James Hansen

Breathless reporting on when the present global heat anomaly will begin to fall is understandable, given heat suffering around the world. However, fundamental issues are in question and a reflection on time scales is in order, for the sake of understanding ongoing climate change and actions that need to be taken.

Global temperature (12-month mean) is still rising at 1.56°C relative to 1880-1920 in the GISS analysis through April (Fig. 1). [Robert Rohde reports that it is 1.65°C relative to 1850-1900 in the BerkeleyEarth analysis.[3]] Global temperature is likely to continue to rise a bit for at least a month, peak this summer, and then decline as the El Nino fades toward La Nina. Acceleration of global warming is now hard to deny. The GISS 12-month temperature is now 0.36°C above the 0.18°C/decade trend line, which is 3.6 times the standard deviation (0.1°C). Confidence in global warming acceleration thus exceeds 99%, but we need to see how far temperature falls with the next La Nina before evaluating the post-2010 global warming rate.

James Hansen affirme que la limite sera dépassée « à toutes fins utiles » d’ici au mois de mai, bien que d’autres experts prévoient que cela se produira dans les années 2030. Le seuil convenu au niveau international pour empêcher la Terre d’entrer dans une nouvelle ère de surchauffe sera « dépassé à toutes fins utiles » en 2024, a prévenu celui que l’on appelle le parrain de la science du climat. James Hansen, l’ancien scientifique de la Nasa à qui l’on doit d’avoir alerté le monde sur les dangers du changement climatique dans les années 80, a déclaré que le réchauffement planétaire causé par la combustion des combustibles fossiles, amplifié par le phénomène climatique El Niño qui se reproduit naturellement, fera grimper d’ici au mois de mai les températures jusqu’à 1,7 °C (3 °F) au-dessus de la moyenne enregistrée avant l’industrialisation.

James Hansen says limit will be passed ‘for all practical purposes’ by May though other experts predict that will happen in 2030s

Global warming is accelerating because the drive for warming, Earth’s energy imbalance, has doubled in the past decade. Measurement of the acceleration is hampered by unforced tropical (El Nino/La Nina) variability, but a good measuring stick is provided by warming between successive large El Ninos. Strengthening of the current (2023-24) El Nino has raised it to a level similar to the 1997-98 and 2015-16 El Ninos. The first six months of the current El Nino are 0.39°C warmer than the same six months of the 2015-16 El Nino, a global warming rate of 0.49°C/decade, consistent with expectation of a large acceleration of global warming. We expect the 12-month mean temperature by May 2024 to eliminate any doubt about global warming acceleration. Subsequent decline of the 12-month temperature below 1.5°C will likely be limited, confirming that the 1.5°C limit has already been passed.

James Hansen est un des plus grand climatologues du monde. Il a alerté le gouvernement des Etats-Unis sur le réchauffement climatique. Dans cette vidéo, les plus grands spécialistes actuels témoignent de l’excellence de ses prévisions climatiques. Il a aussi une énorme expérience du domaine. Je trouve son travail scientifique sur la montée du niveau de la mer publié en 2016 (lien, lien) très convaincant, plusieurs de ses conclusions et postulats ont été confirmés ces dernières années. Il se bat pour le climat depuis des décennies, et a été arrêté pour lors de manifestations pour le climat devant la Maison Blanche. Il a des grandes connaissances de climatologie. J’hésite donc réellement à le contredire mais j’ai quelques objections. Son travail apporte évidemment de nombreux éléments utiles, et il a le mérite d’être disponible aujourd’hui. Vu la situation climatique, nous ne pouvons pas attendre le prochain rapport du GIEC.

September 2023 smashed the prior global temperature record. Hand-wringing about the magnitude of the temperature jump in September is not inappropriate, but it is more important to investigate the role of aerosol climate forcing – which we chose to leave unmeasured – in global climate change. Global temperature during the current El Nino provides a potential indirect assessment of change of the aerosol forcing. Global temperature in the current El Nino, to date, implies a strong acceleration of global warming for which the most likely explanation is a decrease of human-made aerosols as a result of reductions in China and from ship emissions. The current El Nino will probably be weaker than the 1997-98 and 2015-16 El Ninos, making current warming even more significant. The current near-maximum solar irradiance adds a small amount to the major “forcing” mechanisms (GHGs, aerosols, and El Nino), but with no long-term effect. More important, the long dormant Southern Hemisphere polar amplification is probably com

Selon James Hansen – le scientifique des Etats-Unis qui a alerté le monde sur l’effet de serre dans les années 1980 – le monde est en train de basculer vers un climat surchauffé jamais vu l’existence de l’homme, parce que «nous sommes de sacrés imbéciles» pour ne pas avoir réagi aux avertissements concernant la crise climatique.

James Hansen, who testified to Congress on global heating in 1988, says world is approaching a ‘new climate frontier’

Improved knowledge of glacial-to-interglacial global temperature change implies that fastfeedback equilibrium climate sensitivity (ECS) is 1.2 ± 0.3°C (2σ) per W/m2 . Consistent analysis of temperature over the full Cenozoic era – including “slow” feedbacks by ice sheets and trace gases – supports this ECS and implies that CO2 was about 300 ppm in the Pliocene and 400 ppm at transition to a nearly ice-free planet, thus exposing unrealistic lethargy of ice sheet models. Equilibrium global warming including slow feedbacks for today’s human-made greenhouse gas (GHG) climate forcing (4.1 W/m2) is 10°C, reduced to 8°C by today’s aerosols. Decline of aerosol emissions since 2010 should increase the 1970-2010 global warming rate of 0.18°C per decade to a post-2010 rate of at least 0.27°C per decade. Under the current geopolitical approach to GHG emissions, global warming will likely pierce the 1.5°C ceiling in the 2020s and 2°C before 2050. Impacts on people and nature will accelerate as global warming pumps up hydr

While this is not holiday cheer, I thought everyone should know about the following recent climate change research. James Hansen and 14 co-authors recently released a preprint (not yet peer reviewed) paper titled “Global Warming in the...

