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Causes of Climate Change

Have you noticed changes in your environment – be it a backyard, neighborhood or community – that might be connected to climate change?  Have daffodils or hyacinths popped through the soil earlier each spring? Are trees in local parks budding earlier, or are summers hotter than they used to be? Has your yard or garden struggled to survive through periods of drought or excessive heat? Has extreme weather, such as torrential rainfall or winter snowfall, affected your property, personal safety or travel plans more than ever before? If so, what you are experiencing is part of a global change in the Earth’s climate. Scientists once thought that climate change would take many generations to be felt, but instead we are already experiencing its dramatic effects.

Global climate is the average climate over the entire planet. Earth’s climate has changed throughout time due to natural forces. But the planet’s climate is changing (climate change) and warming up fast (global warming) – faster than at any time scientists know about from studying the Earth’s history.

Scientists who study the world’s climate today and who investigate past climates agree that global temperature has increased rapidly and significantly over the past 150 years. In fact, each of the last three decades has been successively warmer at the Earth’s surface than any other preceding decade since 1850.

Many scientists consider climate change to be the preeminent environmental issue of our time. Scientific evidence shows that the Earth’s climate is changing in many ways that can affect people, natural environments, and communities – global temperatures are increasing, precipitation patterns and extreme storm events are changing, and sea levels are rising.

Causes of climate change
Climate change refers to alterations in the long-term record of climate components (such as air temperature, precipitation, or wind patterns) sustained of a time period of decades or longer. Climate change is caused by a combination of natural influences and human activities.

While the Earth’s climate has experienced periods of natural changes and fluctuations over timeframes of hundreds and thousands of years, the large and rapid changes underway today are unprecedented.

Natural factors alone cannot explain today’s rapid pace of change. There is overwhelming evidence that an increase in gases like carbon dioxide in the atmosphere is causing these changes. 

In fact, ninety-seven percent of climate scientists agree that climate-warming trends over the past century are very likely due to human activities.

The Greenhouse Effect and Greenhouse Gases
Our planet’s atmosphere traps energy just like a greenhouse. Energy from the sun can enter the Earth’s atmosphere, but not all of it can easily find its way out again. Molecules in our atmosphere called greenhouse gases absorb the heat - trapping energy in the atmosphere and causing it to warm. Greenhouse gases include water vapor, methane, ozone, nitrous oxide, and carbon dioxide.

This phenomenon is called the greenhouse effect and it is natural and necessary to support life on Earth. In fact, greenhouse gases trap energy and keep the temperatures on our planet mild and suitable for living things. However, elevated levels and the buildup of greenhouse gases can change Earth’s climate and result in dangerous effects to ecosystems and human health. So while the greenhouse effect is not a bad thing, scientists are concerned because we are currently adding more greenhouse gases to our atmosphere, causing an increased greenhouse effect – a very rapid warmup that is causing changes in our planet that can affect our lives.

Over the past century, human activities have released large amounts of carbon dioxide and other greenhouse gases (such as methane and nitrous oxides) into the atmosphere.

Since the Industrial Revolution of the 1800s, the amount of carbon dioxide in the atmosphere has risen by almost 40 percent. The majority of greenhouse gases come from burning fossil fuels to produce energy, although deforestation, industrial processes, and some agricultural practices also emit gases into the atmosphere. Increases in these greenhouse gases (such as carbon dioxide, methane, nitrous oxides) coincide with a worldwide increase in temperature. 

Greenhouse gases act like a blanket around the Earth, trapping energy in the atmosphere and causing it to warm. This phenomenon is called the greenhouse effect and is natural and necessary to support life on Earth. However, the buildup of greenhouse gases can change Earth’s climate and result in dangerous effects to human health and welfare and to ecosystems.

The choices we make today will affect the amount of greenhouse gases we put in the atmosphere in the near future and for years to come.

Global air temperatures are 1.5 degrees higher than they were at the start of the 20th century, and have risen about 1 degree over the last 30 years. The earth is now warmer than it has been during the past several thousand years, and climate models project a continuation of this trend.  According to the latest report from the Intergovernmental Panel on Climate Change, average global temperatures are likely to rise by another 2 to 8.6 degrees F by 2100.

An increase in the surface temperature of the globe means:

  • Wetter weather, since warm air carries more water than cold air;
  • Warming oceans;
  • A loss in arctic sea ice;
  • A loss in land ice; and
  • A rise in sea level, both from the added water from melting ice and the expansion of seawater as it warms up.

Climate change is affecting Delaware now - temperatures are rising, rainfall amounts are increasing, and sea levels are rising. Many of these changes are expected to continue and become more serious, resulting in negative consequences for people, places and the environment.  Individuals, communities and policy makers are working throughout the state to develop programs and projects to reduce vulnerabilities and climate- / hazard-related risks to people, homes, businesses, economies, and ecosystems.

Information on this page was compiled from the following resources: ,National Center for Atmospheric Research and UCAR Office of Programs website  Cornell University Climate Change website, Cornell University Cooperative Extension Fact Sheet, IPCC

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Page Updated on March 30, 2016