For more than 20 years, the work of academic climate scientists and those at groups like the Union of Concerned Scientists has been to analyze, synthesize, and convey the projected and, in recent years, current impacts of climate change. In the earlier years, these impacts were still largely imperceptible and pathways for solving the problem seemed wide and flexible. A key objective of climate science communication during those years was to establish the legitimacy of our work, which faced tremendous public and policy maker scrutiny, as a simultaneous barrage of well-coordinated disinformation had led to unusual skepticism of the science. Now we are clearly seeing the impacts of one degree Celsius of warming, the current and projected climate impacts themselves have grown, and the solutions pathways have become narrow and steep. While the climate context has changed for the worse over those 20 years, scientists have largely soldiered on with the same reticent communication. Visible climate change impacts and alarming projections for future change have far outpaced the growth in experts’ ability to reach people and inspire them to act with urgency. At UCS, we have consciously and deliberately begun to change the tenor of our climate communications in response to the increasingly dire results our own analyses have generated and against a backdrop of accumulating and similarly dire science. In our most recent work on extreme heat, particularly in introducing and concluding our results, we have embraced starkly visceral and impassioned language because, as scientists, we see how dangerous the future looks, how serious this moment is in the arc of climate change, and our own moral obligation to communicate it. In this presentation, we will examine the communications space our climate scientists at UCS—as well as those at other institutions—have leaned into. As sentient humans who see an emergency measured not just by data points in charts and graphs but by the faces of those whose homes have flooded, whose loved ones have lost their lives during heat waves, or whose livelihoods are no longer viable, we can’t “tell it like it is” without letting go of reticence and objectivity. The words we choose may be perceived as dangerous, but they are not as dangerous as the world we are ushering in. The house is objectively on fire. It’s time to shout.

Outdoor workers perform critical societal functions, often despite higher-than-average on-the-job risks and below-average pay. Climate change is expected to increase the frequency of days when it is too hot to safely work outdoors, compounding risks to workers and placing new stressors on the personal, local, state, and federal economies that depend on them. After quantifying the number of outdoor workers in the contiguous United States and their median earnings, we couple heat-based work reduction recommendations from the US Centers for Disease Control and Prevention with an analysis of hourly weather station data to develop novel algorithms for calculating the annual number of unsafe workdays due to extreme heat. We apply these algorithms to projections of the frequency of extreme heat days to quantify the exposure of the outdoor workforce to extreme heat and the associated earnings at risk under different greenhouse gas emissions mitigation scenarios and, for the first time, different adaptation measures. With a trajectory of modest greenhouse gas emissions reductions (RCP4.5), outdoor worker exposure to extreme heat would triple that of the late 20th century baseline by midcentury, and earnings at risk would reach an estimated $39.3 billion annually. By late century with that same trajectory, exposure would increase four-fold compared to the baseline with an estimated $49.2 billion in annual earnings at risk. Losses are considerably higher with a limited-mitigation trajectory (RCP8.5). While universal adoption of two specific adaptation measures in conjunction could reduce future economic risks by roughly 90%, practical limitations to their adoption suggest that emissions mitigation policies will be critical for ensuring the wellbeing and livelihoods of outdoor workers in a warming climate.