The report, released in Lhasa by the Chinese Academy of Sciences (CAS) and the government of Tibet, finds that precipitation has risen by 12 percent since 1960 and temperatures have soared by 0.4 degrees Celsius per decade - twice the global average.
"The Tibetan plateau is getting warmer and wetter. This means that vegetation is expanding to higher elevations and farther north, and growing seasons are getting longer," said Yao Tandong, director of the CAS Institute of Tibetan Plateau Research in Beijing.
But some areas, such as the headwater region of Asia's biggest rivers, have become warmer and drier and are being severely affected by desertification and grassland and wetland degradation, he added.
In addition, glaciers are shrinking rapidly and one-tenth of the permafrost has thawed in the past decade alone.
"This means that the number of lakes has grown by 14 percent since 1970 and more than 80 percent of them have expanded since then, devastating surrounding pastures and communities," the report added.
The plateau and its surrounding mountains cover 5 million square km and hold the largest stock of ice outside the Arctic and Antarctic.
The region is thus often referred to as the Third Pole.
"Like the actual poles, it is increasingly feeling the effects of climate change but rapid development is putting it doubly at risk," the report noted.
The plateau feeds Asia's biggest rivers so these problems are likely to affect billions of people, the report maintained.
Pollution from human and industrial waste as a result of rapid development is also a serious risk.
"Human activity, too, is on the rise. The population of the plateau reached 8.8 million in 2012, about three times higher than in 1951. And the number of livestock has more than doubled, putting more strain on grasslands," said a report published in the journal Nature.
The assessment report calls on the concerned agencies to make conservation and environmental protection top priorities, it added.