What happens when you create a data race in Go?

Console_output

cagocs:examples christopheragocs$ go run shared_memory.go
I am a very global string.I have been to LondonI have been to France
I am a very global string.I have been to London
I am a very global string.I have been to LondonI have been to France
cagocs:examples christopheragocs$ go run -race shared_memory.go
==================
WARNING: DATA RACE
Write by goroutine 4:
  main.writeToSomeString()
      /Users/christopheragocs/personal/golangIntro/examples/shared_memory.go:26 +0x38

Previous write by goroutine 3:
  main.writeToSomeString()
      /Users/christopheragocs/personal/golangIntro/examples/shared_memory.go:26 +0x38

Goroutine 4 (running) created at:
  main.main()
      /Users/christopheragocs/personal/golangIntro/examples/shared_memory.go:15 +0xa7

Goroutine 3 (running) created at:
  main.main()
      /Users/christopheragocs/personal/golangIntro/examples/shared_memory.go:14 +0x79
==================
I am a very global string.I have been to LondonI have been to France
I am a very global string.I have been to London
I am a very global string.I have been to LondonI have been to France
Found 1 data race(s)
exit status 66
cagocs:examples christopheragocs$

shared_memory.go

package main

import (
	"fmt"
	"time"
)

var someString = "I am a very global string."

func main() {

	stringChannel := make(chan string)

	go writeToSomeString("I have been to London", stringChannel)
	go writeToSomeString("I have been to France", stringChannel)

	time.Sleep(1 << 24)

	fmt.Println(someString)

	fmt.Println(<-stringChannel)
	fmt.Println(<-stringChannel)
}

func writeToSomeString(whatToWrite string, sc chan string) {
	someString = someString + whatToWrite
	sc <- someString
}