Do you think scientists have an ethical obligation to speak out when a problem seems so severe

Yes, when a problem is severe or harmful, scientists are ethically and legally obliged to speak out.

Scientific experiments and testing are vital processes that lead to innovations, medicines, procedures, etc., that better human life. While scientific testing is required before a medicine, product or procedure can implemented or introduced in the market, it is essential to stop or prevent further testing when a severe problem or harm arises at the experimental stage.

For instance, if a clinical experiment testing the effects of a new hair loss prevention drug finds that consumption of said drug causes severe nausea and dehydration, scientists must speak out or stop the experiment  to prevent further harm. A failure to prevent harm is both highly unethical and liable to legal consequences.

"menstrual cycle is a complex cycle that consists of several processes. order of occurrence of steps in menstrual cycle are as follows:

1. high progesterone levels maintain the endometrium lining of the uterus.

2. endometrium lining breaks down and low levels of estrogen stimulate the pituitary to release fsh and lh.

3. fsh and lh stimulates the follicles to develop and the oocyte to produce estrogen.

4. rising estrogen levels suppress fsh production and development of other follicles.

5. a spike in lh causes follicle to rupture.

6. a breakdown of corpus luteum causes progesterone level to drop."

any abiotic or biotic factor in an ecosystem that causes a population's size to slow or decrease is a limiting factor.