 Welcome to Learning English, a daily 30-minute program from The Voice of America. I'm Ashley Thompson. And I'm Dan Novak. This program is designed for English learners, so we speak a little slower, and we use words and phrases, especially written for people learning English. On today's program, you will hear stories from Gregory Stockle, Gina Bennett, and Brian Lynn. Later, Faith Perlow and John Russell present a new everyday grammar lesson. Then, Faith joins me for one last time on the Learning English broadcast. But first, here are Greg and Gina. Old sponges from deep in the Caribbean Sea are causing some researchers to think human-caused climate change began sooner than scientists have thought. But if a recent study is correct, world temperatures are increasing faster than United Nations estimates suggest. The researchers from American and Australian universities published their sponge findings recently in Nature Climate Change. They said, if their findings are correct, the world has already gone past a temperature limit set by international negotiators. Negotiators of the Paris Agreement on Climate Change set 1.5 degrees Celsius as a limit for the increase of the world's temperature from pre-industrial times. Pre-industrial times are from about 1850 to 1900. But the American and Australian researchers said that the world hit a 1.7 degree Celsius increase in 2020. The scientists looked at six special sponges that are known to live hundreds of years. They examined the sponge's growth records to find very small levels of the elements calcium and strontium. The scientists said that the amount of calcium and strontium changes depending on the water temperature. Malcolm McCulloch is an ocean scientist at the University of Western Australia. He was the lead writer of the study. McCulloch noted that the currently accepted temperature estimates for the 1850 to 1900 period were too high. That means that present day temperature increases are larger and the Earth's temperature is warming faster than scientists have believed. He said, we have a decade less than we thought. In the past several years, many scientists have noted that there seems to be more extreme weather than they had expected. One explanation would be that the Earth is warming faster than scientists had first believed, said Amos Winter. Winter helped write the study. He is an ocean scientist at Indiana State University. He said the study supports the theory that climate change is quickening. Former top NASA scientist James Hansen also has proposed that theory. Sponges get water flowing from all over them so they can record a larger area of environmental change. Winter and McCulloch said, the research team examined sponges that lived in a special mixed area of the ocean that is 33 to 91 meters deep. The researchers were able to estimate nearly the exact atmospheric temperature of the Earth from the amount of calcium and strontium in the deep sea sponges. Their results were different from the scientifically accepted temperature estimates used by the United Nations Intergovernmental Panel on Climate Change, or IPCC. The IPCC temperature estimates are the basis for the UN temperature goals. The Nature Climate Change study finds that the mid-1800s were about half a degree Celsius cooler than believed. It also found that warming from heat-trapping gases started about 80 years earlier than the measurements the IPCC uses. IPCC numbers show warming started just after 1900. McCulloch and Winter said it makes sense that the warming started earlier than the IPCC stated because by the mid-1800s, industries had begun polluting the air with carbon dioxide. For pre-industrial temperatures, the IPCC and most scientists used data that came from ships whose crews would take the temperature of water near the surface. Some of the measurements could change based on how the collection was done. The researchers said sponges provide better information because of the way they store chemical elements in their skeletons. When waters are warmer, there is more of the element strontium and less of the mineral calcium, Winter said. University of Pennsylvania climate scientist Michael Mann, who was not part of the study, has thought warming started before the IPCC said it did. But he doubted the study's findings. In my view, it begs credulity to claim that the instrumental record is wrong based on paleo sponges from one region of the world, Mann said. But Winter and McCulloch have defended their use of sponges to identify world temperature change. They said, except for the 1800s, their temperature findings based on sponges follow global records from other devices. These include scientific instruments and measurements from things like coral, ice, and tree rings. Princeton University climate scientist Michael Oppenheimer was not part of the sponge study either. He said even if the McCulloch team is right, it should not change warnings from scientists. He said that the danger level is not tied to the exact value of pre-industrial temperatures. McCulloch added that the only way to stop this is to reduce emissions, urgently, most urgently. I'm Gina Bennett. And I'm Gregory Stockle. The rise in private American space missions has led to increasing calls for rules on what can be