We are living during a warm period of an ice age.
New evidence has led scientists to believe that the present warm period could last another 10,000 to 20,000 years, or even longer.
This warm period ran from c. 14,700 to 12,700 years before the present.
But in fact, the world has often gone through warm periods throughout its history.
After the end of the warm period only the named species were able to survive.
Other scientists now suspect there was no warm period after all.
At warm periods in summer up to 2500 visitors are expected.
Today's warm period is known as the Holocene and started about 11,500 years ago.
Towards the end of May there was a brief warm dry period.
Of special interest is evidence that the lake formed after the warm, wet period was thought to have ended.
