Climate Change - General Discussion : Read the Mod Note in post #1 before posting

Akrasia

Gaoth Laidir wrote: »

Look up the definition of accelerating. It's the derivative of speed or rate. It means the rate/slope is getting faster, or in other words, a curve's slope is increasing with time (curving downwards in the case of mass-loss). A straight line curve (such as the mass-balance curve I posted) has a constant rate and hence has zero acceleration.

I know what accelerating means, and so do the authors of those papers I cited

But by having the baseline shifted half a degree upwards by mid-century, agw already had a headstart on where it otherwise would have been without the solar heating. We would have been half a degree cooler today relative to "pre-industrial" levels (whatever that is), given the feedback effect.

There's two sides to the natural variability balance sheet. The last few decades have been in a cooling phase, but global temperatures have still risen.

Disastrous. Catastrophic. It's words like these that make the agw argument laughable at times. We're just going to have to agree to disagree on perception of risk.

Disastrous is a perfectly apt word to use to describe a scenario with more frequent natural disasters. Catastrophic is defined as "adjective
involving or causing sudden great damage or suffering"

Akrasia

Because most of the papers are hidden behind pay walls and we can only read the abstract, here's a video of a lecture given at Brown university which gives a recent overview of the state of greenland ice loss.

She says at the start that there has been an increase in the rate of mass loss at greenland and this started around 1992.

If you actually care about the science, it's worth a watch.

Gaoth Laidir

Akrasia wrote: »

I know what accelerating means, and so do the authors of those papers I cited



There's two sides to the natural variability balance sheet. The last few decades have been in a cooling phase, but global temperatures have still risen.

Disastrous is a perfectly apt word to use to describe a scenario with more frequent natural disasters. Catastrophic is defined as "adjective
involving or causing sudden great damage or suffering"

- Show me where the rate of loss has been increasing since 2002 in the chart I posted above, but more particularly in the last decade. Do that and I'll drop this point.

- So you're dismissing the fact that when the agw started to become less insignificant mid-century, the higher baseline already established by then made us higher now than we would have been without it.

- Sudden great damage? I thought this was gradual, something we can expect to see in the next decades/centuries?

Akrasia

Gaoth Laidir wrote: »

- Show me where the rate of loss has been increasing since 2002 in the chart I posted above, but more particularly in the last decade. Do that and I'll drop this point.

Here's a graphic from science magazine that explains it better. Data based on a paper published in Nature in Dec 2015



http://www.sciencemag.org/news/2017/02/great-greenland-meltdown

- So you're dismissing the fact that when the agw started to become less insignificant mid-century, the higher baseline already established by then made us higher now than we would have been without it.

I'm not dismissing it, I'm saying that it balances out over time with natural variability. Global warming in recent decades has been masked by a cooling natural cycle. You're the one who is talking about natural warming in the first few decades of the 20th century but ignoring natural cooling over the past few decades.

- Sudden great damage? I thought this was gradual, something we can expect to see in the next decades/centuries?

The warming is cumulative but its effects can be sudden. Extreme weather events are infrequent, but when the 10 year storm happens, every decade that passes that storm happens on top of a higher sea, where there is more water in the atmosphere and more energy in the wind.

People can adapt to changing climate if it happens gradually, but more extreme weather events do enormous amounts of damage that can take years to recover from. A few extra percent at the the top of an extreme event can push flood water over flood defences and tear down structures that have stood in previous storms.

Gaoth Laidir

Akrasia wrote: »

Here's a graphic from science magazine that explains it better. Data based on a paper published in Nature in Dec 2015



http://www.sciencemag.org/news/2017/02/great-greenland-meltdown

I'm not dismissing it, I'm saying that it balances out over time with natural variability. Global warming in recent decades has been masked by a cooling natural cycle. You're the one who is talking about natural warming in the first few decades of the 20th century but ignoring natural cooling over the past few decades.

The warming is cumulative but its effects can be sudden. Extreme weather events are infrequent, but when the 10 year storm happens, every decade that passes that storm happens on top of a higher sea, where there is more water in the atmosphere and more energy in the wind.

People can adapt to changing climate if it happens gradually, but more extreme weather events do enormous amounts of damage that can take years to recover from. A few extra percent at the the top of an extreme event can push flood water over flood defences and tear down structures that have stood in previous storms.

- No, you're still not getting it. The graph you posted shows a slight upward turn in 2002, exactly when the GRACE program started. A new type of dataset, so it was not a seamless transition. However, even that line is straight, and when you look at just that dataset (I've posted it below again to help you) you can see no further acceleration during this time, and that doesn't even include the full 2017 data, which had much less loss.



- If it balances out over time then what would have happened with the natural exit from the Maunder Minimum/Little Ice Age (ignore ghc for a second)? Would we still be back in the dark ages 250 years ago or would we have been warmer today? You're saying that these cold centuries would have continued on for ever? Yes, ghc have changed things, but its starting position had already been shifted upwards.

- Your idea of sudden seems to be different to mine.

Akrasia

If your definition of a trend can be skewed by a single half a year worth of data then you're clearly using much too short of a sample to draw conclusions.

here's a graph from Hansen's 2016 paper that shows what I'm talking about.

