Can We Cool the Planet?

As the planet heats up, ice on Earth is melting at an alarming rate. That includes glaciers as well as floating sea ice, like that in the Arctic Ocean. With less ice to reflect sunlight, the darker land or water soaks up the sun’s rays. Earth’s surface warms further, causing even more ice to melt.

Leslie Field, an engineer at Stanford University in California, wants to fight this cycle by sprinkling Arctic sea ice with microscopic glass bubbles. This sand-like powder, which might be sprayed from ships or aircraft, would reflect sunlight and keep ice from melting. Over time, it would thicken remaining ice by allowing more water to freeze in winter.

Field has tested the powder on frozen lakes in Alaska, California, and Minnesota. A thin layer helps ice reflect up to 20 percent more light. Other groups have proposed a similar solution to reduce melting ice: covering glaciers with reflective blankets. But some scientists are skeptical that these tactics would have lasting effects.

As the planet heats up, Earth’s ice is melting very quickly. That includes glaciers and floating sea ice, like ice in the Arctic Ocean. There’s less ice to reflect sunlight, so the darker land or water soaks up the sun’s rays. Earth’s surface becomes warmer. That causes even more ice to melt.

Leslie Field, an engineer at Stanford University in California, wants to fight this cycle. Her idea is to sprinkle tiny glass bubbles on Arctic sea ice. Ships or aircraft could spray this sand-like powder. The powder would reflect sunlight, so ice wouldn’t melt as fast. This would help the remaining ice get thicker over time, says Field. More water would freeze into ice in the winter.

Field tested the powder on frozen lakes in Alaska, California, and Minnesota. Her team found that a thin layer gets results. It helps ice reflect up to 20 percent more light. Other groups have a similar idea to reduce melting of ice. They suggest covering glaciers with reflective blankets. But some scientists doubt the effects would last.

The simplest proposal to control the climate is to plant more trees, says Chris Field, a climate scientist at Stanford University. Trees and other plants pull CO2 from the air as part of photosynthesis. This chemical process uses energy from sunlight to break apart molecules of CO2. Plants use the carbon atoms as building blocks to grow and release oxygen back into the air.

Increasing the number of trees could be a good way to soak up extra CO2 from the atmosphere, explains Field. Scientists have proposed conserving existing forests, replanting those that have been cut down, and even growing trees in new areas.

But finding places to plant additional trees isn’t easy, says Field. People around the world have cleared many forests and now use the land to grow crops and raise livestock. Replanting enough trees to curb climate change would take almost as much land as is now used to produce food.

The simplest idea to control the climate is to plant more trees, says Chris Field. He’s a climate scientist at Stanford University. Trees and other plants pull CO2 from the air. That’s part of the chemical process called photosynthesis. It uses energy from sunlight to break apart CO2 molecules. Plants use the carbon atoms as building blocks to grow. They release oxygen into the air.

Having more trees could be a good way to pull extra CO2 from the atmosphere, says Field. Scientists say we could protect forests, replant forests that have been cut down, and plant trees in new places.

But finding room for more trees isn’t easy, says Field. People around the world have cleared many forests. Now they grow crops and raise livestock on that land. To help control climate change, many trees would have to be replanted. They would need almost as much land as people use now to produce food.

In 2018, people produced more CO2 than in any other year in history. To reduce this greenhouse gas, engineers are developing technology to suck it directly out of the air.

In 2017, one of the world’s first facilities that vacuums up CO2 opened in Switzerland. The outside of the building contains rows of large fans. The fans draw in air and blow it over specially designed filters. The filters use a chemical reaction to trap CO2. Applying heat breaks the chemical bond between the CO2 and the filter. That frees the gas from the filter so it can be collected in containers and pumped into a neighboring greenhouse to grow plants. Engineers have also proposed storing the gas by pumping it into underground rock formations or compressing it into a heavy liquid and sinking it to the ocean floor.

The Swiss facility captures about 1,000 tons of CO2 annually—about the amount released by 200 cars in a year. It would take thousands more facilities like this one to make a dent in global climate change, says Chris Field.

Last year, people produced more CO2 than any year in history. To reduce this greenhouse gas, engineers are finding ways to suck it directly from the air.

In 2017, a factory opened in Switzerland. It’s one of the world’s first that sucks in CO2. The outside of the building contains rows of large fans. The fans draw in air and blow it over specially made filters. The filters use a chemical reaction to trap CO2. Adding heat breaks the chemical bond between the CO2 and the filter. That frees the gas from the filter so it can be collected in containers. Then it’s pumped into a nearby greenhouse to help plants grow. Engineers have also suggested storing the gas. One way is to pump it into underground rock formations. Another is to press it into a heavy liquid and sink it in the ocean.

The Swiss factory sucks in about 1,000 tons of CO2 a year. That’s about how much 200 cars release in a year. One factory like this won’t make a dent in global climate change. It would take thousands more, says Chris Field.

In 1883, the Indonesian volcano Krakatoa erupted violently, spewing hot ash and gases into Earth’s upper atmosphere. Tiny particles of sulfuric acid from the eruption spread around the planet, blocking sunlight and lowering temperatures for about a year. Some scientists are studying how to mimic this effect artificially.

One idea would be to spray a sulfur gas into Earth’s stratosphere, a layer of the atmosphere 20 kilometers (12 miles) above the planet’s surface. The gas would react with the air to form sulfuric acid droplets that would reflect sunlight back into space, says Ben van der Pluijm, a geologist at the University of Michigan.

In 1883, an Indonesian volcano blew its top. Krakatoa shot hot ash and gases into Earth’s upper atmosphere. Tiny particles of sulfuric acid from the blast spread around the planet. They blocked sunlight and lowered temperatures for about a year. Some scientists are looking for a way to imitate this effect.

One idea is to spray a sulfur gas into Earth’s stratosphere. This layer of the atmosphere is 20 kilometers (12 miles) above Earth’s surface. The gas would react with the air to form sulfuric acid particles. They would reflect sunlight back into space, says Ben van der Pluijm, a geologist at the University of Michigan.