[Petrochemicals (OP)]

Now we are all aware that the earth is getting warmer, recently there has been a huge spike in temperature. There is a massive drought in the western USA that is considered to be exceptional, according to Lake sediment studies happening only every 1000ish years.

https://www.theguardian.com/environment/2022/feb/15/us-west-megadrought-worst-1200-years-study

Global-temp-graph.png (140.77 kB . 1123x636 - viewed 5654 times)


2000_years_with_error_v2.png (94.78 kB . 800x600 - viewed 5773 times)
As you can see over the last 1000 years the temperature has fluctuated, but there is a massive spike starting in about 1990 which coinsides with the megadrought in california. Has this sort of spike in heat conditions happened before similarly to the drought, could the recent warming be an anomoly.

[Eternal Student]

Hi.

Is global-warming man-made?
    Yes, if you want a simple answer.
Usually, I'd like to talk for a while about the evidence and the possibilities that it might be something else.   However, that will only confuse and detract from the main message.  So let's just go with clear  "yes, it is man-made".

Best Wishes.

[Origin]

Yes.

[Kryptid]

Don't we already have a thread (and maybe more than one) basically asking this same question? Either way, the experts who study the climate overwhelmingly agree that it's man-made.

[Petrochemicals (OP)]

Hi.

Is global-warming man-made?
    Yes, if you want a simple answer.
Usually, I'd like to talk for a while about the evidence and the possibilities that it might be something else.   However, that will only confuse and detract from the main message.  So let's just go with clear  "yes, it is man-made".

Best Wishes.

Thank you mien fuhrer for the reasoned point and the freedom of ideas. Your bearing is an example to us all.

Don't we already have a thread (and maybe more than one) basically asking this same question? Either way, the experts who study the climate overwhelmingly agree that it's man-made.

I think I missed the mega drought threads, sorry, maybe we can merge them.

Yes.

That was what I wanted, a good clear position on this temperature spike being just a blip.

[Bored chemist]

Hi.

Is global-warming man-made?
    Yes, if you want a simple answer.
Usually, I'd like to talk for a while about the evidence and the possibilities that it might be something else.   However, that will only confuse and detract from the main message.  So let's just go with clear  "yes, it is man-made".

Best Wishes.

Thank you mien fuhrer for the reasoned point and the freedom of ideas. Your bearing is an example to us all.

Don't we already have a thread (and maybe more than one) basically asking this same question? Either way, the experts who study the climate overwhelmingly agree that it's man-made.

I think I missed the mega drought threads, sorry, maybe we can merge them.

Yes.

That was what I wanted, a good clear position on this temperature spike being just a blib.

The answer is still yes.

[Deecart]

I never understand if yes or no.
First time (around 30 years ago) i heard about the possibility human could have change climate (instead of volcanoes or sun) some climatologist explained that within the solar system, the temperature of every planet changed (this was NASA facts)
Obvious explaination was : The sun changed the temperature.
Now we have around 40000 wise peoples (named climatologists) explaining that only man change "the mean" temperature of the earth (temperature is not extensive but who cares).
The one who dont agree with that can not be a climatologist.
Therefore we are sure of that, human changed the climat because of CO2 or other gazes like methane (and this is why humanity is safe...all is under control).

[Origin]

Now we have around 40000 wise peoples (named climatologists) explaining that only man change "the mean" temperature of the earth (temperature is not extensive but who cares).

I highly doubt ANY climatologist would claim such an outrageous thing.

[Bored chemist]

Obvious explaination was : The sun changed the temperature.

For every simple question there is an answer that is simple, obvious, and wrong.

We have independently been monitoring the Sun.
It has stayed the same, but the Earth has got hotter.

[Kryptid]

First time (around 30 years ago) i heard about the possibility human could have change climate (instead of volcanoes or sun) some climatologist explained that within the solar system, the temperature of every planet changed (this was NASA facts)
Obvious explaination was : The sun changed the temperature.

Do you have a source for this?

