Before the 1980s, when it was unclear whether the warming effect of increased greenhouse gases was stronger than the cooling effect of airborne particulates in air pollution, scientists used the term inadvertent climate modification to refer to human impacts on the climate.[24] In the 1980s, the terms global warming and climate change became more common. Though the two terms are sometimes used interchangeably,[25] scientifically, global warming refers only to increased surface warming, while climate change describes the totality of changes to Earth's climate system.[24]Global warming—used as early as 1975[26]—became the more popular term after NASA climate scientist James Hansen used it in his 1988 testimony in the U.S. Senate.[27] Since the 2000s, climate change has increased in usage.[28]Climate change can also refer more broadly to both human-caused changes or natural changes throughout Earth's history.[29] Various scientists, politicians and media now use the terms climate crisis or climate emergency to talk about climate change, and global heating instead of global warming.[30] Observed temperature rise Main articles: Temperature record of the last 2,000 years and Instrumental temperature record In recent decades, new high temperature records have substantially outpaced new low temperature records on a growing portion of Earth's surface.[31] There has been an increase in ocean heat content during recent decades as the oceans absorb over 90% of the heat from global warming.[32] Multiple independent instrumental datasets show that the climate system is warming.[33] A so-called "global warming hiatus" from 1998 to 2013 when warming was relatively slow was likely caused by negative phases of the Pacific Decadal Oscillation (PDO)[34][35] and Atlantic Multidecadal Oscillation (AMO).[36] The 2013-2022 decade warmed to an average 1.15 °C [1.00–1.25 °C] compared to the pre-industrial baseline (1850–1900).[37] Surface temperatures are rising by about 0.2 °C per decade,[38] with 2020 reaching a temperature of 1.2 °C above the pre-industrial era.[39] Since 1950, the number of cold days and nights has decreased, and the number of warm days and nights has increased.[40] Evidence of warming from air temperature measurements is reinforced by a wide range of other observations.[41][42] For example, changes to the natural water cycle have been predicted and observed, such as an increase in the frequency and intensity of heavy precipitation, melting of snow and land ice, and increased atmospheric humidity.[43] Flora and fauna are also behaving in a manner consistent with warming; for instance, plants are flowering earlier in spring.[44] Another key indicator is the cooling of the upper atmosphere, which demonstrates that greenhouse gases are trapping heat near the Earth's surface and preventing it from radiating into space.[45] Different regions of the world warm at different rates. The pattern is independent of where greenhouse gases are emitted, because the gases persist long enough to diffuse across the planet. Since the pre-industrial period, the average surface temperature over land regions has increased almost twice as fast as the global-average surface temperature.[46] This is because of the larger heat capacity of oceans, and because oceans lose more heat by evaporation.[47] The thermal energy in the global climate system has grown with only brief pauses since at least 1970, and over 90% of this extra energy has been stored in the ocean.[48][49] The rest has heated the atmosphere, melted ice, and warmed the continents.[50] The Northern Hemisphere and the North Pole have warmed much faster than the South Pole and Southern Hemisphere. The Northern Hemisphere not only has much more land, but also more seasonal snow cover and sea ice. As these surfaces flip from reflecting a lot of light to being dark after the ice has melted, they start absorbing more heat.[51] Local black carbon deposits on snow and ice also contribute to Arctic warming.[52] Arctic temperatures are increasing at over twice the rate of the rest of the world.[53] Melting of glaciers and ice sheets in the Arctic disrupts ocean circulation, including a weakened Gulf Stream, further changing the climate.[54]