Regarding natural variability, oscillations more or less balance each other out. Long term trends are different but we're not talking about these timescales here, we're talking about multi-decadal variations and oscillations.

Anyway, your suggestion that all of the warming pre 1940 was natural isn't correct either. The majority can be explained by a warmer sun and reduced volcanic activity, but there was still a significant contribution from human GHGs, so it's wrong to discount all of the early 20th century warming. On the other hand, more than 100% of the late 20th century and early 21st century warming can be attributed to anthroprogenic factors because there would have been a naturally cooling trend due to a cooler sun and increased volcanic activity.

And onto your definition of sudden, on a geological timescale all of this climate change is sudden. It's rapid change on geological timescales. Storms on the scale of Maria and Irma and Harvey etc that do additional damage because of increased precipitation and a higher storm surge count as sudden catestrophic events as far as I'm concerned. Then we have the risk of sudden changes to Monsoon patterns associated with climate change. A change that could cause immense suffering for hundreds of millions of people.

And then there are the risks of abrupt climate change which we have mounting evidence for where we can have rapid changes on the scale of a few years. A lot of your assumptions are based on linear changes along whatever trend you have identified, but there is no reason to assume that the changes will be linear all of the time. This is from a very recent paper in Nature

The climate and ecosystems usually respond rather linearly to changes in external conditions. However, there are also occasions when at some point a sudden and large shift to a very different state occurs. An important cause of such behavior can be a positive feedback which leads to a self-amplifying change, making the system very sensitive to external conditions. Such feedback-induced threshold behavior is often referred to as a tipping point1. If the feedback is very strong, alternative stable states can exist under the same external conditions (Fig. 1a). In models, the parameter values at which the system’s dynamics suddenly changes are called bifurcation points. For example, when the system is driven over a bifurcation point where a current equilibrium ceases to exist, an abrupt and irreversible shift toward a different equilibrium can occur......
https://www.nature.com/articles/s41598-018-23377-4

In the case of tipping points, we do not have anywhere near enough information to be able to predict when abrupt changes could occur in important planetary systems. We do know that they have happened in the past, but cannot say with certainty what conditions need to exist to cause them in the future. Uncertainty is not our friend here. The changes we are already making to the biosphere are on a huge scale and the complex interactions between natural systems can create instability that could push important climactic systems into a new state.

Akrasia

Just for interest, the GRACE FO satellites are due to be launched on a Falcon 9 rocket in 2 days time.
They're the first Satellites to have laser interferometers built in to allow them to measure their distance and angle from each other to improve their accuracy and resolution (satellite drift has been an issue with other RSS projects)

Fingers crossed that they get them there safely.

Gaoth Laidir

Akrasia wrote: »

If your definition of a trend can be skewed by a single half a year worth of data then you're clearly using much too short of a sample to draw conclusions.

here's a graph from Hansen's 2016 paper that shows what I'm talking about.

Regarding natural variability, oscillations more or less balance each other out. Long term trends are different but we're not talking about these timescales here, we're talking about multi-decadal variations and oscillations.

Anyway, your suggestion that all of the warming pre 1940 was natural isn't correct either. The majority can be explained by a warmer sun and reduced volcanic activity, but there was still a significant contribution from human GHGs, so it's wrong to discount all of the early 20th century warming. On the other hand, more than 100% of the late 20th century and early 21st century warming can be attributed to anthroprogenic factors because there would have been a naturally cooling trend due to a cooler sun and increased volcanic activity.

And onto your definition of sudden, on a geological timescale all of this climate change is sudden. It's rapid change on geological timescales. Storms on the scale of Maria and Irma and Harvey etc that do additional damage because of increased precipitation and a higher storm surge count as sudden catestrophic events as far as I'm concerned. Then we have the risk of sudden changes to Monsoon patterns associated with climate change. A change that could cause immense suffering for hundreds of millions of people.

And then there are the risks of abrupt climate change which we have mounting evidence for where we can have rapid changes on the scale of a few years. A lot of your assumptions are based on linear changes along whatever trend you have identified, but there is no reason to assume that the changes will be linear all of the time. This is from a very recent paper in Nature

In the case of tipping points, we do not have anywhere near enough information to be able to predict when abrupt changes could occur in important planetary systems. We do know that they have happened in the past, but cannot say with certainty what conditions need to exist to cause them in the future. Uncertainty is not our friend here. The changes we are already making to the biosphere are on a huge scale and the complex interactions between natural systems can create instability that could push important climactic systems into a new state.

- I'm not using a half a year's data so stop making up more lies. I said look at the whole dataset from 2002, and especially the last decade. Again you only showed up to 2015. Overall, there is no runaway steepening of the curve.

- Significant contribution from ghc pre-1940? Again it depends on your definition of significant. I find it amazing that you can attribute such a sizeable proportion of early warming to such a tiny increase in ghc by then.

- Sudden as in the word catastrophic. You again include the big 3 hurricanes as if they're a direct result of agw, but we've been over this before and you're not going to change so no point repeating myself. You seem to want to stick with the hyperbole side of things and that's fine.