[alancalverd]

 Since the sun is the major source of heat for at least the inner planets, its output must be the primary determinant of their temperatures. But none of the planets (except possibly Mercury) is a homogeneous lump of rock with a constant attitude to the sun: they have internal structures and turbulent gaseous atmospheres, and the surface of the most important planet is mostly covered with water or ice.

So a lot depends on what you mean by the temperature of Earth. Most people are interested in the mean temperature of the gaseous bit at sea level, and the geological record shows that it has regulary cycled over a range of 12 degrees at least 4 times in the last half-million years. We have no reason to believe the sun's output was quite that variable or predictably cyclic,and only human vanity and myopia would assert without a proper experimental test that the  addition of homo sapiens to the surface has had a significant effect on a trend that clearly began 15,000 years ago and looks like all the previous ones.

So the physical evidence would not support the assertion under rigorous cross examination in a court, and the prosecution would likely say "what experiments have you done to test your hypothesis?" to which the answer is clearly "none". However good the intentions of various expensive conferences, "We just kept shovelling more coal on  the fire, m'lud." 

Scottish law allows the jury to return "not proven", and I think that should be the stance of anyone with scientific pretensions,

[evan_au]

man only changed "the mean" temperature of the earth

With the Earth's current spin, we can expect a certain day/night temperature excursion; with its current axial tilt and orbital eccentricity we can expect a certain seasonal temperature variation around the mean.

So if you increase the mean temperature, you also increase the peak temperatures, so you break record high temperatures more often (and record low temperatures less often). With higher mean temperatures comes hotter summers, dryer forests, and more severe wildfires (under the right conditions).

Some effects are rather non-linear; for example, the chance of hurricanes increases significantly when the sea surface temperature exceeds 26C. So if you increase the mean temperature, you can expect far more hurricanes. But even without hurricanes, higher sea temperatures means more evaporation, and (under the right conditions), heavier rainfall and more flooding.

With habitat fragmentation, species can't migrate poleward, and we can expect to see accelerating species extinctions.

the sun is the major source of heat for at least the inner planets, its output must be the primary determinant of their temperatures

Yes, but not in the way you mean.
- Over a timescale of billions of years, the Sun will get hotter, as it burns more of its fuel.
- But that's not the timescale here. We are looking at changes over a period of hundreds of years, since humans used the power of coal to mine more coal (and a similar effect with petroleum production), in a positive feedback cycle.

without a proper experimental test

We do have a proper test - it's called a Climate Attribution test.
- It uses supercomputers to model the Earth's atmosphere, with and without the CO₂ humans have added since the start of the Industrial Revolution.
- What this shows is things like "Extreme climate event X will occur Y% more often due to human-added greenhouse gases."
- So this is evidence that humans have increased both the mean and extreme temperatures (and their impact on society)

Some people may claim that this is just statistics - but saying that "smoking increases your chance of lung cancer" is just statistical - but that doesn't invalidate smoking as a major cause of lung cancer.

https://en.wikipedia.org/wiki/Attribution_of_recent_climate_change

[Petrochemicals (OP)]

I never understand if yes or no.
First time (around 30 years ago) i heard about the possibility human could have change climate (instead of volcanoes or sun) some climatologist explained .

Since the sun is the major source of heat for at least the inner planets, its output must be the primary determinant of their temperatures. But none of the planets (except possibly Mercury) is a homogeneous lump of rock with a constant attitude to the sun: they have internal structures and turbulent gaseous atmospheres, and the surface of the most important planet is mostly covered with water or ice.

man only changed "the mean" temperature of the earth

With the Earth's current spin, we can expect a certain day/night temperature excursion; with its current axial tilt and orbital eccentricity we can expect a certain seasonal temperature variation around the mean.

So if you increase the mean temperature, you also increase the peak temperatures, so you break record high temperatures more often (and record low temperatures less often). With higher mean temperatures comes hotter summers, dryer forests, and more severe wildfires (under the right conditions).

Whilst these posts are very informative how do they relate to THE megadrought connection of the opening post?

