NASA Image of the Day (Large)
martes, 25 de agosto de 2009
Feeling the Sting of Climate Change
[music] Every year, farms and fields play host to a symphony, of sorts. Polination... the springtime syncopation of flowering plants and the animals that feast on the nectar and pollen they produce. Over millenia, pollinators like honey bees have evolved a well-timed dance with plants. But now, plants may be changing their tune. Spring green-up... ...when plants wake from winter and sprout leaves. It's such a global phenomenon that NASA satellites can see it from space.
[music] Sensors, such as Modis on NASA's AQUA and TERRA satellites, can show us how green our planet is throughout the year - and they've captured something strange. In the Northern U.S., spring green-up is starting about a half-day earlier each year. The likely cause? Our warming climate. But is pollination also moving earlier? The images can't detect individual flowers, so scientists have been left to guess... until now. NASA research scientist Wayne Esaias spearheads a special team gathering data directly in the field. They're the honey bees in his Maryland backyard.
[Wayne Esaias:] "Honey bees are great data collectors for understanding the processes of pollination. Bees fly two and a half miles in all directions to scout for bee forage and bring back pollen and nectar. So therefore they sample a very large range of environments." Weighing the hives, Wayne can detect when nectar peaks and ebbs each year.
[Wayne Esaias:] "During the winter, the hive loses weight as they eat the honey to feed the babies and keep warm. And then when plants start blooming in abundance, the hive starts gaining weight. It can gain a tremendous amount of weight. I've had a hive gain 25 pounds in one day." Wayne's been keeping tabs on his bees for less than twenty years. But in that time, pollination has moved more than ten days earlier.
[Wayne Esaias:] "That's completely in sync with what the satellite data shows - the world here getting greener earlier in the spring by about a half a day each year." here getting greener earlier in the spring by about a half a day a year."
[Wayne Esaias:] "If we have a few scale hive measurements with the wall-to-wall coverage of the satellite, we can then extrapolate those scale hive measurements of when the nectar flows occur extrapolate those scale hive measurements of when the nectar flows occur to very large areas of the country." Now, to get a bee's eye perspective of how pollination is changing in very different environments - say, deserts or mountains - Wayne's doing a little '"networking."
[Wayne Esaias:] "HoneyBeeNet is a network of citizen-scientist beekeepers that volunteered to weigh their hives to give us more data points, to see how the nectar flows are changing in all different parts of the country." If pollination dates keep creeping forward, plants and pollinators could move out of sync. Currently, young bees are able able to grow and get out on the hunt by the time plants bloom. But if plants bloom before bees are ready, both miss out. The plants don't get pollinated, and the bees go hungry. But more than just bees might miss a meal. NASA satellites can help us understand how climate change might affect what's on our dinner table.
[Wayne Esaias:] "Modern agriculture requires bees as part of the production. It's as mandatory for food production as as pieces of irrigation pipe and fuel for tractors. So if we're to understand the impact of climate change on our ecosystems, we must understand how this plant-pollinator interaction is being impacted by climate change."