Akrasia

Gaoth Laidir wrote: »

- I'm not using a half a year's data so stop making up more lies. I said look at the whole dataset from 2002, and especially the last decade. Again you only showed up to 2015. Overall, there is no runaway steepening of the curve.

Before calling me a liar, try reading what I said. The whole dataset from 2002 showed a deepening curve but with a flattening from 2013 to 2017.

I showed up to 2015 because that happens to be the most recent analysis I could find that had a graph that I could use for illustration.
1 and a half years do not make a trend Gaoth. On one breath you call me a liar for suggesting that a half a year shouldn't be enough to significantly affect an established trend, on the next, you complain that my data ended a year and a half earlier than yours.

- Significant contribution from ghc pre-1940? Again it depends on your definition of significant. I find it amazing that you can attribute such a sizeable proportion of early warming to such a tiny increase in ghc by then.

The increase in temperatures before 1940 averaged as about .13c a decade.

Models have shown between .1 and .15c of the warming prior to 1940 was due to GHGs. This is the minority, but still a significant amount. I've attached an image from
a paper showing that the natural forcings in no way account for the observed warming over the 20th century. If it was just solar, we would be at about the same today as we were in 1880, if we include natural aerosols (volcanoes) this would have driven down global temperatures slightly, Sulphate particles would have cooled the planet by .3c. When GHGs are added in, we get the observed warming
https://journals.ametsoc.org/doi/full/10.1175/1520-0442%282004%29017%3C3721%3ACONAAF%3E2.0.CO%3B2

- Sudden as in the word catastrophic. You again include the big 3 hurricanes as if they're a direct result of agw, but we've been over this before and you're not going to change so no point repeating myself. You seem to want to stick with the hyperbole side of things and that's fine.

Even if those hurricanes were purely natural events completely unaffected by any of the increases in global average temperatures, they're a sign of what is to come if we continue to increase GHGs
None of this is hyperbole. If storms as bad as harvey, irma etc are this bad without any global warming component which is what you assert, then how is it hyperbole to say things will get worse if global warming isn't tackled, given that most scientists predict while storm frequency may not change, storm intensity will increase in a warmer world.

Meteorite58

Mod Note: Need to cut out the personal attacks.

Give other posters the respect you would want shown to you.

There is an unnecessary air of hostility in this thread from sniping and goading posts.

Different opinions can be stated without making it personal or for the purpose of point scoring.

Gaoth Laidir

Akrasia wrote: »

Before calling me a liar, try reading what I said. The whole dataset from 2002 showed a deepening curve but with a flattening from 2013 to 2017.

Thanks you. As I said, it's not accelerating, rather decelerating. As I was saying all along.

I showed up to 2015 because that happens to be the most recent analysis I could find that had a graph that I could use for illustration.
1 and a half years do not make a trend Gaoth. On one breath you call me a liar for suggesting that a half a year shouldn't be enough to significantly affect an established trend, on the next, you complain that my data ended a year and a half earlier than yours.

My point was merely that the extra 2 years would have contributed slightly to flattening the recent trend even more.

Models have shown between .1 and .15c of the warming prior to 1940 was due to GHGs. This is the minority, but still a significant amount. I've attached an image from
a paper showing that the natural forcings in no way account for the observed warming over the 20th century. If it was just solar, we would be at about the same today as we were in 1880, if we include natural aerosols (volcanoes) this would have driven down global temperatures slightly, Sulphate particles would have cooled the planet by .3c. When GHGs are added in, we get the observed warming
https://journals.ametsoc.org/doi/full/10.1175/1520-0442%282004%29017%3C3721%3ACONAAF%3E2.0.CO%3B2




Even if those hurricanes were purely natural events completely unaffected by any of the increases in global average temperatures, they're a sign of what is to come if we continue to increase GHGs
None of this is hyperbole. If storms as bad as harvey, irma etc are this bad without any global warming component which is what you assert, then how is it hyperbole to say things will get worse if global warming isn't tackled, given that most scientists predict while storm frequency may not change, storm intensity will increase in a warmer world.

And I've shown a paper from one of the foremost NHC forecasters, Landsea, that the number of major hurricanes is actually going down, not up. You said you were going off to read it. Any luck?

Akrasia

Gaoth Laidir wrote: »

Thanks you. As I said, it's not accelerating, rather decelerating. As I was saying all along.

Ok, so you are basing your 'trend' on the last 4 years. I prefer to use more considered analysis than just which direction the last bit of the graph is pointing, especially considering the non linear nature of these things.

My point was merely that the extra 2 years would have contributed slightly to flattening the recent trend even more.

your 'recent trend' was 2 years, now it's 4 years. look at the graphs, there are many places where there have been 3 or 4 years of slower declines followed by another spike.
Look, it may well be that the ice loss acceleration will stop when we have enough data to analyse the trend, but as it stands, the best analysis we have is that over the past 30 years, ice loss has been accelerating.