transported to the moon. Individuals and groups have criticized plans by private companies to send things that might not be suitable for the lunar surface. The proposals came from companies that have contracts with the American Space Agency, NASA, to provide spaceflight services and carry equipment and supplies to the moon. Such materials launched from rockets are known as payloads. The efforts are part of NASA's commercial lunar payload services CLPS program. It aims to hand over the nation's major space missions to private companies in an effort to reduce costs. The CLPS program plans to send several landers to the moon in the coming years. The landers will be carrying instruments and exploring tools to help humans learn more about the moon and its surroundings. But some missions also plan on sending human remains or goods that could be used in advertising. Leslie Tenen is a lawyer who specializes in international space law. She told Reuters news agency, We're just at the beginning of exploring the moon and we need to be careful we're not contaminating it. She said she thinks care should be taken to prevent the spread of what she calls litter on the moon. Last month one privately built lunar lander aimed to touch down on the surface of the moon. But the spacecraft called Peregrine developed a fuel leak shortly after launch and did not make it to the moon. The company that built Peregrine is Astrobotic Technology of Pittsburgh, Pennsylvania. The lander was loaded with 20 research experiments involving seven different countries. But it also carried other materials. These included numerous containers of human remains, a piece of rock from Mount Everest, a physical bitcoin, and a can of the Japanese sports drink, Pakari Sweat. Among the remains were ashes of famous space lovers Gene Roddenberry and Arthur C. Clark. Roddenberry was creator of the popular television show Star Trek and Clark was a science fiction writer. The Navajo Nation had sought to stop Peregrine's launch because of the inclusion of the remains. The head of the Native American group called the sending of remains a desecration because his people consider the moon a holy space. A spokesperson for Astrobotic said the objections to Peregrine's launch came too late to reach an agreement on the issue. But the company said it would try to find a good path forward with the Navajo Nation on future missions. Reuters reports that under U.S. law materials can be transported to the moon as long as they do not violate certain general guidelines set by the U.S. Federal Aviation Administration, FAA. The FAA requires companies to show that a payload launched from Earth does not jeopardize public health and safety, U.S. national security, or international obligations of the U.S. This rule permits most materials to be sent to the moon. But legal experts think the issue will likely gain more attention as more private missions make successful landings on the lunar surface. And this could lead to new legal restrictions on what can be transported to the moon. Lawyers with space law experience worry that the absence of rules could lead to disputes between U.S. companies and other nations seeking to operate on the lunar surface. There could also be disagreements over which businesses should be permitted to claim land or sovereignty. The current guidelines for international activities on the moon are included in a document known as the Outer Space Treaty. It states that outer space, including the moon and other bodies, shall be free for exploration and use by all states. The treaty also states that nations involved in space exploration must approve of and supervise the activities of non-government organizations. Experts say few nations have approved their own rules for moon behavior and measures are currently unclear in international law. This has led to calls for new international guidelines. Martha Mahia Kaiser is a Mexican-German space lawyer and a board member of the International Institute of Space Law. She told Reuters, We are already late and we are very urgently in need to start now to discuss the moon at an international level. I'm Brian Lin. It is never easy to say goodbye. But, at least in English, we have many ways to do so. For my final everyday grammar, I want to share the many ways to say goodbye in English. There are polite or formal ways. There are also ways we can say goodbye in everyday conversation, including fun slang that you can use. Goodbye is believed to have come from the expression, God be with ye, about 500 years ago. Ye is an old form of you. Over time, God became good. Today, the expression is for wishing someone well when you are leaving. Goodbye is probably the most common way to say this. Shorter forms include bye and bye-bye. If you enjoy the 1990s pop band NSYNC, you can say bye-bye-bye. It might sound crazy, but it ain't no lie. Baby, bye-bye-bye. When you part with someone and you want to wish them a good time, you can use this general structure. Have, plus a, plus adjective, plus period of time. Have a good night. Have a wonderful weekend. Have a nice day. Have is in the imperative form of the verb. The imperative form gives instructions, directions, or commands. Imperative sentences use the base form of the verb. If parting ways