Some scientists speculate that this may be the beginning of a periodic solar event called a “grand minimum,” while others say there is insufficient evidence to support that position. Credit: NASA/JPL-CaltechĪs mentioned, the Sun is currently experiencing a low level of sunspot activity. It is therefore extremely unlikely that the Sun has caused the observed global temperature warming trend over the past half-century. Over the same period, global temperature has risen markedly. The amount of solar energy that Earth receives has followed the Sun’s natural 11-year cycle of small ups and downs with no net increase since the 1950s. Eleven-year averages are used to reduce the year-to-year natural noise in the data, making the underlying trends more obvious. The lighter/thinner lines show the yearly levels while the heavier/thicker lines show the 11-year average trends. The above graph compares global surface temperature changes (red line) and the Sun's energy that Earth receives (yellow line) in watts (units of energy) per square meter since 1880. Are We Headed for a ‘Grand Minimum’? (And Will It Slow Down Global Warming?) Since 1750, the warming driven by greenhouse gases coming from the human burning of fossil fuels is over 50 times greater than the slight extra warming coming from the Sun itself over that same time interval. Warming from increased levels of human-produced greenhouse gases is actually many times stronger than any effects due to recent variations in solar activity.įor more than 40 years, satellites have observed the Sun's energy output, which has gone up or down by less than 0.1 percent during that period. What Effect Do Solar Cycles Have on Earth’s Climate?Īccording to the United Nations’ Intergovernmental Panel on Climate Change (IPCC), the current scientific consensus is that long and short-term variations in solar activity play only a very small role in Earth’s climate. Scientists don’t yet know with confidence how strong the next solar cycle may be. It’s expected to end sometime between now and late 2020.
The current solar cycle began January 4, 2008, and appears to be headed toward the lowest level of sunspot activity since accurate recordkeeping began in 1750. These changes have a variety of effects in space, in Earth’s atmosphere and on Earth’s surface. Levels of solar radiation go up or down, as does the amount of material the Sun ejects into space and the size and number of sunspots and solar flares. During each cycle, the Sun undergoes various changes in its activity and appearance. The Sun doesn’t always shine at perpetually the same level of brightness it brightens and dims slightly, taking 11 years to complete one solar cycle. But the warming we’ve seen over the last few decades is too rapid to be linked to changes in Earth’s orbit, and too large to be caused by solar activity.
It also influences Earth’s climate: We know subtle changes in Earth’s orbit around the Sun are responsible for the comings and goings of the past ice ages. The Sun powers life on Earth it helps keep the planet warm enough for us to survive.
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