The new paradigm: Un-natural disasters in a changing climate

Almost every day the news discusses one or more new extreme weather-related events having serious impacts on some part of the world. In just the last few weeks there have been record heat and associated wildfires in the western U.S., ongoing drought in the U.S. southwest is continuing to have serious impacts on water supplies, torrential rains and record flooding are occurring in Germany and Belgium, extreme heat and wildfires are impacting Siberia in Russia, and large monsoonal rains are resulting in extensive flooding in India.

It is generally straightforward for a meteorologist to show that such extreme events are connected to a certain weather pattern, but further analysis now almost always shows that the changing climate has led to a severity of the event that otherwise would not have occurred previously. Humanity has long witnessed natural disasters, but now we are seeing an increasing intensity of such events. What were once very rare events are now becoming more common.

Scientists are studying these changes to our climate and their association with extreme events, and the factors driving these changes. The evidence clearly shows that human activities have been driving the changes in our climate. The bottom line is that human-driven climate change is affecting almost all of our weather these days and will continue to affect our weather for many decades. The science shows that these increases in un-natural disasters are happening because of our changing climate. But the changes are occurring at even a faster rate than the scientists expected.

Let’s look at what we are seeing.

Climate change has increased the frequency, size, and duration of extreme heat events. In the United States, multi-day heat waves are occurring about three times more often now than they did 50 years ago.

Drought risk is increasing across many parts of the United States, especially the western states, as rising temperatures accelerate evaporation, increase water uptake by heat-parched plants, and reduce the amount of winter snowpack available to refresh regions during dry summer months.

Increasing temperatures, more extreme heatwaves, increasing drought and resulting increasing distress on vegetation allowing for bark beetle and other infestations, are all significant contributors to the increasing size and intensity of and damage from U.S. wildfires.

When it does rain or snow, it is more likely to be a larger event than in the past. A growing percentage of U.S. precipitation now comes in the form of extreme events, with human-caused climate change directly responsible for much of this increase. Basically, heavy rains are getting heavier. Climate-change-related increases in heavy rain intensity and frequency, and the lingering persistence of these weather events over affected areas, have exacerbated flooding across the United States, especially in the Midwest, increasing the number of cities and expanses of land now at high risk.

Evidence continues to mount that human-induced climate change is causing hurricanes to grow stronger and more destructive. Hurricanes are producing heavier rain, their storm surges are riding atop higher sea levels, and, in some cases, they are lingering longer over land, causing increased flooding and infrastructure destruction.

Let’s look at just one of these types of un-natural disasters in more detail: wildfires. In the western U.S., climate change caused more than half the increase in forest fuel aridity (how dry and flammable vegetation is) since the 1970s and has approximately doubled the cumulative area burned in forest fires since 1984. Climate-change-related declines in western spring snowpack, and increased evaporation from higher temperatures, have in the decades since the early 1980s reduced moisture and contributed to a marked increase in the frequency of large fires and the total area burned. Over the last 50 years, there was an eight-fold increase in the annual area burned in summertime forest fires in the west. The evidence indicates that this dramatic increase was caused primarily by unusually dry air linked to climate change. Recent analyses show that intense wildfires can create their own weather — storms that lead to more lightning and more wildfires. These trends are very likely to increase into the future, with science projections suggesting even more dangerous weather conditions for wildfires over the coming decades.

The science tells us that climate change is a very real and an alarming issue that all Americans, and all people around the world, should be concerned about. The findings from the science may be alarming but that doesn’t mean scientists studying this issue are alarmists. Rather, the science tells us there is an urgent need to determine the right responses.

Many thousands of observational-based studies have documented the increasing surface, atmospheric, and oceanic temperatures on climate time scales. Observations also show many other aspects of a changing climate, e.g., that the vast majority of glaciers, including much of Greenland and Antarctica, are melting, snow cover is diminishing, sea ice is shrinking, sea levels are rising, our oceans are acidifying, and that water vapor in the atmosphere is increasing (a warmer atmosphere can hold more water vapor). Satellite observational datasets along with detection and attribution techniques, termed “fingerprinting,” show that the connection between climate change and human activities is known to over 99.999 percent (in other words, the likelihood that changes in climate are not due to human activities is less than one in a million).

We need to stop acting as if climate change is a political issue. The science shows this is an important issue that is affecting all Americans. The real debate should be how we find the right solutions to climate change and make sure we leave a legacy of hope for the future to our children and grandchildren.

Donald J. Wuebbles is the Harry E. Preble professor of Atmospheric Sciences at the University of Illinois, Urbana. He is an expert in the physics and chemistry affecting the Earth’s climate, as well as analyses of climate impacts on society and ecosystems, plus potential resilience and societal responses.