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Nasa Happily Reports the Earth Is Greener

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Re: Nasa Happily Reports the Earth Is Greener

#141

Post by logfromblammo »

whatshisface wrote: post #95
ajuc wrote: post #68

Earlier quoted context omitted.

> plants love CO2 In artifical conditions in laboratory there is a significant effect, up to 20% when doubling pre-industrial CO2 concentration. But, in practice for wild plants nitrogen quickly becomes the bottleneck, so the real gains are much smaller. And even for farming plants (which have fertilizer providing additional nitrogen) the real gains diminish, and are more in 5-10% range. For some crops CO2 has very l…

If the bottleneck changes from CO2 to Nitrogen, maybe plants will start adapting to get better at fixation, pushing that limit higher than the CO2 limit.

Plants don't really get better at fixing nitrogen. They get better at hosting symbiotic colonies of nitrogen-fixing microbes in their root systems.

It's splitting a hair, to be sure, but developing root nodules for hosting a nitrogen-fixer species is a lot easier than evolving all the biochemical precursors from scratch. Nitrogen fixation symbiosis may have evolved independently in plants at least three times. It would have been a big advantage from 460 to 380 Mya and then again, to a far lesser extent, from 240 to 160 Mya. Teredo shipworms also employ nitrogen-fixing symbionts, in their gill structures, as well as some termites, in their guts, but the latter only derive benefit in an extremely low-nitrogen environment.

Since atmospheric CO2 has dropped after the last peaks, some plant species failed to preserve that symbiosis. They would have an easier time getting it back, now that CO2 partial pressure is rising back to levels experienced in prior geological eras.

The ultimate bottleneck is likely to be iron or magnesium.

Re: Nasa Happily Reports the Earth Is Greener

#142

Post by GlenTheMachine »

BurningFrog wrote: post #137
NeedMoreTea wrote: post #107

Earlier quoted context omitted.

For crops that tolerate the extra heat. Those which don't will need to be grown further toward the poles, which will reduce the length of growing season.

Reseeding a field with a new crop is technology known since thousands of years. I don't think there is any risk of areas reaching temperatures too hot for any plants? > which will reduce the length of growing season Why?

...because plants that are overheated can't grow. Depending on how overheated they get they may merely become stressed, or they can die. But plants also need temperatures, particularly soil temperatures, that rise above some minimum before they germinate. So you need a period when the soil temperature is high enough, but the air temp is not too high. Figuring out the length of that window is very complicated.

Corn, for instance, can't grow when the temp is over 104 or so (depending on cultivar) and dies when exposed to temps over 110 or so. It maximizes its growth rate at around 86 degrees.

So: if you have a summer month when temps are regularly over 104, that's not really a growing season for corn. Thus you have to try to plant earlier and harvest earlier, and the window when you can do that successfully may be considerable shorter than it would if the temp stayed below 104 during the summer.

So then you try to go closer to the poles. But -- depending on temperatures and a lot of other factors -- that may not be a totally satisfying solution either. Corn needs specific amounts of rain, which may or may not coincide with periods when the temperatures are good. It also needs large amounts of soil nitrogen, which may or may not be present in arctic soils, and if the plant doesn't have it growth is slowed. Corn also needs the soil temperature to be relatively high to germinate (above 50 degrees, again depending somewhat on cultivar). In arctic soils, it may take a while for the soil to warm up that much in the spring, and that may reduce your growing season. So how all the factors play out, and whether those factors result in a longer or shorter growing season, are intimately connected to exactly how the climate changes.

I've used corn as an example, but of course other crops and wild plants all rely on complicated, interconnected conditions to thrive. The specifics are a bit different for every plant.

It all depends. There are a lot of factors that we won't really know until people start trying to do it.

Re: Nasa Happily Reports the Earth Is Greener

#143

Post by mamon »

hannob wrote: post #139
maratd wrote: post #138

Earlier quoted context omitted.

Perhaps rather than an ad-hominem you can instead argue the point being made?

Okay, here's the thing: If you have plants with more or less CO2 under otherwise the same conditions you'll have more growth in the plants. However that's not how the planet works. If you put more CO2 in the atmosphere you'll have for example rising sealevels and larger deserts (and probably more effects that diminish food production). You can't just pick a single effect of increased CO2 in isolation. (Except of cour…

ELI5: how will melting ice caps cause rising sea levels? Ice has higher volume than water it's made of, so the effect of ice melting should be sea level falling. At least that's the case of Arctic Sea, which is just this: frozen sea. Antarctic is different, because most of the ice is located on land, above the sea level. But then, shouldn't northern cap melting cancel out melting of the south one?

Re: Nasa Happily Reports the Earth Is Greener

#144

Post by slumdev »

maratd wrote: post #138
hannob wrote: post #125

Earlier quoted context omitted.

The CO2 Coalition is a pseudoscientific climate denial organization.

Perhaps rather than an ad-hominem you can instead argue the point being made?

I can appreciate the idea, but this attitude is why bullshit pervades.

