Environment for me, as An Unknown Kunoichi said. But I'm a green freak so I might not be your perfect example of a normal person.
Why is it the largest concern for me?
In the summer of 2007 more Arctic ice melted than was expected to melt until 2050 to 2100. At that rate all of the Arctic ice could be gone by 2013. The problem with the ice caps melting is that it will raise sea levels (which means less land) and also because ice caps are huge stores of CO2. Therefore the more ice in the ice caps that is melted, the more CO2 that will be released... it's a bad cycle. Right now there are almost 400 parts per million (ppm) of CO2 in the atmosphere which is more than the world has seen in
at least 20 million years. As it is it's given that the temperature will rise 1.5 to 2 degrees C, which means:
Quote:
At least 30 per cent of species will be at risk of extinction due to floods, drought, wildfire, insect infestations and acidification of the oceans.
Ocean currents will slow, threatening marine life.
Tropical and semi-tropical areas will experience more frequent and deadly heat waves.
Arid and semi-arid regions such as the Mediterranean basin, the Middle East, North Africa and coastal Australia will become drier and desertification will set in.
The melting of mountain glaciers and snowpack will accelerate.
Most of Canada will continue to become warmer with increased violent storms and rain in the east. Areas of the southern Prairies will become more arid. The Arctic will experience melting permafrost and melting ice sheets.
Ocean levels will continue to rise for centuries to come to the point where countries such as the Netherlands, Bangladesh and other low-lying regions will likely be inundated.
Crop production will gradually increase for northerly climates, while it will decrease in tropical and semi-arid areas, where most of the Earth’s 6 billion people live.
source
As you can see it's already going to be catastrophic. Due to a delayed reaction we won't be seeing it immediately though. If we don't act soon (making a global agreement at Copenhagen), the world as we know it could very much be doomed. We already have the technology needed to live a greener lifestyle, but because humans are so miserly nobody's been bothering to use green technology. Which is the worst thing about the issue.
...I just did a report on it in my environmental science class so that's why I know so much about it...
