Thursday, September 22, 2022

How Does Solar Radiation Affect Climate

Sunlight Intensity Affects Global Winds Precipitation Patterns And Ocean Circulation Which Are All Components Of Climate

Solar Influence: Climate Change, Lines of Evidence: Chapter 6

At the equator, the Earth receives greater exposure to the suns rays where both air and extensive bodies of water warm under the influence of the sun. Molecules are more closely packed together when cold than they are when warm, which makes warm air and water less dense than cold air and water. This difference in relative density causes heat to rise.The warm air that rises in the tropics is wet. Sunlight causes water to evaporate from plants, soils, and bodies of water. These water molecules rise to become part of the air because the air is warm and less dense, there is sufficient room for water molecules within the air mass. But as the air gains altitude it cools, reducing density and space for water. The water molecules condense to form clouds and eventually fall as precipitation .

Climate Change: Incoming Sunlight

Highlights
  • The Sun’s overall brightness varies on timescales from minutes to millennia, and these changes are detectable in the global temperature record.
  • During strong solar cycles, the Sun’s total average brightness varies by up to 1 Watt per square meter this variation affects global average temperature by 0.1 degrees Celsius or less.
  • Changes in the Sun’s overall brightness since the pre-industrial period have been minimal, likely contributing no more than 0.01 degrees Celsius to the roughly 1 degree of warming that’s occurred over the Industrial period.
  • Projected warming due to increasing greenhouse gas levels in the coming decades will overpower even a very strong Grand Solar Minimum.
  • Rising amounts of atmospheric carbon dioxide have postponed the next Milankovitch-driven ice age by at least tens of thousands of years.

Reconstruction of total solar irradiance based on sunspot observations since the 1600s. During strong solar cycles, the Sun’s total average brightness varies by up to 1 Watt per square meter. Changes in the Sun’s overall brightness since the pre-industrial period have been minimal, making a very small contribution to global-scale warming. NOAA Climate.gov image, based on the Climate Data Record by Coddington, et al., 2016.

Distribution Of Radiant Energy From The Sun

Nuclear fusion deep within the Sun releases a tremendous amount of energy that is slowly transferred to the solar surface, from which it is radiated into space. The planets intercept minute fractions of this energy, the amount depending on their size and distance from the Sun. A 1-square-metre area perpendicular to the rays of the Sun at the top of Earths atmosphere, for example, receives about 1,365 watts of solar power. Because of the slight ellipticity of Earths orbit around the Sun, the amount of solar energy intercepted by Earth steadily rises and falls by ±3.4 percent throughout the year, peaking on January 3, when Earth is closest to the Sun. Although about 31 percent of this energy is not used as it is scattered back to space, the remaining amount is sufficient to power the movement of atmospheric winds and oceanic currents and to sustain nearly all biospheric activity.

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The Suns Direct Influence

The link between solar particles and ozone is reasonably well established, but what about any direct effects solar particles may have on the climate?

We have observational evidence that solar activity influences regional climate variability at both poles. Climate models also suggest such polar effects link to larger climate patterns and influence conditions in mid-latitudes.

The details are not yet well understood, but for the first time the influence of solar particles on the climate system will be included in climate simulations used for the upcoming Intergovernmental Panel on Climate Change assessment.

Read more:Solar weather has real, material effects on Earth

Through solar radiation and particles, the Sun provides a key energy input to our climate system. While these do vary with the Suns 11-year cycle of magnetic activity, they can not explain the recent rapid increase in global temperatures due to climate change.

We know rising levels of greenhouse gases in the atmosphere are pushing up Earths surface temperature . We also know human activities have greatly increased greenhouse gases in the atmosphere. Together these two factors explain the observed rise in global temperatures.

What About The Last 100 Years Or More

Radiational effects for climate change

There are a range of methods for estimating past solar radiation changes that represents an entire field of research.

Suffice to say, reconstructions of changes in solar radiation, over the 20th century in particular, are highly important to climate scientists seeking to understand why our climate has warmed.

The best way to understand how 20th century solar changes affected the climate system is with global climate models.

Changes in solar radiation in a climate model are known as solar forcing. Climate models capture the effects of solar forcing well. The most basic proof of this is that climate models reproduce the diurnal cycle with great accuracy.

Climate models also represent the seasonal cycle in land and ocean temperatures as well as the seasonal cycle in patterns of rainfall, pressure, winds, ocean currents and sea-ice, with impressive fidelity.

Models can also reproduce climates from the geological past, based on palaeo evidence of solar energy changes.

Using the same physics, climate models are able to include observed changes in direct solar forcing over the 20th century. To do this, they use a number of different estimates of solar forcing from different research teams.

All of the modelling conducted over the last 20 years has shown that solar changes do have a discernible affect on the climate of the last 100 years, but that those changes are typically very small compared to those associated with increasing greenhouse gases.

