After applying Boolean and other operators to our keywords, a search on our topic in a database like Scopus would look like this:

Use the + icon option to add more rows.

The search box set-up in a database like Scopus provides the ANDs to combine concepts. It is also possible to put the entire search in one box if you type it out using three pairs of brackets to group Aspects 1, 2 and 3 :

( "climate change"  or  "global warming" )  and   ( "weather event*"  or  thermal  or  rainfall or temperature  or drought ) and ( grain*  or  cereal*  or  wheat  or  barley  or  rye)  and  ( crop* or  production )

Boolean Operators in Google or Google Scholar,

Although a capitalized OR operator is recognized, eg. climate OR rainfall OR temperature OR weather
a search such as the one below will not work as straightforwardly as it would in a Library database.

( "climate change"  OR  "global warming" )  AND  ( "weather event"  OR  thermal  OR  rainfall OR temperature  OR drought)  AND  ( grain  OR  cereal  OR  wheat  OR  barley  OR  rye)  AND  ( crop  OR  production )

For more information see:

6 common misconceptions when doing advanced Google Searching

Google does not support full Boolean logic

Google Searching: Search Operators