(The) endangered planet
When R. D. expresses alarm (concern) at the damage caused by free marketeering (liberalism) and the (current) baby boom (the run away demography) and when Captain Cousteau  denounces (cries out against) (lashes out against) those who pollute the oceans (seas) and those whose aim (purpose) ( goal) is one (some) day to share in the exploitation of Antarctica (the Antarctic) the last remaining virgin (unspoilt) continent, people shrug their shoulders alleging that this is much ado about nothing (that this is making mountains out of molehills) (that what is excessive is insignificant).
 
However, as any frequent traveller can ascertain (see) for himself (with his own two eyes) the planet is changing rapidly,  what with the pillaging of tropical rain forests, the overexploitation (excessive tapping) of the oceans and the human congestion (cramming of people) in towns - particularly in such megapoles as Mexico City or Cairo - the everyday survival of mankind is being put directly at risk (in jeopardy) (all this poses a direct threat to the everyday survival of mankind )

We can always feel reassured by saying that anyway (come what may) man will always find a solution (the answer)(a way out)  (We can always look on the bright side (put our minds at rest). Our trust in science, even when it is at a loss (baffled) as is currently (at the moment) the case with AIDS, makes us forget (lose sight of) the fact that each new conquest (victory)(breakthrough)(advance) has (its)(a) price.

These dangers, threats and worries (concerns) as to (about) the future must be recalled (brought to mind) (spelt out)again and again. The worst does not always (necessarily) come to the worst but it is more likely to (do so) if we are unprepared.