Which came first the forest or the rain?

It is rainy season here. Most days (today included) we get an impressive storm and our water tanks overflow. We are in an equatorial rain forest after all: we have the location, trees and weather to prove it.

Clouds over Bwindi Impenetrable National Park, Uganda. Clouds are often found over forests. What causes what?

Here is an interesting question: is the forest here because of the rain or is it the other way around? Being in a highland area we probably get much of our rain simply due to the terrain (mountains tend to be wet even in dry regions) and the forest vegetation takes advantage of that.

But what about in the wet lowland forests of the Congo and Amazon basins? How does so much rain get so far inland from the oceans? You might think that climate scientists know the answer. Actually they don’t. That troubles me.

Clouds forming over the forest — Bwindi Impenetrable National Park, Uganda.

I have spent some time trying to understand how so much rain gets into the interior of wet continental regions. Why do winds blow the way they do and why do they carry so much rain?

One theory really deserves recognition.  The theory suggests that forests are the reason: they attract rain. The physical principles behind this idea have been explained by two physicists. Their publications are not easy to read and follow … but I have spent some time trying to share their ideas because I think they are important.

The basic concept relates to how water vapour, via condensation and evaporation, gives rise to differences in atmospheric pressure between areas and thus cause winds — these winds in turn control where rain comes from and goes to. If the theory is true we have a whole new way to understand how climate works and a whole new reason to value forests.

Last year April, Daniel Murdiyarso and myself published an overview of the basic ideas that got some media coverage. You may have seen some of it: e.g. Mongabay, New Scientist and Scientific American. We even got a recent mention in to the Economist. If you like you can see our original article in Bioscience (here is a text version, but it lacks the figures, ask me to send the file if you are interested).

Morning time clouds — Bwindi Impenetrable National Park, Uganda. Would the clouds be there without the forest?

So why is this news? Well, I’ll get there in a moment.

Recently I have teamed up with the physicists themselves: Drs. Anastassia Makarieva and Victor Gorshkov. You can lean more if you visit their site.

Perhaps we should not be surprised that there is a lot of critical comment about their climate ideas out there —  science works through critical scrutiny and radical ideas should certainly be well scrutinised. I welcome that.  But it also seems to me that some, perhaps most, of the comments are misdirected — when we look in detail the theory is not being understood in the manner intended. Misreadings and assumptions get in the way.

So to get a fair hearing we need to communicate the ideas as clearly as we can. That’s not so easy for math whizz Russians, writing and talking atmospheric physics, and not for me either, but together we have tried. Since today we have a new manuscript up for anyone, including you, to see.  Feel free to take a look at the text here.  Its technical  because climate science needs to be but we also hope it makes good clear sense.

Will it change the World? I don’t know. But it might.

So now we wait and see what the rest of the scientific community thinks. Some may like it, others may not  … if their comments are insightful I wont mind either way (well not too much). That’s how science moves forward.

Let me know what you think – thanks!

Best wishes


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  1. Jimmy from Ireland
    Posted 15/10/2010 at 8:57 pm | Permalink

    I firmly believe tropical forest cover is vital for climate sustainability and water shed protection. There is increasing evidence for this, particualry from work done in the Amazon.:)

  2. Posted 18/10/2010 at 11:13 am | Permalink

    Thanks Jimmy from Ireland. Glad to have your support! Now we just need to see if we can persuade the climate scientists about this.

    Let me share another informal discussion forum for those interested in this theory. See: http://noconsensus.wordpress.com/2010/10/15/where-do-winds-come-from/

    Best wishes
    Douglas (also from Ireland)

  3. billgreenjeans
    Posted 12/02/2014 at 3:15 pm | Permalink

    I visited the Turks and Caicos Islands many years ago and saw that there were very few trees on the island and when I ask the locals was there no trees because they were cut down so it wouldn’t rain to help with the harvest of salt or was it because it didn’t rain much on the islands. I am still looking for the answer.

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