2017 was world’s hottest year ever without El Nino, says Nasa

Earth's long-term warming trend continued in 2017, government scientists reported on Thursday, with average surface temperatures only slightly below the record heat of the previous year. But unlike 2016, last year's warmth was not aided by El Nino, the Pacific weather pattern that is usually linked to record-setting heat. Nasa ranked 2017 the second-warmest year, after 2016.

Scientists at the National Oceanic and Atmospheric Administration, who use a different analytical method, ranked it third, behind 2016 and 2015. Though 2015 was not technically an El Nino year, the phenomenon contributed to heat records that year and in 2016.

By both analyses, 17 of the 18 warmest years since modern record keeping began in 1880 have occurred since 2001. Overall, fueled by emissions of carbon dioxide and other greenhouse gases, temperatures have increased more than 1 degree Celsius (1.8 degrees Fahrenheit) since the late 19th century. In order to avoid the worst consequences of climate change, scientists say global temperatures must not increase more than 2 degrees Celsius.