Has Plant Life Reached Its Limits?

hessian writes with this news from the New York Times: "Since 2000, Dr. [Steven] Running and his colleagues have monitored how much plant growth covers terra firma, using two NASA satellites in the agency's Earth Observing System. After they crunched the numbers, combining the current monitoring system's data with satellite observations dating back to 1982, they noticed that terrestrial plant growth, also known as net primary production, remained relatively constant. Over the course of three decades, the observed plant growth on dry land has been about 53.6 petagrams of carbon each year, Dr. Running writes in the article. This suggests that plants' overall productivity — including the corn that humans grow and the trees people log for paper products — is changing little now, no matter how mankind tries to boost it, he said."

Comments

Hmmm...

[NettiWelho]

I dont think there will be any actual planetary limits on crop production, just the matter of understading all of variables and how they interact.

But are we really trying?

[__aaltlg1547]

What we're trying to do is grow SPECIFIC plants that are useful to people. We have never cared much if at all that what we are really doing is converting areas that grow one kind of plant to grow another kind of plant. If we were trying to increase primary production, no doubt we could do that, but we would be up against the same things that limit agriculture now: mainly water availability. But if you built a lot of greenhouses and water recycling systems we could probably increase primary production substantially.

Re:But are we really trying?

[fustakrakich]

...mainly water availability.

The stuff falls out of the sky every day. We just have distribution issues, only a tiny percentage of which is technical. But be ready for real fast and massive climate change if we were to suddenly 'green the deserts'.

Re:But are we really trying?

[icebike]

What we're trying to do is grow SPECIFIC plants that are useful to people. We have never cared much if at all that what we are really doing is converting areas that grow one kind of plant to grow another kind of plant. If we were trying to increase primary production, no doubt we could do that, but we would be up against the same things that limit agriculture now: mainly water availability. But if you built a lot of greenhouses and water recycling systems we could probably increase primary production substantially.

Well, that's a nice theory, but its simply not true.

The amount of land dedicated to farming has not substantially increased, (in fact it has decreased) as farming becomes more efficient. Vast tracts of the
midwest have returned to forest because there is simply no economic need to keep these lands under the plow.

This whole theory is nothing but a huge rehash of the Limits To Growth, cited in TFA. Yet 40 years hence, LTG has been proven wrong in just about every single prediction they made. Their methodology and assumptions were simply wrong.

Measurement of plant tonnage via satellite imagery has revealed that plants still grow just about everywhere they ever did. Wow. Major revelation.

Yet the satellites seem to miss the fact that global food production has more than tripled since 1961, and worldwide, we are only using 7% more land in the process. In North America Europe, and Russia, we are actually cultivating less land, and producing vastly more food. Marginal lands have fallen fallow, and returned to prairie or forest of a 2 hundred years ago.

Measuring the area covered by plants says nothing about the tonnage harvested every year off of that land. Nor does it say anything about the reduced pollution produced in the process, and the return of natural flora coverage. The total forest area in the U.S. has been relatively stable for the last 100 years (currently about 747 million acres). The species may change (they always have over time). But its not because we have converted the land to farming. For the last 100 years, the biggest threat to forests has been housing development, not farming.

Re:But are we really trying?

[icebike]

We are greening the desert. More rain has fallen in the Sahara in the last decade than in the previous two millenia. I doubt htis is good.

Why would it be bad? The Sahara has been growing for several hundred years, and halting or reversing that growth could well be positive.

Re:But are we really trying?

[symbolset]

We haven't even begun to exploit clathrates. There's far more of that than there ever was of oil. The arctic and antarctic reserves of oil and gas are far more than those yet discovered. Carbon fuels have a few hundred years to go yet.

As current species move toward the poles, more heat tolerant species are generated at the equator. And life backfills the change with more life. Such is at it has always been. Our dynamic world has never been stable, and should never be.

The supposition of AGC has ever been that a static climate is a desirable thing, despite the fact that such a thing has never existed in the history of the Earth, and never will.

Re:But are we really trying?

[LourensV]

As current species move toward the poles, more heat tolerant species are generated at the equator. And life backfills the change with more life. Such is at it has always been. Our dynamic world has never been stable, and should never be.

Heat tolerant species are generated? By whom? And more importantly, how quickly? Plants generally live quite long (annuals excepted obviously) and take quite a while to reproduce, especially in extreme circumstances. That means that evolution goes slowly. Climate change is currently happening extremely quickly. Hand waving doesn't make that problem go away.

The supposition of AGC has ever been that a static climate is a desirable thing, despite the fact that such a thing has never existed in the history of the Earth, and never will.

Humans haven't existed for most of the history of the Earth. Like all species we have a climatic niche that we fit into (hint: deserts, rain forests and polar regions are very sparsely populated). Now we're changing the planet to reduce the amount of space that falls within that climatic niche. Has the planet seen similar circumstances before? Sure, and it was fine. But what's important to us is that our species survives and thrives. Arguing that the planet will be fine is like saying that it doesn't matter when your only car breaks down halfway during your trip because the road will still be there. That's as correct as it is useless.

Or, another way to look at it...

[EmagGeek]

... no matter how much plant matter humans harvest for various reasons, the Earth is able to replenish it to its maximum level.

Quantity != Quality

[onyxruby]

Quantity of plant life does equal quality of plant life, much less diversity of plant life. Simply saying we have "X" isn't that terribly helpful without context.

So I'll provide some context and let's put a twist on this story which is being spun for political gain. In the year 1980 we had 4,453,831,714 people (the study starts in 1982 but close enough) In just 30 years the world's population grew 6,848,932,929.

Over the course of three decades, the observed plant growth on dry land has been about 53.6 petagrams of carbon each year

In other words, we have grown the population of the world by 50% in thirty years and we still kept just as much plant life. Job well done with planting things to compensate for a growing population! We don't need to change a thing, we doing everything right. Neither answer is right of course, they are both ways of spinning a set of meaningless facts.

Point of the matter is that any given set of statistics can be twisted for a given political agenda with ease. The only thing this study does is show how easily meaningless data can be slanted for gain political purposes when the data is without merit. All it does is measure quantity without context. Might as well say a ranchers supports incredible wildlife, there's 200 cows and a dozen field mice.