Recent letters to the editor on human caused climate change have been sadly lacking in substance. At least Mr. McNamee ("Climate Change. A Senseless Debate, Feb. 7) gets it part right, explaining that climate always has changed, and will continue to change, as a consequence of factors like greenhouse gases, volcanic eruptions, variation in solar output, and variation in earth's orbit. Unfortunately, Mr. McNamee's climate education apparently stopped in the 1960s.
We now know, for example, that without greenhouse gases like carbon dioxide, water vapor, methane, and nitrous oxide earth would be an un-inhabitable ice ball. Indeed, it is the natural greenhouse effect that is primarily responsible for making earth habitable at all. Since the 1970s, we have also known that present variation in solar output and earth's orbit are cooling the earth.
Yet instead of cooling, since 1980 earth has been warming at an unprecedented rate. There has been an associated 1 foot rise in sea level. Storms, heat waves, and droughts have intensified. Of greatest concern is the 12 degree Fahrenheit increase in average annual temperatures in the high arctic, resulting in the loss of up 75 percent of the volume of the Arctic Sea ice pack. This melting trend suggests that within a decade, the Northern Hemisphere may lose all the ice in its arctic cooler every summer leading to even more accelerated warming. We now appear to be locked into a positive feedback loop. The warmer it gets, the warmer it gets.
Why is earth warming? We know that carbon dioxide levels have risen from 280 parts per million to nearly 400, that humans cause 70 percent of methane emissions, and that nitrous oxide emissions are up 20 percent. Yet there have been no volcanic eruptions or other natural events that can account for these increases. Indeed, we know unquestionably that greenhouse gases are up due to human activities such as extracting and burning fossil fuels, raising cattle and sheep, and using nitrogen fertilizers. We have no other causal explanation for earth's warming.
These are the uncontestable facts. Any disagreement with them at this point reflects either a willful ignorance, or a purposeful intent to deceive. Who wins when the public fails to understand the facts? Foremost, the fossil fuel industry, which is currently recording hundreds of billions of dollars of record profits. Who loses? Increasingly, it is all of us, but those who will really suffer have not yet been born. Economic analysis now suggests that the direct present cost of climate change on a global scale exceeds what we would need to spend annually to fix the problem.
Our present pattern of climate change is not normal, and there is plenty we all can do about it. Principally, everyone should support policies that reduce the use of fossil fuels and the excessive consumption of meat, which is not healthy for our bodies anyway.