Climate 101 - What & How
What causes climate change? Who is most responsible and how will it affect or lives, our jobs, our neighbors? Read below for answers to the most common questions on climate change.
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Introduction
Climate 101 - FAQ
What causes climate change? How can a few degrees make such a difference? Who has the most responsibility? How will it impact our lives and jobs? Who is most impacted?
Find answers to the most common questions on climate change below. To learn more, visit the U.S. National Climate Assessment website.
1What causes climate change?
Our atmosphere is like a blanket
How does our climate work? Our atmosphere acts like a blanket, warming our planet and making life possible. You can see our atmosphere – it is the beautiful fuzzy blue line around the earth in the photo to the right. When sunlight hits the Earth, the heat from the sun bounces off to return to space. Our atmosphere is made up of gases, some of which trap the heat as it tries to leave. This warms our planet and is called the Greenhouse Effect. The more heat trapping Greenhouse gases we have in our atmosphere, the more heat is trapped, therefore warming our climate.
Not too hot – not too cold
If we did not have any atmosphere, or if we had very little greenhouse gas in our atmosphere, the Earth would be a frozen ball of ice like Mars and would not support life. On the other hand, if we had too much greenhouse gas in the atmosphere, Earth would be too hot to live on, like Venus. For the last 10,000 years our atmosphere has been stable, with a climate that is just right - not too hot and not too cold. This stable atmosphere has allowed human civilizations to grow and thrive.
What causes greenhouse gases and our climate to change?
Greenhouse gases are now increasing in our atmosphere which is causing our climate to warm. This is happening as a result of human activities. The primary greenhouse gas, carbon dioxide, is created whenever we burn fossil fuels - coal, oil or natural gas. We burn these fuels in everyday activities like driving cars, heating buildings, and making electricity. Carbon dioxide, once emitted, stays in the atmosphere for a very long time - up to thousands of years. In order to stop the climate from warming we need to stop burning fossil fuels and transition to new fuel sources that do not create greenhouse gases, like solar and wind energy. Fortunately, we have the technology we need to make this transition and the cost for these energy sources has dropped dramatically in recent years. Learn more about this technology on the Solutions page.
Another greenhouse gas that has a big impact is methane. Methane is a very powerful greenhouse gas, more powerful than carbon dioxide. It is created through both agricultural practices and landfills. In agriculture, methane is created primarily by some animals during digestion (cattle and sheep), animal wastes (manure) and some crops, like rice. Methane is also created when we throw garbage into landfills. Other less common greenhouse gases include Nitrous Oxide and Chlorofluorocarbons (CFCs).
2Our winter has been colder, how can we have climate change?
The atmosphere determines our global average temperature. As we add greenhouse gases, the global average temperature increases. This increase in average temperature creates average trends like decreased snowfall, more rainfall, larger storms and warmer oceans. However, these are global trends and do not determine the local climate or weather in a particular area. The change in local weather patterns from climate warming varies. Some areas may see much higher temperatures and less rainfall, others may see an increase in rainfall, and others more extreme cold days. An extra cold winter in one area does not mean that the average climate across the world is not warming. Scientists have been tracking the average global temperature by taking measurements in many places around the world. They have established that the global average temperature is increasing. It has increased by about 1.5°F since 1750 when we started to burn fossil fuels, with most of the warming happening since 1970.
3How can only a few degrees make such an impact?
To humans, a few degrees doesn’t sound like much, it is not even the difference between a t-shirt or a sweater. However, we are not talking about a few degrees change in the local weather. We are talking about a change in the average global temperature. A few degrees difference in the global average temperature creates big changes in our world. The global average temperature during the last ice age, 20,000 years ago, was only about 7°F colder than today. However, sea level at the peak of the last ice age was 394 feet lower than it is today. Climate change of only a few degrees will create big changes in our world, including widespread changes in local temperatures, rainfall, snowfall, the size and frequency of storms, and sea level. These changes also have a huge impact on our ecosystems and other species that have difficulty adapting to these extreme changes. The faster the change, the harder it is for species to adapt. The climate change we are experiencing now is happening far more rapidly than natural climate changes in history, and this is threatening many species.
4Climate change has happened before, isn't this a natural process?
- Volcanoes emit aerosol particles that can reach the atmosphere and block the sun, producing a cooling effect.
- The sun’s intensity changes on natural cycles, affecting the amount of energy we receive from the sun. The current 11-year solar cycle is producing the lowest solar output since the mid 1900’s which should produce a cooling effect, not the warming we are observing.
- Changes in the Earth’s orbit and tilt have been the primary driving force for the ice age cycles over the past 800,000 years. However, these changes in Earth’s orbit and tilt happen very slowly, with the associated warming or cooling happening over tens to hundreds of thousands of years.
