Left 4 Dead 2 Download Ocean Of Games

[Michele Firmasyah]

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We all rely on the ocean, whether we know it or not. Earth's vast expanses of water are key to the success of all life on Earth. We eat fish from the ocean, we breathe the oxygen it gives off, we feel the warmth of its huge currents. Without a healthy ocean, humans cannot thrive.

But the ocean has taken a pummelling and we have not been treating it well. It is facing down three huge threats: overfishing, pollution and climate change. Most of these are caused by human mismanagement. Nature is stretching to breaking point. If we don't stop, the ocean could be drastically changed within our lifetimes.

Rivers of pollution flow into the ocean every day, with little sign of slowing down. Marine animals and birds now regularly eat plastic, and so do humans. It is estimated that by 2050 there could be more plastic in the sea than fish.

As the plastic piles up, fish disappear. Since industrialised fishing began in the mid-twentieth century, the oceans have been transformed. Today's seas contain only 10% of the marlin, tuna, sharks and other large predators that were found in the 1950s. To stop this slaughter, conservationists are calling for a third of the world's oceans to be protected from fishing.

As our appetite for seafood grows and fish populations crash worldwide, scientists think that jellyfish might be the big winners. With fewer fish around, jellyfish have less competition for the plankton they feed on. They also thrive in warmer waters and seas polluted by fertilisers from farming. In the oceans of the future, jellyfish could be one of the few things left on the menu.

If we fished more sustainably, the picture would be much brighter. If we all ate seafood less regularly and we allowed stocks time to recover, fish populations would be able to keep up with human appetites.

Earth's oceans have been around for billions of years, and they've gone through periods of warming and cooling before. Museum scientists study these past periods of climate change so they can predict what will happen to ocean animals in the future.

Research leader Prof Richard Twitchett says, 'We have a really good idea of what oceans look like when the climate warms. It has happened to Earth many times before, and here in the Museum we have collections of fossil animals and plants that date back millions of years, so we can see how they responded. The rocks and fossils show us that as temperature increased in the past, oxygen levels fell and huge areas of the seafloor became uninhabitable.

When the oxygen levels go down, dead zones will expand. These are areas of the ocean where the water quality is too poor to sustain life. Pollution will only add to the devastation unless we stop it.

Other animals breathe air, like whales and turtles, so they get their oxygen from the atmosphere. They won't be affected in the same way, but everything else will. Smaller fish will have knock-on effects up the food chain, and result in smaller predators too, like sharks.

Warm water decreases an ecosystem's productivity too. Certain organisms like burrowing sea urchins and mud shrimp that live within the seafloor are really important for nutrient recycling. So if those animals get smaller, there would be less productivity within the oceans systems.

Climate change is causing ice sheets to melt at a rapid rate, which means sea levels everywhere will rise. That could be a tragedy for humans as coastal cities face flooding, but for marine animals it probably won't matter too much.

Richard explains, 'A metre or so of sea level rise isn't a lot at all compared to past ice ages when Earth saw sea levels changes of tens or hundreds of metres. The UK, for instance, has had much higher and much lower sea levels before, and marine ecosystems continued to thrive. Sea level alone is not a problem for marine animals.

The ocean is a major carbon sink. Any animal with a hard and calcareous skeleton, like plankton, stores carbon inside its tiny body. These miniscule organisms are powerhouses in the fight against climate change.

Many animals, including whales, also rely on krill and plankton as a food source. Ocean acidification would affect them too. Blue whales, the largest animal on Earth, have grown so because they are able to take advantage of the wealth of krill and plankton in our oceans. If they lost their food source, it's likely we'd lose them too.

Seaweed could become a staple in our diet. Many seaweeds are grown worldwide without artificial fertilisers or pesticides and they are a nutritious food, rich in protein. Seaweeds can also be used to feed livestock and as a biological alternative to plastic packaging.

For example, throughout their long lives, whales build up large plugs of wax inside their ear canals. Museum scientist Richard Sabin has analysed this earwax and identified traces of toxins which were once used in pesticides, paints and plastics. Whales eat these toxins and pass them onto their young. The chemicals build up over time and can damage the animals' immune systems and ability to reproduce.

