We do not really need to look to the accelerated retreat of arctic sea ice, the steady retreat of glaciers on most continents, the massive iceberg (size of Delaware) that recently split off from the Antarctic to understand that there is a warming of our global climate. Nearer to home the flooding in central Southern USA, the devastating increase in forest fires “fire seasons are now on average 78 days longer than in the 1970’s….The US burns twice as many acres as three decades ago and Forest Service scientists believe that the acreage burned may double again in mid-century”. See the photos on the NASA “Images of Change” website of landscapes from around the world demonstrating the impact of flooding, heat, glaciers retreating etc. Recent research in India has even been able to show that 59,000 farmers may have died as a result of the impact of hotter weather between 1967 and 2013. No surprise that 195 countries signed the Paris Agreement in June.
According to new figures from the US National Oceanic and Atmospheric Administration (NOAA), June 2017 was the third-hottest June on record, beaten only by the two preceding Junes in 2015 and 2016. In summary “the warming trend is clear and primarily the result of human activities. In the US the last 10 years have been the warmest on record.”
“Climate is generally defined as average weather, and as such, climate change and weather are intertwined. Observations can show that there have been changes in weather, and it is the statistics of changes in weather over time that identify climate change. While weather and climate are closely related, there are important differences. A common confusion between weather and climate arises when scientists are asked how they can predict climate 50 years from now when they cannot predict the weather a few weeks from now. The chaotic nature of weather makes it unpredictable beyond a few days. Projecting changes in climate (i.e., long-term average weather) due to changes in atmospheric composition or other factors is a very different and much more manageable issue “
Our challenge in agriculture is that the weather is perhaps the biggest variable for livestock and particularly for crop production so it is vital that we understand what is happening and be better prepared to cope with the expected changes.
Luckily the biggest challenges seem to be in the US South and MidWest where the higher temperatures and reduced rainfall will affect both livestock and crop production. The NorthEast will not go without challenges and I can do no better than give the EPA’s August 2016 assessment of what climate change means for agriculture in Pennsylvania “Changing climate will have both beneficial and harmful effects on farming, but the net effect is unknown. Longer frost-free growing seasons and higher concentrations of atmospheric carbon dioxide would increase yields for many crops during an average year, notably soybeans. But increasingly hot summers are likely to reduce yields of corn, Pennsylvania’s most important crop. The earlier arrival of spring may increase populations of major crop pests, such as the corn ear worm and aggressive weeds. Higher temperatures cause cows to eat less and produce less milk, so a warming climate could reduce the output of milk and beef, which together account for more than one-third of the commonwealth’s farm revenue.
Our crops have been adapted to the historic norms for temperature. Our livestock breeding has also been based on optimizing production for the current climate and dairy producers using the North European Holstein and Shorthorn breeds know that they seek shade on hot days and require fans in barns during the summer. Our plant and livestock breeders will have to select animals for breeding that indicate better resistance to higher temperatures and still maintain productivity. Temperature also affects weeds, insects and diseases. They already cause average losses of 34% (weeds), 18% (insects) and 16% diseases. Research has shown that insects and diseases have been slowly moving north as higher temperature allows overwintering and multiple generations. Climate change is expected to increase the range, or “damage niche” of many weed species.
Rainfall is the other critical component of climate change both in relation to frequency and intensity. “More winter and spring precipitation is projected for the northern United States, and less for the Southwest, over this century. Projections of future climate over the U.S. suggest that the recent trend towards increased heavy precipitation events will continue…. Summer temperatures are projected to continue rising, and a reduction of soil moisture, which exacerbates heat waves, is projected for much of the western and central U.S. in summer. By the end of this century, what have been once-in-20-year extreme heat days (one-day events) are projected to occur every two or three years over most of the nation.” Third National Climate Assessment Report, released by the U.S. Global Change Research Program.
Certainly we can expect more warmer periods and the more intense rainfall events will make it even more critical to be even more diligent about soil conservation to prevent runoff and retain soil moisture. Cover crops are already widely planted but they will need to be standard practice. Since agriculture will be severely affected in the South and MidWest by intense heat, our farming land in Pennsylvania will be even more critical to supply our food needs.
Perhaps we should see climate change as an opportunity to extend the range of our field and horticultural crops both to satisfy increased demand and meet the greater need for more local food production. Certainly we can expect greater challenges in controlling weeds, insects and diseases. On the marketing side US exports have already been increasing and more opportunities may arise. We will certainly need all the research and development of suitable varieties of crops that can cope with the higher temperatures. We are fortunate that our country has highly skilled and professional farmers supported by a comprehensive infrastructure. Critical for us to continue investment in research and development and the preservation of our best farmland to serve future generations.