Deforestation of rainforest is causing climate changes

[jay gw]

SYDNEY (Reuters) - Australian scientists have found that deforestation along the Amazon River in South America was reducing rainfall and causing climate change in the region.

A study in the Amazon found that a loss of forests meant less water evaporated back into the atmosphere, resulting in less rainfall, said Ann Henderson-Sellers, director of environment at the Australian Nuclear Science and Technology Organization.

Key to the study was plotting the cycle of a heavy molecular version of water common in the Amazon that evaporates more readily through plants than from lakes and rivers.

Water from household taps consists of two "regular" hydrogen atoms and one "regular" oxygen atom, explained Henderson-Sellers, but some water molecules see the second hydrogen atom replaced by a heavier version called deuterium.

"Plants transpire the water molecules and pumps them back into the air, without discriminating between heavy or regular molecules," Henderson-Sellers told Reuters.

As the study tracked the water cycle as it flowed from the Amazon River into the Atlantic Ocean, evaporated, fell as rain and returned back to the sea, scientists discovered there had been a reduction in heavy-molecule water since the 1970s.

http://www.tehrantimes.com/Description.asp?Da=3/13/2005&Cat=7&Num=4

 

[Zep]

The "Tehran Times"?? Wow, THEY must be ahead of the rest of the world on this one...

But let me go check with ANSTO on this - I know the people there...

 

[Zep]

I see...

http://www.ansto.gov.au/info/press/2005/anstomedia005_020305.pdf

Nuclear Fingerprinting Identifies New Climate Change Measurements

New climate change research using rainfall data collected throughout the Amazon shows that rare, naturally occurring water isotopes accurately measure deforestation and greenhouse impacts and could provide the world’s first independent accuracy test of Global Climate Models, ANSTO* on-line magazine Velocity reported today.

...

A report on "improved scientific accuracy" gets turned into one about "how bad is deforestation of the Amazon!". And in the process, it loses the plot about how the process works (read the article to find out).

Why does it seem that if you fail basic science and comprehension at school, you can still be a journalist?

 

[jay gw]

That's not what the article from Ansto said in its entirety. The real story is that there is less rainfall around areas of deforestation, compared with fully forested areas.

That's what journalists are paid to do, not start with the headline: "Wow guess what?? There's a new test for climate change!" Who cares?

The real issue is that once areas are deforested, replanting them will become difficult or impossible. The rainfall will continue falling, meaning growth rates will be cut in half or a quarter.

 

[Zep]

No, the ANSTO report said merely that it CONFIRMED ACCURATELY what they ALREADY KNEW about rainfall and deforestation. Thus adding a new and accurate tool to scientists' toolkits.

ANSTO, if you didn't notice, is the Australian atomic science agency. Why they would be making grandiloquent predictions on the current state and projected future of the Amazon basin deforestation (as the Tehran Times makes out), is a subject out of their scope, and is thus a bit ridiculous. However the use of isotope detection as a tool for measuring deforestation IS their scope. Which is what the original release is about.

In short, the Tehran Times report is in large part a piece of journalistic invention and distortion.

 

[Dilb]

That's not what the article from Ansto said in its entirety. The real story is that there is less rainfall around areas of deforestation, compared with fully forested areas.

That's what journalists are paid to do, not start with the headline: "Wow guess what?? There's a new test for climate change!" Who cares?

The real issue is that once areas are deforested, replanting them will become difficult or impossible. The rainfall will continue falling, meaning growth rates will be cut in half or a quarter.

Every time I read both of those articles, they say that the composition of water has changed, and don't say anything about the volume, except for what looks like a mistake in the first aticle. To quote:

However, when trees evaporate (called transpiration), heavy isotopes are
released in the same way as normal water molecules, so there is a different signature of water recycled through trees
than through rivers and lakes.

I don't see anything saying they studied the volume. They have a way of measuring deforestation based on the change it causes in the heavywater concentraion of rain. Yes, heavy water isn't evaporating, but 1. It's about 1 part in 5000, and 2. It's presumably being replaced by light water.
Really, am I horribly missing something? I don't see rain volumes mentioned anywhere. Furthermore, why would they measure heavy water concentration if all they had to do was put a test-tube outside and measure the amount of rain?

 

[Luciana]

The real issue is that once areas are deforested, replanting them will become difficult or impossible. The rainfall will continue falling, meaning growth rates will be cut in half or a quarter.

Evidence?
What I know is that the forest grows back very, very fast. Sure, there can be a point where it is deforested faster than it can grow back. But if deforestation stops, regrowth starts back. That's what has happened numerous times. As short as 5 year's time you can see a forest where once was a burned area. Sure, less dense, less fauna and flora... but just give it time. That's why I'm asking for evidence of your assertion.

The Amazon is so HUGE, that once deforestation destroy a little of its margin, the neighboring forest will rush to "swallow" back the area.

I hear that the Amazon forest will be gone soon since the day I was born. And it's still there.