tropical cyclone activity (frequency, intensity, rainfall) exceed the variability expected through natural causes, after accounting for changes over time in observing capabilities. The present assessment regarding observed trends in tropical cyclone activity is essentially identical to the WMO assessment (Knutson et al., 2010): there is low confidence that any observed long-term (i.e., 40 years or more) increases in tropical cyclone activity are robust, after accounting for past changes in observing capabilities.

I'm well aware that projections possibly suggest an increase of the number of the strongest hurricanes for some basins - but there is no strong consensus on this either (see chapter 14 of the AR5 or SREX).

by Bjinse on Sun Oct 6th, 2013 at 09:10:58 AM EST
[ Parent ]
I wish I could conclude, as you apparently do, that the AR5 allows us to stop worrying about the climate...

You acknowledge the climate disruptions (changes in precipitation, rising temperatures etc, you seem unconcerned about sea level...) but you conclude that these are not a major worry, because lack of data and confounding factors don't yet point to clear causality to catastrophic weather events.

I'm happy for you, I guess.

I'm being hit repeatedly over the head with a sledgehammer, but it's OK, because the medical tests don't give conclusive proof of brain damage yet.

It is rightly acknowledged that people of faith have no monopoly of virtue - Queen Elizabeth II

by eurogreen on Sun Oct 6th, 2013 at 07:15:53 AM EST
[ Parent ]
as you apparently do, that the AR5 allows us to stop worrying about the climate...

you seem unconcerned about sea level...)

you conclude that these are not a major worry, because lack of data and confounding factors don't yet point to clear causality to catastrophic weather events.

All false.

I suggest, again, that you contest me on what I write, not on what you think I 'apparently' write.

by Bjinse on Sun Oct 6th, 2013 at 09:33:27 AM EST
[ Parent ]
With the AR5 the scientific ground for alarmism has noticeably shrunk - although there's plenty left for political activists on other topics.

I'm open to suggestions that I should start worrying more about economic collapse.

So you seem to find that the AR5 gives you reason to worry less about climate change.
(Or where you being ironic?)

For example : you seem to be equating absence of evidence (or inconclusive evidence) with evidence of absence. Because there is not a clear worldwide trend to increased drought, or increased flooding, you conclude we should worry less.

But I wonder why you think the absence of clearly measurable worldwide trends demonstrates anything at all : this smells like a strawman. I don't know anyone who has claimed that "global warming will cause worldwide drought", or "global warming will cause worldwide flooding". On the contrary, global warning is expected to cause disruptive climate change in every region.  Intuitively, I would expect that overall warming would increase both floods and drought; but I wouldn't be surprised if, for example, increased flooding in certain regions coincided with decreases in other regions. And I expect that various regions are experiencing disruptive climate change which is currently poorly measured, or which is measured but lacks a history of measurements to detect trends.

As we have previously discussed with respect to flooding, various confounders such as land use changes make trends difficult to prove, even in areas where relatively good records exist. These also tend to be the wealthier regions, which are better at mitigating the effects anyway. As an anecdotal example : a decade-long drought in Texas hardly causes a blip in economic output; a third world nation which experienced something similar might experience collapse of subsistence food production, mass starvation and failure of institutions.

So, I will certainly be interested in discussing the regional analyses when they are released. Perhaps they will trouble your Panglossian calm.

On the other hand, I have no objection to you worrying more about economic collapse (one can never worry too much!)

It is rightly acknowledged that people of faith have no monopoly of virtue - Queen Elizabeth II

by eurogreen on Sun Oct 6th, 2013 at 02:02:53 PM EST
[ Parent ]
So you seem to find that the AR5 gives you reason to worry less about climate change.

you seem to be equating absence of evidence (or inconclusive evidence) with evidence of absence.

Still false.

I observe that 'the scientific ground for alarmism has noticeably shrunk' for climate extremes and abrupt climate scenario's, which I think the IPCC reports demonstrate. If this reading is incorrect, then I welcome to hear about that.

I appreciate your passion on this subject, and your attention for detail, which also affects my writing, turning more and more science orientated, and thus more emotionally detached.

I live in the Netherlands. If I were 'Panglossian calm' (nice!) about climate change, of course I would not be writing about it.

by Bjinse on Mon Oct 7th, 2013 at 06:04:33 AM EST
[ Parent ]

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