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.