Do you keep hearing about "Earth becoming warmer" and wonder, "what’s the big deal about a little extra heat? In this lesson, we will learn everything about the topic "climate change" - what is climate change, why Earth's climate is changing, and what you can do about it.
Climate change describes a change in the average conditions, such as temperature and rainfall, in a region over a long period of time. Scientists have observed our planet is heating up, and many of the warmest years on record have happened in the past 20 years. For example, about 20,000 years ago, much of the United States was covered in glaciers, but today it has a warmer climate and fewer glaciers.
Earth's climate has changed throughout history. However, since the late 19th century, sea levels are rising, and oceans are becoming warmer. According to NASA, the average global temperature on Earth has increased by a little more than 1° Celsius (or 2°F) since 1880. While 1°C may not sound huge, it means big things for people and wildlife worldwide. The changing climate makes our weather more extreme and unpredictable. As temperatures rise, some areas will get wetter, and many animals couldn't adapt to their changing climate.
The increase in Earth's average temperature is linked to the greenhouse effect, which describes how the Earth's atmosphere traps some of the Sun's energy. Solar energy radiating back to space from the Earth's surface is absorbed by greenhouse gases and re-emitted in all directions. This heats both the lower atmosphere and the surface of the planet. Without this effect, the Earth would be about 30°C colder and hostile to life. Scientists believe we add to the natural greenhouse effect, with gases released from industry and agriculture trapping more energy and increasing the temperature.
Some parts of Earth warm faster than others. Scientists are concerned about this warming. As Earth's climate continues to warm, the intensity and amount of rainfall during storms such as hurricanes are expected to increase. Droughts and heatwaves are also expected to become more intense as the climate warms. When the whole Earth's temperature changes by one or two degrees, that change can have big impacts on the health of Earth's plants and animals, too.
Earth is surrounded by an atmosphere made up of a layer of gases. When sunlight enters the atmosphere, some of the sun’s heat is trapped by the gases, while the rest escapes the atmosphere. The trapped heat keeps Earth warm enough to live on.
But during the past few centuries, the oil, gas, and coal we use have released carbon dioxide into the atmosphere. This gas traps heat that would otherwise escape Earth’s atmosphere. This increases Earth’s average temperature, which changes its climate.
Human activities — such as burning fuel to power factories, cars, and buses — change the natural greenhouse. These changes cause the atmosphere to trap more heat than it used to, leading to a warmer Earth.
Deforestation - Forests absorb huge amounts of carbon dioxide, another greenhouse gas, from the air and release oxygen back into it. The Amazon rainforest is so large and efficient at doing this that it acts like our planet's air conditioner, limiting climate change. Sadly, many rainforests are being cut down to make wood, palm oil and clear the way for farmland, roads, oil mines, and dams.
Burning fossil fuel - Over the past 150 years, industrialized countries have been burning large amounts of fossil fuels such as oil and gas. During this process, the gases released into the atmosphere act as an invisible blanket, trapping heat from the sun and warming the Earth. This is known as the greenhouse effect.
According to the World Meteorological Organization (WMO), the world is about 1°C warmer than before widespread industrialization. However, melting ice is now thought to be the main reason for rising sea levels. Most glaciers in temperate regions of the world are retreating. And satellite records show a dramatic decline in Arctic sea ice since 1979. The Greenland Ice Sheet has experienced record melting in recent years.
Satellite data also shows the West Antarctic Ice Sheet is losing mass. A recent study indicated East Antarctica might also have started to lose mass. The effects of a changing climate can also be seen in vegetation and land animals. These include earlier flowering and fruiting times for plants and changes in the territories of animals.
There is uncertainty about how great the impact of a changing climate will be.
It could cause freshwater shortages, dramatically alter our ability to produce food, and increase the number of deaths from floods, storms, and heatwaves. This is because climate change is expected to increase the frequency of extreme weather events.
As the world warms, more water evaporates, leading to more moisture in the air. This means many areas will experience more intense rainfall - and, in some places, snowfall. But the risk of drought in inland areas during hot summers will increase. More flooding is expected from storms and rising sea levels. But there are likely to be extreme regional variations in these patterns.
Poorer countries, which are least equipped to deal with rapid change, could suffer the most.
Plant and animal extinctions are predicted as habitats change faster than species can adapt. Climate change is already affecting wildlife worldwide, but certain species are suffering more than others.
Polar animals, whose icy natural habitat is melting in the warmer temperatures, are at risk. In fact, experts believe that the Arctic sea ice is melting at a shocking rate - 9% per decade. Polar bears need sea ice to hunt, raise their young, and as places to rest after long periods of swimming. Certain seal species like ringed seals make caves in the snow and ice to raise their pups, feed, and mate.
It's not just polar animals who are in trouble. Apes like orangutans, which live in Indonesia's rainforests, are under threat as their habitat is cut down, and more droughts cause more bushfires.
Sea turtles rely on nesting beaches to lay their eggs, many of which are threatened by rising sea levels. Did you know that the temperature of nests determines whether the eggs are male or female? Unfortunately, with temperatures on the rise, this could mean that many more females are born than males, threatening future turtle populations.
Climate change won't just affect animals; it's already having an impact on people, too. Most affected are some of the people who grow the food we eat every day. Farming communities, especially in developing countries, face higher temperatures, increased rain, floods, and droughts.
For example, in Kenya, climate change is making rainfall patterns less and less predictable. Often there will be droughts followed by huge amounts of rain, which makes it very difficult to grow tea. Farmers might then use cheap chemicals to improve their crops to earn more money, even when long-term use of these chemicals can destroy their soil. And the World Health Organization (WHO) has warned that millions' health could be threatened by increases in malaria, a water-borne disease, and malnutrition.
As more CO2 is released into the atmosphere, uptake of the gas by the oceans increases, causing the water to become more acidic. This could pose major problems for coral reefs.
Global warming will cause further changes that are likely to create further heating. This includes the release of large quantities of methane as permafrost - frozen soil found mainly at high latitudes - melts.
Responding to climate change will be one of the biggest challenges we face this century.
You can do a lot. It's simple to make a difference to keep the Earth healthy. Try some of these tips to reduce the amount of carbon dioxide you add to the atmosphere.