And I've shown a paper from one of the foremost NHC forecasters, Landsea, that the number of major hurricanes is actually going down, not up. You said you were going off to read it. Any luck?

his 2015 paper suggests that the number of storms have gone down and so have average energy per season. His analysis was based on there not being a rise in storm intensity during the 10 years since his previous paper in and since Webster et Al 2005.
His analysis is based on hurricane seasons up to 2014/2015 and it was also at a time when there was the so called 'hiatus' in global warming where temperatures had temporarily stabalised during a natural cooling phase. Since 2014/2015 hurricane season, global warming has surged forwards again and so have hurricane activity. The lead author of that study Landsea study Philip J. Klotzbach wrote a paper discussing the record breaking 2015 Pacific hurricane season and he said that the warmer ssts contributed to that hurricane activity and ascribed it to El Nino.


Then in 2016 there was another above average hurricane season and 2017 saw a hugely active hurricane season which was during a La Nina event (can't blame el nino for this one)
If we look at the hottest years on record, and look at the Atlantic hurricane season we can see what the pattern is. All data is taken from wikipedia.

2016 - Above average season, 7 hurricanes 4 major hurricanes
2015 - Below average Atlantic 4 hurricanes, 2 major
2017 - extremely active hurricane season 10 hurricanes, 6 major
- hurricanes, record breaking ACE
2014 - Below average 6 hurricanes, 2 Major
2010 - Very active hurricane season 19 tropical storms, 12 hurricanes
2013 - well below average 2 hurricanes, no majors
2005 - Most active hurricane in history 15 hurricanes, 7 Major hurricanes
2009 - below average - 3 hurricanes, 2 Major
1998 - very damaging hurricane season, 10 hurricanes, 3 majors
2007 -Above average - 6 hurricanes, 2 majors

So, in the ten hottest years on record, we have 6 above average, and 4 below average, but of the 6 above average years, 4 of them were very significant historic hurricane seasons including the some of the most damaging storms ever recorded in the atlantic basin.

We can do similar lists with the other hurricane basins if you like. Here's the pacific basin

2016 - Above average season, 13 hurricanes, 6 Majors
2015 - Extremely active hurricane season, 16 hurricanes, 11 majors (record breaking), 2nd strongest hurricane on record
2017 - moderatively active - 9 hurricanes, 4 major
2014 - Exceptionally active hurricane season 16 hurricanes 9 majors
2010 - record low activity, 3 hurricanes, 2 majors
2013 - above average, 9 hurricanes, 1 major, most destructive hurricane on record for the pacific due to exceptional flooding
2005 - below average - 7 hurricanes 2 major
2009 - very active 8 hurricanes, 5 majors, 3rd strongest hurricane on record for that basin
1998 - below average - 9 hurricanes, 6 major
2007 -blow average 4 hurricanes 1 major

Same again here, 6 above average, 4 below average and including some record breaking activity and devastating storms.

What this indicates is that hotter global temperatures don't guarantee more hurricanes, but when they do form, they are more likely to be very damaging.

dense

Akrasia wrote: »

His analysis is based on hurricane seasons up to 2014/2015 and it was also at a time when there was the so called 'hiatus' in global warming where temperatures had temporarily stabalised during a natural cooling phase.

The hiatus is the gift that keeps on giving!



According to a study by NOAA scientists, the temperatures didn't stabilise, they were just cleverly evading detection in the ocean for years.
They then decided that the method of recording them was unsatisfactory, which conveniently provided them with an excuse to adjust them upwards in order to claim that the hiatus that the UNIPCC had acknowledged, never happened.



https://eos.org/articles/global-warming-hiatus-never-happened-study-says



The latest news from NASA is that the decision to remotely sense sea levels by satellites in space is paying off and shows a solid increase in sea level rise that blows away even the adjusted un-AGW-cooperative local sea level gauge data, which is surely good news for the Mayor of Tuvalu.







https://mobile.twitter.com/ClimateOfGavin/status/997930450793455617/photo/1

Gaoth Laidir

Akrasia wrote: »

Ok, so you are basing your 'trend' on the last 4 years. I prefer to use more considered analysis than just which direction the last bit of the graph is pointing, especially considering the non linear nature of these things.




your 'recent trend' was 2 years, now it's 4 years. look at the graphs, there are many places where there have been 3 or 4 years of slower declines followed by another spike.
Look, it may well be that the ice loss acceleration will stop when we have enough data to analyse the trend, but as it stands, the best analysis we have is that over the past 30 years, ice loss has been accelerating.


his 2015 paper suggests that the number of storms have gone down and so have average energy per season. His analysis was based on there not being a rise in storm intensity during the 10 years since his previous paper in and since Webster et Al 2005.
His analysis is based on hurricane seasons up to 2014/2015 and it was also at a time when there was the so called 'hiatus' in global warming where temperatures had temporarily stabalised during a natural cooling phase. Since 2014/2015 hurricane season, global warming has surged forwards again and so have hurricane activity. The lead author of that study Landsea study Philip J. Klotzbach wrote a paper discussing the record breaking 2015 Pacific hurricane season and he said that the warmer ssts contributed to that hurricane activity and ascribed it to El Nino.


Then in 2016 there was another above average hurricane season and 2017 saw a hugely active hurricane season which was during a La Nina event (can't blame el nino for this one)
If we look at the hottest years on record, and look at the Atlantic hurricane season we can see what the pattern is. All data is taken from wikipedia.

