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Some problems are easy to solve. If we feel sweaty, we go to the shade. If our soup is too hot, we blow it. If the room is too stuffy, we will open the window.
But!What are the options when the earth gets too hot?
That's the problem that the planet is facing right now – and a huge one.
In recent decades, the earth has begun to have a fever. It is caused by carbon dioxide and other greenhouse gases polluting the atmosphere. The safest approach should be to stop polluting unless people show signs of drastically reducing the burning of fossil fuels that release pollution, so some scientists have begun to seriously consider backup plans.
It involves an "invasion of the Earth".
Researchers suggest several big ways to change the Earth's climate.
Adopting any of the items they propose would be such a significant step that many experts hope that people will never do it. But if successful, this geoengineering could slow global warming, if not reversible.
Risk: If unsuccessful, geoengineering could make things worse.
They propose altering natural processes in some of the most extreme but critical environments on Earth, from the deepest oceans to the upper atmosphere. Some projects propose to alter the atmosphere by eliminating pollution. Others involve reflecting more sunlight into space.
These global-scale projects all address the same big challenge: dealing with the effects of burning large amounts of coal, oil, and other fossil fuels.
Since around 1750, humans have used these fuels in large quantities and increasingly, emitting large amounts of carbon dioxide, methane, and soot into the air. These have dramatically changed the Earth's climate. Scientists now wonder if people can safely change it back.
Global warming is real, in part due to the accumulation of carbon dioxide in the atmosphere. You can't see, taste, or smell the gas, and all animals exhale it when they breathe.
Plants absorb carbon dioxide and use it to create new tissues. This gas is essential for most life on Earth. Problems only arise when there are far more levels in the air and water than can be used or stored by plants.
Once CO2 enters the atmosphere, much higher than what greenery can reach, it becomes a greenhouse gas.
Like glass in a plant greenhouse, carbon dioxide in the air lets light through. But once it hits objects such as the ground, buildings, plants, or water, most of the light is converted into heat.
While CO2 allows light to reflect off the Earth's surface back into space, it absorbs heat. This leads to the warming of the Earth's atmosphere.
Currently, we have a record amount of carbon dioxide in our atmosphere, more than at any time in the last 3 million years.
This excess heat traps more and more heat near the Earth's surface, and the land and oceans are warming slowly but steadily.
Sea levels are also rising in large parts of the planet, in some cases inundating coastal areas or burying islands. Glaciers have been melting, losing stored fresh water that downstream communities rely on to drink and water their crops.
If nothing changes, global temperatures will continue to climb. This will make life more difficult for most creatures, unless they can quickly adapt to a warm new world. Most scientists suspect that they can't adapt quickly enough. This concern has prompted people to consider finding new ways to cool the planet.
The most direct way is for people to burn less fossil fuels. However, the largest users of coal, oil and gas show no signs of cuts. These fuels now power most cars, light most homes, and run the largest factories.
Over the past 250 years, the amount of carbon dioxide in the air has risen by 40%. People don't want to give up the convenience of being powered by fossil fuels now. Many people don't even believe that their actions have caused global warming. Countries** have been slow to develop laws to limit greenhouse gas emissions.
For all these reasons, scientists are now exploring extreme geoengineering measures. But they are also approaching these backup plans with great caution and somewhat reluctance.
We'd rather not do it," said the scientist at the Alfred Wegener Institute in Bremerhaven, Germany. "But if you look at what's happening with the accumulation of carbon dioxide in the atmosphere today, we have to do something about it. ”
Geoengineering projects focus on two approaches: removing carbon dioxide from the atmosphere, or blocking some of the sunlight from reaching the Earth's surface. Measuring the success of both approaches is difficult.
Critics also warn that errors in geoengineering could create new problems. So the stakes are high. No scientist wants to start a full-scale project without knowing more about the potential costs and ***.
In search of answers, engineers began small experiments.
Some experts are testing the ability of equipment to capture the carbon dioxide typically released by power plants. Others are building fake trees;The artificial leaves of the device are coated with a substance that absorbs carbon dioxide from the air.
Scientists are also exploring the idea of burying the charred remains of burned plants, known as biochar. Buried biochar stores its carbon in the ground instead of letting it into the air in the form of carbon dioxide. Biochar also enriches the soil, providing nutrients that help plants grow.
Carbon dioxide can even be converted into liquids, which companies can inject and store deep at the earth's surface. In June 2013, a report by the U.S. Geological Survey estimated that the U.S. could store nearly a century of carbon dioxide emissions in this way.
One method that scientists in the United States have been working on is to bury carbon at the bottom of the ocean, but not directly. Their goal is to leave this work to the microbes in the ocean. To encourage them to help, researchers have been feeding some microbes iron as fertilizer.
Smetacek first began testing the idea in February 2004. The oceanographer boarded an icebreaker and traveled to the Southern Ocean near Antarctica. There, he and his crew dissolved iron in seawater. They want tiny organisms called phytoplankton to absorb carbon dioxide from the air.
The idea goes like this: iron is naturally found in the oceans. Phytoplankton absorb it to promote growth. If there is enough iron, these floating creatures will start eating like crazy.
Smetaček's team hopes that the addition of additional iron will boost the growth of phytoplankton communities.
Along the way, these organisms absorb carbon dioxide from the water. When phytoplankton age and die, their tissues sink and bury at the bottom of the sea, where they carry carbon into their graves.
The ocean naturally absorbs carbon dioxide from the air, and if the gas level at sea level drops, the water absorbs more gas from the air. This explains why the addition of iron to promote phytoplankton growth can reduce the amount of this gas in the air.
