Scientists and technology experts were busy in 2015.

From fighting climate change, to space exploration anddeveloping drones, here is a look back at some of the science stories wecovered at VOA Learning English.

Climate change agreement reached

Most recently, representatives from nearly 200 nationsgathered in Paris to fight climate change.

Almost every ｃountry agreed to limit a rise in globaltemperatures. They agreed that the world should not get any warmer than 2degrees Celsius above what it was in the mid-1700s. The agreement says 1.5degrees is an even better target.

This will require nations to reduce their greenhouse gases,like carbon dioxide. Those gases are released from the burning of fossil fuels,like oil and gasoline, and they are blamed for raising the temperature of theplanet.

As the planet warms, ice melts at the north and south poles,the top and bottom of the planet. This can raise sea levels that flood lowareas, like islands. Climate change also brings damaging storms, severedroughts and flooding, and widespread food and water shortages.

The agreement is supported by the United States and China,the two biggest greenhouse gases polluters in the world.

Self-driving cars

One of the biggest changes coming down the road: the abilityof cars to drive themselves. Some day you may not need to drive a car. You willjust program, or tell the car where you want to go, and it will drive itself.

Andrew Poliak, of automotive technology supplier QNX, saysthe technology is already here. “We expect self-driving cars to be a mainstreamthing between 2020 and 2025.”

Google, an American company, already has self-driving carson the road, mostly in California. There is no steering wheel and no brake orgas pedals.

Water found on Mars, and other NASA stories

NASA scientists discovered water flows on the surface ofMars. The water is salty, and is only there part of the year. But it is animportant discovery for the effort to send humans to live on Mars.

Water on Mars: What Does It Mean?

Michael Meyer is the lead scientist for the NASA MarsExploration Program. He says water is one of the key things needed for sendinghumans to Mars.

Meyer explains: “Not only for the astronauts to drink, butalso to make oxygen, to make fuel, and so having a ready resource there on theplanet makes a big difference in terms of how much stuff you have to bring withyou.”

NASA hopes to send humans to Mars in the 2030s. Now, thespace agency is recruiting new astronauts. Both the U.S. government and privateindustry are developing rockets and spacecraft to take those astronauts toMars.

Meanwhile, astronaut Scott Kelly is spending a year in spacewith Russian cosmonaut Mikhail Kornienko.

NASA is studying Kelly to see how humans survive longperiods of time in the weightlessness of space. What they learn will help themplan human travel to Mars. Kelly and Kornienko are scheduled to return to earthin March 2016.

We got our first close up of one of the farthest awayobjects in our solar system last July. It took the New Horizons spacecraft nineyears to travel nearly 5 billion kilometers to Pluto. It sent back pictures,showing the dwarf planet’s detailed icy landscape— including mountains,glaciers and craters.

Speaking of space … there was this good news: Not to worryresearchers say do not fear an alien invasion. People have been searching andlistening for life on other planets. They say we should not be concerned aboutalien beings any time soon.

Drones

Drones made their way to our website and Facebook pagesquite a few times. They are small aircraft controlled by remote control. TheFAA, the U.S. federal agency that governs drone use, came up with new rulesrecently. Drones used in the U.S. will have to be registered with the federalgovernment. Earlier, the company Amazon received a patent for drones thatdeliver packages.

In France, drones are helping farmers examine their crops.

Animals in danger

These can be helpful machines. Drones are also being used tohelp animals in trouble of becoming extinct, or disappearing forever. InAfrica, drones have been designed to help find poachers—people who illegallykill rhinoceros and elephant for their horns and tusks.

Tiger

It has been a year of insects and animals in trouble ofdisappearing from rhinos to bees and tigers.

At the North Pole, Arctic polar bears are threatened becauseclimate change is melting ice there. It means they are losing their territoryat the top of the world.

Meanwhile, at the bottom of the Earth, scientists found fishand other sea creatures under the ice on the Ross Ice Sheet, off Antarctica.They were surprised to see organisms swimming and crawling in icy waters underthe ice sheet. It is the farthest south that fish have ever been seen.

Deep Under Antarctic Ice Sheet, Life!

Unfortunately, the same cannot be said for some warmerwaters. Scientists studied coral reefs in the U.S. Virgin Islands in the Caribbean.They also studied reefs in Hawaii. And they found that sunscreen from peopleswimming around the reefs is killing the beautiful coral. Other things harmingthe coral include pollution, warmer seas and overfishing.

Human ancestors

In South Africa, scientists found bones in a cave they sayare a new kind of early human ancestor. Those ancestors lived more than 2million years ago. The people who found it named it Homo naledi, but it is nota direct ancestor of modern-day people.

This is also the 40th anniversary of the discovery of Lucy.At 3.2 million years old, Lucy was the oldest human ancestor found at the time.She was found in Ethiopia.

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