Vũ trụ bao gồm tất cả các nguyên tử và các hạt cơ bản cấu thành nên mọi dạng tồn tại của thế giới vật chất. | BIOSPHERE FROM SPACE By the time that report was published in 2000 Sellers was in training as a NASA astronaut so as to observe the biosphere from the International Space Station. The systematic monitoring of the land s vegetation by unmanned spacecraft already spanned two decades. Tucker collaborated with a team at Boston University that quarried the vast amounts of data accumulated daily over that period to investigate long-term changes. Between 1981 and 1999 the plainest trend in vegetation seen from space was towards longer growing seasons and more vigorous growth. The most dramatic effects were in Eurasia at latitudes above 40 degrees north meaning roughly the line from Naples to Beijing. The vegetation increased not in area but in density. The greening was most evident in the forests and woodland that cover a broad swath of land at mid-latitudes from central Europe and across the entire width of Russia to the Far East. On average the first leaves of spring were appearing a week earlier at the end of the period and autumn was delayed by ten days. At the same mid-latitudes in North America the satellite data showed extra growth in New England s forests and grasslands of the upper Midwest. Otherwise the changes were scrappier than in Eurasia and the extension of the growing season was somewhat shorter. We saw that year to year changes in growth and duration of the growing season of northern vegetation are tightly linked to year to year changes in temperature said Liming Zhou of Boston. The colour of the sea Life on land is about twice as productive as life in the sea hectare for hectare but the oceans are about twice as big. Being useful only on terra firma the satellite vegetation index therefore covered barely half of the biosphere. For the rest you have to gauge from space the productivity of the grass of the sea the microscopic green algae of the phytoplankton drifting in the surface waters lit by the Sun. Research ships can sample the algae only locally and
