The early trick was to deny that the world was indeed warming. The next was to deny that it was man-made. Since both are now seen as incredulous, it's time to change tack and argue that increase in temperature caused by Greenhouse Gases is a great thing. Do add your arguments is support of anthropogenic climate change:
1. We are sending spacecrafts across the solar system and beyond it too. As the mass of Earth falls, Gravitational pull from Sun will decrease, and Earth will move further away from Sun. We need to prepare for that by artificially increasing the temperature.
2. As we rid the Arctic region of all that ice, it will significantly cut travel time. You love cheaper stuff, don't you?
3. Aren't the environmentalist always talking of energy conservation? That's what greenhouse gases do, they conserve solar heat, preventing it's escape into space. Wonder why the activists don't support this energy conservation at macro-level and insist on fringe-level conservation.
4. Life will get easier for Jawans in Siachen as the temperature rises. Where's your patriotism?
5. A lot of energy is consumed in heating homes and offices during winters, particularly in the developed (non-developing?) world. As the planet gets warmer, this consumption would fall. You would think activists would be all excited about how energy consumption is about to fall, yet they are all gloomy.
6. Plants make food by using Carbon Dioxide. That's elementary science. More CO2 means more food. What could be more important that fighting hunger?
7. So many people lose their lives to bitter cold. A warmer planet is our best bet to save lives.
8. This CO2 was in the atmosphere to begin with. We are not destroying the planet, we are reversing the damage caused by millions of years of photosynthesis. We may not be able to return to the planet to its pristine Primordial-Soup state, but surely we should give it our best.
9. A warmer planet would see more evaporation from the seas, resulting in more precipitation. Permanent solution to droughts.
10. Spare a thought for the poor migratory birds that have to fly thousands of kilometres just to avoid the chill. They can stay home and flourish.
