Signs of climate change

See the impact

Scorching summers, melting glaciers, stronger storms, the signs of global climate change are all aroung us.

Image of earth from space


The Earth's climate is getting warmer, and the signs are everywhere. Rain patterns are changing, sea level is rising, and snow and ice are melting sooner in the spring. As global temperatures continue to rise, we'll see more changes in our climate and our environment. These changes will affect people, animals, and ecosystems in many ways.

Less rain can mean less water for some places, while too much rain can cause terrible flooding. More hot days can dry up crops and make people and animals sick. In some places, people will struggle to cope with a changing environment. In other places, people may be able to successfully prepare for these changes. The negative impacts of global climate change will be less severe overall if people reduce the amount of greenhouse gases we're putting into the atmosphere and worse if we continue producing these gases at current or faster rates.



The different signs of climate change

The average temperature of the Earth is rising, but that's not the only way we can tell the climate is changing. In fact, the signs are all around us! Observations and measurements from all over the world provide strong evidence that the climate has already started to change.

Learn more about some of the signs of global climate change and what additional changes we'll see in the future

Higher temperatures

Greenhouse gases are trapping more heat in the Earth's atmosphere, which is causing average temperatures to rise all over the world.
What's happening now?

Temperatures have risen during the last 30 years, and 2001 to 2010 was the warmest decade ever recorded. As the Earth warms up, heat waves are becoming more common in some places, including the United States. Heat waves happen when a region experiences very high temperatures for several days and nights.


What will happen in the future?

The choices we make now and in the next few decades will determine how much the planet's temperature will rise. While we are not exactly sure how fast or how much the Earth's average temperature will rise, we know that:

  • If people keep adding greenhouse gases into the atmosphere at the current rate, the average temperature around the world could increase by about 4 to 12°F by the year 2100.
  • If we make big changes, like using more renewable resources instead of fossil fuels, the increase will be less—about 2 to 5°F.
Why does it matter?

Higher temperatures mean that heat waves are likely to happen more often and last longer, too. Heat waves can be dangerous, causing illnesses such as heat cramps and heat stroke, or even death.

Warmer temperatures can also lead to a chain reaction of other changes around the world. That's because increasing air temperature also affects the oceans, weather patterns, snow and ice, and plants and animals. The warmer it gets, the more severe the impacts on people and the environment will be.


Changing rain and snow patterns

As temperatures rise and the air becomes warmer, more moisture evaporates from land and water into the atmosphere. More moisture in the air generally means we can expect more rain and snow (called precipitation) and more heavy downpours. But this extra precipitation is not spread evenly around the globe, and some places might actually get less precipitation than they used to get. That's because climate change causes shifts in air and ocean currents, which can change weather patterns.

Walking in rain
What is happening now?

On average, the world is already getting more precipitation now than it did 100 years ago: 6 percent more in the United States and nearly 2 percent more worldwide.

The effects vary by region, though. For example, states in the Northeast are getting more precipitation than they used to get, but Hawaii is getting less.

What will happen in the future?

Precipitation is expected to increase in higher latitudes and decrease in areas closer to the Equator. The northern United States will become wetter while the South, particularly the Southwest, will become drier


Why does it matter?

Too little or too much water can be a problem. In many places, people depend on rain and snowmelt to fill lakes and streams and provide a source of water for drinking, watering crops, and other uses. However, heavy rain can cause flooding.


More droughts

A drought is an extended period of dry weather caused by a lack of rain or snow. As temperatures rise due to global climate change, more moisture evaporates from land and water, leaving less water behind. Some places are getting more rain or snow to make up for it, but other places are getting less.

dessicated crops



What is happening now?
Since the 1970s, droughts have become longer and more extreme worldwide, particularly in the tropics and subtropics.
What will happen in the future?

Droughts are expected to keep getting longer and more severe. The U.S. Southwest is at particular risk for increasing droughts.

This map uses color-coding to show predictions about the risk of drought in different parts of the world by the end of this century.

This map shows the results of computer models that have projected the risk of drought for the years 2090 to 2099. Source: Adapted from Dai (2011).

Why does it matter?

A drought means there's less water available for drinking, watering crops, making electricity at hydroelectric dams, and other uses. For example, an ongoing drought in the U.S. Southwest is straining water supplies in states like Nevada and Arizona, where water is already scarce.


Warmer oceans

The atmosphere affects oceans, and oceans influence the atmosphere. As the temperature of the air rises, oceans absorb some of this heat and also become warmer.

light breaking through ocean water

What is happening now?

Overall, the world's oceans are warmer now than at any point in the last 50 years. The change is most obvious in the top layer of the ocean, which has grown much warmer since the late 1800s. This top layer is now getting warmer at a rate of 0.2°F per decade.

What will happen in the future?

