Re: Heat Waves 2023
Posted: Thu 06 Jul 2023, 20:54:16
This article discusses that issue:Newfie wrote:I think the point is not that we are at 1.5C or 2.0C but that the in rease will continue for some rather long time.
If we stopped TODAY, went to net zero today what would the ultimate temperature rise be and when?
Anyone gave an estimated range?
Explainer: Will global warming ‘stop’ as soon as net-zero emissions are reached?Matthews and Weaver found that, in a constant concentration scenario, the world would continue to warm by around 0.3C by 2200 – with some additional warming in centuries to come as the deep oceans continued to slowly warm. Given that the world has already warmed by around 1.3C, this means that the 1.5C limit would be breached, if current CO2 concentrations are held steady due to some continued emissions. By contrast, they suggested that temperatures would stabilise in a world of net-zero emissions, remaining roughly at the level they were when emissions ceased.
The different meanings of net-zero emissions
While much of the focus of climate mitigation efforts is on CO2, human emissions of other GHGs and aerosols also have a large impact on global surface temperatures. And whereas global temperatures will stabilise once CO2 emissions fall to zero, the same is not true for zero GHG or aerosol emissions.
Human emissions of aerosols – tiny particles of sulfur or nitrogen suspended in the atmosphere that reflect incoming sunlight back to space – have a strong cooling effect on the planet, though there are large uncertainties as to exactly how large this effect is. Aerosols also have a relatively short atmospheric lifetime and, if emissions cease, the aerosols currently in the atmosphere will quickly fall back out. As a result, the world would be around 0.4C warmer if CO2 and aerosol emissions go to zero, compared to zero CO2 emissions alone. In this scenario (red line), the world would likely exceed the 1.5C target, reaching around 1.75C by 2100.