Al Gore, David Suzuki, etc. are activitists who are trying to convey the implications of the science to the public, but they themselves are irrelevant to the real issue. And if you limit yourself to the media’s representation of the issues, then you will never be decided because the media represents a vast array of different voices, with different motivations, incentives, and biases.
The issue at the heart of your question is where does the weight of scientific evidence fall, and although the science is complex the answer is relatively simple.
Greenhouse gases keep the Earth’s surface temperature at approximately 33 degrees warmer than in their absence. We have increased the atmospheric composition of greenhouse gases, which thereby increases the average temperature of the planet. The science behind this process has been known for over a century. The Earth is warming, the majority of this warming is caused by anthropogenic greenhouse gas emissions, the implications are severe enough for global agriculture, sea level, water supplies, species preservation, etc that continued emissions at current level are not an option, there are significant positive natural feedbacks or tipping points which greatly increase the risk of continuing current emissions.
That’s what the best scientific evidence tells us. There is no competing hypothesis that can account for the warming over the past century, and any competing hypothesis is still left with having to account for the excess radiative forcing inevitably associated with an increase in greenhouse gas concentrations in the atmosphere.
If we take the optimistic route then we have to at least halve current annual emissions before we can even come close to stabilizing greenhouse gas concentrations in the atmosphere (because natural sinks can absorb approximately half of current emissions, though this ratio appears to be weakening).
The overhwelming weight of scientific evidence supports these conclusions which is why the IPCC review came to these conclusions, the world’s national academy of sciences support these conclusions, the world’s governments support these conclusions.
The issue is no longer whether the world’s governments should do something, but whether they can cooperate sufficiently to minimize the impact of climate change over coming centuries.
DOwnload the IPCC summary reports
http://www.ipcc.ch/
The following provides an excellent summary of the common fallacies found on the web and the evidence based responses.
http://www-personal.buseco.monash.edu.au/~BParris/BPClimateChangeQ&As.html