In my last post I summarized the scientific evidence which convinces me that global warming is occurring and is primarily caused by the emission of carbon dioxide from the use of fossil fuels for energy production.
Several Face Book comments on my post suggest that there could be other causes such as a decrease in cloud cover over the earth, sunspot activity and even the carbon dioxide which is exhaled by the 7 billion (and growing number of) humans now alive on earth. I am personally unable to evaluate the validity of these possible causes. I rely on the overwhelming consensus of climate experts that the problem is caused by the burning of fossil fuels.
Perhaps the scariest evidence is the warming of the oceans and the related rising of sea levels by 1/8 of an inch per year (which is equivalent to a one foot rise per century). When I referred to the three recent catastrophic hurricanes of Katrina (2005), Sandy (2012) and now Harvey, several readers responded that there is no proof that the severity of these storms was caused by global warming.
I agree! It is just that warmer oceans mean more evaporation and therefore more rainfall around the world. This means that severe storms will become more likely as the oceans become warmer.
Take a look at the two charts from the current issue of The Economist. They show that various types of natural disasters have been increasing in recent years and that record-breaking precipitation events are on the increase. Conclusion. Global warming is already happening. But we can act to keep it from getting worse. More renewable energy (wind and solar) is only part of the answer. The best way to cut back on carbon emissions is with a (revenue neutral) carbon tax. This would be much more efficient than ad hoc regulations like the Clean Power Plan and ever higher auto gas mileage standards.
Global warming is a controversial issue and I would like to take as dispassionate a look at it as I possibly can. First, I will summarize what I consider to be the main evidence for global warming and then discuss what this means for public policy.
Ocean heat content has been building steadily in recent years. Warmer water means more evaporation into the atmosphere which means more precipitation around the world.
The extent of summer sea ice in the Arctic has gradually been receding.
A big chunk of sea ice (the size of Delaware) has just broken off the Antarctic Peninsula and is floating in the South Atlantic Ocean.
The sea level is rising at the rate of one-eighth of an inch per year which is equivalent to one foot per century. Globally, eight of the world’s ten largest cities are near a coast.
In the U.S. Spring is arriving earlier each year on average, especially in the Southeast.
Some of these phenomena may be beneficial such as more rainfall around the world and longer growing seasons. Less ice in the Arctic Ocean allows more summer navigation. But rising sea levels will become catastrophic in low-lying coastal areas.
Conclusion. The above observational evidence for global warming is well established and hopefully non-controversial. The sources are scientific agencies whose integrity should be beyond reproach. Once we accept the fact that global warming is for real and is caused by human activity, the question is what we should do about it. This will be the topic of my next post.