Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
The tropical belt has been widening over past decades — as estimated from a number of independent lines of evidence — shifting the dry subtropical climate zones polewards around the world.