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Splitting Up The Spectrum

Although the TSI is a key ingredient in Earths global energy budget, the spectrally resolved solar irradiance provides much deeper insight into the impact of solar variability on the atmosphere. Unlike TSI, which integrates the contribution from all spectral bands into one single quantity, SSI reveals variations at specific wavelengths, each of which affects Earths environment in a different way.

Making accurate SSI observations is a real challenge: SSI measurements must be carried out from space.

Unfortunately, the record of SSI observations is fragmented in time and in wavelength, even more so than TSI observations.

Making accurate SSI observations is a real challenge: SSI measurements must be carried out from space to capture radiation that would otherwise be partly absorbed by Earths atmosphere. However, instruments degrade in the harsh environment of space, leaving researchers with large uncertainties in the data.

On the few occasions when several instruments measured the SSI simultaneously, their observations often disagreed, which highlights the importance of calibrating the instruments and having several of them that operate simultaneously. For example, NASAs Solar Radiation and Climate Experiment mission, which started operating in 2003, reported an unusually large solar cycle variability in the UV. This variation remains hotly debated since most wavelengths are monitored only by SORCE, with no alternative observations.

How Does Solar Input Affect Climate

The Earths climate system depends entirely on the Sun for its energy. Solar radiation warms the atmosphere and is fundamental to atmospheric composition, while the distribution of solar heating across the planet produces global wind patterns and contributes to the formation of clouds, storms, and rainfall.

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Milankovitch Cycles And Ice Ages

The 11-year sunspot cycle and its Gleissberg-cycle modulation cause small changes in the Suns actual brightnesshow much sunlight the Sun radiates to Earth. Earths climate is also affected by how much sunlight reaches us due to changes in our planets orbit and position in space relative to the Sun. Called Milankovitch cycles, these predictable orbital patterns have repeat times of tens to hundreds of thousands of years.

For the past million years at least, Milankovitch cycles have coincided with 100,000-year-long ice ages punctuated by short intervals of rapid warming. Although there are pieces of the puzzle experts still dont understand, the key climate influence seems to be changes in the amount of incoming sunlight, or insolation, reaching the high latitudes of the Northern Hemisphere during the summer. The Northern Hemisphere is key to the ice ages because massive ice sheets can only grow over land, not ocean, and most of Earths land area has been concentrated in the Northern Hemisphere for at least tens of millions of years.

The most significant changes in Northern Hemisphere insolation come from three variations in Earths orbit:

  • precession : the slow rotation or wobble in the Earths axis of rotation, which changes where in the annual orbital path Northern Hemisphere summer solstice occurs
  • obliquity : how tilted Earths axis of rotation is
  • eccentricity : how far Earths orbit is from being a perfect circle.

Explainer: Six Ideas To Limit Global Warming With Solar Geoengineering

Solar panels in the winter | How does climate affect solar power?

09.05.2018 | 3:11pmGeoengineering

Scientists agree that cutting global greenhouse emissions as soon as possible will be key to tackling global warming. But, with global emissions still on the rise, some researchers are now more research into measures that could be taken alongside emissions cuts, including controversially the use of solar geoengineering technologies.

Solar geoengineering is a term used to describe a group of hypothetical technologies that could, in theory, counteract temperature rise by reflecting more sunlight away from the Earths surface.

From sending a giant mirror into space to spraying aerosols in the stratosphere, the range of proposed techniques all come with unique technical, ethical and political challenges.

Carbon Brief spoke to the scientists who are pioneering research into these techniques to find out more about their potential uses, shortfalls and overall feasibility.

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Role Of Solar Radiation In Climate Change

Date:
ETH Zurich
Summary:
A growing research field is “global dimming” and “global brightening” of solar radiation. These phenomena, supposedly human-induced, control solar radiation incident at the Earth’s surface and thus influence climate.

A special volume of the Journal of Geophysical Research reviews the growing research field of global dimming and global brightening in over 20 articles. These phenomena, supposedly human-induced, control solar radiation incident at the Earths surface and thus influence climate.

Special instruments have been recording the solar radiation that reaches the Earths surface since 1923. However, it wasnt until the International Geophysical Year in 1957/58 that a global measurement network began to take shape. The data thus obtained reveal that the energy provided by the sun at the Earths surface has undergone considerable variations over the past decades, with associated impacts on climate.

In analyzing more recently compiled data, however, Wild and his team discovered that solar radiation has gradually been increasing again since 1985. In a paper published in Science in 2005, they coined the phrase global brightening to describe this new trend and to oppose to the term global dimming used since 2001 for the previously established decrease in solar radiation.

Only recently, an article in the journal Nature, which Wild was also involved in, brought additional attention to the topic of global dimming/brightening.

Story Source:

Controlling The Global Thermostat

Another unresolved aspect of geoengineering research is the issue of governance. Though ideas are beginning to emerge, it is still not clear who could be responsible for carrying out and regulating solar geoengineering.

At present, research into solar geoengineering is largely restricted to the US, the UK and other parts of Europe although China recently launched the worlds largest geoengineering research programme.