Oceans are expected to continue getting warmer—both in the top layer and in deeper waters. Even if people stop adding extra greenhouse gases to the atmosphere now, oceans will continue to get warmer for many years as they slowly absorb extra heat from the atmosphere.

This line graph shows the average temperature of the ocean surface since 1880.

The surface of the world's oceans has become warmer overall since 1880. In this graph, the shaded band shows the likely temperature range, which depends on the number of measurements and the methods used at different times. Source: EPA's Climate Change Indicators (2014).

Why does it matter?

Warmer oceans affect weather patterns, cause more powerful tropical storms, and can impact many kinds of sea life, such as corals and fish. Warmer oceans are also one of the main causes of rising sea level.


Rising sea level

As water gets warmer, it takes up more space. Each drop of water only expands by a little bit, but when you multiply this expansion over the entire depth of the ocean, it all adds up and causes sea level to rise. Sea level is also rising because melting glaciers and ice sheets are adding more water to the oceans.

Water encroaching on coastal buildings
What is happening now?
Over the past 100 years, the average sea level around the world rose by nearly 7 inches. Did you know that sea level can change by different amounts in different places? 

Why does sea level change by different amounts in differnt places

Sea level is rising faster in some places than others because of wind patterns, ocean currents, and other factors. In addition, sea level may seem like it's 

changing more in certain places than others because the land itself may be rising or sinking.

In some places, the land is rising or sinking because of plate tectonics—the same forces that cause earthquakes, create volcanoes, and build mountain 

ranges. In addition to plate tectonics, land can also sink because people have pumped lots of oil, natural gas, or water out of the ground. When the land 

is also rising, sea level rise might not seem so bad. But in coastal areas where the land is sinking, the effects of sea level rise will be even worse

This diagram illustrates how rising sea level will have worse consequences in places where the land is sinking.

What will happen in the future?

If people keep adding greenhouse gases to the atmosphere, the average sea level around the world by the end of this century (the year 2099) could be anywhere from 7 to 23 inches higher than it was in 1990. Sea level could rise even more if the big ice sheets in Greenland and Antarctica melt faster.

This line graph shows the average sea level around the world since 1870.

Average sea level around the world has been rising for many years. In this graph, the shaded band shows the likely range of sea level, which depends on the number of measurements and the methods used at different times.Source: EPA's Climate Change Indicators (2012).

Why does it matter?

Rising sea level is a threat to people who live near the ocean. Some low-lying areas will have more frequent flooding, and very low-lying land could be submerged completely. Rising sea level can also harm important coastal ecosystems like mangrove forests and coral reefs.


Wilder wheather


Hurricanes and other tropical storms get their energy from warm ocean water. As the top layer of the ocean gets warmer, hurricanes and other tropical storms grow stronger, with faster winds and heavier rain. Because of higher temperatures and increased evaporation, climate change causes other types of storms to get stronger, too. 

Hurricane in suburban neighborhood


What is happening now?

Over the past 20 years, hurricanes and other tropical storms in the Atlantic Ocean have become stronger. Since the 1980s, the United States has also experienced more intense single-day storms that are dumping a lot more rain or snow than usual.

What will happen in the future?

As the climate gets warmer, heavier rainstorms and snowstorms (with more precipitation than normal) are expected to happen more often, and hurricanes around the world could keep getting stronger.

This graph shows two lines. One is an index that measures the strength of hurricanes, and the other shows the temperature of the ocean surface. The two lines show a similar pattern.

Hurricanes in the northern half of the Atlantic Ocean have become stronger over the last few decades. This graph shows the Power Dissipation Index, which measures total hurricane power each year based on the number of hurricanes and their wind speed. The graph also shows how hurricane strength is related to water temperature. Source:EPA's Climate Change Indicators (2014).

Why does it matter?

Hurricanes and other storms can cause flooding; damage buildings, roads, and other structures; harm crops; and put people's lives in danger.


Increased ocean acidity

Carbon dioxide is added to the atmosphere whenever people burn fossil fuels. Oceans play an important role in keeping the earths carbon cycle in balance.. As the amount of carbon dioxide in the atmosphere rises, the oceans absorb a lot of it. In the ocean, carbon dioxide reacts with sea water to form carbonic acid. This causes the ocean to become more acidic.


Coral reef


What is happening now?

Over the last few decades, the amount of carbon dioxide dissolved in the ocean has increased all over the world, and so has ocean acidity.

What will happen in the future?
As long as we keep putting extra carbon dioxide in the atmosphere, the ocean will continue to become even more acidic.
This graph shows three lines. Each line represents the amount of carbon dioxide in the ocean at a particular place where measurements have been collected.

The world's oceans are absorbing more carbon dioxide, as shown by the three sets of measurements in this graph. More carbon dioxide means more acidity (lower pH). Source: EPA's Climate Change Indicators (2010).

This diagram shows the pH of several common substances.

