How difficult will it be to live with almost 100% dry land?

[AlanGomez]

Here I share this analysis from data obtained at: https://data.unccd.int/countries-affected-by-drought?epoch=e5

As you can see (with coefficient of determination of ~ 96%), regression says that we will face a moderate-severe droughts over nearly 100% Planet Earth lands by 2048.

[Ken Fabian]

2 hours ago, AlanGomez said:

Here I share this analysis from data obtained at: https://data.unccd.int/countries-affected-by-drought?epoch=e5

As you can see (with coefficient of determination of ~ 96%), regression says that we will face a moderate-severe droughts over nearly 100% Planet Earth lands by 2048.

I am not convinced this kind of extrapolation can tell us a lot, let alone give reliable predictions about something as complicated as the rainfall responses to global warming. There are a whole lot of factors including and especially those affecting sea surface temperatures and their geographic distributions - which are affected by ocean currents and oscillations. These influence wind directions and their humidity. Regional geography matters. Throw in the possibility of the slowing and cessation of the Atlantic Meridional Overturning Circulation and other ocean effects any simple extrapolations will break down even more.

Overall rainfall is predicted to increase globally because warmer air takes up more water vapor; where conditions for rain occur there is likely to be heavier rainfall. The corollary to that is that in arid climate zones warmer air needs more water vapor to reach saturation, in order for rain to occur, so is likely to be less frequent and lighter. That said, the warmer it is the quicker that water deficits (droughts) can occur.

[Genady]

The source gives the following "warning" before one reads the details:

Pay attention to the last sentence.

[exchemist]

10 hours ago, AlanGomez said:

Here I share this analysis from data obtained at: https://data.unccd.int/countries-affected-by-drought?epoch=e5

As you can see (with coefficient of determination of ~ 96%), regression says that we will face a moderate-severe droughts over nearly 100% Planet Earth lands by 2048.

This has to be the hockey stick to end all hockey sticks! How in hell can anybody have confidence in this vast, apparently exponential, extrapolation from such a noisy data set? 

[studiot]

11 hours ago, AlanGomez said:

over nearly 100% Planet Earth lands

Gosh so where will all the water in the atmousphere and oceans go  in this unlikely scenario ?

When in geological time did we ever have near 100 desert conditions, even in much hotter periods than we have or are heading for ?

Edited October 2 by studiot

[AlanGomez]

About data source, I must to say that despite some warnings related to completeness, I said "regression says" not "data shows that...", also noisy data are not a problem since we got good prediction intervals (CI) and R squared.

More and completed data are required to confirm or reject my initial hypothesis.

Edited October 2 by AlanGomez

[AlanGomez]

13 hours ago, Ken Fabian said:

I am not convinced this kind of extrapolation can tell us a lot, let alone give reliable predictions about something as complicated as the rainfall responses to global warming. There are a whole lot of factors including and especially those affecting sea surface temperatures and their geographic distributions - which are affected by ocean currents and oscillations. These influence wind directions and their humidity. Regional geography matters. Throw in the possibility of the slowing and cessation of the Atlantic Meridional Overturning Circulation and other ocean effects any simple extrapolations will break down even more.

Overall rainfall is predicted to increase globally because warmer air takes up more water vapor; where conditions for rain occur there is likely to be heavier rainfall. The corollary to that is that in arid climate zones warmer air needs more water vapor to reach saturation, in order for rain to occur, so is likely to be less frequent and lighter. That said, the warmer it is the quicker that water deficits (droughts) can occur.

Is also known that such natural compensation mechanisms have 'elastic limits', so it's not so speculative to apply a simple regression model that fits future data, as can be done with carbon emissions, global temperature... and so on. Later I will provide those analysis.

Also an important projections also have been done by others:  "By the end of the century, the duration of moderate, severe and exceptional droughts in some regions of China will double, and the drought intensity will increase by over 80%." https://link.springer.com/article/10.1007/s11430-021-9927-x

Edited October 2 by AlanGomez

[studiot]

18 minutes ago, AlanGomez said:

Is also known that such natural compensation mechanisms have 'elastic limits', so it's not so speculative to apply a simple regression model that fits future data, as can be done with carbon emissions, global temperature... and so on. Later I will provide those analysis.

