warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia.
warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia.
global warming:4
while there have been prehistoric periods of global warming, many observed changes since the mid-20th century have been unprecedented over decades to millennia.