James Hansen says limit will be passed \u2018for all practical purposes\u2019 by May though other experts predict that will happen in 2030s.<\/p>\n\n\n\n
The internationally agreed threshold to prevent the Earth from spiraling into a new superheated era will be \u201cpassed for all practical purposes\u201d during 2024, the man known as the godfather of climate science has warned.<\/p>\n\n\n\n
James Hansen, the former Nasa scientist credited for alerting the world to the dangers of climate change<\/a> in the 1980s, said that global heating caused by the burning of fossil fuels, amplified by the naturally reoccurring El Ni\u00f1o climatic event, will by May push temperatures to as much as 1.7C (3F) above the average experienced before industrialization.<\/p>\n\n\n\n This temperature high, measured over the 12-month period to May, will not by itself break the commitment made by the world\u2019s governments to limit global heating to 1.5C (2.7F) above the time before the dominance of coal, oil and gas. Scientists say the 1.5C ceiling cannot be considered breached until a string of several years exceed this limit, with this moment considered most likely to happen at some point in the 2030s<\/a>.<\/p>\n\n\n\n But Hansen said that even after the waning of El Ni\u00f1o, which typically drives up<\/a> average global heat, the span of subsequent years will, taken together, still average at the 1.5C limit. The heating of the world from greenhouse gas emissions is being reinforced by knock-on impacts, Hansen said, such as the melting of the planet\u2019s ice, which is making the surface darker and therefore absorbing even more sunlight.<\/p>\n\n\n\n \u201cWe are now in the process of moving into the 1.5C world,\u201d Hansen told the Guardian. \u201cYou can bet $100 to a donut on this and be sure of getting a free donut, if you can find a sucker willing to take the bet.\u201d<\/p>\n\n\n\n In a bulletin<\/a> issued with two other climate researchers, Hansen states that \u201cthe 1.5C global warming ceiling has been passed for all practical purposes because the large planetary energy imbalance assures that global temperature is heading still higher\u201d. Hansen has promoted a view<\/a>, disputed by some other climate scientists, that the rate of global heating is accelerating due to a widening gap between the amount of energy being absorbed by the Earth from the sun and the amount returning to space.<\/p>\n\n\n\n Hansen, renowned for his role in publicly revealing the onset of the greenhouse effect to the US Congress in 1988<\/a>, added that the looming loss of the 1.5C guardrail should provide a jolt the United Nations\u2019 Intergovernmental Panel on Climate Change (IPCC), the foremost body of climate science that has charted pathways<\/a> to avoid breaching the target.<\/p>\n\n\n\n \u201cPassing through the 1.5C world is a significant milestone because it shows that the story being told by the United Nations, with the acquiescence of its scientific advisory body, the IPCC, is a load of bullshit,\u201d Hansen said.<\/p>\n\n\n\n \u201cWe are not moving into a 1.5C world, we are briefly passing through it in 2024. We will pass through the 2C (3.6F) world in the 2030s unless we take purposeful actions to affect the planet\u2019s energy balance.\u201d<\/p>\n\n\n\n Last year was the hottest ever recorded, scientific agencies in the US and the European Union are expected to confirm this week, with the global temperature for 2023 close to being 1.5C above the pre-industrial era. El Ni\u00f1o, which heats up sections of the Pacific Ocean and normally adds to the overall global temperature, is anticipated to be even stronger this year than last, before fading away.<\/p>\n\n\n\n Governments meeting at UN climate talks held in Dubai in December reaffirmed the previous commitment<\/a>, made in Paris in 2015, to strive to restrain the global temperature rise to 1.5C, although scientists have warned the world is well off track<\/a> to avoid this due to persistently high greenhouse gas emissions and ongoing plans<\/a> for a massive glut<\/a> of oil and gas drilling. Carbon emissions from fossil fuels hit another record high<\/a> last year.<\/p>\n\n\n\n While the 1.5C target is a political as much as a scientific one, researchers say there will be worsening impacts<\/a> in terms of heatwaves, droughts, flooding and other calamities should the world exceed this temperature. For developing countries and small island states at existential risk from sea level rise and extreme weather, the agreed goal is a hard-fought and totemic one, with \u201c1.5 to stay alive\u201d now a common mantra heard at international climate talks.<\/p>\n\n\n\n Hansen\u2019s assertion that this year will herald the start of an escalating 1.5C era has received a cautious response from other scientists contacted by the Guardian. Drew Shindell, a climate scientist at Duke University, said this year was an \u201cunusually warm one\u201d due to El Ni\u00f1o and that following years will best judge whether the 1.5C target has vanished.<\/p>\n\n\n\n But he added the world was closing in on this point and the 1.5C limit would probably be hit \u201cin the 2020s and not the 2030s any more given recent years have warmed so rapidly, so Jim\u2019s larger point that we\u2019re moving rapidly into the post-1.5C era is correct in my opinion.<\/p>\n\n\n\n \u201cTo my mind, whether it\u2019s 2024 or 2027 makes little difference in the end to informing our actions \u2013 we have to change course immediately or we\u2019ll lose our ability to keep below 2C the same way the 1.5C goal has now become out of reach,\u201d Shindell said.<\/p>\n\n\n\n Zeke Hausfather, a climate scientist at Stripe and Berkeley Earth, said \u201cI disagree a bit with Hansen\u201d that global temperatures will not be less than 1.4C above pre-industrial times once there is a countervailing La Ni\u00f1a, a reverse climatic condition to El Ni\u00f1o. \u201cBut longer term those sorts of temperatures will no longer be seen as the Earth continues to warm,\u201d Hausfather said, adding that he still expected the long-term average to fully pass 1.5C in the early 2030s.<\/p>\n\n\n\n Andrew Dessler, climate researcher at Texas A&M University, said that he also expected it to take \u201c10-ish years\u201d to break the 1.5C barrier, but that Hansen\u2019s views should be taken seriously. \u201cJim is probably the greatest climate scientist in history, so I am hesitant to disagree with him because perhaps he\u2019ll turn out to be right,\u201d Dessler said.<\/p>\n\n\n\n Even if the world\u2019s temperature is to break the 1.5C barrier, researchers stress that this doesn\u2019t mean that all will irretrievably be lost, with every fraction of a degree added, or not, significant in shaping the severity of climate impacts. By current government pledges to cut emissions \u2013 if not their actual actions to date \u2013 the world is still heading<\/a> for at least 2.5C (4.5F) warming by the end of this century.<\/p>\n\n\n\n \u201cI do think that in worrying about some particular threshold we are addressing the wrong question,\u201d said Kerry Emanuel, a climate and meteorological expert at the Massachusetts Institute of Technology. \u201cThere are no magic numbers in climate change, just rapidly growing risks.\u201d<\/p>\n\n\n\n Emanuel pointed to recent severe\u00a0heatwaves<\/a>,\u00a0fires<\/a>\u00a0and\u00a0storms<\/a>\u00a0that are already being supercharged by global heating of around 1.2C (2.1F) above what it was a little more than a century ago. \u201cPerhaps, once half the population of the planet has experienced at least one of these weather catastrophes, they will get their leaders to act,\u201d Emanuel said. \u201cI hope it doesn\u2019t take that much pain.\u201d<\/p>\n\n\n\n