LOS ANGELES - Average global temperatures for each of the past 12 months hit record highs, marking an unprecedented streak, according to a NASA analysis released on Tuesday.

Based on temperature readings from a huge network of weather stations on land and instruments in oceans, scientists find that the records are part of a long-term warming trend driven by human activities, especially greenhouse gas emissions

"It's clear we are facing a climate crisis," said NASA Administrator Bill Nelson in a news release. "Communities across the globe are feeling first-hand extreme heat in unprecedented numbers."

The average global temperature over the past 12 months was 1.30 °C above the 20th-century baseline (1951 to 1980), the analysis shows.

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Based on temperature readings from a huge network of weather stations on land and instruments in oceans, scientists find that the records are part of a long-term warming trend driven by human activities, especially greenhouse gas emissions.

"We're experiencing more hot days, more hot months, more hot years," said Kate Calvin, NASA's chief scientist and senior climate advisor. "We know that these increases in temperature are driven by our greenhouse gas emissions and are impacting people and ecosystems around the world."

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The trend has become evident over the past four decades, with the last 10 consecutive years being the warmest 10 since record-keeping began in the late 19th century, according to the analysis.