Climate trends not promising for Wisconsin's agriculture future
The likelihood of an increase in Wisconsin's average temperature over the coming decades would extend the growing season but it does not bode well in the long term for corn and soybean crops, not to mention the effect on milk production.
That was the outlook that University of Wisconsin-Madison soil scientist and climate specialist Bill Bland presented at the Extension Service's semi-annual farm management update.
While there is strong evidence for temperature trend prospect, uncertainty reigns with precipitation totals other than that heavy rainfalls and perhaps long periods without rain are likely to be more frequent, Bland said.
As a soil scientist, this concerns him because of the potential for soil erosion and subsequent loss of productivity.
Citing the data obtained from hundreds of observation sites around Wisconsin since the 1950s and published as the Wisconsin Initiative on Climate Change Impacts report, Bland noted that the average temperature in the state has risen by 1.5 degrees during that period.
It also noted that annual rainfall is up by about six inches.
Based on data through 2011, "we're getting less cold, not more hot," Bland observed.
He pointed to the data, which indicates that the average number of nights with temperatures below zero has fallen by 12 since the 1950s while the number of days (before 2012) above 90 degrees had not been increasing.
In line with those numbers is the shortened period of ice on lakes, an earlier time for the last freezie in the spring, and a later date of the first freeze in the fall, Bland observed. He said this has extended the effective growing season by as much as 20-24 days in some years.
If the temperature trend continues, more and longer heat waves will become common and more precipitation will fall as rain during the winter, Bland indicated.
Eau Claire, for example, which has averaged 10 days per year with a temperature of 90 or above, would have 27 such days by 2055, he said.
Such temperature changes are becoming evident on plant growth and in other elements of nature, Bland remarked. This has enormous implications for agriculture, both in Wisconsin and the United States, he stated.
While the increase in temperatures and rainfall could be credited for a portion of the per acre yield increases of 40 percent for corn and 35 percent for soybeans in Wisconsin from 1976 through 2006, a reverse trend might be setting in, Bland warned.
He mentioned analyses that project corn yield reductions of 30-82 percent in parts of the United States by 2100 as the number of days with temperatures above 84 degrees increases.
In Wisconsin, one prediction is that an 1.8-degree increase in the average temperature would clip 13 and 16 percent, respectively from corn and soybean yields, Bland reported.
Based on the 1950 to 2006 data for Wisconsin, some models suggest that the average temperature increase from 1980-2055 could be as much as six to seven degrees, he noted.
It's no secret that milk production by dairy cows tends to decrease with temperatures above 75 degrees, Bland said. He noted that 60 degrees tends to be ideal for them but cited the likely effects of temperatures remaining in the upper 70s or above during many nights.
For the relatively long term, Wisconsin retains some advantage because it is likely to sit near the middle of a precipitation zone, which suggests less rain to the south and more to the north, Bland observed.
In a larger context, however, he said the West faces the prospect of less of a snowpack in the mountains (no sustained period of melt for water runoff) and that the densely populated country of India faces a similar threat.
What's already happening around the world as a result of the climate or weather has certainly gotten the attention of entities such as managers of huge investment funds and reinsurance companies, Bland reported. "Climate is what you expect, weather is what you get."
Every planet has its climate that results from its orbit, distance from the sun, and atmosphere, Bland noted. "The interaction between them creates the weather."
Two prominent features on the Earth that play into that interaction are the greenhouse gases and the oceans, Bland pointed out.
He explained that the oceans are able to absorb much of the heat generated by the burning of materials that excrete carbon dioxide (a greenhouse gas) but that those loadings have increased to beyond what the oceans can handle.
Some carbon dioxide is needed to make the Earth habitable but its portion of the greenhouse gases in the atmosphere has been building in recent centuries, Bland stated. The result of the increased carbon dioxide is a warming of the Earth, he noted.
Bland believes that the climate and weather are receiving so much attention today because of a better theoretical understanding of them and to observations of accelerating changes.
He likens the introduction of new volumes of carbon dioxide to the mix of greenhouse gases to the changes that steroids can bring in human physical performance.