Global heat, greenhouse gases and sea levels all climbed to record highs last year, making 2015 the worst in modern times across a range of key environmental indicators, international scientists said today.
A dire picture of the Earth's health is painted in the State of the Climate report, a peer-reviewed 300-page tome that comes out once a year and is compiled by 450 scientists from around the world.
The record heat that the planet experienced last year was driven partially by global warming, and was exacerbated by the ocean heating trend known as El Nino, it said.
El Nino, which just ended in July, was one of the strongest the Earth has seen "since at least 1950," said the report, led by the National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information.
"This 'annual physical' of Earth's climate system showed us that 2015's climate was shaped both by long-term change and an El Nino event," said Thomas Karl, director of the NOAA division.
"Last year's El Nino was a clear reminder of how short-term events can amplify the relative influence and impacts stemming from longer-term global warming trends."
Major concentrations of greenhouse gases -- including carbon dioxide (CO2), methane and nitrous oxide -- are the by-products of fossil fuel burning.
All three "rose to new record high values during 2015," said the findings, based on tens of thousands of measurements from multiple independent datasets.
The annual average atmospheric carbon dioxide (CO2) concentration at Mauna Loa, Hawaii, reached 400.8 parts per million (ppm), surpassing 400 ppm for the first time, marking "the largest annual increase observed in the 58-year record."
On average globally, 2015's CO2 level was 399.4 ppm, an increase of 2.2 ppm over 2014.
The report also confirmed NOAA and NASA's finding that Earth's average land and ocean surface temperatures warmed to record levels in 2015.
And global sea levels swelled to their highest point ever, about 70 millimeters (about 2.75 inches) higher than the 1993 average.
Sea level is creeping up gradually around the globe, averaging about 3.3 millimeters per year, said the report.
Some places in the western Pacific and Indian Ocean are seeing waters rise faster.
Even though the current pace may appear slow, experts warn that sea level rise will accelerate in the coming decades as glaciers and polar ice caps melt, putting millions of lives at risk in coastal communities around the world.
