If we take a look at last 10 or 15 years we can clearly see the global warming trend, for instance 1998 was the warmest record year, followed by 2005. Some believe there is no global warming because this winter was very cold but this is unfortunately not true, because cold winters used to be much more common than there are today, so this year's cold winter was more an exception to clear pattern than the actual proof that there's no global warming.
Ice on both our poles is melting very fast, and sea level rise up to one metre by the end of the century looks imminent from the current point of view. Many scientists believe that if current greenhouse gas emissions continue to rise Arctic will be ice free before the end of this century. We still very much depend on fossil fuels to satisfy our demand for energy, and we must change this very soon if we want to fight global warming. If we continue with fossil fuels burning we won't stop current levels of greenhouse gases, in fact we will make things even worse. Answer perhaps lies in the renewable energy sector but this sector needs lot more developing before becoming sufficient to satisfy energy demand on global scale.
Many scientists agree that given the current trend temperatures will rise by more than 2C by the end of this century. This could cause weather to become totally unpredictable, significantly rise sea levels, and much more frequent hurricanes could flood many coastal areas worldwide, severe droughts could become more common causing severe food shortages, and species unable to adapt to these changes will pay with their lives. Many believe that solution to global warming problem is cutting greenhouse gases to reduce the impact of global warming.
Take a look at this excellent global warming video that will give you more insight to what global warming is all about.