I've heard many Michiganians here saying this year that we hardly had a winter this past year.
As a matter of fact many snowbirds who went to Florida returned home earlier than usual.
They used to return home in June. Now many of them returned in April.
Apparently something is happening in the climate.

Greenhouse gases created by humanity tend to get blamed for the global warming.
Somehow we are all convinced on that.
The concept is as popular as new hot fashion of the day.
However, mostly, this is by indirect evidence and hypothetical imaginations.
It could be a fashion of today and it may be something different tomorrow.
There are a lot of scholars who don't believe the greenhouse gases is the main culprit.

The world has been getting warmer ever since the dissolution of the last glacial age
approximately about 100,000 to 10,000 years ago.

When did the humanity start to produce the greenhouse gases?
It may be from about 1800AD when the industrial revolution started and accelerated.
The global warming had been going on even way before.
Nevertheless, certainly, the acceleration of the warming matches the acceleration of our industrial revolution.

Anyway, being aware of the climatic change and search for the cause are good things.
I hope we can find out why and possibly do something about it. Or can we really?
Without any doubt, the control of air pollution is a good thing,
regardless if it has anything to do with the global warming or not.

I see an interesting observation of seasonal migration of the people between Michigan and Florida.
In Colorado, the trend is the other way.
People used to return to Colorado from winter stay of Arizona and California in April,
but, lately, they are retuning back in May or even June. I guess the locality may make the difference.

Today as it was yesterday, Detroit area is in heat advisory until 8 PM.
The temp before noon is approaching 100 degree, and the real feel will reach 105 degree.
My car registered 102 degree around 1 PM yesterday.
I once again decided not to play golf today.
Instead I was practicing chipping and putting in my cool basement.

Thank you, WM, for the counterpoints on the subject.
Perhaps we need to update ourselves on this controversial subject.

This is what I learned:

The earth went through many climate changes. Once the Korean peninusular was tropical forest, and that is  why we have many coal mines.
Some of them, brown coal, indicating remaining wood fibers, which we used to call Galtan.

The sun's heat/light is reflected back into the space 30%. 70% absorbed.
Darker color absorbes more heat. If the earth is complely covered with white gas or cloud, it will cool off very quickly. If earth is warmed up and is covered with more cloud, it will cools off as if you put a white curtain
over your window.

If earth is warmed up, plants will grow much faster than now and earth will be covered with "rain forest." and will absorb most of CO2 present now. Too much oxygen will be created?

Question is how hot it will be?
Maybe we have to move all to Russian Siberia and tropical zone will be uninhabitable, until another cool cycle starts. 

"Changes in Earth’s orbit have had a big impact on climate over tens of thousands of years. In fact, the amount of summer sunshine on the Northern Hemisphere, which is affected by changes in the planet’s orbit, appears to control the advance and retreat of ice sheets. These changes appear to be the primary cause of past cycles of ice ages, in which Earth has experienced long periods of cold temperatures (ice ages), as well as shorter interglacial periods (periods between ice ages) of relatively warmer temperatures. ^{[1] [2] "}

 Maybe human being will be extinct and another species chosen by God may take over the earth. 

Eventually the sun will disappear like any other star when it loses all the radio active energy.

 

 

 

The Role of the Greenhouse Effect in the Past

In the distant past (prior to about 10,000 years ago), CO₂ levels tended to track the glacial cycles. During warm ‘interglacial’ periods, CO₂ levels have been higher. During cool ‘glacial’ periods, CO₂ levels have been lower. ^{[1] [2]} This is because the heating or cooling of Earth’s surface can cause changes in greenhouse gas concentrations. ^[1] These changes often act as a positive feedback, amplifying existing temperature changes. ^[1]

The Recent Role of the Greenhouse Effect

Since the Industrial Revolution began around 1750, human activities have contributed substantially to climate change by adding CO₂ and other heat-trapping gases to the atmosphere. These greenhouse gas emissions have increased the greenhouse effect and caused Earth’s surface temperature to rise. The primary human activity affecting the amount and rate of climate change is greenhouse gas emissions from the burning of fossil fuels.

