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Climate (from Ancient Greek κλίμα 'inclination') is commonly defined as the weather averaged over a long period. [9] The standard averaging period is 30 years, [10] but other periods may be used depending on the purpose. Climate also includes statistics other than the average, such as the magnitudes of day-to-day or year-to-year variations.
Climate change can also be used more broadly to include changes to the climate that have happened throughout Earth's history. [32] Global warming—used as early as 1975 [33] —became the more popular term after NASA climate scientist James Hansen used it in his 1988 testimony in the U.S. Senate. [34] Since the 2000s, climate change has ...
If the annual precipitation is less than 50% of this threshold, the classification is BW (arid: desert climate); if it is in the range of 50%–100% of the threshold, the classification is BS (semi-arid: steppe climate). [9] [11] A third letter can be included to indicate temperature.
The key conclusions of Working Group I [11] were: . An increasing body of observations gives a collective picture of a warming world and other changes in the climate system (The global average surface temperature has increased over the 20th century by about 0.6 °C; Temperatures have risen during the past four decades in the lowest 8 kilometres of the atmosphere; Snow cover and ice extent have ...
Global mean sea levels (GMSL) rose by 3.66 mm (0.144 in) per year which is "2.5 times faster than the rate from 1900 to 1990". [7]: 2 [8] At the rate of acceleration, it "could reach around 30 cm (12 in) to 60 cm (24 in) by 2100 even if greenhouse gas emissions are sharply reduced and global warming is limited to well below 2 °C, but around 60 cm (24 in) to 110 cm (43 in) if emissions ...
Cooler climate causes Carboniferous rainforest collapse: 251.9: Permian–Triassic extinction event: 199.6: Triassic–Jurassic extinction event, causes as yet unclear 66: Perhaps 30,000 years of volcanic activity form the Deccan Traps in India, or a large meteor impact. 66
Throughout Earth's climate history (Paleoclimate) its climate has fluctuated between two primary states: greenhouse and icehouse Earth. [1] Both climate states last for millions of years and should not be confused with the much smaller glacial and interglacial periods, which occur as alternating phases within an icehouse period (known as an ice age) and tend to last less than one million years ...
RCP 2.6 is a "very stringent" pathway. [6] According to the IPCC, RCP 2.6 requires that carbon dioxide (CO 2) emissions start declining by 2020 and go to zero by 2100.It also requires that methane emissions (CH 4) go to approximately half the CH 4 levels of 2020, and that sulphur dioxide (SO2) emissions decline to approximately 10% of those of 1980–1990.