Climate change is already impacting coffee crops around the world, according to the report by the Climate Institute, commissioned by Fairtrade Australia & New Zealand.
In Tanzania, where 2.4 million people's livelihoods rely on coffee, production has fallen by about 137kg per hectare for every 1C rise in the minimum temperature on farms. Overall there has been a 50 per cent decline there since the 1960s.
In 2012-13 the damage in Central America amounted to about USD 500 million and put 350,000 people out of work.
How climate change will impact coffee growers in coming decades will vary by region.
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Scientists think Nicaragua could lose the majority of its coffee-growing areas by 2050, and in Tanzania, coffee yields were projected to reach "critically low levels" by 2060.
For consumers of coffee, all of this will impact flavour, aroma and price, the Guardian said quoting the report as saying.
Since most coffee growers are poor smallholders, their ability to adapt to climate change on their own is limited.
To adapt, coffee farmers could move to higher ground or away from the equator. But since coffee plants take several years to become productive, that would often be impossible without assistance. Other strategies involve developing more resilient production systems and diversifying crops, which also require support.
Connor said consumers should only buy brands that "provide a fair return to farmers and their communities while helping to build their capacity to adapt to climate change".