There is debate as to why and how climate changes, whether you are referring to changes on multi-decadal, multi-century, or long-term time scales. Some scientists and researchers say humans are the cause of recent warming (1950 – Present), while others like myself say it is primarily natural or totally natural.
The two words “climate change” have lost their true definition over time. Climate change simply means “a change in climate.” The media’s hysteria and scientists riding on the political train have changed its meaning to the point where one says climate change, they refer to anthropogenic (man-made) climate change.
As we have discussed in the previous pages, there are many plausible causes for climate change. The biggest control knob of Earth’s climate is ultimately the Sun. Without it, life on Earth would cease to exist. Studies show that without urban heating, the Sun may account for 50% to 70% of the warming between 1900 and 2017 through indirect effects, because direct solar influences are minimal.
The largest apparent driver of climate change on multi-decadal time scales seems to be the Atlantic Multi-decadal Oscillation (AMO), as it has a 71% correlation to global temperatures. When the AMO turns negative, it brings on global cooling, whereas the positive phase causes natural global warming. The Pacific Decadal Oscillation also tends to have large effects, but the AMO has much more impact.
We have also looked into volcanoes and their impact on global climate. Research has shown that volcanoes have a major impact on short-term global cooling lasting two to four years because of their sulfur dioxide emissions getting turned into sulfate aerosols, which form a stratospheric aerosol layer, thus blocking out sunlight, causing cooling. Studies have also shown that decades-long cooling periods tend to see an uptick in volcanoes, further cooling the Earth. However, recent decades have seen a decline in volcanic activity, which has caused the 1990s aerosol layer to dissipate, likely amplifying recent warming.
Other climatic changes can be attributed to mankind (NOT through CO2!), but rather through urbanization and land use changes. These changes in climate are localized, thus they really have no affect on global climate, however, because most of NOAA‘s recent temperature data has been coming from cities, the data they use has a warm bias, thus causing the global temperature record to be unreliable, because they left out rural station data, which covers more than 97% of Earth’s surface.
We have also discussed carbon dioxide (CO2) and its (possible) effects on climate, which turn out to be minimal, or NONE. Firstly, there is no clear linkage between CO2 and temperature over the geological record. We have had warmer times with less CO2 in the atmosphere and colder times with more. Therefore, we can only conclude that carbon dioxide’s forcing is very, very little, maybe even nothing at all. Even IF carbon dioxide can cause global warming of some sort, the runaway greenhouse effect is impossible because the CO2 absorption spectrum is nearly 100% saturated. This means that the more CO2 that is added to the atmosphere, the temperature rise becomes less and less to the point where it will eventually just level off. Because of the saturation point, the temperature rise would never meet or exceed 2.35°C. Basically, if you were to plot this on an x and y graph, the asymptote would be 2.35, meaning the y-value (temperature) will never reach 2.35, therefore it will never go over that number, no matter how far the x-value (year) goes.
Despite global warming/cooling/climate change being an important issue to discuss about in science, politicians and politically active climate scientists have turned it into a political issue rather than a scientific one. There are still some people out there who treat climate change scientifically, and I am one of them.
The term global warming has also been misrepresented as well. Global warming simply refers to a long-term temperature increase. However, the hysterians have changed its meaning (like climate change) to imply that humans are the primary cause through carbon dioxide emissions, despite the lack of scientific evidence.
What is very disappointing is that very little research has been funded in recent years to search for natural climate control knobs. Climate change has simply become so much of a political issue, that funding for natural global warming is few and far between.
The bottom line is that climate changes. It always has and always will regardless of whether humans are in existence or not.