Cette étude est d’une importance majeure. Elle réévalue l’ampleur du réchauffement climatique à venir, réchauffement qui pourra aller, selon les auteurs, jusqu’à 10 ° C. Une valeur bien supérieure à celles estimées dans les pires scénarios du GIEC, et sur la seule base des quantités actuelles de GES émis jusqu’à ce jour… Makiko Sato, Leon Simons, Larissa S. Nazarenko, Karina von Schuckmann, Norman G. Loeb, Matthew B. Osman, Pushker Kharecha, Qinjian Jin, George Tselioudis, Andrew Lacis, Reto Ruedy, Gary Russell, Junji Cao, Jing Li ___ : ___ source : https://transitionecologique.org/2022/12/20/rechauffement-climatique-en-vue/

Improved knowledge of glacial-to-interglacial global temperature change implies that fast- feedback equilibrium climate sensitivity is at least ~4°C for doubled CO2 (2×CO2), with likely range 3.5-5.5°C. Greenhouse gas (GHG) climate forcing is 4.1 W/m2 larger in 2021 than in 1750, equivalent to 2×CO2 forcing. Global warming in the pipeline is greater than prior estimates. Eventual global warming due to today’s GHG forcing alone – after slow feedbacks operate – is about 10°C. Human-made aerosols are a major climate forcing, mainly via their effect on clouds. We infer from paleoclimate data that aerosol cooling offset GHG warming for several millennia as civilization developed. A hinge-point in global warming occurred in 1970 as increased GHG warming outpaced aerosol cooling, leading to global warming of 0.18°C per decade. Aerosol cooling is larger than estimated in the current IPCC report, but it has declined since 2010 because of aerosol reductions in China and shipping. Without unprecedented global actions to

The eyes of history will pierce the fog of politics. Science has exposed the course upon which our quest for energy has set our planet. Consequences will fall mainly on young people, their children, and grandchildren — unless decisive political leadership abandons wishful thinking and superficial half-measures. Climate change is a global matter and demands a global perspective.

It’s hot and getting hotter. The first six months of the year are about 0.2°C cooler than the first six months of 2016 and 2020 (Fig. 1), but that’s only because the current La Nina continues to cool the tropics. Global temperature is rising despite the La Nina. Earth is out of energy balance (more solar energy absorbed than heat radiated to space) by an astounding amount – more than any time with reliable data – so, within a few years, we will be setting new global temperature records.

What else is new? Hotspots are getting hotter. The major hotspot in April stretched from Iraq to India and Pakistan, and toward the northeast through Russia (Fig. 1). Temperature exceeded 45°C (113°F) in late April in at least nine Indian cities,[1] on its way to 50°C (122°F) in Pakistan in May,[2] where a laborer says “It’s like fire burning all around” and a meteorologist describing growing heatwaves since 2015 says “The intensity is increasing, and the duration is increasing, and the frequency is increasing.” Halfway around the world, Canada and north-central United States were cooler than their long-term average, but people in British Columbia and northwest United States remember being under their own record-breaking hotspot last summer.

Le 23 juin 1988, en pleine sécheresse outre-Atlantique, James E. Hansen s’adresse au Congrès des États-Unis. Son discours déclenche une vague d’intérêt pour le réchauffement climatique dans le monde. Le 23 juin 2008, devant la commission parlementaire sur l’indépendance énergétique et le réchauffement global de ce même Congrès, cet homme libre a lancé un nouveau cri d’alarme à ses compatriotes, qui choisiront, lors d’une élection décisive pour le sort de la planète, leur nouveau président dans quelques semaines.

The past season – meteorological NH winter, SH summer – was the 5th warmest Dec-Jan-Feb in the instrumental record, despite the continuing La Niña (the cold tongue in the equatorial Pacific). Most of Eurasia was remarkably warm, 2-5°C above normal. The winter seemed cold to many people in North America, but a very warm December (Fig. 1) made the season well above normal in the U.S.

There’s a new horse race in 2022. It’s one that we would rather lose than win. If our analysis is right, the world will probably blow through the 1.5°C global warming ceiling this decade; if we’re wrong, it could be delayed a decade. We argue[1],[2] that the apparent acceleration of global warming in the past decade is driven by an acceleration in the growth rate of human-made climate forcings, especially reduced human-made aerosol cooling – an effect that is not going away and may grow.

La planète Terre, la création, ce monde dans lequel la civilisation s’est développée, qui est doté de schémas climatiques que nous connaissons et de rivages stables, ce monde est en péril imminent. Ce n’est qu’au cours des dernières années que l’urgence de la situation s’est cristallisée. Nous disposons désormais de preuves évidentes de la crise, grâce aux informations toujours plus détaillées sur la manière dont la Terre a réagi, au fil de son histoire, aux forces perturbatrices : de manière très sensible, avec un certain décalage dû à l’inertie de la masse océanique.