Acidity is measured using the pH scale. The lower the pH, the more acidic the substance. For more information about pH, Adapted fromEnvironment Canada (2010).

Why does it matter?

Increasing acidity will make it harder for corals to build skeletons and for shellfish to build the shells they need for protection. Corals are particularly important because they provide homes for many other sea creatures.


Shrinking sea ice

The Arctic Ocean around the North Pole is so cold that it is usually covered with ice. In the winter, the area covered by ice gets bigger, and in the summer it gets smaller. If the air and water are warmer than usual, Arctic sea ice will melt more than usual during the summer.

Ice blocks in arctic ocean

What is happening now?

The amount of summer ice in the Arctic Ocean in recent years was the smallest it's been since scientists started using satellites to measure the area covered by ice back in the 1970s. The ice is also getting thinner.


What will happen in the future?

Overall, Arctic sea ice will continue to shrink in the coming decades. However, the amount of sea ice may vary from year to year depending on factors such as local temperatures, wind patterns, and ocean currents.


Why does it matter?

Many animals depend on sea ice for their homes and hunting grounds, and native people in the Arctic need these animals as a source of food. In addition, ice and snow reflect a lot of sunlight back out to space and help keep the planet from getting too warm. If there's less ice, the Earth will absorb more energy from the sun and get even warmer. This is an example of a positive feedback loop, which happens when warming causes changes that lead to even more warming.


Melting Glaciers


Glaciers are large sheets of snow and ice that are found on land all year long. They're found in the western United States, Alaska, the mountains of Europe and Asia, and many other parts of the world. Warmer temperatures cause glaciers to melt faster than they can accumulate new snow.


What is happening now?

Glaciers all over the world have been melting for at least the last 50 years, and the rate of melting is speeding up. Many glaciers in Alaska and other parts of the United States have shrunk dramatically.


What will happen in the future?

If temperatures keep rising, glaciers will continue melting, and some could disappear completely.

These two photographs of the McCall Glacier in Alaska were taken from the same location in 1958 and 2003. The newer photo shows how far the glacier has receded since the first photo was taken.

Source: Post (1958) and Nolan (2003), National Snow and Ice Data Center


Why does it matter?
As glaciers and the giant ice sheets on Greenland and Antarctica melt, they add more water into the ocean, which causes sea level to rise.

Less snowpack

Snowpack refers to the total amount of snow and ice on the ground. In high mountain ranges and other cold places, snowpack builds up in the winter and melts in the spring and summer. As the world gets warmer, some places will get more rain instead of snow, so the snowpack won't be as deep. Plus, when the air is warmer, snow melts faster.

Mountainside with sparse snow

What is happening now?

Many places have less snowpack than they used to, and this snowpack is melting earlier. For example, the map on the right shows that in many parts of North America, Europe, and Asia, snow doesn't stay on the ground in the spring as long as it used to.


What will happen in the future?
As temperatures keep getting warmer, snowpack is expected to continue to shrink in most of North America and around the world.
Why does it matter?

When snowpack melts in spring and summer, it provides fresh water for rivers and streams, and it fills reservoirs that supply drinking water to cities and towns. Snowpack is also important for winter sports like skiing and snowboarding.


Thawing permafrost 

Permafrost refers to a layer of soil or rock that is frozen all year round. Permafrost is found throughout much of Alaska, parts of Canada, and other countries in the far north. You might think a place with permafrost would be barren, but plants can still grow in the soil at the surface, which is not frozen during warmer parts of the year. However, there may be a thick layer of permafrost underneath. As air temperature rises, so does the temperature of the ground, which can cause permafrost to thaw (or melt).


What is happening now?
Ground temperatures have increased throughout Alaska since the late 1970s, and permafrost has already thawed in many places.
What will happen in the future?

As temperatures keep getting warmer, permafrost will continue to thaw. For example, the map on the right shows how permafrost in northwestern Alaska could change by the year 2100.

Why does it matter?

When permafrost melts, the land above it sinks or changes shape. Sinking land can damage buildings and infrastructure such as roads, airports, and water and sewer pipes. It also affects ecosystems. For example, the top photo shows a forest where the trees are leaning or falling over because the permafrost underneath them has melted.

Another reason to be concerned about permafrost is because it has a lot of carbon trapped inside. As permafrost thaws, this carbon is released to the atmosphere in the form of methane, a powerful greenhouse gas. This process leads to more climate change and is an example of a positive feedback loop, which happens when warming causes changes that lead to even more warming.

This graphic includes two maps of the Seward Peninsula in northwestern Alaska. One map shows where permafrost is currently located, and the other shows where scientists expect permafrost to be found at the end of this century.

Source: Adapted from U.S. Global Change Research Program (2009).


Special thanks to EPA US for all the information on this website.

Next month we will look into the effects climate change has on people and the environment.

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