Re: what is your opinion on global warming?

I am a scientist, working in the areas of satellite Earth observation with specialties in observations of atmospheric aerosols and fires.

Humans occupy every last corner of the world's land surface. Large fractions of both the plant photosynthesis that occurs and the fresh water generated by precipitation are diverted for human use. Just as we modify the land surface vegetation and divert the water, we also alter the atmosphere.

Human activity has caused the concentration of carbon dioxide (CO2) in the atmosphere to increase by more than 20% over the past 150 years, and by more than 10% since direct measurements began in the 1950s. The concentration of CO2 continues to increase.

This large change in atmospheric composition, by addition of a gas that interacts strongly with the thermal radiation of the Earth, should change the climate. The evidence is that the climate has changed, most significantly in the Arctic regions.

The change in climate will produce winners and losers. Some areas will find their climate becoming better suited to some kinds of human activity; others will see previously productive activities become costly or impossible in a changed climate. Over the globe, the disruption associated with the change will be costly. Humans have taken over the globe by adapting their behaviors very closely to the environmental conditions of the poles, temperate zones, and tropics that we occupy.

Changes in these environmental conditions will prove disruptive to human activity; for instance, the climatic zones suitable for growing the staple crops that feed the world's growing population will move, and will likely shrink temporarily as the world's farmers adjust to the new conditions.

Thus, the changing climate seems like something worth worrying about. However, alternations to the Earth's climate are not the only consequence of our dependence on fossil fuels. We call them "fossil fuels" because, like fossils, no more are being created. In other words, they are not renewable. The total quantity of fossil fuels is unknown, but because they are not renewable, we know that there is a limit, and as we consume more, we must keep moving to new places to drill and dig for them, which renders large areas of land unusable for humans or animals. Because fossil fuels are not evenly distributed geographically, we have created another set of winners and losers: wealthy oil-rich nations, and poor oil- starved nations.

Finally, burning of fossil fuels releases more chemicals and particles besides CO2. These chemicals and particles are responsible for the poor air quality in our cities, and are one of the most serious threats to human health in the 21st century.

So, as one scientist's opinion, I believe that global warming is real, and I believe humans should actively pursue alternatives to fossil fuels to meet our energy needs. But in terms of ranking the benefits of alternative energy, avoiding further climate change comes in a distant third. The best reasons to immediately, radically change our energy consumption habits come from 1) air quality and human health, and 2) global geopolitics.