Climate change has been a big factor. Robusta tolerates higher temperatures – typically 22 – 30 degrees Celcius (72 – 86 degrees Fahrenheit) – than Arabica – typically 15C – 20C (59 – 68F) – and is more resistant to disease, insects and funguses. Studies have shown that by 2050 as much as 50 percent of the land used to grow Arabica today might be unsuitable for production.