YDS 2016-2 Soru=54

What is the main purpose of the passage?

Australia experienced the worst and most consistent
period of drought in its recorded history over much of
the past decade. The Murray River failed to reach the
sea for the first time ever in 2002. Fires swept much of
the country, and dust storms covered major cities for
days. Australia's sheep population dropped by 50
percent, and rice and cotton production collapsed in
some years. The drought ended in 2010 with heavy
rains and flooding. Australia's Millennium Drought is a
wake-up call for residents of the drought-plagued
southwestern US where droughts have devastating
consequences to the region and to the nation. The
US can avoid the worst, however, if they pay attention to
Australia's experience and learn the right lesson. Both
Australia and the US have dry regions where thirsty
cities and irrigated agriculture are exhausting water
supplies and damaging ecosytems. The Colorado River
no longer flows to the sea in most years. Changing
global climate in both countries increases the risk of
drought. As the climate continues to change, smart
water planning may help ease the impacts of
unexpected and severe droughts in the US that now
appear inevitable