Leave it alone.

Or if its really long, set the mower on the highest setting to trim the tops off and let the clippings fly. Ours here is now completely brown or dun coloured in parts, not growing at all.

I was wondering if to scarify my lawn, I have green grass with a lot that has gone brown?

Not yet, you would be left with bare patches which would struggle to re-generate without water.

Thanks for that info Owdboggy.
Jackie x