Is climate change real?
There is a broad-based agreement within the scientific community that climate change is real. The U.S. Environmental Protection Agency, the National Aeronautics and Space Administration, and the National Oceanic and Atmospheric Administration concur that climate change is indeed occurring and is almost certainly due to human activity.
This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, provides evidence that atmospheric CO2 has increased since the Industrial Revolution. (Credit: Luthi, D., et al.. 2008; Etheridge, D.M., et al. 2010; Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO2 record.)
Scientific evidence for warming of the climate system is unequivocal.
Sea level rise
Global sea level has been rising over the past century, and the rate has increased in recent decades. In 2014, the global sea level was 2.6 inches above the 1993 average—the highest annual average in the satellite record (1993-present). Sea level continues to rise at a rate of about one-eighth of an inch per year.
Extreme Events
Extreme events are natural phenomena that generally occur over very short time scales of hours to days to weeks. Extreme events include tropical cyclones (hurricanes, typhoons), tornadoes, floods, heat and cold waves, wildfires, earthquakes, tsunamis, and volcanic eruptions. These events can have significant, sometimes catastrophic direct impacts on the environment and humans. Major extreme events are referred to as natural disasters.
Warming Oceans
The oceans of the world are warming up, their average temperatures pushed higher and higher each year by human-caused global warming. The oceans have absorbed much of this increased heat, with the top 700 meters (about 2,300 feet) of ocean showing warming of more than 0.4 degrees Fahrenheit since 1969
Decreased Snow Cover
While snow cover affects climate, changes in climate also affect snow cover. Overall, warmer temperatures are shortening the amount of time snow is on the ground in the Northern Hemisphere.
Satellite observations reveal that the amount of spring snow cover in the Northern Hemisphere has decreased over the past five decades and that the snow is melting earlier.
Glacial Retreat
The retreat of mountain glaciers, notably in western North America, Asia, the Alps and tropical and subtropical regions of South America, Africa, and Indonesia, provide evidence for the rise in global temperatures since the late 19th century. The acceleration of the rate of retreat since 1995 of key outlet glaciers of the Greenland and West Antarctic ice sheets may foreshadow a rise in sea level, which would affect coastal regions.
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