All of these natural processes can be measured; however, scientists have found that these natural causes are not explaining the warming we see today. The cause of the current warming is emissions of carbon dioxide and other greenhouse gases by humans. The historical scientific evidence clearly shows a direct link between the levels of carbon dioxide (CO2) in the atmosphere and the global average temperature. This relationship is well established and 97% of climate scientists agree that the current changes in our climate are due to human activities, specifically human activities creating carbon dioxide and other greenhouse gas emissions.
The biggest difference between current warming and the climate changes in history is the speed at which it is happening. We are currently warming the Earth many times faster than natural cycles. The faster we change the climate, the more difficult it is for other species on the planet to adapt. Even slower climate change events in history have resulted in species extinction. Our current rapid speed of warming threatens a significant number of species with extinction.
5What about China? Who is most responsible?
With climate change, it is actually the total emissions of CO2 and greenhouse gases over time that determine the impact on climate. If we look at this measure of total responsibility, the picture looks quite different
(graph middle right). Here the U.S. clearly has the most responsibility for total emissions to date with China in third place after the U.S. and the entire European Union.
If we look at this in emissions per person across the top emitters the picture changes again (graph bottom right). Here the U.S. again has one of the highest rates of emissions, much higher than China, India, Brazil and the world average.
China has a responsibility to lower emissions along with the U.S. and all other emitting countries. China’s actions will be critical in addressing climate change. China has made strong commitments along with the U.S. and all of the countries in the world to reduce carbon dioxide and greenhouse gas emissions. China has also helped the global transition
away from fossil fuels by making a substantial investment in solar manufacturing. This investment is one of the main reasons the price of solar has dropped so dramatically in recent years which has helped to make clean, renewable energy affordable and possible on a larger scale.
With the largest responsibility for emissions over time and the most resources of any country in the world, the U.S. must lead in this effort. We have the technology and solutions; all we need is to make the decision to move solutions forward. This transition has the opportunity to create jobs and many other benefits. We will be in the strongest position to strengthen our economy by leading and developing the skills and the markets for the technology that will drive the clean energy transition globally. Most importantly, we need to lead in order to create a safe and healthy future for our children.
6How will this affect my family and my job?
Many people worry that the costs of addressing climate change will negatively affect their jobs and their family. However, the cost of not taking action has a far greater potential impact. The impacts of climate change will be broad and affect most people in the U.S. As the climate continues to warm, food and water prices will rise in most areas. For some families, there will be the added costs of damage from severe storms, fires or flooding. If you live near the ocean, storm surges or sea level rise could impact your home or business. The damage from Hurricane Sandy alone cost $50 billion and both Hurricane Katrina and the wildfires in California cost over $100 billion. These impacts will risk jobs and increase family expenses. They also threaten our health and safety. The faster we make the transition to clean, renewable energy sources, the lower the impacts will be in the future.
The cost of clean, renewable energy has decreased dramatically in the last few years, making the tranition to clean energy far less expensive than predicted even a few years ago. Electric cars are much cheaper to operate than gasoline vehicles and will help families save significantly on transportation costs. We don't need to choose between economic prosperity and addressing climate change. Clean, renewable energy like solar and wind technologies are now the same or cheaper than fossil fuel energy in many areas in the U.S. and will be cheaper in most areas soon. Prices for renewable energy will continue to drop and will lower energy costs for families and businesses over time.
Also, clean energy creates jobs! Manufacturing and installation of new clean energy technologies will create hundreds of thousands of local, U.S. jobs and new opportunities for families. There are over 3 million clean energy jobs in the U.S. now; that’s nearly 3 times the total number of fossil fuel jobs. A small number of workers will lose jobs in the fossil fuel industry, however, we can and should provide assistance and job training to help them transition to new jobs and industries. We should not leave anyone behind. A very important part of building a clean energy future is supporting fossil fuel workers and their communities through the transition to a safer future.
Finally, the transition away from fossil fuels will also greatly improve our health. Electric vehicles do not emit the harmful tailpipe air pollution that creates smog. Imagine a world with no more smog! This alone will save thousands of lives and create a safer, healthier atmosphere for our children. Burning fossil fuels like natural gas in our homes for heating also impacts air quality and contributes to asthma and other health problems. Overall, this transition will be a benefit to our economy, our quality of life and to families across the U.S.
7Will impacts affect everyone equally?
Even though the droughts are in one country or region, the conflicts emerging over resources can impact many other countries, including the United States. Refugees from climate impacts or from conflicts over scarce resources, and relief aid will impact many countries across the world. In the Philippines, typhoon Haiyan destroyed over 1 million homes and displaced over 4 million people. These countries have been hit the hardest, yet they have the least responsibility for creating the problem and the least resources to deal with the impacts.
This applies not only to other countries, but to neighborhoods and families in the U.S. as well. The health impacts of fossil fuels are much higher in disadvantaged communities where fossil fuel power plant and transportation emissions tend to be much higher than in other communities. As the country with the highest total emissions and one of the highest emissions per person, we have an opportunity to make the biggest impact. We also have a responsibility as neighbors to take action to create a safer, healthier, and more equitable future both at home and around the world.