At the ends of the world, the sun’s reach
is weak. Life struggles or is entirely absent. And indeed what life could survive in a world
of freezing temperatures for most or all of the year? A treeless world of hardy shrubs, lichen and
moss dominates the north, while a permanent layer of ice covers the south. These are the last of the biomes of our planet. This is the Arctic and Antarctic. This is the tundra and ice. The poles of our world receive sunlight at
only an oblique angle, bringing little in the way of heat. And for almost half the year there is no sun
at all. This dynamic of poor solar heating produces
the coldest of the biomes - the tundra and ice. What separates these two biomes is only ten
degrees of Celsius. In the tundra, summer temperatures rarely
exceed 10°C. This prevents the growth of trees, and so
marks the boundary between the boreal forest or taiga, and the tundra. Only hardy shrubs, herbs, moss and lichen
can grow here, covering the bleak landscape when it’s not already covered in ice as
it is for most of the year. These lands fringe the entirely of the arctic
ocean, from North America and the coasts of Greenland to the north of Russia. The ice biome permanently covers ground that
never sees temperatures rise above 0°C, which… makes sense when you consider that this is
the point at which liquid water freezes. That liquid is essential to life, and so,
in a permanent state of frost, no plant life would have been possible even if the ground
wasn’t covered in a kilometres-deep layer of solid ice. The overlap of these two biomes with their
respective climate zones of the same names is pretty much total – and so those climate
zones are not misnomers. Because of this, I have covered both zones
in detail in my Secrets of World Climate series in two episodes. And you’ll find these linked top-right and
also in the description. For a full treatment of this subject, please
watch these in conjunction with this video, as unlike in real-life, I am not going to
repeat myself here. In our Holdridge Lifezones chart, we find
the tundra and ice in the top two rows. It is worth noting that the term desert is
used, which is, technically accurate, since the ice is deserted of life. Note also that the cooling of the temperate
scale is not just in terms of increasing latitude, but also in altitude. And so tundra and ice are found in the high
places of the world, above the treeline in the Rockies, Andes, Alps and Himalayas. However, in terms of percentage of land area
covered, these are tiny in comparison to the Arctic and Antarctic regions. The permafrost, a permanently frozen layer
of soil and ice stretching up to a kilometre down, is present in all Arctic tundra, as
it is in the Taiga. And like in that other biome, leads to extensive
bogs and lakes, since liquid water cannot drain into the rocks below. The permafrost is all but absent in alpine
tundra, and in the small tundra-like areas and islands found around the southern ocean,
such as Tierra del Fuego, the Falklands, the South Sandwich Islands and so on. Beneath the permanent icecap, no life exists,
but in the tundra life does, albeit in a limited form. In the short tundra summer, there are only
about 50-60 growing days permitted. This is too short for tree species to germinate,
and so this realm is dominated by plants that can quickly flower and reproduce in such a
short window. Lichen – a mix of fungi and algae is the
hardiest of all plant classes globally, and is found in all parts of the tundra. Mosses are the next-most hardy plant class
and these simple and ancient plants are also found throughout the biome. Sedges and cotton grass can be found in the
often boggy, peaty conditions existing in the tundra plains while on slightly elevated
sites, low willows, other grasses and rushes can be found. The tallest tundra species are found on better
drained, sandy soils of river banks, and come from species families that include willow,
sunflower and legume. Isolated stands of coniferous trees, known
as forest tundra, can be found in certain areas. These are vestigial remnants of taiga from
earlier times when the climate was once warmer, and have survived as clonal colonies, unable
to reproduce through the normal channel of seed germination. Fungi and bacteria are found throughout the
soil and act as essential vectors in the breakdown and recycling of dead plant material. The fauna in the tundra is limited, but where
it exists, is well-known. Polar bears patrol the coasts, while inland
areas feature large herds of grazing giants such as reindeer, caribou, musk-ox, and their
accompanying predators, arctic wolves. As in the taiga, these species are larger
than normal, since a bigger body is easier to keep warm than a small one. But not all tundra mammals are large, and
arctic hares, foxes and lemmings are also common, with many sporting seasonal white
coats as camouflage during the long icy winters. Antarctic fauna is well-known, in the form
of enormous colonies of penguins, as well as the seals that prey upon them. But strictly speaking, these animals are not
a part of the tundra or ice biome, as such, since they rely entirely upon the ocean, instead
of the land, for their survival. In terms of threats, the tundra and ice are
not directly threatened by human activity, since so few people live in these regions,
less than several hundred thousand in a planet of billions. However with the advent of climate change,
whether man-made or natural, the permafrost of the tundra is melting, as are the icecaps
of Greenland and Antarctica. The melting of the permafrost leads to the
release of methane, a potent greenhouse gas, while the melting of the icecaps will lead
to sea-levels rising, and global consequences. The tundra and ice make up the last two biomes
in the LONS08 classification system. And while other specialised biomes exist,
such as in the subtropical highlands around the equator, or the wetlands found across
the globe, this will be all I’ll be covering for now in this series. We have travelled from the equator to the
poles, exploring the amazing living landscapes across our varied planet. The greatest biodiversity of all within the
broadleaf forests of the tropics. The intense heat of the tropical savannahs
and the great herds and their predators. The desolation of the hot and cold deserts
that by land area make up the largest of the biomes. The unique and often-forgotten shrublands
of the subtropics and Mediterranean areas. The endless grasslands of the temperate regions,
and their geographic neighbours - the beautiful mixed forests of North America, Europe and
Eastern Asia. The dark and forbidding expanse of the taiga. The wasteland of tundra and ice at the top
and bottom of our world. It’s been an epic journey, and I hope you
learned or experienced something from it. Thanks again for watching. Please hit the like button if you enjoyed
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in a few weeks from now. Until then, stay green!