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Extreme Weather: What’s Climate Change Got to Do With It?

If one had to develop a fictional narrative to accompany scientific projections of a warming world, perhaps the writers might have come up with a story of extreme weather events similar to what we have seen over the past month. But it would have taken place decades in the future. Unfortunately, there is nothing fictional about these deadly events, which have destroyed lives, homes and business around the world.

Just in the last few weeks, we have witnessed:

  • An unrelenting heat wave in California, reaching 106 degrees F in San Francisco, that left six dead, strained the state’s power grid and left thousands without electricity;

  • More than 40 million people affected by massive floods across India, Bangladesh and Nepal, with 1,300 killed and at least 1.5 million homes destroyed or damaged;

  • Hurricane Irma decimating the northern Caribbean, with at least 27 dead, flattening buildings, and leaving many without essential supplies, while in Florida, the hurricane killed at least four, wiped out power for 64 percent of the state and produced record storm surges;

  • Hurricane Harvey causing catastrophic flooding across Texas, with at least 70 deaths;  Harvey and Irma combined caused an estimated $150-200 billion in damage in the United States, and

  • More than 80 wildfires burning across almost 1.5 million acres in nine western U.S. states; this year, the U.S. Forest Service has already spent about $1.75 billion on fire suppression and the Department of Interior has spent an additional $400 million.

In light of these events, we must ask: What’s climate change got to do with it?

President Donald Trump said last week that his views on climate change haven’t changed even after witnessing the impacts of Hurricane Harvey and Irma on millions of Americans. Similarly, EPA Administrator Scott Pruitt has said that talking about climate change at a time like this is “insensitive” and “misplaced.”

But many elected decision-makers closer to the storm disagree. As Miami’s Republican Mayor Tomas Regalado stated: “This is the time to talk about climate change. This is the time that the president and the EPA and whoever makes decisions needs to talk about climate change.” We should be talking about how to reduce risks and prepare for future threats, just as we do after a terrorist attack or building fire.

In the United States, for some, the term “climate change” has become so politicized that it is being erased from websites, funding proposals and official documents. The most important task right now is to provide comprehensive care for the injured and to those who have suffered property damage. As we do that, and as we rebuild these communities, we also have an obligation to consider how we can reduce risks to protect lives and property in the future.

And while the growing impacts of climate change are bad for people in the developed world, many in developing countries have it much worse, given their increased vulnerability and lack of resources and capacity to adapt. These people need far greater support to cope with these mounting disasters.

What Does Climate Science Say?

So what does climate science tell us about the links between climate change and extreme weather and what impact is this likely to have on future events? Is science making progress on the attribution of any one extreme event to climate change?

Here is some of what we know:

  • Heat waves: It is no surprise that warming in the atmosphere leads to heat waves, or periods of very hot weather lasting days to weeks. In recent years, the frequency of heat waves has been increasing in many parts of the world, and the risk associated with extreme heat increases with further warming.

  • Storms and flooding: We also know that warming leads to higher sea levels, which in turn increases the risk of storm surge, contributing to the damage brought by hurricanes. Climate change also warms oceans, adding energy that can fuel coastal storms. Compounding this, a warmer atmosphere can hold more moisture, so there can be more moisture for storm systems, resulting in heavier rainfall. The U.S. National Climate Assessment finds that there has been a substantial increase – in intensity, frequency, and duration as well as the number of strongest (Category 4 and 5) storms – in Atlantic Ocean hurricanes since the early 1980s, linked in part to higher sea surface temperatures. By late this century, models on average project a slight decrease in the number of tropical cyclones each year, but an increase in the number of the strongest (Category 4 and 5) hurricanes and greater rainfall rates in hurricanes (increases of about 20 percent averaged near the center of hurricanes).

  • Fires: We know that higher temperatures lead to increased rates of evaporation, leading to rapid drying of soils. This can not only contribute to drought conditions but can stoke forest fires. The U.S. National Climate Assessment finds that in the western forests, large and intense fires are projected to occur more frequently, with large and longer wildfires given higher temperatures and earlier spring snowmelt.

These trends in extreme weather events are accompanied by longer-term changes as well, including surface and ocean temperature increase over recent decades, snow and ice cover decrease and sea level rise.

Science is always advancing, whether it is finding new ways to combat cancer or understanding how to better track hurricanes and storms. We are also learning more about climate science all the time.  Specifically, the science of attribution – looking at how much climate change increases the odds of any one particular event occurring – has advanced remarkably. For example, the National Academies recently published a study on the attribution of extreme events in the context of climate change, noting that “advances have come about for two main reasons: one, the understanding of the climate and weather mechanisms that produce extreme events is improving, and two, rapid progress is being made in the methods that are used for event attribution.“ The Bureau of the American Meteorological Society has now published five reports focused on explaining how climate change may have affected extreme events from 2011 to 2015. In addition, several international research programs came together to develop the World Weather Attribution project to analyze the role of climate change in extreme events.

It will still take time for researchers to determine the precise degree to which human-caused warming increased the odds of any one of the recent extreme events of happening. We certainly don’t need to wait to know the exact statistic to strengthen communities’ abilities to withstand these types of events and reduce the risk for the future.

The priority today should be on recovery, and as we do that we should better protect ourselves for the next event. We know that we can both reduce the risks associated with climate change by cutting global emissions to a safe level, and making smart investments to ensure our communities and infrastructure are more resilient.

We need to face the realities of climate change today, not fall for the fantasy that we can just ignore them and they will go away.

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