[alancalverd]

If the average temperature of a chaotic system like the Earth's atmosphere increases, you can expect the distribution of stuff in it to alter. Whilst the temperature is increasing, you'd expect there to be more water going up than coming down, and whilst there will be more water in the sky, less of it will fall and possibly not in the places or at the times it used to.

75% of the planet's surface is ocean, and California is a very  tiny bit of the remaining 25%. It used to be very attractive to human settlement but atmospheric physics is indifferent to the aspirations of one species.

[Bored chemist]

So the physical evidence would not support the assertion under rigorous cross examination in a court, and the prosecution would likely say "what experiments have you done to test your hypothesis?" to which the answer is clearly "none". However good the intentions of various expensive conferences, "We just kept shovelling more coal on  the fire, m'lud."

Someone might pose a question on this forum along the lines of "what would happen to the members of the forum if they each ate an ounce of arsenic oxide?"
Most of us would be prepared to use past data, models and analogies.
Alan would insist on an experiment.

[Origin]

Whilst these posts are very informative how do they relate to THE megadrought connection of the opening post?

The title of the thread is "Is global warming man-made?"  I think most people were answering that question, That is what I was answering.

On the "mega" drought,

As you can see over the last 1000 years the temperature has fluctuated, but there is a massive spike starting in about 1990 which coinsides with the megadrought in california. Has this sort of spike in heat conditions happened before similarly to the drought,

Not recently, according to the graph you provided. Do high temperatures make droughts worse?  The answer is yes.

could the recent warming be an anomoly.

Yes, it is seems to be a rather large anomaly caused by green house gases put into the atmosphere by human activity 

[Petrochemicals (OP)]

Whilst these posts are very informative how do they relate to THE megadrought connection of the opening post?

The title of the thread is "Is global warming man-made?"  I think most people were answering that question, That is what I was answering.

it is sometimes difficult to fit all you wish to say in the title, forum etiquette usually transpires to the opening post or the OP as it is known.

On the "mega" drought,

please read the OP

As you can see over the last 1000 years the temperature has fluctuated, but there is a massive spike starting in about 1990 which coinsides with the megadrought in california. Has this sort of spike in heat conditions happened before similarly to the drought,

Not recently, according to the graph you provided. Do high temperatures make droughts worse?  The answer is yes.

I would disagree

could the recent warming be an anomoly.

Yes, it is seems to be a rather large anomaly caused by green house gases put into the atmosphere by human activity 

good, temperatures will normalise themselves then.

[Petrochemicals (OP)]

If the average temperature of a chaotic system like the Earth's atmosphere increases, you can expect the distribution of stuff in it to alter. Whilst the temperature is increasing, you'd expect there to be more water going up than coming down, and whilst there will be more water in the sky, less of it will fall and possibly not in the places or at the times it used to.

75% of the planet's surface is ocean, and California is a very  tiny bit of the remaining 25%. It used to be very attractive to human settlement but atmospheric physics is indifferent to the aspirations of one species.

Mega drought not first.

[alancalverd]

Alan would insist on an experiment.

Only if it hadn't been done before.

So far, we have a one-way correlation between a temperature trend that looks like several previous ones and began at least 15,000 years ago, and anthropogenic carbon dioxide emissions in the last 150 years.  A gap of 14,850 years between the onset of effect and the presence of supposed cause would worry anyone working in a different field of science and suggest that maybe we need to investigate a little deeper before asserting causality. Particularly as all the previous evidence shows that the huge variations of non-anthropogenic CO2 followed, rather than led, the temperature fluctuations.

The obvious experiment to test the hypothesis is to reduce anthropogenic CO2 and see what happens.

That hasn't been done before, and sadly won't be done in our lifetimes.

[Origin]

I would disagree

You disagree that high temperatures make a drought worse?  Higher temperatures increase moisture loss from the soil which makes a drought worse, in that more plants will die from the drought.

good, temperatures will normalise themselves then

What do you think that means?  Normalize to what and why?