Iron fertilization was first proposed by oceanographer John Martin in the late 80s of the 20th century. Since then, laboratory experiments have shown that the number of marine organisms skyrockets when additional iron is provided.
The vortex is like a giant test tube in the ocean," Smetaček explains. "If you fertilize a piece of land, it won't go away. ”
In 2012, Smetacek's team published their findings in the scientific journal Nature. They found that when phytoplankton die, they sink for at least 1,000 meters and may all the way to the bottom of the sea.
It would be cheaper to test these concepts somewhere in the lab, however, the high seas are a much more complex system. Therefore, Smetaček believes that "experimenting with iron fertilization on the high seas is the best way to understand how the ocean works." ”
Scientists like Smetaček study the oceans to find answers, while others look up to the sky.
The sun bathes the earth in light and heat, but water vapor – clouds – filters out sunlight.
In the process, they help cool the planet. Scientists are now looking to build long-lasting clouds. But only in the right place.
The Earth naturally reflects some of the sun's warming energy back into space, and clouds play an important role. Scientists talk about the albedo of clouds, which is a measure of how much light a cloud reflects.
For example, thick clouds low in the sky reflect a lot of sunlight, which means it has a high albedo, and tall, thin clouds allow most of the sunlight to pass through, and the albedo is low.
Since clouds play an important role in many climate processes, the geoengineering of clouds is complex.
Scientists often use computers to find out how the climate will change if certain conditions change. These computer programs are called models. Even without geoengineering, different models can provide different insights into how cloud cover responds to climate change.
Clouds are a major uncertainty about greenhouse warming. Some models suggest that their [number] increases and reflects more sunlight – and mitigates the effects of CO2," Rob Wood said. He is an atmospheric scientist at the University of Washington in Seattle. Other models, he noted, "suggest that the number of clouds will be reduced by a few percentage points, enough to allow more sunlight to enter and enhance the greenhouse effect." ”
Scientists know that clouds reflect some sunlight back into space, which is why they are investigating the possibility of "cloud brightening".
The idea: to inject salt particles from high up into the ocean above the ocean, where the particles stimulate the formation of new clouds or increase the albedo of existing clouds.
In August 2012, Wood and his collaborators proposed an experiment to brighten clouds. They even described boats that might have been used to make a saline-infused spray. Such a ship will be equipped with a chimney-like high tube. The cylinder shoots water droplets above the ocean, creating bright clouds.
Wood says the cloud brightening test may help scientists better understand the cloud. However, he doesn't think cloud brightening will save the planet, it won't have enough impact at all.
He is exploring a related idea — one that he says seems more promising, one that would eject tiny sulfur particles into the Earth's higher atmosphere.
Sometimes, nature has already done just that. Whenever a powerful volcano erupts, it spews a stream of sulfur particles upstream into the atmosphere. These particles are called aerosols and can reflect sunlight and cool the earth.
For example, in 1883, a group of volcanoes erupted in and around the island of Krakatoa in the South Pacific. The following year, global temperatures dropped by more than 1 degree Celsius in 1991, when Mount Pinatubo sent a cloud of debris into the atmosphere, lowering global temperatures by 0At 5°C, geoengineers are already thinking about transporting sulfur aerosols to the air to mimic these volcanoes.
Jay Apter, a physicist at Carnegie Mellon University, has been studying how much this might cost.
They evaluated the use of ** labels for existing aircraft that deposited particles at flight altitude. Then they thought about flying higher with more expensive aircraft in the future.
They even considered the use of high-power rockets to deliver particles to the highest parts of the Earth's atmosphere. Finally, they estimated the cost of building tall pipelines, which were supported on floating platforms at sea to regularly pump aerosols into the air.
When a powerful volcano erupts, millions of tons of sulfur aerosols can be transported into the stratosphere. (The stratosphere is the layer of the atmosphere that is 10 kilometers to 50 kilometers above the Earth's surface.) ）
Scientists estimate that using airplanes or other technology to do the same thing could cost up to $8 billion a year. Apte's team concluded that aerosols reflecting sunlight would stop global temperatures from rising, at least temporarily.
Since the aerosols will all fall back to Earth one day, the sky needs more aerosols on a regular basis.
Apt warns that no one wants to pump aerosols into the stratosphere.
It's a terrible idea," Apt said, and can only be used to slow global warming until a more lasting solution is found. Moreover, this expensive remedy does nothing to reverse the problem of excessive CO2 pollution.
Managing the amount of solar radiation passing through the Earth's atmosphere may quickly alleviate the problem of global warming in the short term.
However, this and every other geoengineering proposal could backfire, perhaps in some unexpected way.
For example, scientists do not know the consequences of putting aerosols into the upper atmosphere, after all, aerosols are a type of pollution. Researchers don't know if these particles affect the weather, such as rainfall, or how organisms grow.
Smetaček believes that it is too early to carry out any large-scale geoengineering projects. There is too much uncertainty. "We need to do more experiments before we start large-scale studies. ”
At the same time, global warming is a problem that is not going away.
In fact, atmospheric scientist Wood said, the problem could get worse over time.
Something has to change, and he hopes that more young scientists will be interested in better understanding the Earth's climate. He also hopes that budding experts will be able to study how to avoid the catastrophic effects that climate change is expected to have.
"I think a lot of us are willing to believe that we don't have to do anything because humanity will wake up at some point and realize that this is going to be a big problem," Wood said.
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