2016 - Above average season, 7 hurricanes 4 major hurricanes
2015 - Below average Atlantic 4 hurricanes, 2 major
2017 - extremely active hurricane season 10 hurricanes, 6 major
- hurricanes, record breaking ACE
2014 - Below average 6 hurricanes, 2 Major
2010 - Very active hurricane season 19 tropical storms, 12 hurricanes
2013 - well below average 2 hurricanes, no majors
2005 - Most active hurricane in history 15 hurricanes, 7 Major hurricanes
2009 - below average - 3 hurricanes, 2 Major
1998 - very damaging hurricane season, 10 hurricanes, 3 majors
2007 -Above average - 6 hurricanes, 2 majors

So, in the ten hottest years on record, we have 6 above average, and 4 below average, but of the 6 above average years, 4 of them were very significant historic hurricane seasons including the some of the most damaging storms ever recorded in the atlantic basin.

We can do similar lists with the other hurricane basins if you like. Here's the pacific basin

2016 - Above average season, 13 hurricanes, 6 Majors
2015 - Extremely active hurricane season, 16 hurricanes, 11 majors (record breaking), 2nd strongest hurricane on record
2017 - moderatively active - 9 hurricanes, 4 major
2014 - Exceptionally active hurricane season 16 hurricanes 9 majors
2010 - record low activity, 3 hurricanes, 2 majors
2013 - above average, 9 hurricanes, 1 major, most destructive hurricane on record for the pacific due to exceptional flooding
2005 - below average - 7 hurricanes 2 major
2009 - very active 8 hurricanes, 5 majors, 3rd strongest hurricane on record for that basin
1998 - below average - 9 hurricanes, 6 major
2007 -blow average 4 hurricanes 1 major

Same again here, 6 above average, 4 below average and including some record breaking activity and devastating storms.

What this indicates is that hotter global temperatures don't guarantee more hurricanes, but when they do form, they are more likely to be very damaging.

Wait a minute, are you doing exactly what you berated me for doing and referring to the last ĺ2-3 years' data?

Anyway, that's not what the paper said. It says that the previously-noted upward trend in activity was erroneous and due to a difference in detection technology. It included the trend from. 1972, not just the previous 10 years, which yes, we're relatively quiet. Ironic after the bumper 2005 season, which, at the time, was proclaimed to be the new norm. Then no landfalls in the US for 13 years.

ACE is also showing no major trend one way or the other, just its usual multi-decadal oscillation.

Akrasia

Gaoth Laidir wrote: »

Wait a minute, are you doing exactly what you berated me for doing and referring to the last ĺ2-3 years' data?

Anyway, that's not what the paper said. It says that the previously-noted upward trend in activity was erroneous and due to a difference in detection technology. It included the trend from. 1972, not just the previous 10 years, which yes, we're relatively quiet. Ironic after the bumper 2005 season, which, at the time, was proclaimed to be the new norm. Then no landfalls in the US for 13 years.

That's not really what he did Gaoth. He had a hypothesis that the number and strength of hurricanes in certain basins were under reported in the early part of this series (starting in 1970). He used the apparent plateau in hurricane strength post 2004 in a statistical analysis to conclude that he was right that early records were indeed underestimated.

He also stated that since 2005, ocean ssts had continued to rise, but showed a graph that apart from the south indian basin and the northwest pacific, the ssts plateaued or even declined in that 10 year period. So he's using a time period with stable SSTS, and observing a relative stability in extreme hurricane activity (he still measures an increase in the percentage of major hurricane formation, but calls it insignificant)


In the basin that had the fastest SST increase, lets look at the past 10 years of hurricane activity and see if they were above or below average

South-West Indian Ocean cyclone season
From Wikipedia, the free encyclopedia
04-05 Above average 3 intense cyclones, 2 very intense cyclones (record equalling high for this basin)
05-06 Significantly below average 2 intense cyclones, 0 very intense
06-07 Above average 6 intense cyclones (record for this basin) 0 very intense
07-08 Above average 4 intense cyclones 0 very intense
08-09 Above average 2 intense cyclones 0 very intense
09-10 Average ace but above average intense storms 4 intense, 1 very intense
10-11 Very inactive, 0 intense or v intense storms (also cooler ssts due to walker circulation)
11-12 Above average, 2 intense cyclones 0 v intense
12-13 Above average 3 intense cyclones 0 v intense
13-14 Above average 5 intense cyclones, 2 v intense (record equalling high for this basin)
14-15 Above average 3 intense, 2 very intense (record equalling high for this basin) (these record equalling seasons have all happened since 2005)
15-16 Below average, 3 intense cyclones, 1 very intense cyclone
16-17 Below average 1 intense cyclone, 0 v intense


So looking at the figures for this basin. If we just look at the period Landsea used in his study, we have 10 years worth of data, 2 are classed as below average, 7 as above average, and one as 'near average'
Of the 7 above average years, 3 of them were record breaking/equalling for intense and v intense storms.
The near average season included fewer weak storms, but had above average strong storms
Of the below average years, they had below normal SSTs

If we extend it outwards to the most recent complete season, we have another record equalling year for very intense cyclones, and another year with below average activity but above average intense and v intense cyclones

No matter how you break it down, there are more above average years than below average years correlating with hotter ssts.

