Earth is Becoming a Greener Greenhouse


Background: Plant growth in the northern latitudes is seasonal, that is, growth begins with the arrival of Spring, peaks during the summer and declines towards the end of Autumn. These temporal changes in plant growth can be monitored by sensors onboard satellites, year after year. The data thus collected over a period of time, say 20 years, can be used to answer the following questions ...

Has the growing season become longer or shorter? We find that spring advanced by about 8 4 days in North America and 6 2 days in Eurasia. The decline of plant growth in autumn was delayed by 4 3 days in North America and 11 3 days in Eurasia. Therefore, the growing season is now about 12 5 days longer in North America and 18 4 days in Eurasia (see the figure below).