Variations in CO2
, temperature and dust from the Vostok ice core
over the last 400,000 years
Climate change means the difference in the Earth's global climate or in regional climates over time.
It describes changes in the state of the atmosphere over time scales ranging from decades to millions of years. These changes can be caused by processes inside the Earth, forces from outside (e.g. variations in sunlight intensity) or, more recently, human activities. Ice ages are prominent examples.
Climate change is any significant long-term change in the expected patterns of average weather of a region (or the whole Earth) over a significant period of time. Climate change is about abnormal variations to the climate, and the effects of these variations on other parts of the Earth. Examples include melting of the ice caps at the South Pole and North Pole. These changes may take tens, hundreds or perhaps millions of years.
In recent usage, especially in the context of environmental policy, climate change usually refers to changes in modern climate (see global warming).
Images for kids
Pacific Decadal Oscillation 1925 to 2010
A schematic of modern thermohaline circulation. Tens of millions of years ago, continental-plate movement formed a land-free gap around Antarctica, allowing the formation of the ACC, which keeps warm waters away from Antarctica.
Variations in solar activity during the last several centuries based on observations of sunspots and beryllium isotopes. The period of extraordinarily few sunspots in the late 17th century was the Maunder minimum.
In atmospheric temperature from 1979 to 2010, determined by MSU NASA satellites, effects appear from aerosols released by major volcanic eruptions (El Chichón and Pinatubo). El Niño is a separate event, from ocean variability.
Global temperature anomalies for 2015 compared to the 1951-1980 baseline. 2015 was the warmest year in the NASA/NOAA temperature record with starts in 1880. It has since been superseded by 2016 (NASA/NOAA; 20 January 2016).
Comparisons between Asian Monsoons from 200 AD to 2000 AD (staying in the background on other plots), Northern Hemisphere temperature, Alpine glacier extent (vertically inverted as marked), and human history as noted by the U.S. NSF.
Arctic temperature anomalies over a 100-year period as estimated by NASA. Typical high monthly variance can be seen, while longer-term averages highlight trends.
Decline in thickness of glaciers worldwide over the past half-century
The estimated change in sea level caused by carbon dioxide emissions.