If Earth's tilt was 0 degrees:

Earth's axial tilt, currently at 23.5 degrees, is responsible for the planet's seasons. Without this tilt, the Earth would experience minimal seasonal variations. The Sun's rays would hit the planet in a more uniform manner, resulting in relatively consistent temperatures throughout the year.

Key effects of a 0-degree tilt:

• No significant seasons: The lack of tilt would eliminate the extreme variations in sunlight received at different latitudes, effectively erasing the distinct seasons we currently experience.
• Reduced temperature contrast: The Earth's temperature distribution would become more uniform, with less pronounced temperature differences between the equator and the poles.
• Impact on ecosystems: The absence of distinct seasons could disrupt the life cycles of many plants and animals adapted to seasonal changes.

If Earth's tilt was 90 degrees:

A 90-degree tilt would produce extreme seasonal variations, with half of the planet experiencing six months of continuous sunlight and the other half facing six months of uninterrupted darkness.

Key effects of a 90-degree tilt:

• Extreme temperature swings: The polar regions would experience extreme temperature fluctuations, with scorching summers and frigid winters.
• Disrupted climate patterns: The extreme temperature differences would disrupt global climate patterns, potentially leading to drastic changes in precipitation and weather patterns.
• Impact on life: The harsh conditions at the poles would make them uninhabitable for most life forms, while the equator could experience extreme heat and humidity.

In summary, Earth's axial tilt plays a crucial role in maintaining a relatively stable climate and supporting a diverse range of life forms. Changes to this tilt, whether eliminating it or increasing it to 90 degrees, would have profound and potentially catastrophic consequences for the planet's ecosystems and the survival of many species.

Dr Murtadha Shukur thank you for your contribution to the discussion

Earth without a tilt would be stratified into climate bands that would get progressively colder as you moved away from the equator. Humans would never survive the continuous winter of the high latitudes, and so we would likely congregate in the planet's tropical midsection. Basically, we would not have any seasons. Earth would be warm at the equator and cold at the poles. The poles would still experience the most impact because the sun would always be low on the horizon. Other planets are also tilted such as Uranus at 97° giving the planet extreme seasons. The easiest way to think about this is to imagine the two extremes: zero tilt and 90°. If our planet's axis had zero tilt, we would experience no seasons no winter or summer, no change in temperature throughout the year. Northern Hemisphere, if there were no axial tilt, i.e. Earth's obliquity would be zero degrees, and then there would be no change in the seasons from year to year. This would be because there would be no difference in the amount of solar irradiation received, year-round, anywhere on Earth. Earth's tilt plays a significant role in the seasonal changes throughout the year, and a 90-degree tilt would certainly change which areas would experience snowy winters and which areas would experience warmer summers. With an axial tilt of 90 degrees, the magnetic and rotational north and south poles would be at the "equator" of the planet. This means that the planet would spin about in the 'Z' axis and thus the range of climate would be very much reduced to what we experience here on Earth. The earth's spin axis is tilted with respect to its orbital plane. This is what causes the seasons. When the earth's axis points towards the sun, it is summer for that hemisphere. When the tilt is less (toward 22.5 degrees), the seasons will vary less. Remember, if there were no tilt to the axis, there would be no seasons at all. Less of a tilt causes the Sun's radiation to be more evenly distributed between summer and winter. It the tilt angle was zero, then the days and nights would stay at the same length and there would be no seasons. The higher latitudes would not get the extremes of weather that they get now. It would have a big impact on migratory animals as there would be no need to migrate. f the earth didn't have a tilt, we wouldn't have seasons. Instead, the environment would be unchanging, and the temperature would vary upon latitude. Equatorial regions would be constantly hot and humid, and Polar Regions would always be cold. There would no variability to the climate as the year progresses. Interestingly, the authors claim that if the Earth had an axial tilt of 90 degrees, but at 210 million km from the sun, then: its climate would be positively balmy -- the equator would be 11 deg C (52 deg F), and the poles would never rise above 46 deg C (115 deg F) or fall below 3 deg C (37 deg F). Spring and fall are not affected by tilt because they are at the point in orbit where sunlight is hitting the earth evenly. However, less tilt would mean less of a change in angle around the orbit and therefore cooler summers and warmer winters.