사용자:Aspere/연습장

Direct measurement and time series

Update on the 2007 solar change and climate paper by Lockwood and Fröhlich, extending the data to the present day. Panels from top to bottom show: global mean air surface temperature $T_{S}$ anomaly from the HadCRUT4 dataset; the mixing ratio of Carbon dioxide in Earth's atmosphere from observations (blue dots) and ice cores (mauve line); the international sunspot number $R_{ISN}$, smoothed using averaging intervals $\tau$ between 8 years and 14 years (the black line connects the yellow points where the mean is independent of $\tau$ and so shows the solar activity trend without making an assumption about the solar cycle length); the total solar irradiance ($TSI$) the blue dots are the PMOD composite of observations and the black and mauve lines are annual and 11-year means of the SATIRE-T2 model of the effect of sunspots and faculae with the addition of a quiet-Sun variation derived from cosmic ray fluxes and cosmogenic isotopes; the open solar flux $F_{S}$ from (mauve line) geomagnetic observations and (blue dots) spacecraft data; Oulu neutron monitor cosmic ray counts, $O$, (blue dots) observed and (mauve line) extrapolated using cosmogenic isotope data; and (grey) monthly and (mauve) annual international sunspot numbers, $R_{ISN}$. The green and yellow shaded bands show sunspot cycles 14 and 24

Neither direct measurements nor proxies of solar variation correlate well with Earth global temperature, particularly in recent decades when both quantities are best known.

The oppositely-directed trends highlighted by Lockwood and Fröhlich in 2007, with global mean temperatures continuing to rise while solar activity fell, have continued and become even more pronounced since then. In 2007 the difference in the trends was apparent after about 1987 and that difference has grown and accelerated in subsequent years. The updated figure (right) shows the variations and contrasts solar cycles 14 and 24, a century apart, that are quite similar in all solar activity measures (in fact cycle 24 is slightly less active than cycle 14 on average), yet the global mean air surface temperature is more than 1 degree Celsius higher for cycle 24 than cycle 14, showing the rise is not associated with solar activity. The total solar irradiance (TSI) panel shows the PMOD composite of observations with a modelled variation from the SATIRE-T2 model of the effect of sunspots and faculae with the addition of a quiet -Sun variation (due to sub-resolution photospheric features and any solar radius changes) derived from correlations with comic ray fluxes and cosmogenic isotopes. The finding that solar activity was approximately the same in cycles 14 and 24 applies to all solar outputs that have, in the past, been proposed as a potential cause of terrestrial climate change and includes total solar irradiance, cosmic ray fluxes, spectral UV irradiance, solar wind speed and/or density, heliospheric magnetic field and its distribution of orientations and the consequent level of geomagnetic activity.

주야

Global average diurnal temperature range has decreased. Daytime temperatures have not risen as fast as nighttime temperatures. This is the opposite of the expected warming if solar energy (falling primarily or wholly during daylight, depending on energy regime) were the principal means of forcing. It is, however, the expected pattern if greenhouse gases were preventing radiative escape, which is more prevalent at night.

Solar variation theory

A 1994 study of the US National Research Council concluded that TSI variations were the most likely cause of significant climate change in the pre-industrial era, before significant human-generated carbon dioxide entered the atmosphere.

Scafetta and West correlated solar proxy data and lower tropospheric temperature for the preindustrial era, before significant anthropogenic greenhouse forcing, suggesting that TSI variations may have contributed 50% of the warming observed between 1900 and 2000 (although they conclude "our estimates about the solar effect on climate might be overestimated and should be considered as an upper limit.") If interpreted as a detection rather than an upper limit, this would contrast with global climate models predicting that solar forcing of climate through direct radiative forcing makes an insignificant contribution.

Sunspot and temperature reconstructions from proxy data

In 2000, Stott and others reported on the most comprehensive model simulations of 20th century climate to that date. Their study looked at both "natural forcing agents" (solar variations and volcanic emissions) as well as "anthropogenic forcing" (greenhouse gases and sulphate aerosols). They found that "solar effects may have contributed significantly to the warming in the first half of the century although this result is dependent on the reconstruction of total solar irradiance that is used. In the latter half of the century, we find that anthropogenic increases in greenhouses gases are largely responsible for the observed warming, balanced by some cooling due to anthropogenic sulphate aerosols, with no evidence for significant solar effects." Stott's group found that combining these factors enabled them to closely simulate global temperature changes throughout the 20th century. They predicted that continued greenhouse gas emissions would cause additional future temperature increases "at a rate similar to that observed in recent decades". In addition, the study notes "uncertainties in historical forcing" — in other words, past natural forcing may still be having a delayed warming effect, most likely due to the oceans.

Stott's 2003 work largely revised his assessment, and found a significant solar contribution to recent warming, although still smaller (between 16 and 36%) than that of greenhouse gases.

A study in 2004 concluded that solar activity affects the climate - based on sunspot activity, yet plays only a small role in the current global warming.

Correlations to solar cycle length

In 1991, Friis-Christensen and Lassen claimed a strong correlation of the length of the solar cycle with northern hemispheric temperature changes. They initially used sunspot and temperature measurements from 1861 to 1989 and later extended the period using four centuries of climate records. Their reported relationship appeared to account for nearly 80 per cent of measured temperature changes over this period. The mechanism behind these claimed correlations was a matter of speculation.

In a 2003 paper Laut identified problems with some of these correlation analyses. Damon and Laut claimed:

the apparent strong correlations displayed on these graphs have been obtained by incorrect handling of the physical data. The graphs are still widely referred to in the literature, and their misleading character has not yet been generally recognized.

Damon and Laut stated that when the graphs are corrected for filtering errors, the sensational agreement with the recent global warming, which drew worldwide attention, totally disappeared.

In 2000, Lassen and Thejll updated their 1991 research and concluded that while the solar cycle accounted for about half the temperature rise since 1900, it failed to explain a rise of 0.4 °C since 1980. Benestad's 2005 review found that the solar cycle did not follow Earth's global mean surface temperature.

In 2022, Chatzistergos updated the cycle length series with recent sunspot and solar plages data, extending them to more recent periods than previous studies, and also considering the various available time series. This is important because of the plentiful updates and corrections that have been applied to the sunspot data over the last decade. He showed that cycle lengths significantly diverge from Earth's temperatures and concluded that the strong correlation reported by Friis-Christensen and Lassen was an artefact of their analysis. Owing largely to their guess of next extrema times, arbitrarily restricting the analysis over a specific time period, along with other arbitrarities in their methodology.