If a person or group consistently advances bullshit, it eventually becomes a useful heuristic to dismiss that person's or group's ideas without consideration.

It takes more energy to argue against the bullshit than it does to advance it in the first place, so insisting on that argument hurts dialogue more than it helps.

Re: Nasa Happily Reports the Earth Is Greener

#145

Post by vardump »

mamon wrote: post #143
hannob wrote: post #139

Earlier quoted context omitted.

Okay, here's the thing: If you have plants with more or less CO2 under otherwise the same conditions you'll have more growth in the plants. However that's not how the planet works. If you put more CO2 in the atmosphere you'll have for example rising sealevels and larger deserts (and probably more effects that diminish food production). You can't just pick a single effect of increased CO2 in isolation. (Except of cour…

ELI5: how will melting ice caps cause rising sea levels? Ice has higher volume than water it's made of, so the effect of ice melting should be sea level falling. At least that's the case of Arctic Sea, which is just this: frozen sea. Antarctic is different, because most of the ice is located on land, above the sea level. But then, shouldn't northern cap melting cancel out melting of the south one?

> At least that's the case of Arctic Sea, which is just this: frozen sea.

There's Greenland in north.

> But then, shouldn't northern cap melting cancel out melting of the south one?

Cancel out? Melting can't decrease water level, so I don't see how canceling out is possible.

Re: Nasa Happily Reports the Earth Is Greener

#146

Post by onefuncman »

keithnz wrote: post #50
andy_ppp wrote: post #47

Would it be possible to turn a desert region into a rain forest? For example if Nevada decided to plant trees in the dessert is it possible with enough irrigation or would all the trees just die?

https://www.youtube.com/watch?v=vpTHi7O66pI I watched this talk a while back, TL;DW Yes, you can.

it was a little mystifying that he answered the question about how they bootstrap the process with "we've never had to supplement feed" alongside "no grass in sight for 100 miles"... does anyone have a longer answer?

Re: Nasa Happily Reports the Earth Is Greener

#147

Post by NeedMoreTea »

BurningFrog wrote: post #137
NeedMoreTea wrote: post #107

Earlier quoted context omitted.

For crops that tolerate the extra heat. Those which don't will need to be grown further toward the poles, which will reduce the length of growing season.

Reseeding a field with a new crop is technology known since thousands of years. I don't think there is any risk of areas reaching temperatures too hot for any plants? > which will reduce the length of growing season Why?

It may become hotter, but solar declination isn't going to change. Move towards the poles and the sun will have lower elevation, fewer hours of light, and the balance of seasons will change.

How much is enough to matter? Will the net effect be more or less than change from CO2 or temperature? You tell me. We seem to have a lot of unknowns.

Re: Nasa Happily Reports the Earth Is Greener

#148

Post by jdblair »

Wowfunhappy wrote: post #136
marcosdumay wrote: post #127

Earlier quoted context omitted.

I doubt anybody really knows. It is well known that CO2 improves plants growth. It is also well known that plants grow better within a narrow band of temperatures. Increasing both the CO2 contents of the atmosphere and Earth's temperature will have some complex results where on the places within that temperature band, plants grow slightly faster, on places that cross from too cold into the band plants grow much faste…

These all seem like variables a robust computer model could account for, no?

Yes, and then the model will give you some result, but you will never know if you are accurately accounting for reality in all its complexity. The more complex your model, the less likely you are to match reality precisely. To quote a cliche, the model is the map, not the territory.

Re: Nasa Happily Reports the Earth Is Greener

#149

Post by throwaway29319 »

maratd wrote: post #138
hannob wrote: post #125

Earlier quoted context omitted.

The CO2 Coalition is a pseudoscientific climate denial organization.

Perhaps rather than an ad-hominem you can instead argue the point being made?

No. Disproving bullshit takes 100x times more than producing it.

This idea that we should argue ad infinitum is bad. It allows https://en.wikipedia.org/wiki/Sealioning

Reputable sources are worth arguing. Other should be ignored.

Re: Nasa Happily Reports the Earth Is Greener

#150

Post by tonmoy »

mamon wrote: post #143
hannob wrote: post #139

Earlier quoted context omitted.

Okay, here's the thing: If you have plants with more or less CO2 under otherwise the same conditions you'll have more growth in the plants. However that's not how the planet works. If you put more CO2 in the atmosphere you'll have for example rising sealevels and larger deserts (and probably more effects that diminish food production). You can't just pick a single effect of increased CO2 in isolation. (Except of cour…

ELI5: how will melting ice caps cause rising sea levels? Ice has higher volume than water it's made of, so the effect of ice melting should be sea level falling. At least that's the case of Arctic Sea, which is just this: frozen sea. Antarctic is different, because most of the ice is located on land, above the sea level. But then, shouldn't northern cap melting cancel out melting of the south one?

Even if the poles were modeled as just ice cubes floating on water, then melting them would not decrease the sea level, as 1/12th volume of the ice would be above water. So even with this very simple model the South Pole has no way to compensate the north pole’s contribution.
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