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  • This video was made in collaboration with the National Center for Science Education

  • It's the beginning of summertime high in the alpine meadows of the Colorado Rocky Mountains,

  • and colorful displays of native wildflowers are just starting to bloom. But if you listen

  • carefully, you might notice something a little off. The usual buzz of bees foraging for food

  • has to yet begin.

  • In this particular alpine ecosystem, climate change has reduced the annual winter snowpack,

  • and warmer spring temperatures accelerate snowmelt. This extends the growing season

  • for plants - meaning that flowers bloom earlier than in decades past - but also makes them

  • more vulnerable to drought. But for the bees, warming temperatures have had a different

  • effect - instead of emerging earlier, as the plants did, many are now found higher up the

  • mountain, where the temperatures are cooler and better suited for bee activity. Bees and

  • plants are now experiencing less synchrony - they're less often in the same place at

  • the same time. As a result, bee's are struggling to find food and populations have declined.

  • This disruption of closely evolved symbiotic, or mutually beneficial, relationships - like

  • bees and flowering plants - can potentially lead to the extinction of other related organisms,

  • such as small mammals who dine on alpine plants, because, ultimately, the fate of multiple

  • species in this ecosystem are closely intertwined. But the bees and flowers in the alpine meadows

  • of the Colorado Rockies are just a small snapshot of what's to come. As the climate changes

  • and the world warms we are beginning to witness a global trend of decreasing biodiversity.

  • At its simplest, biodiversity is a measure of the variety and variability of life. Measures

  • of biodiversity include the total number of species in an ecosystem, the number of endemic,

  • or geographically unique, species, and the genetic diversity of a single species in the

  • ecosystem. Though there are many ways to measure biodiversity, these all seek to capture the

  • distribution of the variation of life we see around us. And as we've just seen with bees

  • in Colorado, climate change, along with habitat fragmentation, urbanization, and pollution,

  • are having huge impacts on global biodiversity. Today we are going to explore some ecosystems

  • whose biodiversity has been impacted by climate change.

  • Meet the Hawaiian honeycreeper, a unique family of birds endemic to the Hawaiian islands.

  • The 51 species of honeycreeper were once abundant throughout the islands, but today almost half

  • are extinct. A combination of invasive species and human land-use changes have decimated

  • the honeycreeper's lower-altitude habitats, while climate change in Hawaii keeps forcing

  • the birds to roost higher and higher, into much more limited space. Essentially, the

  • honeycreeper is running out of room to live. It is predicted that in the next 100 years,

  • all remaining species of this bird will be extinct.

  • But this loss of biodiversity isn't specific to Hawaii, it's occurring on islands around

  • the world. Islands are not only home to many endemic ecosystems, but they also represent

  • excellent case studies for understanding how climate change might affect worldwide biodiversity.

  • Islands have limited space, exacerbated by climate change-induced sea-level rise, which

  • makes it harder for species like the honeycreeper to change geographical ranges. In Polynesia,

  • the International Union for the Conservation of Nature estimates that 305 species may be

  • vulnerable to the direct effects of climate change, through restriction of their ranges,

  • increases in temperatures, and the effects of fires and other extreme weather events.

  • Currently, island species go extinct at a much higher rate than mainland species, with

  • that number expected to go up as climate change becomes more pronounced.

  • We are seeing the effects of climate change on biodiversity now and will continue to see

  • them worsen in the future. The record-breaking high temperatures and severe drought in Australia

  • from 2019-2020 is yet another example. This extreme weather brought an onslaught of unusually

  • massive bushfires across the country. Millions of hectares were burned, decimating an estimated

  • half a billion mammals, birds, reptiles, and insects, clearly decreasing the biodiversity

  • of Australia. The fires also destroyed mature trees that provide shelter for many organisms;

  • reduced the amount of food available in burnt areas, and decreased biodiversity by limiting

  • which plants are able to recover from the devastated areas. Biodiversity is like a network

  • of interactions directly and indirectly dependent on one another and climate change will only

  • disrupt these networks even more in the future.

  • Biodiversity hotspots, like Australia, are irreplaceable in that they contain endemic

  • plants and animals that can't be found anywhere else. These hot spots also support human populations

  • that are often dependent on interactions with the land through subsistence agriculture and

  • foraging. Decreasing biodiversity due to anthropogenic-induced climate change threatens their survival. The

  • United Nations Department of Economic and Social Affairs states, “Climate change poses

  • threats and dangers to the survival of Indigenous communities worldwide, even though Indigenous

  • peoples contribute the least to greenhouse gas emissions.” In the face of these challenges,

  • the report points out, “Many Pacific Islander communities are also building new infrastructure

  • and creating relocation plans. For example, the Native Hawaiian people are some of the

  • global leaders in climate change policy, planning, and adaptation. In 2018, the Hawai'i legislature

  • passed two bills pledging to make the state carbon neutral by 2045.”

  • We can all draw inspiration from the leadership of indigenous communities in addressing climate

  • change by taking steps to help preserve biodiversity. This can include supporting conservation efforts,

  • such as preserving critical habitat and restoring degraded ecosystems or it can mean connecting

  • with environmental centers, conservation societies, and environmental advocacy groups in your

  • community. Ultimately, efforts to reduce the rate of global warming are our best bet for

  • preserving earth's biodiversity. From advocating for environmental policies in national and

  • state government, to working with habitat restoration groups, or even reducing your

  • own carbon footprint, local actions that you take today can have a huge impact on maintaining

  • the diversity- of bees and other animals - worldwide.

  • Hey everyone, Charlie here. If you've been watching Our Changing Climate for a while

  • or just stumbled across this video and are wondering how you can help me make more videos,

  • then consider supporting the show on Patreon. As an OCC patron, you'll gain early access

  • to videos, special behind the scenes updates, as well as a members only group chat. In addition,

  • each month my supporters vote on an environmental group that I then donate a portion of my monthly

  • revenue to. So if you want to support the channel or are feeling generous, head over

  • to patreon.com/ourchangingclimate and become an OCC patron. The script for this video was

  • written by two National Center for Science Education Graduate Student Outreach Fellows,

  • Cat and DJ. It was awesome to work with them and I hope you liked the video as much as

  • I enjoyed making it. Thanks for watching and I will see you in two weeks.

This video was made in collaboration with the National Center for Science Education

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全球生物多样性正在崩溃(Biodiversity is collapsing worldwide. Here's why.)

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    joey joey 發佈於 2021 年 06 月 12 日
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