Changes

Sunspot activity is a factor in climate fluctuations, however, little details were known about how much of an impact these fluctuations had on the Earth's climate. During the deepest solar minimum ever recorded, from 2005 to 2010, NASA measured the Earth's energy balance, i.e. the amount of energy absorbed by the sun subtract the amount of energy lost to radiation into space. They concluded:

Sunspot activity is a factor in climate fluctuations, however, little details were known about how much of an impact these fluctuations had on the Earth's climate. During the deepest solar minimum ever recorded, from 2005 to 2010, NASA measured the Earth's energy balance, i.e. the amount of energy absorbed by the sun subtract the amount of energy lost to radiation into space. They concluded:

<blockquote>If the Sun were the only climate forcing or the dominant climate forcing, then the planet would gain energy during the solar maxima, but lose energy during solar minima. The fact that Earth gained energy at a rate 0.58 W/m² during a deep prolonged solar minimum reveals that there is a strong positive forcing overwhelming the negative forcing by below-average solar irradiance. That result is not a surprise, given knowledge of other forcings, but it provides unequivocal refutation of assertions that the Sun is the dominant climate forcing.<ref>Hansen, James, Sato, Makiko et al. (January 2012). [http://www.giss.nasa.gov/research/briefs/hansen_16/ "Earth's energy imbalance"] nasa.gov/Goddard Institute for Space Studies.  Retrieved on September 26, 2014.</ref></blockquote>

<blockquote>If the Sun were the only climate forcing or the dominant climate forcing, then the planet would gain energy during the solar maxima, but lose energy during solar minima. The fact that Earth gained energy at a rate 0.58 W/m² during a deep prolonged solar minimum reveals that there is a strong positive forcing overwhelming the negative forcing by below-average solar irradiance. That result is not a surprise, given knowledge of other forcings, but it provides unequivocal refutation of assertions that the Sun is the dominant climate forcing.<ref>Hansen, James, Sato, Makiko et al. (January 2012). [http://www.giss.nasa.gov/research/briefs/hansen_16/ "Earth's energy imbalance"] nasa.gov/Goddard Institute for Space Studies.  Retrieved on September 26, 2014.</ref></blockquote>

But heat energy is not the only force of the Sun affecting the Earth.  The Sun also produces magnetic activity, the effect of which was not measured in this study, and which could affect the Earth's climate in little-understood ways.

But heat energy is not the only force of the Sun affecting the Earth.  The Sun also produces magnetic activity, the effect of which was not measured in this study, and which could affect the Earth's climate in little-understood ways. British astrophysicist Piers Corbyn, speaking in May 2017, claimed that low sunspot activity heralds a mini ice age which could last for 20 years.<ref>https://abruptearthchanges.com/2017/06/14/mini-ice-age-is-here-to-stay-says-astrophysicist/</ref>

==Economics of global warming==

==Economics of global warming==