How 2023 Broke Our Climate Models with Neil deGrasse Tyson & Gavin Schmidt

Aerosols in the atmosphere—including dust, sea salt, and especially industrial pollution particles—reflect solar radiation back to space, creating a net cooling effect that has been masking underlying warming from greenhouse gases

“the net effect of these aerosols is to cool the climate a little bit because they interfere with the sun's radiation they reflect a lot of it back to space”

Geoengineering through stratospheric aerosol injection is not viable as a sustainable solution because it creates permanent lock-in: once started and working, it cannot be stopped for hundreds of years, and any interruption causes abrupt temperature spikes larger than gradual warming

“if we want to cool the Earth abruptly we could reintroduce aerosols of a particular size into the atmosphere there are some real problems with that as a as a as a solution uh the main one is is that once you start and it's working you can't stop like ever and uh and and when I say ever I mean like hundreds of years um and so uh because you're constantly fighting what how tie the temperature would be and if you then if you stop then boom boom the temperature jumps”

NASA is launching a satellite in early February that will produce for the first time a global map of aerosol composition across the atmosphere, enabling precise quantification of the aerosol uncertainties that currently limit climate prediction accuracy

“we're actually launching a satellite um in uh beginning febal Pace uh which for the first time will produce uh a map of the composition of all of these different Aerosoles all these different particles in the atmosphere across the globe um and we're we're fingers crossed that goes well uh but uh but we have the possibility from then on uh to really uh kind of nail down those uncertainties uh by quite a lot”

Uncertainty in aerosol measurements and modeling represents one of the largest remaining gaps in climate prediction capability, limiting confidence in short-term temperature forecasts even when long-term greenhouse-gas-driven trends are well understood

“one of the most mysterious things that we we don't really have great data for yet uh is uh what what the what the particles in the air are doing so these are called aerosols”

Pollution control regulations have successfully reduced atmospheric aerosol concentrations over recent decades, removing the unintended cooling effect that had partially masked greenhouse-gas warming

“there's been changes in uh in in in particulate matter in the air because we've been we've been writing laws and saying no you can't pollute quite as much you have to be you have to do cleaner stuff so we've seen uh We've we've seen drops in in these uh in these aerosols”

2023 was the warmest year on record globally, and it set the biggest new temperature record that has ever been set in the instrumental record dating back to the late 19th century

“2023 uh was the warmest of all of those years by a record margin right so not just a record but it was the the biggest new record that has ever been set”

The long-term warming trend has been particularly pronounced since the 1970s, with steadily increasing decade-by-decade temperatures driven by increases in carbon dioxide, methane, and other greenhouse gases

“it comes on the back of a long-term Trend uh particularly since the 1970s of steadily increasing decade by decade temperatures [4:45] that are that's driven by what we've been doing right so the the increases in carbon dioxide increases in methane and other greenhouse gases”

If humanity stopped emitting carbon dioxide into the atmosphere immediately, global warming would stop—the temperature would stabilize rather than continue rising, demonstrating that climate change is not a runaway process but one controlled by ongoing human emissions

“if you take if you take these same models you take the same thing and you and you match everything uh if you suddenly stop making the problem worse if you suddenly stop adding carbon dioxide into the atmosphere it basically stops right this the the global warming just stops things don't get any worse”

The timeframe for continued decision-making on climate is the remainder of this century, and ongoing decisions about emissions and mitigation strategies will be required to slow and eventually stop warming

“and we're going to be making those decisions you know from now you know you know for the rest of this Century uh and we have to make better decisions if this is going to slow down and stop”

Climate models failed to predict the magnitude of 2023's record warming despite accurately understanding long-term greenhouse gas-driven trends, because of underestimation of aerosol reduction effects from pollution control measures

“we thought we had a pretty good idea about how you know the long-term trends uh are affected by things like the greenhouse gases so we we we think we've got that down uh and then we have uh you know 150 years of History where we've seen when you get an El Nino event”

Approximately half of the CO2 emitted into the atmosphere is sequestered immediately (absorbed by oceans and other sinks), while the other half remains in the atmosphere; when CO2 is removed from the atmosphere, approximately half comes back out of the ocean to re-equilibrate

“so uh for every uh ton that we put into the atmosphere half of it get sequestered straight away and half of it is still in the atmosphere and so when you take out uh a ton uh you have to take out a half from the atmosphere and a half from the ocean as well”

In 2023, the El Niño/La Niña predictive heuristic that had been reliable for 150 years failed completely to forecast the magnitude of warming, suggesting that underlying dynamics may be changing and prior patterns may no longer be reliable guides to future climate

“it's not like it's peaked either because isn't it like nine more months it will over the next N9 months or so beyond this point it'll continue to get hotter but but this this this year Well in 2023 total failure total fail”

Humanity has agency and control over the future of climate—the future is determined by our actions, not by an uncontrollable runaway process, meaning conscious decisions can slow down or stop warming if societies align around that goal

“the future is determined by our actions we're not we're not uh we're not on a runaway train here uh we're not out of control we have agency and we control what is going to happen in the future”

Climate models are useful for understanding the mechanisms driving temperature change (greenhouse gases, aerosols, solar forcing) and distinguishing between human-caused and natural factors, even when their short-term predictive accuracy is limited by aerosol uncertainties

“we use the models for you know explaining you know how much of this is our fault how much of it is is natural cycles and then we use the models for you know explaining”

NASA's Goddard Institute for Space Studies has maintained the longest-running global temperature dataset since the 1980s, integrating weather station data, ocean buoy measurements at multiple depths (down to ~700 meters), and satellite data to produce continuous temperature records back to the late 19th century

“we have the the longest running time series of of global temperatures that uh that that anybody has had um and we started doing that in the 1980s”

At solar maximum (peak of the 11-year cycle), the sun's energy output increases particularly at high-energy wavelengths, amplifying ozone production in the stratosphere and causing large temperature shifts in the stratosphere, with a surface effect of approximately 0.05–0.1 degrees Celsius (0.1–0.2 degrees Fahrenheit)

“at solar maximum there's higher energy output of the sun especially at high energy wavelengths yeah so so it affect it very um it amplifies ozone uh so you get these these very large temperature shifts in in the stratosphere uh at the surface you you can see you know it's it's a pretty small number it's it's around you know 05 to 0.1 Dees celsus”