The National Academies have a wide-ranging body of work related to our understanding of the climate system, of current and anticipated climatic changes, of ways to adapt to these changes, and of potential options to mitigate or lessen future climate change and its impacts on society. Current efforts at the National Academies are underway to unlock the storehouse of work we have amassed on climate-related topics to make the information more useful and relevant to decision makers. Here we provide a snapshot of the state of the science on these topics. Follow links to learn more and view additional resources.
Understanding the Climate System
Earth’s climate is changing, and human activities are a major contributor to this change. This is supported by multiple lines of evidence, including temperature records and a range of other observations of our physical world—such as shrinking Arctic sea ice, decreasing snow cover in the Northern Hemisphere, and increasing global average sea level. Computer models of the climate system help us understand why climate changed in the past and how it may change in the future. Recent climate change is happening much faster than most previous natural climate variations. Earth’s climate will continue to warm in the future because of carbon dioxide (CO2) and other greenhouse gases in the atmosphere; the amount of warming experienced depends on future emissions from human activities.
Recent increase in the global average surface temperature has been accompanied by warming of the ocean, a rise in sea level, a strong decline in Arctic sea ice, and many other associated climate effects. Oceans are both warming and becoming more acidic, harming corals and other marine life. As the climate warms, we are also seeing trends in many weather extremes, such as more-frequent heat waves, less-frequent cold snaps, heavier rains in some areas, and wildfires burning larger areas over longer seasons. Warming and precipitation changes are altering the geographical ranges of many plant and animal species and the timing of their life cycles. Abrupt changes—also known as tipping points—have been previously observed in the climate system and may already be underway today. Some future climate change is unavoidable, necessitating steps to adapt to current and anticipated impacts, and appropriate measures to adapt to climate change will vary from location to location.
Future climate change can be lessened by taking steps to reduce emissions of CO2 and other greenhouse gases. Emissions can be reduced by using energy more efficiently, switching to fuels that produce less (or no) greenhouse gases, and capturing the emissions before they enter the atmosphere. There are many sources of energy that produce little or no CO2 emissions, including solar, wind, geothermal, and hydropower. Negative emissions technologies, which remove CO2 from the atmosphere and sequester it, will also be an important part of the portfolio of climate responses.
Society’s need for information about the potential risks of a changing climate and what to do about them has never been greater. People are faced with making decisions about earth and human systems that are complex and sometimes unpredictable. Communicating the science clearly and educating students is necessary for more people to participate in making informed choices about the climate. However, people rarely make decisions based only on scientific information; they also take into account their own goals and needs, knowledge and skills, values and beliefs.