Planetary healthcheck delivers 'unprecedented', 'terrifying' picture
The world authority on climate change has delivered its strongest statement yet: unprecedented human-made heat is already here, along with floods and other extremes. The window to stay inside 1.5 degrees Celsius hotter than pre-industrial times, as most countries are aiming to do, is rapidly closing. That threshold will likely be crossed not long after 2030. Even under the most optimistic projections, Earth will overshoot 1.5C though with dramatic carbon cuts, this could only be temporary. READ MORE: * Why August 9 is a huge day for climate action * Budget 2020: trading coronavirus for the climate crisis * We've slowed climate change once. Can we do it again? * 'Life-altering' changes needed to avoid the worst of climate change Every fraction of a degree of extra warming will cause more extreme heat waves, heavy rain, drought and sea level rise. Tropical cyclones and wildfires are also expected to worsen. The findings are in the latest report from the IPCC (Intergovernmental Panel on Climate Change), which has released its first full assessment of the physical science of climate change in eight years. It is the culmination of three years work by more than 200 scientists from 66 countries . Over the last two weeks, every word in the reports summary was pored over and agreed on by government representatives working with key scientific authors , setting the scene for Novembers crucial UN climate summit in Glasgow. If pollution keeps rising, the oceans and forests wont be able to keep absorbing the huge proportion of greenhouse emissions theyve sucked in to date. Collapse of a chunk of Antarctica, while unlikely, cant be ruled out this century. However, the report shows its not too late to change course. With very low emissions, air quality could improve within just a few years. A few decades after starting strong emissions cuts, global temperatures would begin to stabilise. But stopping heating of 2.5C, 3C or even 4C requires a swift shift towards net zero carbon dioxide emissions as well as strong reductions in methane and other gases, the report confirms. Without action, a baby born today is likely to see global temperatures tip into more dangerous levels of warming beyond 2C before his or her 40th birthday, the report found. The report is much stronger than its predecessors at making a firm link between human-made heating and weather extremes. Heating from climate pollution has already caused unprecedented hot spells, and heavier rain, concludes the report, which landed just as large swathes of the world suffered deadly, record-breaking heat . Extreme heat waves that have already happened would have had very little chance of happening without human influence, it says. Andy Reisinger, vice chair of IPCC working group three, said the evidence is clear: Human fingerprints can be seen all over the climate system, not just increasing global average temperature, but much more real and present tangible damaging aspects. For example, the attribution of human influence on changing extreme heat waves, floods, droughts in many regions, reductions in the Arctic sea ice, retreat of glaciers... ocean acidification [and] intensification of tropical cyclones. Events like the recent Canterbury floods and Auckland droughts are expected to hit more frequently with warming temperatures, which exacerbate both wet and dry conditions. Global temperatures are now about 1.1C higher on average than before human influence, but the temperatures people actually experience air temperatures over land are heating faster than air over oceans. Many big land masses, such as Australia, are warming particularly quickly, and faster than ocean-buffered countries such as New Zealand. Australia has heated 1.4C since 1910, compared with New Zealands 1.1C, the report says. Globally, each of the last four decades has been successively warmer than any decade since 1850. The last time it was this warm was 125,000 years ago around the time humans evolved into our current state. Meanwhile, in 2019, atmospheric carbon dioxide concentrations were likely higher than at any time in at least two million years. The release sets the scene for Novembers crucial UN climate summit in Glasgow, where virtually every nation on Earth has agreed to make their toughest pledge possible to cut climate pollution. To halt heating at 1.5 or 2C, the report confirms, carbon dioxide emissions need to reach net zero (or better), along with strong reductions of other gases, such as methane and nitrous oxide. While the report does not make policy suggestions, it says that purely from a physical science perspective, stopping heating requires strong reductions in non-carbon dioxide gases. Globally, methane from leaky oil and gas production is a major source, along with landfills and agriculture ( New Zealands major methane source ). Cutting aerosol pollution as a result of decarbonising electricity production and other sectors will, perversely, result in some temporary warming, because some aerosols cool the planet. Strong, rapid and sustained reductions in [methane] emissions would... limit the warming effect resulting from declining aerosol pollution, and would improve air quality, says the IPCCs key points summary. Climate Change Minister James Shaw reacted to the report by re-affirming the Governments promise to improve its emissions-cutting pledge, though a new pledge wont be announced before Glasgow. New Zealands current pledge (knocking off 30 per cent from 2005 emissions by 2030) has been ruled incompatible with global efforts to stay inside 1.5C by the Climate Change Commission. In real terms, New Zealand has achieved little in the way of cutting emissions industrial emissions in 2019 were the highest theyve been since Statistics NZ started tracking them in 2007. We have to up our game in terms of our commitment to the global effort to limit global warming, but also make sure that our emissions reduction plan and response to the [Climate Change] Commission's recommendations is as strong as possible, in terms of driving action in our domestic economy, Shaw said. 1.5 degrees is bad enough, two degrees is worse, four-and-a-half or five degrees is just catastrophic. As well as cutting gases, many climate scientists stressed the need to start adapting. Even with