How can a script access a variable thats in another script?

I have a script that plays a song and when it does it has a variable called tempo. The tempo changes depending on the song. And I am trying to let tempo be accessed in another script but it says unknown global?

Theres the first script, tempo is only in the first block with Mr Blue Sky

local MrBlueSky = 862680756
local Believer = 685388224
local HowFarItGoes = 1058515832
local music = script.Parent
local musictitle = script.Parent.MusicName.MusicTeller.MusicTitle
local tempo = wait()

while true do
	wait()
	musicpicker = math.random(1,3)
	if musicpicker == 1 then
		musictitle.Text = "ELO - Mr Blue Sky"
		music.SoundId = "rbxassetid://"..MrBlueSky
		music:Play()
		music.PlaybackSpeed = 1
		music.Volume = 2
		tempo = wait(.3)
		music.Ended:wait()
		wait(3)
	end
	if musicpicker == 2 then
		musictitle.Text = "Imagine Dragons - Believer"
		music.SoundId = "rbxassetid://"..Believer
		music:Play()
		music.PlaybackSpeed = 1
		music.Volume = 2
		music.Ended:wait()
		wait(3)
	end
	if musicpicker == 3 then
		musictitle.Text = "Moana - How Far I'll Go"
		music.SoundId = "rbxassetid://"..HowFarItGoes
		music:Play()
		music.PlaybackSpeed = 0.673
		music.Volume = 2.5
		music.Ended:wait()
		wait(3)
	end
end

brick = script.Parent

while true do
	color = math.random(1,5)
	if color == 1 then
		brick.BrickColor = BrickColor.new(196/255, 40/255, 28/255) -- Bright Red
			wait(tempo)
	end
	if color == 2 then
		brick.BrickColor = BrickColor.new(4/255, 175/255, 236/255) -- Cyan
			wait(tempo)
	end
	if color == 3 then
		brick.BrickColor = BrickColor.new(52/255, 142/255, 64/255) -- Sea Green 
			wait(tempo)
	end
	if color == 4 then
		brick.BrickColor = BrickColor.new(123/255, 47/255, 123/255) -- Plum
			wait(tempo)
	end
	if color == 5 then
		brick.BrickColor = BrickColor.new(218/255, 133/255, 65/255) -- Bright Orange
			wait(tempo)
	end
end

Tempo is blue in this script and there both scripts not local scripts so I figured they could access each other. But they cant and I am a little confused on it.