The latest trend in these days is about the study of the environment. There are many aspects of the environment that you can study. The top problem these days is called the global warming. This name indicates that global mean whole world and warming mean heating. This can be said that the earth is getting warmer and the increase of the climate temperature is started. This is done due to the green house gases.
Green house gas: the CO2 or the carbon dioxide is called the greenhouse gas. This is because the green house houses are made in a way that they will only allow the light to come in and do not let the heat to go out. Global warming is done, but to increase in the greenhouse gas. The increase in this gas is due to higher burning of the fuels and other pollutions. The CO2 will not let the light to reflect and go your and make an environment which will heat the world more and more till there is a drastic change in the temperature of the earth.
The drastic change will make the big changes in the environment because when the temperature of the oceans will rise a few degrees, there will be an increase of the sea level and the glaciers will melt. The world will not be like it is now. This is just like much extinction in the past. To avoid it the US must make reforms to make things greener and avoid excessive use of the fuels.