Global warming will cause hotter SSTs. Landsea's lead author on that study acknowledges that hotter SSTs were responsible for record hurricane activity in the Pacific basin in 2015...

Landsea's study doesn't seem do any correlation analysis between hotter SSTs and more intense storms, and even his analysis of hurricane tracks is 'They appear visually similar'
I have looked carefully at this study and I'm not convinced that it supports it's conclusions with enough data. It conflicts with other studies which have shown increases in intense storm activity, and it conflicts with the fact that the last couple of years have seen remarkable record breaking storms in many of the worlds hurricane basins coinciding with a surge in global average temperatures.

ACE is also showing no major trend one way or the other, just its usual multi-decadal oscillation.

You've done it again Gaoth, you've posted a graph that clearly shows the opposite of what you say it shows.
Look at that graph again, it clearly shows an increase in ACE as we get into the 21st century, there are very clearly more years north of the baseline in the 21st century than in the 19th century, and even from the 1960s onwards the percentage of positive ace anomalies versus negative ace anomalies is clearly going up. And when you consider that global warming has been measured to have had a fewer number of storms, but the ACE is still increasing, it means that there by definition must be more energy per storm.

I know you won't believe me, so I've downloaded the raw data from your graph and I'll post the decadal averages later on.

Akrasia

Here are the 10 year moving average of the Atlantic ACE as per the data in your graph. (note, this is just one storm basin)


The models for hurricane activity appear to show that the overall number of storms will decline, but the number of cat 4 and 5 storms will increase as global temperatures increase. The ACE figure also doesn't include rainfall or the increased threat from storm surges on top of rising sea levels.

Gaoth Laidir

Akrasia wrote: »

Here are the 10 year moving average of the Atlantic ACE as per the data in your graph. (note, this is just one storm basin)


The models for hurricane activity appear to show that the overall number of storms will decline, but the number of cat 4 and 5 storms will increase as global temperatures increase. The ACE figure also doesn't include rainfall or the increased threat from storm surges on top of rising sea levels.

Only on the phone so can't look at actual figures, but for now it's striking how much higher ACE was around 1880-1900 than the rest of the 20th century. Similar and second only to the recent spike. How did that happen way back then, I wonder?

Akrasia

Gaoth Laidir wrote: »

Only on the phone so can't look at actual figures, but for now it's striking how much higher ACE was around 1880-1900 than the rest of the 20th century. Similar and second only to the recent spike. How did that happen way back then, I wonder?

Its interesting, I've had a quick look and couldn't find any studies into what conditions might have caused such an active period in that region. If you find something post it here I'd love to read it.

Gaoth Laidir

Akrasia wrote: »

Its interesting, I've had a quick look and couldn't find any studies into what conditions might have caused such an active period in that region. If you find something post it here I'd love to read it.

Yep, the science is settled.

Akrasia

Gaoth Laidir wrote: »

Yep, the science is settled.

wow

there goes some of the respect I had for you.

Gaoth Laidir

Akrasia wrote: »

wow

there goes some of the respect I had for you.

Why?

I was just pointing at the irony of the fact that not much seems to be understood about why something that is claimed to be due to agw was in fact already happening 150 years ago. In fact, for the 120 years up to the start of the current peak, the trend in ACE was downwards, despite the upward trends in both OHC and lower tropospheric temperature, both of which are said to be drivers for the future.

I've posted the data for both time periods below. Make of it what you will.

Akrasia

Gaoth Laidir wrote: »

Why?

Because it shows your mindset. You cherrypick data and cherrypick quotes. The 'science is settled' relates to the greenhouse effect. That agw is real. No scientist in history has ever said that all the science relating to storms or historical weather events is fully understood.

Why do you insist on slicing up graphs and charts. You can do that with any data to make it give you any result you like.

You talk a big game but consistently make claims about data that are false, even the data you present yourself doesn't always say what you think it says. You claim to be a critical thinker but it took me ages to convince you that an American scientist used Fahrenheit. You've fallen down the rabbit hole of climate change cynicism and are too hubristic to admit that you might not know as much as 97%+ of the expert currently publishing PhDs in relevant fields

Gaoth Laidir

Akrasia wrote: »

Because it shows your mindset. You cherrypick data and cherrypick quotes. The 'science is settled' relates to the greenhouse effect. That agw is real. No scientist in history has ever said that all the science relating to storms or historical weather events is fully understood.

Why do you insist on slicing up graphs and charts. You can do that with any data to make it give you any result you like.

You talk a big game but consistently make claims about data that are false, even the data you present yourself doesn't always say what you think it says. You claim to be a critical thinker but it took me ages to convince you that an American scientist used Fahrenheit. You've fallen down the rabbit hole of climate change cynicism and are too hubristic to admit that you might not know as much as 97%+ of the expert currently publishing PhDs in relevant fields

Can you explain the negative trend in ACE for 120 years (not 1.2 or 12 years, but 120), despite the warming trend? I posted two graphs particularly so that you wouldn't accuse me of cherry picking, but looks like I was wrong.

