Answer: Nothing. You just sit there and relax. If you have to work outside, drink about 80 ounces of water throughout the day. The human body is remarkably capable of dealing with temperature extremes, so no worries, mate!
“Yes, but we caused this heat-wave, didn’t we?”
Nope, we did not. How do I know? Well, how about this…
The record temperature in New York City for June 20th is 98°, set in 1923.
World population in 1923: Around 2,000,000,000.
World population in 2012: Around 7,000,000,000.
So, 89 years have gone by since 1923. We now have an extra 5,000,000,000 humans roaming the planet and we still haven’t beaten that temperature record for New York City set in 1923.
Conclusion: The earth does what it wants. It is not “fragile”. An extra five billion humans has made no difference. Now go get one of those plastic kiddie-pools, fill it with water, and sit there and relax, just like Perkins the dog.
The earth’s around 4 1/2 billion years old. We have truly accurate temperature records dating back a couple of hundred years. Oh sure, there’s arctic core-ice, fossils, and glaciers, but we don’t really know how hot or cold it’s actually been, do we?