In a recent study, former NASA top scientist James Hansen has raised concerns that global warming is not only continuing but is actually accelerating at a dangerous pace. However, some experts have criticized his claims, describing them as overstated.

Hansen, a renowned climate scientist who has become an advocate against the usage of fossil fuels, argues that since 2010, the rate of warming has increased by 50%. He attributes this acceleration to the increase in sun energy in the atmosphere and the reduction of particles that can reflect it back into space, as a result of efforts to reduce pollution. Consequently, the cooling effect provided by these particles has diminished.

During a press briefing, Hansen emphasized that a key calculation used to determine the extent of global warming predicts a much faster rate of warming than estimated by the United Nations' Intergovernmental Panel on Climate Change. He views the international target of limiting warming to 1.5 degrees Celsius since pre-industrial times as practically unattainable and believes the goal of 2 degrees Celsius is now also in jeopardy. The implications of rising global temperatures include more frequent and intense extreme weather events.

While some climate scientists respect Hansen's long-term work, several experts remain skeptical about the findings presented in his study. Robin Lamboll, a climate scientist at the Imperial College of London, questions the analytical depth and consistency of Hansen's claims, suggesting they are primarily aimed at influencing policymakers rather than providing substantial evidence.

Michael Mann, a climate scientist from the University of Pennsylvania, countered Hansen's claims, stating that while the warming trend has been steady since 1990, there is no evidence of acceleration. Mann advises against overstating the case for climate change, asserting that the current situation is alarming enough. He asserts that Hansen's claims deviate significantly from the mainstream scientific consensus, warranting a high standard of evidence that has not been met.

Interestingly, data from the National Oceanic and Atmospheric Administration (NOAA) appears to support Hansen's modeling. The NOAA data shows a warming rate of 0.27 degrees Celsius per decade since September 2010, coinciding with the period when the effect of clean air regulations on aerosol pollution and sulfur reduction began to manifest. Hansen and other scientists argue that traditional air pollutants with a cooling effect have been masking a fraction of the warming caused by the combustion of fossil fuels.

Central to the calculation of future and historical warming is climate sensitivity, which measures the degree of warming when carbon dioxide levels double. Hansen's study estimates climate sensitivity as 4.8 degrees Celsius, the highest within the range provided by previous research but still within the broadest range. He attributes the higher value to incorrect calculations made in previous studies that failed to consider the adaptation of microbiotic organisms to warming.

While opinions on climate sensitivity vary, with some experts skeptical of Hansen's calculations, others, including Stanford University's Rob Jackson, express trust in Hansen's assessment. Jackson predicts that Hansen's contention - that the IPCC has underestimated climate sensitivity - will prove accurate.

With ongoing debates surrounding global warming, recent scientific observations of record-breaking heat in the air and deep oceans, alongside a strong El Niño event, have further divided scientists over the current state of the planet. Mann dismisses these findings as statistically insignificant, while Zeke Hausfather, a climate scientist at Berkeley Earth, puts the rate of warming at 0.24 degrees Celsius per decade.

Hansen's study, published in Oxford Open Climate Change, has added fuel to the ongoing discussion regarding the pace and severity of global warming. As the scientific community evaluates and scrutinizes these claims, the urgency to address climate change remains undeniable.