The Main Greenhouse Gases

The most important GHGs directly emitted by humans include CO₂, CH₄, nitrous oxide (N₂O), and several others. The sources and recent trends of these gases are detailed below.

Carbon dioxide
Carbon dioxide is the primary greenhouse gas that is contributing to recent climate change. CO₂ is absorbed and emitted naturally as part of the carbon cycle, through animal and plant respiration, volcanic eruptions, and ocean-atmosphere exchange. Human activities, such as the burning of fossil fuels and changes in land use, release large amounts of carbon to the atmosphere, causing CO₂ concentrations in the atmosphere to rise.

Atmospheric CO₂ concentrations have increased by almost 40% since pre-industrial times, from approximately 280 parts per million by volume (ppmv) in the 18th century to 390 ppmv in 2010. The current CO₂ level is higher than it has been in at least 800,000 years. ^[1]

Some volcanic eruptions released large quantities of CO₂ in the distant past. However, the U.S. Geological Survey (USGS) reports that human activities now emit more than 135 times as much CO₂ as volcanoes each year.

Human activities currently release over 30 billion tons of CO₂ into the atmosphere every year. ^[1] This build-up in the atmosphere is like a tub filling with water, where more water flows from the faucet than the drain can take away.

For more information on the human and natural sources and sinks of CO₂ emissions, see the Carbon Dioxide page in the Greenhouse Gas Emissions section of the website.

Methane
Methane is produced through both natural and human activities. For example, natural wetlands, agricultural activities, and fossil fuel extraction and transport all emit CH₄.

Methane is more abundant in Earth’s atmosphere now than at any time in at least the past 650,000 years. ^[2] Due to human activities, CH₄ concentrations increased sharply during most of the 20th century and are now more than two-and-a-half times pre-industrial levels. In recent decades, the rate of increase has slowed considerably. ^[1]

For more information on CH₄ emissions and sources, and actions that can reduce emissions, see EPA’s Methane page in the Greenhouse Gas Emissions section of the website.

Nitrous oxide
Nitrous oxide is produced through natural and human activities, mainly through agricultural activities and natural biological processes. Fuel burning and some other processes also create N₂O. Concentrations of N₂O have risen approximately 18% since the start of the Industrial Revolution, with a relatively rapid increase towards the end of the 20th century. ^[3] In contrast, the atmospheric concentration of N₂O varied only slightly for a period of 11,500 years before the onset of the industrial period, as shown by ice core samples. ^[3] For more information on N₂O emissions and sources, and actions that can reduce emissions, see EPA’s Nitrous Oxide page in the Emissions section of the website.

Other Greenhouse Gases

• Water vapor is the most abundant greenhouse gas and also the most important in terms of its contribution to the natural greenhouse effect, despite having a short atmospheric lifetime. Some human activities can influence local water vapor levels. However, on a global scale, the concentration of water vapor is controlled by temperature, which influences overall rates of evaporation and precipitation. ^[1] Therefore, the global concentration of water vapor is not substantially affected by direct human emissions.
• Tropospheric ozone (O3), which also has a short atmospheric lifetime, is a potent greenhouse gas. Chemical reactions create ozone from emissions of nitrogen oxides and volatile organic compounds from automobiles, power plants, and other industrial and commercial sources in the presence of sunlight. In addition to trapping heat, ozone is a pollutant that can cause respiratory health problems and damage crops and ecosystems.
• Chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6), together called F-gases, are often used in coolants, foaming agents, fire extinguishers, solvents, pesticides, and aerosol propellants. Unlike water vapor and ozone, these F-gases have a long atmospheric lifetime, and some of these emissions will affect the climate for many decades or centuries.

For more information on greenhouse gas emissions, see the Greenhouse Gas Emissions section. To learn more about actions that can reduce these emissions, see the What You Can Do section.

Changes in the sun’s energy affect how much energy reaches Earth’s system

Climate is influenced by natural changes that affect how much solar energy reaches Earth. These changes include changes within the sun and changes in Earth’s orbit.