But earlier this month, a group of scientists and policymakers from the global south published a letter in Nature calling for developing nations to take the lead on SRM research.

Developing countries are likely to be the most affected by future climate change, research shows.Therefore, it is right for these nations to play a central role in solar geoengineering research, discussion and evaluation, the group argues.

A small number of initiatives aim to widen participation in SRM research. The Solar Radiation Management Governance Initiative recently released funding for research projects that plan to model the impacts of SRM in developing nations.

In addition, the Carnegie Climate Geoengineering Governance Initiative has been established to encourage a broader, society-wide discussion about the risks, potential benefits, ethical and governance challenges raised by climate geoengineering.

The challenge could be so large that it could stop the development of solar geoengineering altogether, says Dr Anthony Jones:

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Can We Limit The Amount Of Sunlight To Stop Climate Change

Large volcanic eruptions are able to send gases high in the atmosphere. These gases form particles called aerosols that can travel worldwide, reducing the amount of sunlight that gets to the Earths surface. This happened in June of 1991 when Mt Pinatubo erupted. The climate cooled about 0.3 for a couple of years. Researchers are looking at ways to engineer a similar effect shading the planet and helping to cool our climate.

Blocking some solar radiation from getting to Earth could involve sending gases or particles into the atmosphere like volcanoes do. It could also include methods like making clouds or the Earths surface brighter so that they reflect more sunlight back out into space. Methods like these could help slow climate change.

While Earths albedo is 0.3 on average, which means that about a third of solar energy is reflected back out into space, albedo varies worldwide, with more energy reflected near the poles than near the equator.Credit: NOAA

Researchers are looking for ways to increase the albedo of Earth, because If less solar energy is absorbed by the planet, then the surface of the Earth will cool. This concept is called solar radiation management. Two examples include:

Illustration showing how particles of sea salt or other aerosols released from a ship over the Arctic could help create brighter clouds that reflect more incoming solar energy away from Earth.US Department of Energy, Office of Science

How Does Solar Variability Affect Climate

This is a picture of how volcanic radiation effects radiation from the ...

Solar variability affects Earths climate in many intricate and nonlinear ways. Most effects are ultimately driven and modulated by the solar magnetic field and its conspicuous solar cycle, which repeats approximately every 11 years.

Careful statistical analysis is required to extract the effect of solar variability on climate from a noisy background.

The effect of solar variability on climate is mostly hidden in the natural variability of the climate system thus, careful statistical analysis is required to extract it from a noisy background. Such analyses require records that extend over a long period of time, but the paucity of observations in existing records poses a serious challenge. For example, scientists have been making direct measurements of the total solar radiative input into Earths atmosphere only since 1978, although there had been earlier attempts to measure it from the ground.

Although solar radiation represents more than 99.9% of the energy entering Earths system, radiation is not the only means by which solar variability affects climate. Another source of variability comes from energetic particles, some of which originate from the Sun.

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Is The Sun Causing Global Warming

No. The Sun can influence Earths climate, but it isnt responsible for the warming trend weve seen over recent decades. The Sun is a giver of life it helps keep the planet warm enough for us to survive. We know subtle changes in Earths orbit around the Sun are responsible for the comings and goings of the ice ages. But the warming weve seen in recent decades is too rapid to be linked to changes in Earths orbit and too large to be caused by solar activity.

One of the smoking guns that tells us the Sun is not causing global warming comes from looking at the amount of solar energy that hits the top of the atmosphere. Since 1978, scientists have been tracking this using sensors on satellites, which tell us that there has been no upward trend in the amount of solar energy reaching our planet.

A second smoking gun is that if the Sun were responsible for global warming, we would expect to see warming throughout all layers of the atmosphere, from the surface to the upper atmosphere . But what we actually see is warming at the surface and cooling in the stratosphere. This is consistent with the warming being caused by a buildup of heat-trapping gases near Earth’s surface, and not by the Sun getting hotter.

READ MORE

Solar Energy Contributes To Climate Change Some Study Finds

A recent study reveals an aspect about solar energy we never expected or thought possible it contributes to climate change.

The study, conducted by climate change research scientist Aixue Hu of the National Center for Atmospheric Research and published Monday in the journal Nature Climate Change, found that solar panels tend to cause regional cooling when converting sunlight into electricity and increase urban area temperatures when said electricity transforms into heat.

Researchers conducted climate model sensitivity experiments to look at the effects of solar panels placed in various regions.

If just a little amount of energy would help us for years, wouldnt it be smart to install copious amounts of solar panels for an endless supply? As the study reveals, probably not.

Large solar installations affect global and regional climate by taking solar radiation and distributing it in a different manner than natural processes. In turn, the farms change local radiation balance, resulting in changes in atmospheric circulation.

Furthermore, aside from the study results, the production of solar panels has its own negative environmental impacts.

But in the end, despite the drawbacks of instillations, solar energy consumption is still a better alternative to using fossil fuels. “Globally it will not affect the global climate much,” Hu told The Washington Post.

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