Surely 120 years is a valid timescale to use, given that the temperature graphs quoted are of a similar length? If not then maybe the Keeling Curve is too short at around 60 years.

I have no idea why the ACE was so high back then. The highest ever ACE for a single storm was in 1899, but even then, that year as a whole was not too spectacular. The years before that were higher. If a key metric like ACE, which is being repeatedly used as an omen for the future catastrophic world, is not well-understood, it raises questions about the exact extent of settled science. You, on the other hand, continue to lecture us all regardless. Go off and find an answer to this before letting loose on those of us who ask a question.

Akrasia

Gaoth Laidir wrote: »

Can you explain the negative trend in ACE for 120 years (not 1.2 or 12 years, but 120), despite the warming trend? I posted two graphs particularly so that you wouldn't accuse me of cherry picking, but looks like I was wrong.

Surely 120 years is a valid timescale to use, given that the temperature graphs quoted are of a similar length? If not then maybe the Keeling Curve is too short at around 60 years.

I have no idea why the ACE was so high back then. The highest ever ACE for a single storm was in 1899, but even then, that year as a whole was not too spectacular. The years before that were higher. If a key metric like ACE, which is being repeatedly used as an omen for the future catastrophic world, is not well-understood, it raises questions about the exact extent of settled science. You, on the other hand, continue to lecture us all regardless. Go off and find an answer to this before letting loose on those of us who ask a question.

You ended your time series at the lowest point before it started increasing again. That's the definition of cherry picking

Gaoth Laidir

Akrasia wrote: »

You ended your time series at the lowest point before it started increasing again. That's the definition of cherry picking

So I take it you have no answer then.

I openly stated I was taking it up to the start of the current peak. Three full peaks and troughs over 120 years. How is that cherrypicking? Only including years since 2000 does the overall trend start to go positive, which I also openly showed.

If you can't figure it out either then just say so.

Akrasia

Just because you're open about it doesn't mean it's not cherrypicking.

You provided this data saying 'there is no major trend line one way or another' when there actually was a trend in upward ACE especially at the end of the last century and into the 21st century when we have experienced most of the warming.

You said that there was no upward trend in the ACE in the Atlantic basin. I showed that there was a trend, now you're off saying that I have to explain why the trend is downwards if you exclude the last 30 years of data which also happens to be the period with the highest ACE in the entire series.


If you genuinely do care about explaining the data, you might look at the MJO. There was a stochastic analysis of MJO cycles and the period at the end of the 18th century had a higher number of MJO events per year compared to any time in the early 20th century, but the likelyhood of high frequency of MJO events increased from the 1970s and from the 1990s to 2008 the likelyhood of a very active MJO season was more than twice what it was in the late 19th century.

High frequency of MJO transitions seems to correlate with greater cyclogenesis, and the models predict that as the planet warms, MJO transitions will be faster

The results also point out to significant decadal changes in probabilities of very active years (5 or more MJO events): 0.214 (1880–1895), 0.076 (1896–1917), 0.197 (1918–1947) and 0.193 (1948–1972). After a change in behavior in the 1970s, this probability has increased to 0.329 (1973–1989) and 0.510 (1990–2008). The observational and stochastic simulations presented here call attention to the need to further understand the variability of the MJO on a wide range of time scales.
https://link.springer.com/article/10.1007/s00382-009-0660-2

Climate change is predicted to have very significant effects on the MJO (which is also a risk for changes to SSW events and Monsoon rains)

Global warming's impact on the Madden‐Julian Oscillation (MJO) is assessed using one of the few models capable in reproducing its key features. In a warmer climate predicted for the end of the century, the MJO increases in amplitude (by ~30%) and frequency, showing a more circumglobal propagation tendency. The MJO spatial extent becomes enhanced, deeper, and more zonally extended but meridionally confined. A stronger vertical tilting structure in diabatic heating, moisture, and convergence fields is seen.

MJO drives cyclogenesis by creating low wind sheer conditions that allow cyclones to grow and stablise. Warmer SSTs and atmospheric warming caused by Climate change means that when these cyclones do generate, they are likely to be stronger and to hold more water.

Gaoth Laidir

Akrasia wrote: »

Just because you're open about it doesn't mean it's not cherrypicking.

You provided this data saying 'there is no major trend line one way or another' when there actually was a trend in upward ACE especially at the end of the last century and into the 21st century when we have experienced most of the warming.

You said that there was no upward trend in the ACE in the Atlantic basin. I showed that there was a trend, now you're off saying that I have to explain why the trend is downwards if you exclude the last 30 years of data which also happens to be the period with the highest ACE in the entire series.


If you genuinely do care about explaining the data, you might look at the MJO. There was a stochastic analysis of MJO cycles and the period at the end of the 18th century had a higher number of MJO events per year compared to any time in the early 20th century, but the likelyhood of high frequency of MJO events increased from the 1970s and from the 1990s to 2008 the likelyhood of a very active MJO season was more than twice what it was in the late 19th century.

High frequency of MJO transitions seems to correlate with greater cyclogenesis, and the models predict that as the planet warms, MJO transitions will be faster




Climate change is predicted to have very significant effects on the MJO (which is also a risk for changes to SSW events and Monsoon rains)


MJO drives cyclogenesis by creating low wind sheer conditions that allow cyclones to grow and stablise. Warmer SSTs and atmospheric warming caused by Climate change means that when these cyclones do generate, they are likely to be stronger and to hold more water.

