Back as promised to the US Fourth National Climate Assessment (NCA):
https://edition.cnn.com/2018/11/23/health/climate-change-report-bn/index.html
These are some more of the specific claims made in the NCA, and highlighted by CNN:
Farmers will face extremely tough times. The quality and quantity of their crops will decline across the country due to higher temperatures, drought and flooding. In parts of the Midwest, farms will be able to produce less than 75% of the corn they produce today, and the southern part of the region could lose more than 25% of its soybean yield.
This is exactly what the NCA has to say, in the Midwest chapter:
Projections of mid-century yields of commodity crops65 ,66 show declines of 5% to over 25% below extrapolated trends broadly across the region for corn (also known as maize) and more than 25% for soybeans in the southern half of the region, with possible increases in yield in the northern half of the region. Increases in growing-season temperature in the Midwest are projected to be the largest contributing factor to declines in the productivity of U.S. agriculture
However, as even the NCA is forced to admit, summer temperatures in the Midwest have not been increasing. What they fail to point out is that temperatures have actually been falling instead.
Even the scorching summer of 2012 was cool in comparison to earlier heatwaves.
Most US corn is grown in the Midwest, and nationally US corn yields have been steadily rising:
http://worldofcorn.com/#us-average-corn-yield
One reason is that the climate is wetter than it used to be prior to 1970:
Astonishingly the NCA manages to turn that into a bad thing:
Increases in warm-season absolute humidity and precipitation have eroded soils, created favorable conditions for pests and pathogens, and degraded the quality of stored grain
I suggest whoever wrote this drivel go out and talk to a few farmers and ask them if they would instead like to return to the dustbowl years.
As the Iowa Corn website notes:
The United States is the world leader in corn production after growing 15.1 billion bushels in 2017. No state grows more corn than Iowa, producing 2.7 billion of those bushels.
What makes Iowa such a great place to grow corn? It starts with the soil. Iowa is home to the most fertile topsoil on the planet and that’s not all.
Heat stress could cause average dairy production to fall between 0.60% and 1.35% over the next 12 years — having already cost the industry $1.2 billion from heat stress in 2010.
Claim No. 2 concerns dairy production.
But far from declining due to “heat stress”, dairy yields have been rising unabated since the cool decades of the 1960s and 70s:
http://www.fao.org/faostat/en/#compare
When it comes to shellfish there will be a $230 million loss by the end of the century due to ocean acidification, which is already killing off shellfish and corals
Alarmist claims such as this are not supported by the actual data, as supplied by NOAA, which show that shellfish landings have remained stable.
https://www.st.nmfs.noaa.gov/commercial-fisheries/fus/fus15/index
Higher temperatures will also kill more people, the report says. The Midwest alone, which is predicted to have the largest increase in extreme temperature, will see an additional 2,000 premature deaths per year by 2090.
Yet throughout the Midwest, summer temperatures peaked much higher in the past, and are now not exceptional at all.
For instance, Algona, IA. The chart below shows the highest temperature recorded each year:
http://climod2.nrcc.cornell.edu/
The NCA uses a projection of the number of days over 100F in Chicago to “prove its point”:
Marengo, IL, is the nearest small town USHCN site to Chicago, just 43 miles away.
Temperatures there this summer have got nowhere near 100F. The highest was 91F
The record of 109F was set in 1936 when 11 days exceeded 100F.
http://climod2.nrcc.cornell.edu/
In contrast, the most recent day over 100F was in 2012, when a temp of 103F was set.
None of these claims made in the NCA about the Midwest have any basis in reality. Indeed they turn the facts on their head, in order to concoct a story that fits a pre-ordained agenda.
Read more at Not A Lot Of People Know That
