Nearly Every Major U.S. City Has Warmed Significantly Since 1970, Climate Report Finds

Climate Change Accelerates: U.S. Cities and States Warm Since 1970

Since the first Earth Day in 1970, organized by Sen. Gaylord Nelson, D-Wisc., the United States has experienced significant warming due to rising carbon dioxide levels. In 1970, the annual average atmospheric CO₂ concentration was 326 parts per million (ppm). By 2025, it had increased by 31% to 427 ppm.

“It may sound small, but it’s reshaping daily life,” said Shel Winkley, a meteorologist at Climate Central, in a video accompanying the report. The nonprofit’s new analysis, published today, found that since 1970, all 50 states and 99% of major U.S. cities have warmed, with an average city-level increase of 1.6°C (2.9°F).

On average, the 49 states analyzed warmed by 1.7°C (3.0°F) since 1970. The six fastest-warming states since 1970 are:

• Alaska: 2.4°C (4.4°F)
• New Jersey: 2.1°C (3.7°F)
• New Mexico: 2.1°C (3.7°F)
• Delaware: 2.0°C (3.6°F)
• Massachusetts: 2.0°C (3.6°F)
• Vermont: 2.0°C (3.6°F)

Hawaii was excluded from the dataset, so trends for the state were not calculated.

2025 Temperatures Exceed 20th Century Averages

In 2025, the United States was 1.4°C (2.6°F) warmer than the 20th century average. The Paris Agreement aims to limit global warming to 1.5°C (2.7°F) above preindustrial levels, though scientists warn this threshold may already have been breached.

Southwest Cities Warm Faster Than States

Warming trends are most pronounced in the Southwest, where cities have warmed an average of 1.9°C (3.5°F) since 1970. In some cases, cities are warming much faster than their respective states. The five fastest-warming cities since 1970 include:

• Reno, Nev.: 4.4°C (7.9°F)
• Las Vegas, Nev.: 3.3°C (6.0°F)
• El Paso, Texas: 3.3°C (5.9°F)
• Albuquerque, N.M.: 3.1°C (5.6°F)
• Phoenix, Ariz.: 2.9°C (5.2°F)

In 240 of the 242 cities analyzed, temperatures have warmed at the local, state, and national levels.

Good News: Renewable Energy Growth

The report highlights progress in renewable energy, noting that solar and wind power generation have reached new highs. This progress offers a glimmer of hope amid the broader warming trends.

“It may sound small, but it’s reshaping daily life.”
— Shel Winkley, Meteorologist, Climate Central

Explore Your City’s Warming Trends

Climate Central provides tools to check warming trends in your city. Visit their report for detailed data and insights.

Credit: Climate Central, CC BY 4.0