The image shows two views of the rabbit-proof fence, stretching aobut 2,000 miles across South-Western Australia. It separates off native land from farmland with the idea of keeping rabbits out.
Clouds form a lot more on the native side than the other, showing a correlation between farmland and decreased rainfall. That’s it really, but there are some speculations and other stuff in a NY Times article about it.
There is a research paper by Tom Lyons of Murdoch University, impact_of_clearing (pdf) which goes into detail, and an abstract of another paper: The role of land use change on the development and evolution of the west coast trough, convective clouds, and precipitation in southwest Australia on the JGR site
(And the fence, it doesn’t work, obviously — what kind of idiot would try to build a 2,000 mile long version of something they haven’t invented a one mile version of yet? And more to the point, what kind of idiot would pay them to do it? Oh, hang on, the kind of idiot that would chop all the trees down and expect to just keep on farming without them forever. The fence builders saw them coming didn’t they?!