This is partly due to pollution, but even in the cleanest air the sky is lighter near the horizon due to the effect of earth's atmosphere on sunlight.
Research has indicated that wide-spread industrial air pollution goes at least as far back as the ancient Greeks and Romans.
Can you imagine that the lowly clam would take on a role as water based pollution detector?
A study published this week shows that fish larvae exposed to elevated levels of CO2 in their larvae state are heedless to the scent of proximate predators.
It's a big deal when an oil tanker spills its contents into the ocean. And for good reason. But what about oil spills that aren't caused by humans?
Contrary to popular belief, some dolphins find habitat in river waters.
Could coal, a carbon-rich fuel, be the key to fixing America's rising gas prices?
What's so important about having clean air and reducing air pollution? Find out on this Moment of Science.
There's more bad news for the spring-legged amphibians---male toads living near farms are likely to develop female sex organs.
Did you know that soil deterioration is one of the main contributors to global warming?