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Phenology is the study of the timing of life cycle events at the population level, most often focusing on how they respond to climate change. It often makes use of long-term records and includes events such as flowering, leaf fall, hatching and annual migration.
Greening—increasing leaf area index—affects regional climate in a number of contradictory ways. The net global effect is now revealed to be cooling that has offset the equivalent of 12% of global land-surface warming over the past 30 years.
Predicting plant responses to increasing temperatures is integral to assessing the global impact of climate change. But the authors of a comparative study assert that warming experiments may not accurately reflect observational data. Climate and ecosystem scientists discuss how impact prediction should proceed. See Letter p.494