Climate change is happening and humans are the primary cause.
So say the hundreds of scientists on the Intergovernmental Panel on Climate Change. The panel recently published the first section of its fifth assessment report on the state of the world’s climate. The report is massive, nearly 2,000 pages of dense scientific and bureaucratic writing, and covers a vast array of topics citing 9,200 scientific articles. Its scope is global, directed primarily at governments around the world, but several issues discussed are pertinent right here in Montana.
The IPCC report addresses two main issues: mounting global carbon dioxide levels and the resulting rise in global temperature. Climate change comes largely from adding carbon dioxide to the atmosphere. It is a natural process but is greatly accelerated by our heavy use of coal and other fossil fuels. This carbon dioxide traps the sun’s heat in the earth’s atmosphere, warming the planet. The IPCC report finds higher CO2 levels now than at any time in human history, and these levels continue to rise at an unprecedented rate.
Extreme weather events
Science predicts more extreme weather events, such as heat waves, storms, and floods caused by heavy rainfall, will occur as temperatures continue to rise. The increase in the number of extreme weather events in recent years gives a sense that these changes are already occurring. Just this year, a heat wave in the United Kingdom is thought to have resulted in more than 700 deaths. Flooding in Colorado from massive rains caused an estimated $2 billion in property and infrastructure damage. Here in Montana, we’ve seen a record three inches of rain in September. Although science cannot tie a single incident directly tied climate change, these extreme weather events are in line with the predictions of climate science.
Severe weather has obvious implications for livestock and crops. Heat waves pose significant danger not only for human health but also for livestock. In some recent heat waves, the USDA reports losses of as many as 5,000 head of cattle in individual states. Floods and storms cause significant crop damage, and these, too, are predicted to occur more frequently. Worse, scientists predict flooding from heavy rains during the spring and early fall, when crops and harvests are most susceptible to damage.
Changes in rainfall influence water availability. Milder, drier winters and warmer springs decrease snowpack that feeds our streams, something we’ve seen in recent years. At the same time, the hotter and drier summers from warmer temperatures demand greater use of scarce water resources.
Scientists don’t know how the combined increasing CO2 concentrations and warmer temperatures will affect crops. Although plants use carbon dioxide in their growth and energy production and generally benefit from higher CO2 levels, warmer temperatures cause significant heat stress, weakening plants. However, one major plant group thrives under such conditions: weeds. This further stresses crops and increases the amount herbicides needed to keep the weeds at bay.
Global temperatures have risen more than 1.5 degrees Fahrenheit since the early 1900s. This is a huge increase. A temperature rise of 2.5 degrees Fahrenheit is the point beyond which we will be unable to control climate change. At this temperature, ocean currents which stabilize the earth’s climate will be unable to function as they currently do, causing massive climate fluctuations. If we allow the temperature to rise to this point, the consequences will be disastrous.
No simple solution
There is no simple solution to climate change. Slowing or halting humankind’s changes to the world’s climate is not going to be easy and will involve the cooperative efforts of people and governments around the world. The issue is one we can no longer afford to ignore, especially here in Montana.