Richard says, 'Many of these pollutants were banned decades ago but they are very persistent and are still circulating through marine ecosystems. In addition, our studies indicate the effects of other sub-lethal stressors such as ocean noise pollution, which hampers the ability of large whale species to communicate with each other. This is particularly important for solitary species like the blue whale who call to each other across large distances to find a mate, and social species like killer whales who communicate when they hunt.

'As apex predators in the ocean, cetaceans play an important role in maintaining the delicate balance of marine ecosystems. Imagine a world where we lose our ocean giants, our resident coastal cetacean communities, and the ability to show our children the beauty and extreme diversity of these incredible animals.'

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Visitors, including Dead Sea researcher Yael Kiro from Israel's Weizmann Institute of Science (second from left), examine salt formations on the shore of the Dead Sea in Israel on Nov. 5. Ofir Berman for NPR hide caption

Gregory, a recent immigrant from Russia, floats in the Dead Sea at a beach connected to an Israeli hotel resort on Nov. 10. The water of the lake is so full of salt that bathers float right to the top. Ofir Berman for NPR hide caption

Tourists bathe in the Dead Sea near an Israeli hotel resort on Nov. 10. The lake's southern basin, where Israel's resorts are located, is actually an artificial evaporation pool of Dead Sea water maintained by the Dead Sea Works, an Israeli chemical company that extracts minerals from the lake's water. Ofir Berman for NPR hide caption

As the lake recedes, it changes the landscape around it in both beautiful and ominous ways. Exquisite salt formations are revealed where the water dries up. But there are also apocalyptic scenes of condemned beaches and parking lots swallowed up by sinkholes along the shore.

A large sinkhole in the middle of the road in the Ein Gedi area west of the Dead Sea in Israel on Nov 5. Ein Gedi Beach is completely closed to bathers due to the danger of sinkholes. Ofir Berman for NPR hide caption

Solutions have been proposed to replenish the Dead Sea, but no significant action has been taken to prevent its further destruction. Climate change makes rehabilitation of the lake seem even further out of reach.

Israel's Dead Sea Works factory piles up white potash, which is extracted from the Dead Sea and exported for fertilizer, in the southern part of the Dead Sea on Nov. 10. The company was founded by Israel in 1952 and mines the lake for minerals such as potash, bromine and bromine compounds. Ofir Berman for NPR hide caption

It's a human-made problem, say environmental researchers and officials. In a region where water is scarce, Israel, Jordan and Syria in the last several decades have diverted the freshwater sources that feed the Dead Sea, for drinking water and irrigation. Plus, Israeli and Jordanian companies evaporate Dead Sea water to harvest its rich minerals for export. The part of the lake dotted with Israeli hotel resorts, a popular spot for tourists to float in Dead Sea water and lather the lake's mineral-rich mud on their skin, is actually an artificial evaporation pool in the lake's southern basin.

It's shocking to see the ridges along the shore, a clear four-foot drop every single year. The salty sea is receding so quickly, it leaves behind stunning salt formations along the shores: small salt pebbles on the beach, large salt mushrooms on the shore and tall salt chimneys sticking out from inside the lake.

"You've seen a living disaster in front of your eyes," says Jake Ben Zaken, an Israeli who says he operates the only passenger boats on the Dead Sea. Ofir Berman for NPR hide caption

Rachel Kiro, 13, the daughter of Dead Sea researcher Yael Kiro from Israel's Weizmann Institute of Science, sits atop a salt formation in the northern basin of the Dead Sea. Ofir Berman for NPR hide caption

"It breaks my heart because there's just so much destruction," says Dead Sea researcher Yael Kiro from Israel's Weizmann Institute of Science, standing at the edge of the sunken road. "This is just a direct result of the lake level drop."

Left: Sinkholes near the western shores of the Dead Sea. Right: Researcher Yael Kiro from Israel's Weizmann Institute of Science at the Dead Sea on Nov. 5. Ofir Berman for NPR hide caption

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