What is climate change?
Climate vs. weather
Climate change definition
Climate change is a significant variation of average weather conditions—say, conditions becoming warmer, wetter, or drier—over several decades or more. It’s that longer-term trend that differentiates climate change from natural weather variability.11
Climate change vs. global warming
While “climate change” and “global warming” are often used interchangeably, global warming—the recent rise in the global average temperature near the earth’s surface—is just one aspect of climate change.11
Natural causes vs. human causes of climate change11
Natural causes of climate change
Earth has gone through warm and cool phases in the past, and long before humans were around. Forces that contribute to climate change include the sun’s intensity, volcanic eruptions, and changes in naturally occurring greenhouse gas concentrations. But records indicate that today’s climatic warming—particularly the warming since the mid-20th century—is occurring much faster than ever before and can’t be explained by natural causes alone. According to NASA, “These natural causes are still in play today, but their influence is too small or they occur too slowly to explain the rapid warming seen in recent decades.”
Human causes of climate change
Humans—more specifically, the greenhouse gas (GHG) emissions we generate—are the leading cause of the earth’s rapidly changing climate. The burning of fossil fuels for electricity, heat, and transportation is the primary source of human-generated emissions. A second major source is deforestation, which releases sequestered carbon into the air. Other human activities that generate air pollution include fertilizer use (a primary source of nitrous oxide emissions), livestock production (cattle, sheep, and goats are major methane emitters), and certain industrial processes that release fluorinated gases (i.e.- refrigerants).