After this summer, there might not be a need for a climate scientist to state the obvious, but I will: Human-caused climate change has become a major problem, not just around the globe, but for the United States as well. And it is quickly becoming worse.
In the Southwest U.S., climate change is hitting hard in the form of unprecedented heatwaves, dust storms and wildfires. Yet, the truly existential climate change impact is on water supply. The principal source of water for the region is the Colorado River (with my old home state Arizona right in the middle of the growing crisis). Flows in this river have declined about 20 percent since “drought” struck 22 years ago. We now know that this isn’t a drought that will simply end when the snows return to the headwaters. It is progressive aridification due mostly to global warming.
Let climate change continue and the semi-arid West will see their surface water supplies continue to dwindle in a largely irreversible manner. The Colorado River could lose more than one-third of its flows by mid-century, and more thereafter. The once-mighty Rio Grande of New Mexico and Texas is already becoming a trickle in some years. Many are turning to groundwater to make up for lost river flows, but across much of the semi-arid West, groundwater is fossil water accumulated over repeated ice ages, and this water will simply run out as it is pumped dry.
Groundwater depletion is an invisible problem getting worse, but above ground the Western U.S. wildfire crisis is a storm of destruction and toxic smoke that no one can ignore. Heatwaves and wildfires will kill and destroy more and more unless climate change is halted fast. The western water crisis is already expanding out of the Southwest and will get much worse absent of bold climate action.
Our emissions of greenhouse gases to the atmosphere have warmed the planet just over 1 degree Celsius (almost 2 degrees Fahrenheit). If we fail to act boldly now, we risk crossing tipping points, or climate system thresholds, where much larger (3 degrees Celsius or more) warming and associated climate disasters become inevitable and largely irreversible. This is a principal reason climate scientists recommended that world leaders cap global warming at 1.5 to 2 degrees Celsius — the goal of the Paris Agreement as agreed to by virtually every country of the world.
Even 1 degree Celsius of warming is already turning the U.S. West into a disaster zone, and it is also starting to hit the rest of the country harder and harder. Hurricanes fueled by warmer oceans and atmosphere are becoming monster storms that often intensify at record speed. Even worse are the ever-increasing rainfall rates, amounts and floods associated with the storms. Coastal areas are getting hammered more than ever, and storm-driven rains are tracking much farther inland — flooding communities from Appalachia all the way to New England. In the years ahead, many more such storms will wreak havoc unless we act boldly on climate change now.
Sea-level rise due mostly to ocean warming and expansion (coupled with glacier and ice sheet melting) has been slow, but it is inexorable and accelerating. Cities in Florida are the poster children of on-going coastal flooding, but up and down the Gulf and Atlantic Coasts, communities are starting to feel the impacts of sea-level rise. However, if we fail to act boldly on climate change now, we risk crossing the irreversible thresholds beyond which huge parts of our polar ice sheets melt and become tens of feet of sea-level rise. It’s a hugely expensive pipedream to believe that coastal walls or dikes will be able to save U.S. coastal cities under such a sea-level rise onslaught.
There come times when leaders must lead. The nation and the planet are faced with myriad existential threats that will play out if climate change is allowed to continue. The solutions are well known, technologically proven and surprisingly affordable. These same climate change solutions will also largely rid our air of deadly air pollution and will create a net increase in new jobs. What’s more, citizens in every part of the country will benefit. Almost all of the countries of the world are lining up to do their part and are looking to the United States to lead.
I’m a scientist who has studied climate change and the impacts of climate change for years, but I’m also just like everyone reading this message. I care about our country, its economy, its people — rich and poor, rural and urban. And I care about future generations, who stand to inherit either an unimaginable climate change disaster or a world transformed that is free of climate change, toxic air pollution, mass extinction and the terrible economic and health burdens that massive climate change is sure to create.
Congress can’t lose sight of the fact that our nation’s big climate change push has to be made now, or else we will risk crossing those tipping points beyond which the impacts become much more devastating and irreversible.
If we don’t act now, every part of the country will suffer impacts that will make the summer of 2021 look like a walk in the park. The citizens of our country deserve bold action — and business-as-usual infrastructure spending alone is not enough. Success in our battle against climate change requires the deliberate and strategic spending to ensure that the United States cuts its greenhouse gas emissions by more than half in this decade.
Our eyes are on Congress, and the whole world is watching with us. As a country, and as a planet, we must do whatever it takes to stop climate change now.
Jonathan Overpeck, Ph.D., is a climate scientist, professor and dean of the School for Environment and Sustainability at the University of Michigan. He has researched drought, climate variability and climate change on five continents. Follow him on Twitter: @GreatLakesPeck