Leaders from nations around the world have vowed to try to limit the Earth's warming to no more than 1.5 degrees Celsius above pre-industrial levels, in an effort to head off catastrophic sea level rise, ever-deadlier extreme weather events and other climate-related catastrophes. But hitting that ambitious target would require a rapid, transformational shift away from fossil fuels that has yet to materialise. Instead, global greenhouse gas emissions hit a record high in 2019, even as they fell slightly in the United States, and the amount of carbon dioxide in the atmosphere now sits at the highest level in human history - a level probably not seen on the planet for 3 million years. The 2019 figures from NASA and NOAA match similar data released by Berkeley Earth, an independent group that analyses temperature data. The findings also are in line with data released last week by the Copernicus Climate Change Service, a science initiative of the European Union. The World Meteorological Organisation confirmed the analysis. In fact, Berkeley Earth researchers said, no place on Earth experienced a record cold annual average during 2019. But 36 countries - from Belize to Botswana, from Slovakia to South Africa - experienced their hottest year since instrumental records began. Those same researchers estimated that more warming lies ahead, and that a 95 per cent chance exists that 2020 will become one of the five hottest years. Loading Replay Replay video Play video Play video

Wednesday's figures offer the latest evidence of the globe's inexorable temperature rise, particularly in recent decades. But the warming over the past century - and the impacts of climate change - have affected different parts of the world in vastly different ways. A recent Washington Post analysis found numerous locations around the globe that already have warmed by at least 2 degrees Celsius over the past century. That's a number that scientists and policymakers have identified as a red line if the planet is to avoid catastrophic and irreversible consequences. Some entire countries, including Switzerland and Kazakhstan, have warmed by 2C, and other hot spots exist around the world, particularly in the fast-warming Arctic. Scientists say extreme warming is helping to fuel fires from Australia to California, melt permafrost from Alaska to Siberia and fuel more intense storms and floods. It is also altering marine ecosystems from Canada to South America to the African coast, threatening wildlife and the livelihoods of those who depend on the sea. "The evidence isn't just in surface temperature," Benjamin Santer, a researcher at Lawrence Livermore National Laboratory, said of the human-fuelled warming trend. "It's Arctic sea ice. It's atmospheric water vapor increases. It's changes in glaciers in Alaska. It's changes in the Greenland Ice Sheet. It's all of the above." The warming over the past century - and the impacts of climate change - have affected different parts of the world in vastly different ways. Credit:AP

The past year alone featured a litany of disasters that scientists say were worsened by climate change - disasters they argue are only more likely in the future unless global emissions begin to fall sharply. During a tragic and terrifying December in Australia, with bushfires proliferating amid heat and drought, the country shattered its record for the hottest-ever day. On December 18, the national average high temperature was a blistering 50.6 Celsius. Europe recorded its hottest year ever, and a sizzling heat wave in July saw temperature records crumble. Paris, for example, registered a sweltering 108.7 degrees on July 25, shattering a record set in 1947. Alaska also had its hottest year on record in 2019. It included an alarming lack of ice cover during the winter in the Bering and Chukchi Seas, and in the summer the temperature at Ted Stevens Anchorage International Airport hit 32.2 degrees Celcius for the first time. Hurricanes such as Dorian devastated the Bahamas and other areas after rapidly intensifying, which some studies show is linked to warming seas and air temperatures. A pair of powerful cyclones hit Mozambique in rapid succession, killing hundreds of people, destroying homes and causing devastating floods. The year also brought signs that the natural systems that serve to store huge quantities of carbon dioxide and methane, another powerful greenhouse gas, may be faltering as temperatures increase.

Loading In December, a federal report indicated that melting permafrost throughout Arctic may already be a net source of atmospheric carbon, a shift that could accelerate global warming. Raging fires in the Amazon now threaten to turn the world's most productive rainforest into a drier, less carbon-rich savanna. Widespread reports from the UN Intergovernmental Panel on Climate Change (IPCC) last year detailed how climate change is already threatening food and water supplies, increasing the threat of droughts and floods, killing coral reefs, supercharging monster storms, fuelling deadly marine heat waves and contributing to record losses of sea ice. A new study this week also found that 2019 was the warmest on record for the world's oceans, with all of the top five hottest years coming since 2015. The oceans have long absorbed the vast majority - about 93 per cent - of the extra heat humans are adding to the climate through greenhouse gas emissions. Still, even as millions of protesters have taken to the streets to demand action, world leaders have so far shown little ability to move as fast as scientists say is necessary to cut greenhouse gas emissions.

Loading In a bleak report last fall, the United Nations warned that the world had squandered so much time mustering the willpower to combat climate change that drastic, unprecedented cuts in emissions are now the only way to avoid an ever-intensifying cascade of consequences. The UN report said global temperatures are on pace to rise as much as 3.2 degrees Celsius by the end of the century, and that emissions must begin falling by 7.6 per cent each year beginning 2020 to meet the most ambitious goals of the Paris climate accord. So far, many countries have failed to live up to the promises they made as part of the 2015 global agreement, including some of the world's largest emitters. More than 100 countries have vowed to submit more ambitious plans to fight climate change the end of 2020, but they collectively represent only about 15 per cent of global emissions. The Trump administration plans to exit the international accord later this year. Zeke Hausfather, a climate researcher for Berkeley Earth, said that despite the clear warming trend, humans still have an opportunity to shape what lies ahead. "We don't have any sign yet of global warming slowing down, but we also don't have any sign of global emissions slowing down," he said. "What happens in the future depends a lot on our emissions of greenhouse gases as a society. If we continue emitting at current levels, we will continue warming at about the same rate.