with someone during the night time, we combine good with night to wish someone a good night. We use this expression usually when going to sleep at night. I always say good night to everyone in my house before bedtime. We use other command forms in formal settings to say goodbye. Take care of yourself is meant to wish someone physical or emotional health. If we have enjoyed our time with someone we can say, it was a pleasure speaking with you. It, plus form of be in present or past tense, plus article and noun or adjective, plus gerund, plus with you. It was great seeing you this weekend. We can also say that we look forward to seeing or speaking with someone. This expression suggests hope for the future. I look forward to our next meeting. I look forward to seeing you then. I look forward to speaking with you. Shorter forms of this expression include a sentence with will. I will see you then. See you then. Speak to you then. When speaking with friends and family, you can use informal ways to communicate leaving. Shorter forms like see you are said even more conversationally when you becomes ya in fast speech. We can combine the expression with an adverb to say when we will see someone in the future. See you soon. See you later. See you around. Catch you later. Catch you later. To express a similar meaning we can use a prepositional phrase with until. There is no subject or object, just the preposition is used. Until plus time expression. Until then. Until Tuesday. Until next week. If you need to leave quickly you can use these expressions. Gotta is a contraction that is used in everyday speech. I've got to go. I've got to go. I'm heading off. If you want someone to connect with you in the future you can use these. Don't be a stranger. Keep in touch. If someone is leaving you on a trip you can wish them a safe journey. Have a safe trip. Drive safely. Drive safe. Safe travels. Note that in drive safe, safe is what is sometimes called a flat adverb. These are older adverb forms in English that do not use the L-Y ending. Phrases sleep tight or go slow are examples. Another expression that uses a flat adverb is take it easy. And lastly if you must leave quickly you can use the expression. I've got to hit the road. I gotta hit the road. We often use it when we are going to drive somewhere but we can use it for other means of travel. Finally we have a few slang words that are used very informally in speech especially by some groups of people. Slang is often spoken by young people and is generational meaning that each new generation has its own slang. Remember using slang is very informal and not a good idea in groups of people who are of several different age groups. From the expression see you later we get the one word slang expression later. You can use this word by itself or with the person's name. Later. Later John. We also have the expression I'm out of here. We can make this even more informal by shortening out of to outa. I'm outa here. One of my favorite expressions was often heard in 1990s and early 2000s hip-hop music. Bounce. According to Urban Dictionary to bounce means to leave and go somewhere else better or quickly. A song by Destiny's Child say my name uses this expression. See you gotta bounce when two seconds ago you said you just got in the house. In today's everyday grammar we talked about different expressions we can use to say goodbye. Many goodbye expressions in both formal and everyday language use the imperative form. We also looked at some fun slang words for goodbye. I wanted to thank our audience for the past two years here at VOA Learning English. This might not be goodbye. Maybe it's just see you later. Take care. I'm Faith Perlow. And I'm John Russell. You just heard Faith Perlow and John Russell present this week's everyday grammar lesson. Faith is here now to talk more about it. Hi Faith, welcome to the show. Thanks Ashley. This will be my final chat with you. I am moving on from VOA to teach again in a classroom. So that is why you wrote about different ways to say goodbye. I have to say we are all sad to see you leave. Different situations call for different ways to say goodbye. Sometimes the situation is very formal and calls for more professional ways to say goodbye. But if you know the person well, you can use more informal expressions, even silly ones. Silly ones? Yeah, in English we actually use animals and rhymes together. Children love these ways to say goodbye. So growing up we often use these silly expressions. Like see you later alligator. Oh yeah, and in a while crocodile. Alligators and crocodiles look similar. They are both large reptiles with long snouts or noses. Alligators prefer fresh water and crocodiles prefer saltwater areas. They are very scary either way. Both expressions rhyme and the number of syllables of each animal matches up with the goodbye phrase. See you later alligator. Four syllables each. In a while crocodile. Three syllables each. Thanks again for sharing faith. Thank you once again for having me. And a special thank you to our listeners. Bye bye butterflies. And toodaloo kangaroo. And that's our program for today. Join us again tomorrow to keep learning English through stories from around the world. I'm Ashley Thompson. And I'm Dan Novak.