I am responding to the questions asked by David Powell of Oak Harbor regarding the contributions of humans to global warming.
Firstly, the writer asked if the same natural processes that caused global warming after the last ice age are happening now? The short answer is no!
A more detailed answer would recognize that scientists have known for at least 100 years that variations in the Earth’s orbit primarily control the timing of glaciation. By this orbital clock, we should be entering a new glacial period with both terrestrial and sea ice in rapid expansion. However, we are experiencing the opposite with rapid melting of both.
If one looks further back in the Earth’s history, then there was a much warmer period about 55 million years ago associated with a period of massive carbon injection into the atmosphere. Since then the Earth has cooled. Such a carbon release warming scenario is in line with present understanding of global warming although our current warming rate is 10 times that rate.
Secondly, the writer asked if man’s pollution of the environment is contributing to global warming. The short answer to this one is yes!
In the 19th century, scientists realized that gases in the atmosphere cause a “greenhouse effect.” The atmospheric concentrations of the greenhouse gases have clearly all increased since the Industrial Revolution due to human activity. Today, the concentration of carbon dioxide exceeds the pre-industrial levels by about 120 percent and substantially exceeds the highest concentrations determined from ice cores over the past 55 million years.
Lastly, the writer suggested that “global warming is nonsense and a hoax.”
In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans. Climate change is clearly for real and most definitely is not a hoax.
The human contribution is clearly significant and it would be utterly irresponsible to both current and future generations to not attempt to limit the change and its effects to the extent we can.