I Study Climate Change. The Data Is Telling Us Something New.

Source: Berkeley Earth Land/Ocean Temperature Record Dr. Hausfather is the climate research lead at the payments company Stripe and a research scientist at Berkeley Earth, an independent organization that analyzes environmental data. Staggering. Unnerving. Mind-boggling. Absolutely gobsmackingly bananas. As global temperatures shattered records and reached dangerous new highs over and over the past few months, my climate scientist colleagues and I just about run out of adjectives to describe what we have seen. Data from released on Wednesday shows that September was an astounding 0.5 degree Celsius (almost a full degree Fahrenheit) hotter than the prior record, and July and were around 0.3 degree Celsius (0.5 degree Fahrenheit) hotter. 2023 is almost certain to be the hottest year since reliable global records began in the mid-1800s and probably for the (and ). While natural weather patterns, including a , are playing an important role, the record global temperatures we have experienced this year could not have occurred without the approximately 1.3 degrees Celsius (2.3 degrees Fahrenheit) of from human sources of carbon dioxide and other greenhouse gas emissions. And while many experts have been cautious about acknowledging it, there is increasing evidence that global warming has accelerated over the past 15 years rather than continued at a gradual, steady pace. That acceleration means that the effects of climate change we are already seeing extreme heat waves, wildfires, rainfall and sea level rise will only grow more severe in the coming years. I dont make this claim lightly. Among my colleagues in climate science, there are sharp divisions on this question, and arent convinced its happening. Climate scientists generally focus on longer-term changes over decades rather than year-to-year variability, and some of my peers in the field have expressed concerns about overinterpreting short-term events like the extremes weve seen this year. In the past I doubted acceleration was happening, in part because of a long debate about whether global warming had paused from 1998 to 2012. In hindsight, that was . Im worried that if we dont pay attention today, well miss what are increasingly clear signals. Annual average temperatures since 1850 Source: Berkeley Earth Land/Ocean Temperature Record I wouldnt be making this argument if I didnt have strong evidence to back it up; the data were getting from three sources tells a worrying story about a world warming more quickly than before. First, the rate of warming weve measured over the worlds land and oceans over the past 15 years has been 40 percent higher than the rate since the 1970s, with the past nine years being the nine warmest years on record. Second, there has been over the past few decades in the total heat content of Earths oceans, where over 90 percent of the energy trapped by greenhouse gases in the atmosphere is accumulating. Third, of Earths energy imbalance the difference between energy entering the atmosphere from the sun and the amount of heat leaving show in the amount of heat trapped over the past two decades. If Earths energy imbalance is increasing over time, it should drive an increase in the worlds rate of warming. There are a number of factors driving the acceleration of warming. While the world has in slowing down the growth of carbon dioxide and other greenhouse gas emissions, they have yet to peak and decline. And on top of this, we are reaping the results of what the climate scientist James Hansen our Faustian bargain with air pollution. For decades, air pollution from sulfur dioxide and other hazardous substances in fossil fuels has had a strong temporary cooling effect on our climate. But as countries around the world have begun to clean up the air, the cooling effect provided by these aerosols has since 2000. Aerosols have fallen even more in the past three years, after a decision to largely in marine fuels in 2020. These reductions in pollution on top of continued increases in atmospheric greenhouse gas concentrations mean that we are encountering some of the unvarnished force of climate change for the first time. Recent global temperatures compared with estimates of what they might have been if aerosol pollution had continued at its 2005 level Source: Based on FAIR model runs performed by Dr. Chris Smith at the University of Leeds Note: This model does not fully account for the 2020 change in marine fuel standards to lower sulfur emissions, as updated emissions data is not yet available. We are having trouble retrieving the article content. Please enable JavaScript in your browser settings. Thank you for your patience while we verify access. If you are in Reader mode please exit and your Times account, or for all of The Times. Thank you for your patience while we verify access. Already a subscriber? . Want all of The Times? .