Tariffs reduce real purchasing power for consumer. This reduces aggregate demand. Probably the biggest signal is coming from the bond market. The yield curve is inverted. There has been a flight to longer maturity Treasuries which is usually a precursor to a recession. You would probably want to look at some leading indicators like housing starts, building permits etc..
The fact that many major imndustrial economies have negative interest rates leaves little wiggle room for coordinated monetary expansion which means the the global economy is quite vulnerable.