What is driving the changes?

Greenhouse gases

Certain gases in the Earth’s atmosphere act as a large planetary blanket. Without these gases, called greenhouse gases, it is unquestioned the Earth would be well below freezing. Greenhouse gases are so powerful that they trap all this heat while making up less than 1% of the atmosphere. Scientists have measured more and more greenhouse gases in the air each year. Their measurements show the Earth’s atmospheric blanket is getting thicker and warming the planet further.

Source: NASA

These extra gases can be traced back to human sources such as burned gasoline and coal through unique ‘chemical fingerprints’. This unnatural warming from greenhouse gases and its related impacts are what’s known as climate change. These conclusions have been accepted by the vast majority of scientists — including those at the largest oil companies, such as ExxonMobil and Shell. Greenhouse gases warm the Earth by trapping the sun’s natural heat, much like how a blanket retains body heat. These gases include carbon dioxide, methane, and many others. The process of how greenhouse gases warm the Earth is the greenhouse gas effect.

Dr. Gavin Schmidt, Director of NASA's Goddard Institute

“The planet is warming. The reason it’s warming is because we are pumping increasing amounts of carbon dioxide into the atmosphere.”

MIT Joint Program on the Science and Policy of Global Change

“The question today is no longer if climate change is happening, but how we can confront the social, economic and health challenges it presents.”

Alan Mulally, Former CEO of Ford

“The time for debating whether climate change is real has passed. It is time for a conversation about what we, as a society, intend to do to address it.”

Still rising

The Earth’s climate responds to many other factors aside from greenhouse gases. For example, it responds to changes in the sun’s brightness, ocean currents, and the Earth’s orbit. Over the past 50 years, these natural factors have influenced the rate of warming. But claims that climate change has stopped are simply untrue. 

Average Temperature Change Since 1900

How are climate & weather different?

Climate means the long term behavior of weather. Weather is local and short-term; climate describes the average weather for a region at a given time of year based on historical patterns. Climate change means the average temperature and precipitation is not following those old patterns.

Where is there scientific agreement?

The world’s leading scientific organizations, including MIT and NASA, agree that human-caused climate change is happening and just a few more degrees of warming will increase the risk of intense storms, sea level rise and other extreme weather events.

How much warming has happened?

People have caused about 1.5ºF of unnatural warming by putting greenhouse gases into the air since 1889. While it may not sound like much, the extra warming has been linked to some natural disasters such as wildfires in the U.S. and drought in the Mediterranean.

Tipping the scales

Although the greenhouse effect is natural, people are unnaturally warming the planet by adding more greenhouse gases, through actions like burning gasoline and clearing forests. Scientists have been actively studying changes in the Earth’s climate for over 50 years and nothing but greenhouse gases can plausibly explain recent temperature increases. The level of future warming is somewhat uncertain because it is not precisely understood how all of Earth’s weather patterns will react to higher levels greenhouse gases. 

Sources and Citations

  1. NASA, “Climate Change: Impacts”:
  2. MIT, “Climate Change: Impacts”:
  3. MIT, “Climate Change: Impacts”:


  1. Fred Hotchkins, NASA.