Mega Drought Shaking the Future of the American Southwest: Could Last Until the End of the 21st Century

1. Introduction: The "Southwest" Turning into a Desert

In July in Phoenix, Arizona, temperatures exceed 45 degrees Celsius, and the air is so dry it feels like it could ignite even a single strand of hair. The canals that once nourished lush cotton fields have dried up, and residents pour rainwater collected from their roofs onto their garden trees in a bucket brigade. People's hopes were pinned on the North American monsoon, but in recent years it has amounted to little more than "passing showers that quickly evaporate," and groundwater levels continue to decline. Amidst this sense of crisis, a recent paper published by a research team from the University of Texas indicated the possibility that the Southwest could be "locked into a drought-dominant state by the end of the century."Phys.org

2. Core of the Research: "Rhythm Disruption" of the PDO

The PDO is known as a natural oscillation that switches the sea surface temperature patterns of the North Pacific every 20 to 30 years, adjusting precipitation in the western United States. However, the paper warns that global vegetation changes due to global warming could amplify solar radiation absorption, potentially "fixing" the PDO in a long-term negative phase. Analysis of lakebed sediments from the mid-Holocene, 6,000 to 9,000 years ago, showed winter precipitation decreased by about 20%, with droughts persisting for thousands of years. Future projections averaged from multiple modern climate models also suggest a similar North Pacific atmospheric-oceanic response, indicating a scenario where winter precipitation continues to decrease until 2100.Phys.org

3. Impact on the Colorado River Basin

The Colorado River is a lifeline supporting the water needs of over 7 million people and 5 million acres of farmland, but its flow is said to have decreased by about 15% over the past 20 years. Associate Professor Shanahan, a co-author of the study, stated, "Water management plans based on recovery will fail," urging water resource managers to immediately adapt to the "New Normal." The Nevada Water Authority has already announced a new plan to increase the ratio of recycled water to 40% by 2030, and an ordinance banning non-essential lawn irrigation has passed in Las Vegas County.

4. The "Reality of Depletion" Spreading on Social Media

Immediately after the research announcement, "

#ColoradoRiverCrisis" surged on X (formerly Twitter). Official accounts of NIDIS and NOAA posted, "Early monsoon rains are only short-term relief, with drought continuing in 65% of the region," garnering over 10,000 reposts. Users from the Navajo Nation shared, "We are already living with water trucks twice a week," along with on-site photos, receiving numerous voices of empathy and calls for support. A high school student from Phoenix posted a TikTok video titled "Showers under 5 minutes, gardens with cacti" and the "water-saving routine" video surpassed 2 million views. Social media is becoming a hub for visualizing the crisis and grassroots movements.Drought.gov

5. The Limits of Relying on the Monsoon

The North American monsoon of 2025 began in late June in New Mexico and West Texas, bringing heavy rains with localized flooding, but Arizona and Utah remain in a state of waiting for rain clouds. According to the latest analysis by NIDIS, monsoon rains account for up to 60% of annual precipitation in some areas, but remain a "supplementary presence" in terms of overall water resources. With the long-term reduction in snowmelt water, it concludes that complete recovery relying solely on the monsoon is unlikely.Drought.gov

6. Economy and Policy: Rising Water Prices and Infrastructure Investment

The prolonged drought affects agriculture, power generation, and tourism. As of 2024, almond producers in California have reduced over 30,000 acres due to rising water costs. In April 2025, a river rafting company in Moab, Utah, announced "season closure due to insufficient water levels." At the federal level, a revised version of the Infrastructure Reduction Act (IRA) is under Senate review, proposing $11 billion in subsidies targeting three pillars: recycled water, seawater desalination, and large-scale pumped storage.

7. Actions Residents Should Take

1. Water Conservation at Home: Install low-flow showerheads to save 40,000 liters annually.

2. Dryland Landscaping: Replace lawns with native succulents, cutting irrigation by 80%.

3. Community Water Storage: Jointly purchase rainwater tanks to supply fire departments and farms.

4. Policy Participation: Submit opinions in public comments for regional water districts to promote rate structure reform.

8. Future Scenarios: Adaptation or Migration

In the worst-case scenario depicted by the research for 2100, snowfall in the southern Rocky Mountains is down by 40% compared to now, the basin population surpasses 50 million, and water demand reaches twice the supply. Conversely, if emissions reductions align with the 1.5°C scenario and large-scale recycled water and desalination infrastructure are operational, basin storage rates are projected to stabilize at +10% compared to now. The choice is "adaptation" or "migration"—either way, there is little time to spare.

9. Conclusion: Survival Strategies in the Era of "Perpetual Drought"

This research shatters the optimism of "waiting for rain" based on natural variability, presenting the reality that "climate change measures are water crisis measures." The urgent voices on social media visualize the gap between science and policy, increasing pressure for action. The Southwest has now become a litmus test for the sustainability of civilization.