Biological consequences of global warming: is the signal already apparent?

Trends Ecol Evol. 2000 Feb;15(2):56-61. doi: 10.1016/s0169-5347(99)01764-4.

Abstract

Increasing greenhouse gas concentrations are expected to have significant impacts on the world's climate on a timescale of decades to centuries. Evidence from long-term monitoring studies is now accumulating and suggests that the climate of the past few decades is anomalous compared with past climate variation, and that recent climatic and atmospheric trends are already affecting species physiology, distribution and phenology.