Source:
"Geological evidence shows that for billions of years, the world has gone through cycles of global warming and global cooling.
Any cold period when permanent ice sheets exists in both polar regions is defined as an “Ice Age.”
According to this definition and because ice sheets exist in both Greenland and Antarctica, the Earth is currently in an ice age but in a relatively mild period called an “interglacial period,” which is not as extreme as the “glacial periods” that we typically think of when we think of “Ice Ages”.
Geological records indicate that five major ice ages existed during the last 2.5 billion years starting with the Huroian ice age (from 2.4 until 2.1 billion years ago) and ending with the present one called the Quaternary (from 2.6 million years ago until the present).
Geological records indicate that five major ice ages existed during the last 2.5 billion years starting with the Huroian ice age (from 2.4 until 2.1 billion years ago) and ending with the present one called the Quaternary (from 2.6 million years ago until the present).
Warm periods, when there were no large areas of permanent ice present on the Earth, are sometimes called “greenhouse (or hothouse) periods.”
From geological evidence, the Earth has been in a “greenhouse period” about 85% of the time.
... the shape of the Earth’s elliptical orbit is not constant.
... the shape of the Earth’s elliptical orbit is not constant.
Due to the gravitational effects of the moon and planets, it can vary approximately every 100,000 years from being nearly circular to being more elliptical.
... we also must consider that the Sun is not a constant star (i.e., the amount of sunlight the Sun produces every year is not constant).
... we also must consider that the Sun is not a constant star (i.e., the amount of sunlight the Sun produces every year is not constant).
Every so often, dark areas, called sunspots, occur on the Sun’s surface.
... We now know that the occurrence of sunspots is quasi-periodic (or quasi-cyclical) with periods of about 11 years between the maximum and minimum number of sunspots on the surface.
... We now know that the occurrence of sunspots is quasi-periodic (or quasi-cyclical) with periods of about 11 years between the maximum and minimum number of sunspots on the surface.
We say these “sunspot cycles” are quasi-periodic because although the average length of a cycle is about 11 years, the exact length of each cycle can vary from as short as 8 years to as much as 14 years.
However, from around 1645 to 1715 CE (known as the Maunder minimum), virtually no sunspots occurred on the Sun’s surface.
Since the discovery of sunspots, much debate has occurred over what effect, if any, they have on the Earth’s climate.
... Many non- scientists assume that the scientific process is linear, and science always moves forward.
Since the discovery of sunspots, much debate has occurred over what effect, if any, they have on the Earth’s climate.
... Many non- scientists assume that the scientific process is linear, and science always moves forward.
That is, scientists find an answer to one problem and then move on to the next.
Science is much messier as, unlike common sense, science is not intuitive.
Scientists analyzing the same data can often arrive at different conclusions.
New data and insights are constantly revising our previous understanding.
Thus, we encourage you to dig deeper and ask questions."