Query: The particular signature of warming in 2016 was also revealing in another way, Overpeck said, noting that the stratosphere… saw record cold temperatures last year

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Nuclear winter <=SEP=> Nuclear winter is the severe global-climatic-cooling-effect , hypothesized to occur after the ignition of a number of firestorms , from nuclear bomb detonations , or wide spread bombardments . Such fires , which can inject soot into the stratosphere , have historically occurred in a number of cities , with nuclear winter researchers using both Hamburg and the less ferocious Hiroshima firestorms as the principal examples . However , as firestorms are most frequently encountered in much larger area wildfires , these latter fires are the most significant today in assessing both the initial and present-day `` nuclear winter '' computer models .

Satellite temperature measurements <=SEP=> The temperature of the atmosphere at various altitudes as well as sea and land surface temperatures can be inferred from satellite measurements . These measurements can be used to locate weather fronts , monitor the El Niño-Southern Oscillation , determine the strength of tropical cyclones , study urban heat islands and monitor the global climate . Wildfires , volcanos , and industrial hot spots can also be found via thermal imaging from weather satellites .   Weather satellites do not measure temperature directly . They measure radiances in various wavelength bands . Since 1978 microwave sounding units ( MSUs ) on National Oceanic and Atmospheric Administration polar orbiting satellites have measured the intensity of upwelling microwave radiation from atmospheric oxygen , which is related to the temperature of broad vertical layers of the atmosphere . Measurements of infrared radiation pertaining to sea surface temperature have been collected since 1967 .   Satellite datasets show that over the past four decades the troposphere has warmed and the stratosphere has cooled . Both of these trends are consistent with the influence of increasing atmospheric concentrations of greenhouse gases .

Ozone depletion <=SEP=> Ozone depletion describes two distinct but related phenomena observed since the late 1970s : a steady decline of about four percent in the total amount of ozone in Earth 's stratosphere ( the ozone layer ) , and a much larger springtime decrease in stratospheric ozone around Earth 's polar regions . The latter phenomenon is referred to as the ozone hole . In addition to these well-known stratospheric phenomena , there are also springtime polar tropospheric ozone depletion events .   The details of polar ozone hole formation differ from that of mid-latitude thinning but the most important process in both is catalytic destruction of ozone by atomic halogens . The main source of these halogen atoms in the stratosphere is photodissociation of man-made halocarbon refrigerants , solvents , propellants , and foam-blowing agents ( chlorofluorocarbon ( CFCs ) , HCFCs , freons , halons ) . These compounds are transported into the stratosphere by winds after being emitted at the surface . Both types of ozone depletion were observed to increase as emissions of halocarbons increased .   CFCs and other contributory substances are referred to as ozone-depleting substances ( ODS ) . Since the ozone layer prevents most harmful UVB wavelengths ( 280 -- 315 nm ) of ultraviolet light ( UV light ) from passing through the Earth 's atmosphere , observed and projected decreases in ozone generated worldwide concern , leading to adoption of the Montreal Protocol that bans the production of CFCs , halons , and other ozone-depleting chemicals such as carbon tetrachloride and trichloroethane . It is suspected that a variety of biological consequences such as increases in sunburn , skin cancer , cataracts , damage to plants , and reduction of plankton populations in the ocean 's photic zone may result from the increased UV exposure due to ozone depletion .

Eocene <=SEP=> The Eocene ( -LSB- pronˈiːəˌsiːn , _ ˈiːoʊ - -RSB- ) Epoch , lasting from , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era . The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch . The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope 13C in the atmosphere was exceptionally low in comparison with the more common isotope 12C . The end is set at a major extinction event called the Grande Coupure ( the `` Great Break '' in continuity ) or the Eocene -- Oligocene extinction event , which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay . As with other geologic periods , the strata that define the start and end of the epoch are well identified , though their exact dates are slightly uncertain .   The name Eocene comes from the Ancient Greek ἠώς ( ēṓs , `` dawn '' ) and καινός ( kainós , `` new '' ) and refers to the `` dawn '' of modern ( ` new ' ) fauna that appeared during the epoch .