Now imagine that the Titanic's captain insists that the ship is not sinking, people are inclined to listen. Not only because he is the captain and therefore he has an influential voice. But also because people would prefer to stay inside. If, in addition, enough people listen and ignore the slow tilting of the ship, that will cause the disinformation to spread quickly. Because people will want to believe the ship is not sinking.
Climate change is a different beast, however. When enough people do not take action to mitigate its effects, everybody suffers. Therefore, loud and influential climate-change deniers are neglecting their responsibility. Yes, they have a right to free speech. But their right to swing fists about ends where humanity's nose begins.
Cherry picking. To illustrate what I mean by cherry picking, look at the picture above. (I used the Matlab/GNU Octave code snippet below to generate the data, run it in Matlab if you have it, or download your copy of GNU octave to run it yourself). The data (blue line) was generated by taking 20 random numbers, and plotting it on top of a slope of 1/10. I then compare the last 4 numbers, and see if there is a downward trend. If not, I create a new set of random numbers, and try again. I keep trying until I see a downward trend in the last 4 numbers. As you can see, you have to do this quite a few times (40 in this case) to get a downward trend in the last 4 numbers (red line). It is clear, however, if you look at the overall trend, it is going up (black line).
Climate change deniers usually look at a subset of the evidence. While the overall temperature (blue line) fluctuates around a rising overall trend (black line), there may be a small set of temperatures that will be going down (red line). It is obviously a wrong approach to do so.
Now, some may say that to say the climate is changing, is basically falsely yelling fire in a crowded theater. The problem with that argument?
The theater is on fire, the Titanic is sinking, and the climate is changing.
deniable = 0;
i = 0;
slope = 1/10;
n = 20;
while deniable == 0,
i = i + 1;
x = [0:n-1]';
y = rand(n, 1)+slope*x;
if and(y(n) < y(n-1), y(n-1) < y(n-2), y(n-2) < y(n-3))
deniable = 1;
plot(x, y, 'b-', 'Linewidth', 2);
plot(x(n-3:n), y(n-3:n), 'r-', 'Linewidth', 3);
plot(x, x*slope+1/2, 'k-', 'Linewidth', 3)
legend('The Data', 'OMG it is going down!', 'No it is not', 'Location', 'SouthEast')
title([num2str(i) ' runs had to be ignored'])
set(gcf,'PaperUnits','inches','PaperPosition',[0 0 4 3])