|Nov 29, 2017 @ 10:20 AM |
NASA Will Stare At The Sun For Climate Science - And SpaceX Is Helping
Marshall Shepherd , Contributor
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Recent data continues to suggest that 2017 is on track to be the third warmest year since record-keeping began (even without an El Nino, which can often boost global temperature averages). One of the most enduring zombie theories (a theory that has long been refuted by the science but lives on in social media, blogs, and opinion editorials) is that recent changes in climate are just related to the Sun. On December 4th, NASA and SpaceX will be sending a new instrument, the Total and Spectral Solar Irradiance Sensor (TSIS-1), to the International Space Station (ISS) to continue forty years of solar monitoring with the intent of understanding the Sun's activity and impacts on Earth's climate.
Our weather and climate system's initial power supply comes from the Sun, but once it reaches our atmosphere, there is a complex web of interactions involving reflection, absorption, and emission of energy by greenhouse gases, clouds, aerosol particles, and the land surface. For example, Mount Agung has been erupting in Bali over the past week, and it is possible that volcanic sulfate material lofted into the stratosphere will block some of the Sun's energy and temporarily cool the planet. The daily, weekly, and monthly input of energy from the Sun is important for weather processes, ocean currents, and climate. Without the Sun, we could not live on the planet.
The "so-called Greenhouse Effect" provides the balance that we need to live comfortably on the planet. As Colorado State University climate scientist Dr. Scott Denning often says,
We know the Greenhouse Effect exists because we survive night every day Denning's point is that absorption and emission processes associated with clouds and gases in the atmosphere make the Earth's temperature range habitable (not too cold).
Earth's Greenhouse Effect
In a NASA press release this week, Peter Pilewskie, TSIS-1 lead scientist at the Laboratory for Atmospheric Physics (LASP) in Boulder, Colorado said,
You can look at the Earth and Sun connection as a simple energy balance. If you have more energy absorbed by the Earth than leaving it, its temperature increases and vice versa Unfortunately, it is not quite that simple and that is pretty typical of nature, right? The Sun's output varies on an 11-year cycle (one solar cycle). The Sun cycles between a relatively quiet period and solar maximum (see diagram below). During solar minimum, the Sun has fewer sunspots, which have been correlated with increased solar activity. NASA points out that,
Over the course of one solar cycle (one 11-year period), the Sun’s emitted energy varies on average at about 0.1 percent. That may not sound like a lot, but the Sun emits a large amount of energy – 1,361 watts per square meter. Even fluctuations at just a tenth of a percent can affect Earth.
A composite of Total Solar Irradiance as measured by NASA satellites over the past 40 years.
One of the key roles of TSIS-1 will be to monitor the decade to decade variability in solar cycles. The last solar minimum (2008 to 2009 was a particularly quiet period, according to NASA, and the next minimum is expected within the next three years. TSIS-1 will be positioned to monitor it.
TSIS-1 has two instruments, the Total Irradiance Monitor and the Spectral Irradiance Monitor. These instruments detect energy coming from the Sun as visible, infrared (heat), and ultraviolet portions of light. Understanding variability in ultraviolet (UV) radiation is important for understanding the health of the ozone layer. The ozone layer is the planet's version of a UV sponge or sunscreen.
Understanding variations in the Sun's energy is also important in evaluating natural and anthropogenic impacts on climate change. Remember, climate change should not be framed as "either/or" but "and." The chart below is very important because it provides the relative roles of factors that influence warming and cooling in the climate system. A proper understanding of this graphic really helps to convey the relative roles of the sun, greenhouse gases, and other forcing. Satellites like TSIS-1 will continue to help refine such charts and the uncertainty in them.
Climate forcing (from the IPCC)
Dr. Marshall Shepherd, Dir., Atmospheric Sciences Program/GA Athletic Assoc. Distinguished Professor (Univ of Georgia), Host, Weather Channel's Sunday Talk Show, Weather (Wx) Geeks, 2013 AMS President