This is a very broad question and has no definitive answer.
Some may consider scientists such as Charles Darwin, Isaac newton, Albert Einstein and Max Plank as very significant.
However, modern science has so many contributors all adding valuable knowledge and discoveries in many different fields, that it is difficult to single out the most significant.
When it comes to scientists who were also artists, Leonardo DaVinci clearly stands out for his significant accomplishments in BOTH art AND science.
Data Scientists can help determine whether or not that difference is significant enough to warrant increased attention.
Malthus
There are significant changes in climate and/fossils.
Most scientists do!
Because scientists have family's to feed
Those that are statistically significant.
Most scientists don't like to lie.
They discovered a significant amount of water in the Moon's Cabeus crater
There were these major breakthroughs by those other scientists.
If they did not use rules all their calculations would simply lead to random digits!
Since tornadoes are a weather phenomenon most of the scientists who study them are meteorologists. Most storm chasers are not scientists.