一本教会你“做对”题的6级阅读书 day15 passage5
Passage 5 Climate Change: How Fast Is the Earth Shifting?
气候变化新标准 《时代周刊》
There are many units by which to measure the impact of climate change:
degrees of increasing temperature, feet of rising sea level,
dollars needed to adapt to a warming world.
But a group of scientists in California
have put forth an intriguing new unit of measurement: kilometers per year.
Writing in a paper published Wednesday in Nature,
scientists describe what they call the velocity of climate change,
or more specifically, the speed of Earth's shifting climatic zones.
As global temperature rises over the next century, the scientists argue,
Earth's habitable climatic zones will start moving too,
generally away from the Equator and toward the poles.
[01:01]That means many species of plants and animals will also have to move in order to survive.
[01:11]Whether or not they do will depend on several factors,
[01:15]but two of the most important are how fast a species can adjust its habitat range,
[01:24]and how quickly that range is moving out from under it.
[01:29]Until now, ecologists have mostly focused on these factors as they affect individual species,
[01:39]but the new paper takes a more global view.
[01:44]By combining temperature projections on a very fine scale with global topographic maps,
[01:52]researchers have predicted change not for specific species,
[01:57]but for the climatic zones they need to keep up with.
[02:02]Indeed, because global temperature is rising now, ecosystems are already on the move.
[02:11]"Once you explain it to people, it makes intuitive sense," says co-author David Ackerly,
[02:19]a University of California, Berkeley, biologist.
[02:24]"We know what it's like to drive north to escape the heat.
[02:30]It's concrete, rather than the abstractness of rising average temperatures."
[02:36]More than intuitive, this new index could also prove very useful,
[02:43]especially to conservationists who work to keep species from extinction.
[02:50]While the average velocity of climate change may be a bit less
[02:56]than a half-kilometer per year worldwide, according to the paper,
[03:02]it can be significantly faster or slower depending on the local topography.
[03:10]In deserts and other flat areas, such as the Amazon basin,
[03:16]climatic zones will move faster, while hilly or mountainous terrain will slow things up.
[03:24]"In the Northern Hemisphere, for example,"
[03:28]explains lead author Scott Loarie, "north-facing slopes tend to be cooler
[03:35]and wetter than south-facing slopes."
[03:39]In short, opposite sides of a mountain may have different climates,
[03:45]even though they're close to each other.
[03:49]In areas with varied terrain including lots of hills, therefore,
[03:55]hospitable conditions might be available relatively nearby.