The federally mandated study "Fourth National Climate Assessment", was supposed to come out in December but was released by President Donald Trump's administration on Friday, reports CNN.
David Easterling, Director of the Technical Support Unit at the National Oceanic and Atmospheric Administration (NOAA), said: "The global average temperature is much higher and is rising more rapidly than anything modern civilisation has experienced, and this warming trend can only be explained by human activities."
Coming from the US Global Change Research Programme, a team of 13 federal agencies, the report was put together with the help of 1,000 people, including 300 leading scientists.
It's the second of two volumes. The first, released in November 2017, concluded that there was "no convincing alternative explanation" for the changing climate other than "human activities, especially emissions of greenhouse gases".
The costs of climate change could reach hundreds of billions of dollars annually, according to the report.
The Southeast alone will probably lose over a half a billion labour hours by 2100 due to extreme heat.
Farmers will face extremely tough times. The quality and quantity of their crops will decline across the US due to higher temperatures, drought and flooding.
Heat stress could cause average dairy production to fall between 0.60 and 1.35 per cent over the next 12 years -- having already cost the industry $1.2 billion from heat stress in 2010.
When it comes to shellfish there will be a $230 million loss by the end of the century due to ocean acidification, which is already killing off shellfish and corals, CNN quoted the report as saying.
Higher temperatures will also kill more people, it added.
The Midwest alone, which is predicted to have the largest increase in extreme temperature, will see an additional 2,000 premature deaths per year by 2090.
There will be more mosquito- and tickborne diseases like Zika, dengue and chikungunya. West Nile cases were expected to more than double by 2050 due to increasing temperatures.
Wildfire seasons -- already longer and more destructive than before -- could burn up to six times more forest area annually by 2050 in parts of the US. Burned areas in Southwestern California alone could double by 2050.