So, here it is November 3rd and it’s 88 degrees with high humidity down here in Texas, 75 miles from the Gulf of Mexico. It is a miserable, dripping sauna outside. We had a tease of fall earlier in the week, it was actually cold at night for a couple of days. (I know cold is a relative term; folks up north might laugh at our 38 degree cold nights). I grew up in this area and I don’t remember it being this warm and humid in November.
I have been skimming the 2017 Climate Science Special Report. It begins by stating this period is now the warmest in the history of modern civilization. The last few years have also seen record-breaking, climate-related weather extremes, and the last three years have been the warmest years on record for the globe. These trends are expected to continue over climate timescales. For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence other than human activities. With the crazy weather this fall, I think the reality of climate change is becoming apparent.
In addition to warming, many other aspects of global climate are changing, primarily in response to human activities. Thousands of studies conducted by researchers around the world have documented changes in surface, atmospheric, and oceanic temperatures; melting glaciers; diminishing snow cover; shrinking sea ice; rising sea levels; ocean acidification; and increasing atmospheric water vapor. The humidity today certainly is an example of the increase in temperature and water vapor. But this is only one more data point of the preponderance of evidence showing the evident changes in our climate.
For example, global average sea level has risen by about 7–8 inches since 1900, with almost half (about 3 inches) of that rise occurring since 1993. Human-caused climate change has made a substantial contribution to this rise since 1900, contributing to a rate of rise that is greater than during any preceding century in at least 2,800 years. Global sea level rise has already affected the United States; the incidence of daily tidal flooding is accelerating in more than 25 Atlantic and Gulf Coast cities. I have fished along the gulf coast for decades. I can attest there are shorelines we used to love to fish that are covered at high tide today. When I was a child, you could drive the entire island, from East beach to West beach, along the shore below the seawall. You can’t do that now, the water comes all the way to the seawall in many places.
Annual trends toward earlier spring melt and reduced snowpack are already affecting water resources in the western United States and these trends are expected to continue. Under higher scenarios, and assuming no change to current water resources management, chronic, long-duration drought is increasingly possible before the end of this century. Even here in Texas, we suffered a difficult drought a few years ago. There was a fire near my home, we could smell the smoke. The lake was so low, all the water piers were over dry ground. We had to let our vegetable garden go- the water bill made it impractical. But even the fruits and vegetables we bought locally were tasteless because of the drought. So many of our fruits and vegetables come from California, droughts and wildfires out West will cost us at the grocery store.
The global atmospheric carbon dioxide (CO2) concentration has now passed 400 parts per million (ppm), a level that last occurred about 3 million years ago, when both global average temperature and sea level were significantly higher than today. Continued growth in CO2 emissions over this century and beyond would lead to an atmospheric concentration not experienced in tens to hundreds of millions of years. There is broad consensus that the further and the faster the Earth system is pushed towards warming, the greater the risk of unanticipated changes and impacts, some of which are potentially large and irreversible.
Here is the website for the report if you want to study the details.