That paper still doesn't explain why the high MJO-count in the late 19th century or resolve the question of what happened during the 20th. Had you been looking at this topic just 20 years ago you'd have been seeing up to that point a decreasing trend in ACE and a decreasing/flat trend in MJO. How would that have tallied with the warming that had occured in the same timeframe? Warmer SST, warmer atmosphere, yet decreasing ACE. Again, there is still a lot we don't understand.

I'm not going to entertain your continued cheryypicking claim.

Akrasia

Gaoth Laidir wrote: »

That paper still doesn't explain why the high MJO-count in the late 19th century or resolve the question of what happened during the 20th. Had you been looking at this topic just 20 years ago you'd have been seeing up to that point a decreasing trend in ACE and a decreasing/flat trend in MJO. How would that have tallied with the warming that had occured in the same timeframe? Warmer SST, warmer atmosphere, yet decreasing ACE. Again, there is still a lot we don't understand.

I'm not going to entertain your continued cheryypicking claim.

You said SSTs were warming, but most of the warming attributed to humans has taken place since the 1950s

Why don't you check to see if the Atlantic SSTs were actually warmer in the first half of the 20th century?
You know about the AMO, you know there are multi decadal oscillations.
Why not check if these line up with the changes in ACE and MJO.

Never mind. I'll check for you.
It seems the SSTs were warm at the end of the 19th century, then they cooled in the first half of the 20th century before warming again to where they are now, at the warmest they've been on record.

The warmer phases of Atlantic SSTs correlate with the periods of increased ACE and higher MJO counts. Just like the warmest years are more likely to have above average hurricane seasons as per the data I posted a few days ago

Gaoth Laidir

Akrasia wrote: »

You said SSTs were warming, but most of the warming attributed to humans has taken place since the 1950s

I don't think hurricanes especially care what caused warming.

Why don't you check to see if the Atlantic SSTs were actually warmer in the first half of the 20th century?
You know about the AMO, you know there are multi decadal oscillations.
Why not check if these line up with the changes in ACE and MJO.

Never mind. I'll check for you.
It seems the SSTs were warm at the end of the 19th century, then they cooled in the first half of the 20th century before warming again to where they are now, at the warmest they've been on record.

The warmer phases of Atlantic SSTs correlate with the periods of increased ACE and higher MJO counts. Just like the warmest years are more likely to have above average hurricane seasons as per the data I posted a few days ago

Wrong, it was the opposite. SST were cooler at the end of the 19th century and then warmed significantly in the first half of the 20th century. By mid century they were much higher than the 19th. ACE was the opposite. So, still no further along with an answer.

Akrasia

Your data doesn't contradict what I said. First of all, the atlantic SST graph you posted covers the entire atlantic ocean, but this is misleading because the entire atlantic ocean isn't where hurricanes form and track. So we should be correllating SSTs in the parts of the atlantic that affect cyclone formation and wind shear

The NAO index graph does correlate with the ACE graph, where the NAO is higher, the ace is generally higher.

Secondly, hurricanes and SSTs vary year by year, so you would need to do a correlation year on year rather than using the 10 year smoothed curve which can show trends but multi year oscillations can balance each other out. A full analysis should be comparing individual years and seeing if the warmest ssts correlate with the strongest or highest frequency storm years.
(and the data should only include SSTs during the hurricane season)

Finally, the MJO needs to be thrown into the mix because it plays a big role in whether the cyclones can form as MJO dictates wind sheer

We need a proper study, not just throwing graphs out there in isolation.
Emanuel 2007 gave us this graph


Here's another study that looked at data going back to the 1940s. The reason they didn;t go back further is because data is less reliable the further back we go

The modest sensitivity of intensity to uniform warming appears to be consistent with the small sensitivity of the global-mean potential intensity (PI) from coupled global climate models (CGCMs) in twenty-first century warming scenarios (e.g., Vecchi and Soden 2007). Further, the modest implied sensitivity of the intensity of strongest storms to uniform warming suggests that the observed 1980–2006 increase in the intensity of the strongest storms in the North Atlantic was not driven by the uniform warming component of the observed SST change, but by the warming of the Atlantic relative to the tropical mean over this period. The negative frequency of hurricane frequency to uniform warming is consistent with the atmospheric general circulation model (AGCM) results of Zhao and Held (2011).

The sensitivity to nonuniform SST changes is much more marked. These results indicate that increases in tropical Atlantic SST relative to the tropical mean SST should lead to large changes in tropical storm and hurricane frequencies and intensity scale, with a reduction in duration scale. It is harder to explain the opposite sensitivity of the duration scale to uniform and nonuniform warmings. Our results suggest that for nonuniform warming, storms become more frequent and stronger, but they spend, on average, less time as strong storms. On the other hand, for uniform warming there are fewer storms that are approximately of the same maximum intensity but, on average, they remain strong for longer.
https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-11-00146.1

One of the authors of this paper gave this presentation this year and it explains and updates the results of his study.