Changes occurring in the sun itself can affect the intensity of the sunlight that reaches Earth’s surface. The intensity of the sunlight can cause either warming (during periods of stronger solar intensity) or cooling (during periods of weaker solar intensity). The sun follows a natural 11-year cycle of small ups and downs in intensity, but the effect on Earth’s climate is small. ^{[1] [5]}

Changes in the shape of Earth’s orbit as well as the tilt and position of Earth’s axis can also affect the amount of sunlight reaching Earth’s surface. ^{[1] [2]}

The Role of the Sun’s Energy in the Past

Changes in the sun’s intensity have influenced Earth’s climate in the past. For example, the so-called “Little Ice Age” between the 17th and 19th centuries may have been partially caused by a low solar activity phase from 1645 to 1715, which coincided with cooler temperatures. The “Little Ice Age” refers to a slight cooling of North America, Europe, and probably other areas around the globe. ^{[1] [2]}

Changes in Earth’s orbit have had a big impact on climate over tens of thousands of years. In fact, the amount of summer sunshine on the Northern Hemisphere, which is affected by changes in the planet’s orbit, appears to control the advance and retreat of ice sheets. These changes appear to be the primary cause of past cycles of ice ages, in which Earth has experienced long periods of cold temperatures (ice ages), as well as shorter interglacial periods (periods between ice ages) of relatively warmer temperatures. ^{[1] [2]}

The Recent Role of the Sun’s Energy

Changes in solar energy continue to affect climate. However, solar activity has been relatively constant, aside from the 11-year cycle, since the mid-20th century and therefore does not explain the recent warming of Earth. Similarly, changes in the shape of Earth’s orbit as well as the tilt and position of Earth’s axis affect temperature on relatively long timescales (tens of thousands of years), and therefore cannot explain the recent warming.

Changes in reflectivity affect how much energy enters Earth’s system

When sunlight reaches Earth, it can be reflected or absorbed. The amount that is reflected or absorbed depends on Earth’s surface and atmosphere. Light-colored objects and surfaces, like snow and clouds, tend to reflect most sunlight, while darker objects and surfaces, like the ocean, forests, or soil, tend to absorb more sunlight.

The term albedo refers to the amount of solar radiation reflected from an object or surface, often expressed as a percentage. Earth as a whole has an albedo of about 30%, meaning that 70% of the sunlight that reaches the planet is absorbed. ^[1] Absorbed sunlight warms Earth’s land, water, and atmosphere.

Reflectivity is also affected by aerosols. Aerosols are small particles or liquid droplets in the atmosphere that can absorb or reflect sunlight. Unlike greenhouse gases (GHGs), the climate effects of aerosols vary depending on what they are made of and where they are emitted. Those aerosols that reflect sunlight, such as particles from volcanic eruptions or sulfur emissions from burning coal, have a cooling effect. Those that absorb sunlight, such as black carbon (a part of soot), have a warming effect.

The Role of Reflectivity in the Past

Natural changes in reflectivity, like the melting of sea ice or increases in cloud cover, have contributed to climate change in the past, often acting as feedbacks to other processes.

Volcanoes have played a noticeable role in climate. Volcanic particles that reach the upper atmosphere can reflect enough sunlight back to space to cool the surface of the planet by a few tenths of a degree for several years. ^[1] These particles are an example of cooling aerosols. Volcanic particles from a single eruption do not produce long-term change because they remain in the atmosphere for a much shorter time than GHGs. ^{[1] [7]}

The Recent Role of Reflectivity

Human changes in land use and land cover have changed Earth’s reflectivity. Processes such as deforestation, reforestation, desertification, and urbanization often contribute to changes in climate in the places they occur. These effects may be significant regionally, but are smaller when averaged over the entire globe.

In addition, human activities have generally increased the number of aerosol particles in the atmosphere. Overall, human-generated aerosols have a net cooling effect offsetting about one-third of the total warming effect associated with human greenhouse gas emissions. Reductions in overall aerosol emissions can therefore lead to more warming. However, targeted reductions in black carbon emissions can reduce warming. ^{[1] [8]}

References:

[1] NRC (2010). Advancing the Science of Climate Change . National Research Council. The National Academies Press, Washington, DC, USA.