Scientists believe that earth is becoming warmer. this idea will become unacceptable over time if
it is not discussed in a scientific forum
scientific evidence supports a new idea
scientists propose alternative hypothesis
new instruments are invented to measure temperature

Scientific evidence supports a new idea.

Explanation:

Any hypothesis or scientific statement can only be considered valid if it is supported by a evidences and data obtain or produced after the implementation of experimental procedures. The scientific statement or hypothesis can be considered incorrect or false if more valid evidences obtain in future which may be more acceptable.

Therefore, the idea, Scientists believe that Earth is becoming warmer can become unacceptable over time if new ideas which contradict the given idea comes with valid and supportive ideas.

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.