drastic emissions cuts, Earths temperature will keep rising for at least 20 years, causing more frequent and intense heat waves , droughts and heavy rain, the report shows. Sea levels will continue rising for centuries or millennia, because of processes already locked in. New Zealand scientists described the findings as scary, sobering, and frightening. As a climate scientist, the updated knowledge presented here is as fascinating as it is impressive, said Nathanael Melia, a senior research fellow at Victoria University's Climate Change Research Institute. However, as a human, with a young family... the contents of this report are nothing short of terrifying. In the space of eight years since the last report, the language seems to have changed from a position of warning, this could happen, to a position of brace for impact, Melia said. Victoria University climate researcher James Renwick, a climate commissioner, agreed. If we allow the warming to get much beyond where we are now, theres going to be even more catastrophe, damage and loss of life... This really is the biggest problem the world faces. Laura Revell, a senior lecturer in environmental physics at the University of Canterbury, said the scale of changes were unprecedented for many centuries or millennia : The science will not get much clearer than this. Olaf Morgenstern, Niwa principal scientist and a lead author of one of the chapters, noted the first major human settlements are just 5,000 years old. Human civilisation has never existed in a climate this hot, he said. Every fraction of a degree of additional warming makes most of these events, especially floods, heatwaves, and droughts, more likely and more intense. It is in our hands, Morgenstern added. Victoria Universitys Nick Golledge, who helped prepare the reports ice and oceans section, said one of the main takeaways was that Earths climate system was responding faster than politicians. It's accelerating. Anytime you see an accelerating system, that's bad news. It means you've got to up your game quickly. Ultimately, the science hasn't changed since the first assessment report in 1990. We're still using the same physics, we're still looking at the earth system in the same way. Some models have got a bit more complicated and some numbers have changed a little bit, but the message is exactly [the same], said Golledge. We are warming the planet, it's us, it's nothing else. New Zealand has had a record-breaking run of warm summers and winters . While the shape of our land and complexity of our climate mean the report cannot drill down into much local detail, in future, fire risk is expected to increase in many places.When the rains come, it will bucket down, increasing the risk of floods. At the same time, droughts during the summer months will become more common. The El Nino weather cycles which brew in the Pacific Ocean and can cause drought on the East Coast and flooding in the west will be amplified. In summer, the storms that bring rain to the West Coast will track to the south, drying out the region. However, southern and western areas will get more rain in winter and spring, while winter snow lines and glaciers will continue to retreat. The report highlighted the devastating impacts of warming on Pacific nations. Rising seas will encroach on coastal towns and villages and contaminate drinking water supplies, said Mark Howden, an Australian National University climate researcher and an IPCC vice-chair. Tropical cyclones will gain power from the warmer seas. This, coupled with sea level rise, will worsen already deadly storm surge events in countries like Fiji and Vanuatu, Howden said. Globally, the Northern Hemisphere is heating more than the Southern Hemisphere, partly because it has more land cover. This is particularly pronounced in the Arctic. The melting of polar sea ice in this region could snowball heating, because white ice reflects more heat back to space than water. In the Southern Hemisphere, the fastest-heating areas include subtropical South America, southern Africa, and Australia. The Mediterranean, southern Africa and parts of Australia, South America, and southwest North America are expected to rapidly warm and dry. Cities will warm more than the countryside, as urban heat islands trap heat. In coastal cities, sea level rises and storm surges, combined with extreme rainfall, will make floods more likely. The rising acidity of the ocean will threaten fish species, and the communities dependent on them for food and jobs. The report says melting polar ice sheets and glaciers together will likely raise sea levels by 40-80cm by 2100, compared with 1995-2014 levels. But wildcard runaway processes in Antarctica could add an extra metre on top of that, said Victoria Universitys Nick Golledge. A collapse of the ice sheets remains unlikely this century, but cant be ruled out, the report concluded. A lack of understanding of how Antarcticas ice sheets will react to ongoing warming remains the elephant in the room, said Tim Naish of Victoria Universitys Antarctic Research Centre. The polar ice sheets built up over tens of thousands of years of snowfall, and now hold enough freshwater between them to raise sea levels by 65m. While Greenlands ice sheet is melting from top, as the air heats, Antarcticas ice sheets are being melted around the edges by a warming ocean. As land-based ice that touches the ocean melts, it allows ice further inland to flow towards the sea, and melt. Golledge said that scientists now had a better understanding of ice models, allowing them to better separate the knowns from the unknowns. One certain thing is that half a metre of sea level rise is now locked in, he said. Humanitys chance to hit the 1.5C target is only possible because the natural world has absorbed more than half of carbon emissions since 1850. Since then, plants, soil and oceans have taken up 59 per cent of all emissions, the report says, drastically slowing the rate of warming. But if pollution continues to rise, the oceans and forests wont be able to keep pace, only absorbing a smaller share of emissions. Niwa scientist Sara Mikaloff-Fletcher said the decreasing ability for forests to absorb our carbon pollution will be a particular challenge for New Zealand. Our forests and land use offsets roughly a third of our total greenhouse gas emissions.