Also an important projections also have been done by others:  "By the end of the century, the duration of moderate, severe and exceptional droughts in some regions of China will double, and the drought intensity will increase by over 80%." https://link.springer.com/article/10.1007/s11430-021-9927-x

You have now posted twice since my simple questions.

 

I see you are new here so please note the forum's requirement to support your claims.

 

[TheVat]

57 minutes ago, AlanGomez said:

Also an important projections also have been done by others:  "By the end of the century, the duration of moderate, severe and exceptional droughts in some regions of China will double, and the drought intensity will increase by over 80%." https://link.springer.com/article/10.1007/s11430-021-9927-x

Some regions of China is far from a working model for extrapolation on 100 percent of dry land on the Earth.  For every modeling of drier places, like the US West or parts of Asia, there are also modelings of a much wetter region elsewhere.  Remember when moisture-laden air fails to precipitate one place, it can go somewhere else and meet a cool front and/or a zone rich with condensation nuclei and then rain like crazy.

[AlanGomez]

9 minutes ago, TheVat said:

Some regions of China is far from a working model for extrapolation on 100 percent of dry land on the Earth.  For every modeling of drier places, like the US West or parts of Asia, there are also modelings of a much wetter region elsewhere.  Remember when moisture-laden air fails to precipitate one place, it can go somewhere else and meet a cool front and/or a zone rich with condensation nuclei and then rain like crazy.

In fact, now we have nearly 50% of moderate drought lands in US, notoriously increasing from paleodata, according to https://www.drought.gov/historical-information?dataset=0&selectedDateUSDM=20240924&selectedDatePaleo=20170101&selectedDateSpi=20240801,

[AlanGomez]

11 hours ago, studiot said:

Gosh so where will all the water in the atmousphere and oceans go  in this unlikely scenario ?

When in geological time did we ever have near 100 desert conditions, even in much hotter periods than we have or are heading for ?

Well, you ask/say that we had warmer periods... well, there were 3 to 10 million years ago, and there was no human civilization at that time.

[Harrot]

On 10/2/2024 at 1:28 AM, AlanGomez said:

Here I share this analysis from data obtained at: https://data.unccd.int/countries-affected-by-drought?epoch=e5

As you can see (with coefficient of determination of ~ 96%), regression says that we will face a moderate-severe droughts over nearly 100% Planet Earth lands by 2048.

 

You perform a data regression, but the people from whom the data comes explicitly say you can't do it.

Quote

Globally, drought intensity fluctuates on an annual basis as a function of changes in the temporal and spatial distribution of global and regional precipitation patterns. The years 2002 and 2001 were particularly extreme with 58 per cent and 57 per cent of the global reported land area under drought, respectively, of which 12.2 and 7.3 per cent of the land area was under extreme or severe drought. However, the maximum proportion of land under severe or extreme drought was reported in 2019 for 13.8 per cent of the global reported land area. Due to natural climate variability it is inadvisable to infer trends from any observed changes in the proportion of land under drought.

https://data.unccd.int/countries-affected-by-drought?epoch=e5

[studiot]

On 10/2/2024 at 11:55 PM, AlanGomez said:

Well, you ask/say that we had warmer periods... well, there were 3 to 10 million years ago, and there was no human civilization at that time.

 

Why the funny slide bar ?

 

In Roman times, the climate in the UK was much warmer and Britain was noted for wine exports.

How many million years ago do you thing that was ?

A bit later we had a colder period known as a mini ice age or lower dryas.

There was also a younger dryass prior to the Roman period.

 

But my main question, which remains unanswered,  was

 

On 10/2/2024 at 11:57 AM, studiot said:

Gosh so where will all the water in the atmousphere and oceans go  in this unlikely scenario ?

 

[exchemist]

41 minutes ago, studiot said:

Why the funny slide bar ?

 

In Roman times, the climate in the UK was much warmer and Britain was noted for wine exports.

How many million years ago do you thing that was ?

A bit later we had a colder period known as a mini ice age or lower dryas.

There was also a younger dryass prior to the Roman period.

 

But my main question, which remains unanswered,  was

 

 

The Americans here will just love "dryass"😁.

[studiot]

2 hours ago, exchemist said:

The Americans here will just love "dryass"😁.

I thought I had corrected that one.